CSV → Instant Chart

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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>CSV → Instant Chart</title>
<style>
/* sloprun design tokens — inline this block into every demo (self-contained rule).
   Identity: instrument-panel. Machine facts in mono; human words in sans.
   Green is EARNED: only for "it ran / it worked" states, never decoration. */
:root {
  --bg: #F6F6F3;          /* neutral paper, not cream */
  --surface: #FFFFFF;
  --ink: #1A1D21;
  --muted: #5A6068;
  --line: #E3E2DC;
  --accent: #C05600;      /* phosphor amber, darkened for light bg */
  --accent-soft: #FFF3E6;
  --run: #1A7F37;         /* earned green */
  --run-soft: #E7F4EA;
  --danger: #C93C37;
  --radius: 10px;
  --font-sans: system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Cascadia Code", Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #14161A; --surface: #1C1F26; --ink: #E8E6E1; --muted: #9AA0A8;
    --line: #2A2E36; --accent: #FFB454; --accent-soft: #2A2118;
    --run: #3FB950; --run-soft: #16281B; --danger: #F47067;
  }
}
:root[data-theme="dark"] {
  --bg: #14161A; --surface: #1C1F26; --ink: #E8E6E1; --muted: #9AA0A8;
  --line: #2A2E36; --accent: #FFB454; --accent-soft: #2A2118;
  --run: #3FB950; --run-soft: #16281B; --danger: #F47067;
}
body { background: var(--bg); color: var(--ink); font-family: var(--font-sans); }

/* native controls follow the theme too (selects, scrollbars) */
:root { color-scheme: light; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) { color-scheme: dark; } }
:root[data-theme="dark"] { color-scheme: dark; }

/* ---- categorical series palette (validated: adjacent CVD dE 9.1 light / 8.4 dark,
   normal-vision 19.6 / 19.3, against surfaces #FFFFFF and #1C1F26).
   Three light slots sit under 3:1 on white — relief is shipped: legend, direct
   labels and a table view, so hue never carries meaning alone. ---- */
:root {
  --s1:#2a78d6; --s2:#eb6834; --s3:#1baf7a; --s4:#eda100; --s5:#e87ba4; --s6:#008300;
  --s-other:#7C838C;
  --plot-ink: var(--ink); --plot-muted: var(--muted); --plot-grid: var(--line);
  --field: #FBFBF9;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --s1:#3987e5; --s2:#d95926; --s3:#199e70; --s4:#c98500; --s5:#d55181; --s6:#008300;
    --s-other:#8B929B; --field:#171A20;
  }
}
:root[data-theme="dark"] {
  --s1:#3987e5; --s2:#d95926; --s3:#199e70; --s4:#c98500; --s5:#d55181; --s6:#008300;
  --s-other:#8B929B; --field:#171A20;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; padding: 18px 16px 28px; line-height: 1.5;
  font-size: 15px; overflow-x: hidden;
}
.wrap { max-width: 1120px; margin: 0 auto; }

/* ---- header ---- */
header { margin-bottom: 16px; }
.kicker {
  font-family: var(--font-mono); font-size: 11px; letter-spacing: .08em;
  text-transform: uppercase; color: var(--muted); margin: 0 0 6px;
}
h1 { font-size: clamp(21px, 4.6vw, 27px); line-height: 1.2; margin: 0 0 6px; letter-spacing: -.01em; }
.lede { margin: 0; color: var(--muted); max-width: 62ch; font-size: clamp(13.5px, 3.4vw, 15px); }

/* ---- layout ---- */
.grid { display: grid; gap: 14px; grid-template-columns: minmax(0,1fr); align-items: start; }
@media (min-width: 900px) { .grid { grid-template-columns: 330px minmax(0,1fr); } }
.panel {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 14px; min-width: 0;
}
.panel + .panel { margin-top: 0; }
.panel-head {
  display: flex; align-items: baseline; justify-content: space-between;
  gap: 10px; margin-bottom: 10px; flex-wrap: wrap;
}
h2 {
  font-size: 12px; font-family: var(--font-mono); font-weight: 600; margin: 0;
  letter-spacing: .06em; text-transform: uppercase; color: var(--muted);
}

/* ---- controls ---- */
button, select, textarea, input { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.btn {
  background: var(--surface); border: 1px solid var(--line); color: var(--ink);
  border-radius: 8px; padding: 5px 10px; cursor: pointer;
  font-size: 12.5px; font-family: var(--font-mono); line-height: 1.4;
}
.btn:hover { border-color: var(--accent); background: var(--accent-soft); }
.btn[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--accent); }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }

.field { display: grid; gap: 4px; min-width: 0; }
.field > span {
  font-family: var(--font-mono); font-size: 10.5px; letter-spacing: .07em;
  text-transform: uppercase; color: var(--muted);
}
select {
  background: var(--field); border: 1px solid var(--line); border-radius: 8px;
  padding: 6px 8px; font-size: 13px; width: 100%; max-width: 100%;
  font-family: var(--font-mono); cursor: pointer;
}
select:hover { border-color: var(--accent); }
select:disabled { opacity: .55; cursor: not-allowed; }

/* segmented radio group */
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 8px; overflow: hidden; background: var(--field); }
.seg input { position: absolute; opacity: 0; pointer-events: none; }
.seg label {
  padding: 6px 11px; font-family: var(--font-mono); font-size: 12.5px;
  cursor: pointer; color: var(--muted); border-right: 1px solid var(--line);
  user-select: none; white-space: nowrap;
}
.seg label:last-of-type { border-right: 0; }
.seg label:hover { color: var(--ink); background: var(--accent-soft); }
.seg input:checked + label { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.seg input:focus-visible + label { outline: 2px solid var(--accent); outline-offset: -2px; }

/* ---- data panel ---- */
.drop { position: relative; border-radius: 8px; }
.drop.over::after {
  content: "drop CSV to load"; position: absolute; inset: 0;
  display: grid; place-items: center; border-radius: 8px;
  border: 2px solid var(--accent); background: var(--accent-soft);
  font-family: var(--font-mono); font-size: 13px; color: var(--accent);
}
textarea {
  width: 100%; background: var(--field); border: 1px solid var(--line);
  border-radius: 8px; padding: 9px 10px; font-family: var(--font-mono);
  font-size: 11.5px; line-height: 1.55; resize: vertical; min-height: 132px;
  height: 156px; white-space: pre; overflow: auto; tab-size: 4;
}
@media (min-width: 900px) { textarea { height: 210px; } }
textarea:hover { border-color: var(--accent); }

.status {
  display: flex; flex-wrap: wrap; align-items: center; gap: 6px 8px;
  margin-top: 10px; font-family: var(--font-mono); font-size: 11.5px;
}
.ok {
  color: var(--run); background: var(--run-soft); border: 1px solid transparent;
  border-radius: 999px; padding: 1px 8px; font-weight: 600;
}
.warnpill {
  color: var(--accent); background: var(--accent-soft);
  border-radius: 999px; padding: 1px 8px;
}
.status .facts { color: var(--muted); }
.status .facts b { color: var(--ink); font-weight: 600; font-variant-numeric: tabular-nums; }
.status .facts > span { white-space: nowrap; }

.issues { margin: 10px 0 0; padding: 0; list-style: none; display: grid; gap: 4px; }
.issues li {
  font-family: var(--font-mono); font-size: 11px; color: var(--muted);
  display: flex; gap: 7px; align-items: baseline;
}
.issues li .row { color: var(--accent); flex: none; }
.issues li.bad .row { color: var(--danger); }

.cols { margin-top: 12px; display: grid; gap: 5px; }
.colbtn {
  display: flex; align-items: center; gap: 8px; width: 100%; text-align: left;
  background: none; border: 1px solid transparent; border-radius: 7px;
  padding: 4px 6px; cursor: pointer; min-width: 0;
}
.colbtn:hover { border-color: var(--line); background: var(--field); }
.colbtn .nm {
  font-family: var(--font-mono); font-size: 12px; overflow: hidden;
  text-overflow: ellipsis; white-space: nowrap; flex: 1 1 auto; min-width: 0;
}
.colbtn .ty {
  font-family: var(--font-mono); font-size: 10px; letter-spacing: .06em;
  text-transform: uppercase; border: 1px solid var(--line); border-radius: 5px;
  padding: 0 5px; color: var(--muted); flex: none;
}
.colbtn .ty.number { color: var(--accent); border-color: var(--accent); }
.colbtn .rng {
  font-family: var(--font-mono); font-size: 10.5px; color: var(--muted);
  flex: none; font-variant-numeric: tabular-nums;
}
.colbtn[data-active="x"], .colbtn[data-active="y"], .colbtn[data-active="g"] {
  background: var(--accent-soft); border-color: var(--accent);
}
.colbtn .role {
  font-family: var(--font-mono); font-size: 10px; letter-spacing: .07em;
  color: var(--accent); flex: none; font-weight: 600;
}

/* ---- chart panel ---- */
.controls {
  display: flex; flex-wrap: wrap; gap: 10px; align-items: end;
  padding-bottom: 12px; border-bottom: 1px solid var(--line); margin-bottom: 12px;
}
.controls .field { flex: 1 1 130px; max-width: 210px; }
.autoflag {
  font-family: var(--font-mono); font-size: 10.5px; color: var(--muted);
  display: inline-flex; align-items: center; gap: 6px;
}
.linkbtn {
  background: none; border: 0; padding: 2px 4px; color: var(--accent);
  font-family: var(--font-mono); font-size: 11px; cursor: pointer; text-decoration: underline;
}
.chart-head { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 10px; margin-bottom: 8px; }
.chart-title { font-weight: 600; font-size: 15px; }
.chart-note { font-family: var(--font-mono); font-size: 11px; color: var(--muted); }
.plotwrap { position: relative; width: 100%; }
canvas { display: block; width: 100%; height: 300px; border-radius: 6px; touch-action: pan-y; }
@media (min-width: 640px) { canvas { height: 340px; } }
canvas:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.tip {
  position: absolute; z-index: 3; pointer-events: none; opacity: 0;
  transform: translate(-50%, -100%); transition: opacity .12s ease;
  background: var(--surface); border: 1px solid var(--line); border-radius: 8px;
  padding: 7px 9px; min-width: 118px; box-shadow: 0 6px 20px rgba(0,0,0,.14);
}
.tip.on { opacity: 1; }
.tip .tx { font-family: var(--font-mono); font-size: 10.5px; color: var(--muted); margin-bottom: 4px; letter-spacing: .04em; }
.tip .row { display: flex; align-items: center; gap: 7px; margin-top: 2px; }
.tip .key { width: 12px; height: 2px; border-radius: 2px; flex: none; }
.tip .nm { font-size: 11.5px; color: var(--muted); flex: 1 1 auto; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.tip .v { font-family: var(--font-mono); font-size: 12.5px; font-weight: 600; font-variant-numeric: tabular-nums; }

.legend { display: flex; flex-wrap: wrap; gap: 4px 6px; margin-top: 10px; }
.legend button {
  display: inline-flex; align-items: center; gap: 6px; background: none;
  border: 1px solid transparent; border-radius: 999px; padding: 3px 9px 3px 5px;
  cursor: pointer; font-size: 12px; color: var(--ink);
}
.legend button:hover { border-color: var(--line); background: var(--field); }
.legend button[aria-pressed="false"] { color: var(--muted); text-decoration: line-through; }
.legend button[aria-pressed="false"] svg { opacity: .4; }
.legend svg { flex: none; display: block; }

.chartfoot { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; justify-content: space-between; margin-top: 12px; }
.hint { font-family: var(--font-mono); font-size: 10.5px; color: var(--muted); }
.tablebox { margin-top: 10px; max-height: 260px; overflow: auto; border: 1px solid var(--line); border-radius: 8px; }
table { border-collapse: collapse; width: 100%; font-size: 12px; }
th, td {
  text-align: right; padding: 5px 9px; border-bottom: 1px solid var(--line);
  font-family: var(--font-mono); font-variant-numeric: tabular-nums; white-space: nowrap;
}
th { position: sticky; top: 0; background: var(--surface); color: var(--muted); font-weight: 600; font-size: 10.5px; letter-spacing: .05em; text-transform: uppercase; }
th:first-child, td:first-child { text-align: left; }
tbody tr:last-child td { border-bottom: 0; }
.err {
  border: 1px solid var(--danger); border-radius: 8px; padding: 12px 13px;
  background: var(--surface); display: grid; gap: 5px;
}
.err strong { color: var(--danger); font-size: 13.5px; }
.err span { color: var(--muted); font-size: 13px; }
.err code { font-family: var(--font-mono); font-size: 12px; color: var(--ink); }
[hidden] { display: none !important; }
.sr {
  position: absolute; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap;
}
footer {
  margin-top: 22px; padding-top: 12px; border-top: 1px solid var(--line);
  font-family: var(--font-mono); font-size: 11px; color: var(--muted);
}
@media (prefers-reduced-motion: reduce) {
  * { animation-duration: .001ms !important; transition-duration: .001ms !important; }
}
</style>
</head>
<body>
<div class="wrap">
  <header>
    <p class="kicker">sloprun · dataviz</p>
    <h1>CSV → Instant Chart</h1>
    <p class="lede">Paste or drop any CSV. It sniffs each column's type, picks the chart that fits the data, and draws it — entirely in this tab, with nothing uploaded anywhere.</p>
  </header>

  <main class="grid">
    <!-- ---------- data panel ---------- -->
    <section class="panel" aria-labelledby="h-data">
      <div class="panel-head">
        <h2 id="h-data">CSV in</h2>
        <div class="chips" id="samples" role="group" aria-label="Load a sample dataset">
          <button class="btn" type="button" data-sample="weather">weather</button>
          <button class="btn" type="button" data-sample="cars">cars</button>
          <button class="btn" type="button" data-sample="bugs">bugs</button>
          <button class="btn" type="button" data-sample="messy">messy</button>
        </div>
      </div>

      <div class="drop" id="drop">
        <label class="sr" for="csv">CSV text</label>
        <textarea id="csv" spellcheck="false" autocomplete="off" aria-describedby="status"></textarea>
      </div>

      <div class="chips" style="margin-top:8px">
        <button class="btn" type="button" id="pickFile">choose file…</button>
        <input type="file" id="file" accept=".csv,.tsv,.txt,text/csv,text/plain" class="sr" tabindex="-1" aria-label="Choose a CSV file">
        <span class="hint" style="align-self:center">…or drag one onto the box</span>
      </div>

      <div class="status" id="status" role="status">
        <span class="ok" id="okPill" hidden>✓ parsed</span>
        <span class="warnpill" id="warnPill" hidden></span>
        <span class="facts" id="facts"></span>
      </div>

      <ul class="issues" id="issues"></ul>

      <div class="cols" id="cols" role="group" aria-label="Detected columns — click one to plot it"></div>
    </section>

    <!-- ---------- chart panel ---------- -->
    <section class="panel" aria-labelledby="h-chart">
      <div class="panel-head">
        <h2 id="h-chart">Chart</h2>
        <span class="autoflag" id="autoflag"></span>
      </div>

      <div class="controls" id="controls">
        <div class="field" style="flex:0 0 auto;max-width:none">
          <span id="lbl-type">Type</span>
          <div class="seg" role="radiogroup" aria-labelledby="lbl-type">
            <input type="radio" name="ctype" id="t-line" value="line"><label for="t-line">line</label>
            <input type="radio" name="ctype" id="t-bar" value="bar"><label for="t-bar">bar</label>
            <input type="radio" name="ctype" id="t-scatter" value="scatter"><label for="t-scatter">scatter</label>
          </div>
        </div>
        <label class="field"><span>X axis</span><select id="selX"></select></label>
        <label class="field"><span>Y axis</span><select id="selY"></select></label>
        <label class="field"><span>Colour by</span><select id="selG"></select></label>
      </div>

      <div id="chartArea">
        <div class="chart-head">
          <span class="chart-title" id="chartTitle"></span>
          <span class="chart-note" id="chartNote"></span>
        </div>
        <div class="plotwrap" id="plotwrap">
          <canvas id="cv" tabindex="0" role="img" aria-describedby="hint"></canvas>
          <div class="tip" id="tip" aria-hidden="true"></div>
        </div>
        <div class="legend" id="legend" role="group" aria-label="Series — toggle visibility"></div>
        <div class="chartfoot">
          <span class="hint" id="hint">hover or focus the chart, then ← → to step through points</span>
          <button class="btn" type="button" id="tableBtn" aria-expanded="false" aria-controls="tablebox">show data table</button>
        </div>
        <div class="tablebox" id="tablebox" hidden></div>
        <p class="sr" id="live" role="status" aria-live="polite"></p>
      </div>

      <div class="err" id="chartErr" hidden>
        <strong id="errTitle"></strong>
        <span id="errBody"></span>
      </div>
    </section>
  </main>

  <footer>demo · sloprun.dev</footer>
</div>
<script>
(function () {
"use strict";

/* ============================ sample data ============================ */
var SAMPLES = {
weather: 'month,city,avg_temp_c,rainfall_mm,sunshine_hours\n' +
'2024-01,Reykjavik,0.5,76,20\n2024-02,Reykjavik,1.0,72,55\n2024-03,Reykjavik,1.5,82,110\n' +
'2024-04,Reykjavik,3.9,58,141\n2024-05,Reykjavik,6.9,44,177\n2024-06,Reykjavik,9.6,50,168\n' +
'2024-07,Reykjavik,11.2,52,175\n2024-08,Reykjavik,10.9,62,153\n2024-09,Reykjavik,8.2,67,120\n' +
'2024-10,Reykjavik,4.8,86,90\n2024-11,Reykjavik,2.3,73,41\n2024-12,Reykjavik,0.9,79,17\n' +
'2024-01,Cairo,14.0,5,213\n2024-02,Cairo,15.5,4,234\n2024-03,Cairo,18.2,4,269\n' +
'2024-04,Cairo,22.5,1,285\n2024-05,Cairo,26.3,0,324\n2024-06,Cairo,28.6,0,357\n' +
'2024-07,Cairo,29.2,0,363\n2024-08,Cairo,29.0,0,351\n2024-09,Cairo,27.4,0,311\n' +
'2024-10,Cairo,24.5,1,292\n2024-11,Cairo,19.8,3,248\n2024-12,Cairo,15.6,6,203\n' +
'2024-01,Singapore,26.6,242,174\n2024-02,Singapore,27.2,161,183\n2024-03,Singapore,27.6,186,190\n' +
'2024-04,Singapore,28.0,179,175\n2024-05,Singapore,28.4,171,180\n2024-06,Singapore,28.4,161,177\n' +
'2024-07,Singapore,28.0,159,183\n2024-08,Singapore,27.9,177,180\n2024-09,Singapore,27.7,169,156\n' +
'2024-10,Singapore,27.5,194,156\n2024-11,Singapore,27.0,257,132\n2024-12,Singapore,26.6,315,134\n',

cars: 'model,origin,weight_kg,mpg,horsepower\n' +
'Chevy Impala,USA,1980,14,165\nFord Torino,USA,1650,17,140\nBuick Skylark,USA,1560,20,150\n' +
'Dodge Challenger,USA,1730,15,190\nPontiac Catalina,USA,1990,14,175\nChevy Nova,USA,1450,22,100\n' +
'Ford Maverick,USA,1400,21,88\nAMC Gremlin,USA,1310,21,90\nPlymouth Fury,USA,1900,14,180\n' +
'Ford Pinto,USA,1150,25,75\nChevy Vega,USA,1080,28,72\nMercury Monarch,USA,1620,18,120\n' +
'VW Rabbit,Europe,880,41,48\nAudi 100LS,Europe,1120,24,90\nVolvo 145E,Europe,1330,18,112\n' +
'Peugeot 504,Europe,1300,23,87\nBMW 2002,Europe,1060,26,113\nSaab 99E,Europe,1150,25,95\n' +
'Fiat 128,Europe,900,29,75\nVW Dasher,Europe,940,36,67\n' +
'Toyota Corolla,Japan,970,32,75\nHonda Civic,Japan,830,38,53\nDatsun 510,Japan,1010,27,97\n' +
'Mazda GLC,Japan,860,34,65\nSubaru DL,Japan,940,30,67\nToyota Corona,Japan,1130,24,95\n',

bugs: 'team,severity,open_issues,median_age_days\n' +
'Platform,critical,3,4\nPlatform,major,11,12\nPlatform,minor,24,38\n' +
'Payments,critical,5,2\nPayments,major,14,7\nPayments,minor,9,21\n' +
'Mobile,critical,1,9\nMobile,major,8,17\nMobile,minor,31,52\n' +
'Growth,critical,2,6\nGrowth,major,6,14\nGrowth,minor,18,44\n' +
'Data,critical,4,3\nData,major,17,9\nData,minor,12,27\n',

messy: 'date,city,temp_c\n' +
'2024-01-01,Oslo,-3.2\n' +
'2024-01-02,Oslo,not measured\n' +
'2024-01-03,Oslo,-1.8,sensor B\n' +
'2024-01-04;Oslo;0.4\n' +
'\n' +
'2024-01-05,"Oslo, Norway",2.1\n' +
'2024-01-06,Oslo,\n' +
'2024-01-07,Oslo,3.9\n' +
'2024-01-08,"Oslo, Norway",1.2\n' +
'2024-01-09,Oslo,-0.6\n' +
'2024-01-10,Oslo,-2.4\n' +
'2024-01-11,"Oslo, Norway",0.8\n' +
'2024-01-12,Oslo,2.7\n' +
'2024-01-13,Oslo,4.1\n' +
'2024-01-14,Oslo,3.3\n'
};

/* ============================ tiny helpers ============================ */
function $(id) { return document.getElementById(id); }
function el(tag, cls, text) {
  var n = document.createElement(tag);
  if (cls) n.className = cls;
  if (text != null) n.textContent = text;
  return n;
}
function clear(n) { while (n.firstChild) n.removeChild(n.firstChild); }
var MON = ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'];
var MONIDX = {};
(function () {
  var full = ['january','february','march','april','may','june','july','august','september','october','november','december'];
  for (var i = 0; i < 12; i++) { MONIDX[full[i]] = i; MONIDX[full[i].slice(0, 3)] = i; }
  MONIDX.sept = 8;
})();

/* ---- number parsing: tolerant of $ € £ ¥, %, thousands commas, (negatives),
   and of decimal commas when the file is not comma-separated ---- */
var DEC_COMMA = false;
function parseNum(raw) {
  if (raw == null) return NaN;
  var s = String(raw).trim();
  if (!s) return NaN;
  var mul = 1;
  if (s.charAt(0) === '(' && s.charAt(s.length - 1) === ')') { s = s.slice(1, -1).trim(); mul = -1; }
  s = s.replace(/^[$€£¥]\s*/, '').replace(/\s*[$€£¥]$/, '');
  if (s.charAt(s.length - 1) === '%') s = s.slice(0, -1).trim();
  if (/^[-+]?\d{1,3}(,\d{3})+(\.\d+)?$/.test(s)) s = s.replace(/,/g, '');
  else if (DEC_COMMA && /^[-+]?\d+,\d+$/.test(s)) s = s.replace(',', '.');
  s = s.replace(/\s/g, '');
  if (!/^[-+]?(\d+\.?\d*|\.\d+)([eE][-+]?\d+)?$/.test(s)) return NaN;
  var v = parseFloat(s);
  return isFinite(v) ? v * mul : NaN;
}
function isPct(raw) { var s = String(raw == null ? '' : raw).trim(); return s.charAt(s.length - 1) === '%'; }

/* ---- date parsing: ISO, ISO month, slashed, month-name forms ---- */
/* Date.UTC silently rolls 2024-13-01 forward into 2025 and 2024-02-30 into
   March. A column that says month 13 is not a date column — refuse the value
   so it lands in the "not a date" count instead of inventing a point. */
function utcDay(y, mo, dy, prec) {
  if (!(mo >= 1 && mo <= 12) || !(dy >= 1 && dy <= 31)) return null;
  var t = Date.UTC(y, mo - 1, dy), d = new Date(t);
  if (d.getUTCFullYear() !== y || d.getUTCMonth() !== mo - 1 || d.getUTCDate() !== dy) return null;
  return { t: t, prec: prec };
}
function parseDate(raw, dayFirst) {
  var s = String(raw == null ? '' : raw).trim();
  if (!s) return null;
  var m;
  if ((m = /^(\d{4})[-\/](\d{1,2})[-\/](\d{1,2})(?:[T ].*)?$/.exec(s)))
    return utcDay(+m[1], +m[2], +m[3], 'd');
  if ((m = /^(\d{4})[-\/](\d{1,2})$/.exec(s)))
    return utcDay(+m[1], +m[2], 1, 'm');
  if ((m = /^(\d{1,2})[-\/](\d{1,2})[-\/](\d{4})$/.exec(s))) {
    var a = +m[1], b = +m[2];
    return utcDay(+m[3], dayFirst ? b : a, dayFirst ? a : b, 'd');
  }
  if ((m = /^([A-Za-z]{3,9})\.?\s+(\d{4})$/.exec(s))) {
    var i1 = MONIDX[m[1].toLowerCase()];
    if (i1 == null) return null;
    return utcDay(+m[2], i1 + 1, 1, 'm');
  }
  if ((m = /^([A-Za-z]{3,9})\.?\s+(\d{1,2}),?\s+(\d{4})$/.exec(s))) {
    var i2 = MONIDX[m[1].toLowerCase()];
    if (i2 == null) return null;
    return utcDay(+m[3], i2 + 1, +m[2], 'd');
  }
  if ((m = /^(\d{1,2})\s+([A-Za-z]{3,9})\.?\s+(\d{4})$/.exec(s))) {
    var i3 = MONIDX[m[2].toLowerCase()];
    if (i3 == null) return null;
    return utcDay(+m[3], i3 + 1, +m[1], 'd');
  }
  return null;
}
function fmtDate(t, sameYear, prec) {
  var d = new Date(t);
  if (prec === 'y') return String(d.getUTCFullYear());
  if (prec === 'm') return MON[d.getUTCMonth()] + (sameYear ? '' : " '" + String(d.getUTCFullYear()).slice(2));
  return MON[d.getUTCMonth()] + ' ' + d.getUTCDate() + (sameYear ? '' : ' ' + d.getUTCFullYear());
}
function fmtDateFull(t, prec) {
  var d = new Date(t);
  if (prec === 'm') return MON[d.getUTCMonth()] + ' ' + d.getUTCFullYear();
  return d.getUTCFullYear() + '-' + String(d.getUTCMonth() + 1).padStart(2, '0') + '-' + String(d.getUTCDate()).padStart(2, '0');
}
function fmtVal(v) {
  if (!isFinite(v)) return '—';
  var a = Math.abs(v);
  if (a >= 1e9) return (v / 1e9).toFixed(2).replace(/\.?0+$/, '') + 'B';
  if (a >= 1e6) return (v / 1e6).toFixed(2).replace(/\.?0+$/, '') + 'M';
  if (Number.isInteger(v)) return v.toLocaleString('en-US');
  if (a >= 100) return v.toFixed(1);
  if (a >= 1) return String(+v.toFixed(2));
  return String(+v.toPrecision(3));
}
function fmtY(v, dec) {
  if (!isFinite(v)) return '—';
  if (Math.abs(v) >= 1e6) return fmtVal(v);
  return v.toLocaleString('en-US', { minimumFractionDigits: dec || 0, maximumFractionDigits: dec || 0 });
}
function decimalsOf(col) {
  var dec = 0, nonInt = false, i, sv, dot;
  for (i = 0; i < col.values.length && i < 800; i++) {
    sv = String(col.values[i]);
    dot = sv.indexOf('.');
    if (dot >= 0) dec = Math.max(dec, Math.min(3, sv.length - dot - 1));
    if (col.nums && isFinite(col.nums[i]) && !Number.isInteger(col.nums[i])) nonInt = true;
  }
  if (!dec && nonInt) dec = 2;
  return dec;
}
function decOf(step) {
  if (!isFinite(step) || step <= 0) return 0;
  var s = String(step);
  /* the cap has to clear the smallest step nice ticks can hand back, or a
     near-constant axis prints the same label on every gridline */
  if (s.indexOf('e') >= 0 || s.indexOf('E') >= 0) return Math.min(12, Math.max(0, Math.ceil(-Math.log10(step))));
  var dot = s.indexOf('.');
  return dot < 0 ? 0 : Math.min(12, s.length - dot - 1);
}
function fmtTick(v, step) {
  var dec = decOf(step);
  var a = Math.abs(v);
  if (a >= 1e6) return +(v / 1e6).toFixed(1) + 'M';
  if (a >= 1e4) return +(v / 1e3).toFixed(a >= 1e5 ? 0 : 1) + 'k';
  return v.toLocaleString('en-US', { minimumFractionDigits: dec, maximumFractionDigits: dec });
}

/* ============================ CSV parsing ============================ */
function countOutside(line, ch) {
  var q = false, n = 0;
  for (var i = 0; i < line.length; i++) {
    var c = line.charAt(i);
    if (c === '"') q = !q;
    else if (!q && c === ch) n++;
  }
  return n;
}
function sniffDelim(text) {
  var lines = text.split(/\r?\n/), probe = '', i;
  for (i = 0; i < lines.length; i++) { if (lines[i].trim()) { probe = lines[i]; break; } }
  var best = ',', bestN = 0, cands = [',', ';', '\t', '|'];
  for (i = 0; i < cands.length; i++) {
    var n = countOutside(probe, cands[i]);
    if (n > bestN) { bestN = n; best = cands[i]; }
  }
  return best;
}
function splitRows(text, d) {
  var rows = [], row = [], cell = '', q = false, line = 1, start = 1, atFieldStart = true;
  function pushCell() { row.push(cell); cell = ''; atFieldStart = true; }
  function pushRow() { rows.push({ cells: row, line: start }); row = []; }
  for (var i = 0; i < text.length; i++) {
    var c = text.charAt(i);
    if (q) {
      if (c === '"') { if (text.charAt(i + 1) === '"') { cell += '"'; i++; } else q = false; }
      else { if (c === '\n') line++; cell += c; }
    } else if (c === '"' && atFieldStart) { q = true; atFieldStart = false; }
    else if (c === d) pushCell();
    else if (c === '\r') { /* ignore */ }
    else if (c === '\n') { pushCell(); pushRow(); line++; start = line; }
    else { cell += c; atFieldStart = false; }
  }
  if (cell !== '' || row.length) { pushCell(); pushRow(); }
  return rows;
}

var MAX_ROWS = 20000;

function parseCSV(text) {
  var out = { ok: false, issues: [], cols: [], rows: [], delim: ',', truncated: 0 };
  if (!text || !text.trim()) {
    out.fatal = { title: 'Nothing to chart yet', body: 'Paste some CSV into the box, drop a file on it, or press one of the sample buttons above.' };
    return out;
  }
  var d = out.delim = sniffDelim(text);
  DEC_COMMA = d !== ',';
  var raw = splitRows(text, d).filter(function (r) {
    return r.cells.some(function (c) { return String(c).trim() !== ''; });
  });
  if (!raw.length) {
    out.fatal = { title: 'No rows found', body: 'Every line in that input was blank.' };
    return out;
  }
  var head = raw[0].cells.map(function (c) { return String(c).trim(); });
  var allNumericHeader = head.every(function (h) { return h !== '' && !isNaN(parseNum(h)); });
  var body;
  if (allNumericHeader) {
    head = head.map(function (_, i) { return 'column_' + (i + 1); });
    body = raw;
    out.issues.push({ kind: 'note', row: '', text: 'first line looked numeric — treated as data, columns auto-named' });
  } else {
    body = raw.slice(1);
  }
  var seen = Object.create(null);
  head = head.map(function (h, i) {
    var base = h || ('column_' + (i + 1)), name = base, k = 1;
    while (seen[name]) { k++; name = base + '_' + k; }
    seen[name] = 1;
    return name;
  });
  if (head.length < 2) {
    out.fatal = {
      title: 'Only one column found',
      body: 'A chart needs at least two columns. Detected separator: "' + (d === '\t' ? '\\t' : d) + '" — if your file uses a different one, that is probably the problem.'
    };
    return out;
  }

  var rows = [], skipped = [];
  for (var i = 0; i < body.length; i++) {
    var r = body[i];
    if (rows.length >= MAX_ROWS) { out.truncated = body.length - i; break; }
    if (r.cells.length !== head.length) { skipped.push({ line: r.line, got: r.cells.length }); continue; }
    rows.push(r.cells.map(function (c) { return String(c).trim(); }));
  }
  if (!rows.length) {
    out.fatal = body.length ? {
      title: 'No usable rows',
      body: 'Every data row had a different number of fields than the header (' + head.length + '). Check for stray separators or unclosed quotes.'
    } : {
      title: 'Header row only',
      body: 'Found ' + head.length + ' column names but no data rows underneath them. Add at least one row of values.'
    };
    return out;
  }
  if (skipped.length) {
    var shown = skipped.slice(0, 3);
    for (var s = 0; s < shown.length; s++) {
      out.issues.push({ kind: 'bad', row: 'line ' + shown[s].line, text: 'has ' + shown[s].got + (shown[s].got === 1 ? ' field' : ' fields') + ', expected ' + head.length + ' — skipped' });
    }
    if (skipped.length > shown.length) {
      out.issues.push({ kind: 'bad', row: '+' + (skipped.length - shown.length), text: 'more rows skipped for the same reason' });
    }
  }
  if (out.truncated) out.issues.push({ kind: 'note', row: 'limit', text: out.truncated.toLocaleString('en-US') + ' rows past ' + MAX_ROWS.toLocaleString('en-US') + ' ignored' });

  out.cols = head.map(function (name, ci) { return profileColumn(name, ci, rows); });

  /* Cells that survived the row check but not their column's type still vanish
     from the plot — name them here rather than letting the count quietly shrink. */
  var noisy = 0;
  for (var c = 0; c < out.cols.length; c++) {
    var col = out.cols[c], parts = [];
    if (col.bad) parts.push(col.bad + (col.bad === 1 ? ' value that is not a ' : ' values that are not ') + (col.type === 'date' ? 'date' : 'number') + (col.bad === 1 ? '' : 's'));
    if (col.blanks) parts.push(col.blanks + ' blank');
    if (!parts.length) continue;
    noisy++;
    if (noisy <= 3) out.issues.push({ kind: 'note', row: col.name, text: parts.join(' · ') + ' — left out of the plot' });
  }
  if (noisy > 3) out.issues.push({ kind: 'note', row: '+' + (noisy - 3), text: 'more columns with gaps' });

  out.rows = rows;
  out.skipped = skipped.length;
  out.ok = true;
  return out;
}

function profileColumn(name, ci, rows) {
  var col = { name: name, index: ci, blanks: 0, distinctCount: 0, values: [], unit: '' };
  var vals = [], i, v;
  for (i = 0; i < rows.length; i++) {
    v = rows[i][ci];
    vals.push(v);
    if (v === '') col.blanks++;
  }
  col.values = vals;
  var nonEmpty = rows.length - col.blanks;

  /* date? */
  var dayFirst = false;
  for (i = 0; i < vals.length; i++) {
    var mm = /^(\d{1,2})[-\/](\d{1,2})[-\/]\d{4}$/.exec(vals[i]);
    if (mm && +mm[1] > 12) { dayFirst = true; break; }
  }
  var times = new Array(vals.length), dOK = 0, prec = 'm';
  for (i = 0; i < vals.length; i++) {
    var p = vals[i] === '' ? null : parseDate(vals[i], dayFirst);
    if (p) { times[i] = p.t; dOK++; if (p.prec === 'd') prec = 'd'; } else times[i] = NaN;
  }
  if (nonEmpty > 0 && dOK / nonEmpty >= 0.8) {
    col.type = 'date'; col.times = times; col.prec = prec; col.dayFirst = dayFirst;
    var tmin = Infinity, tmax = -Infinity;
    for (i = 0; i < times.length; i++) { if (isFinite(times[i])) { if (times[i] < tmin) tmin = times[i]; if (times[i] > tmax) tmax = times[i]; } }
    col.min = tmin; col.max = tmax;
    col.bad = nonEmpty - dOK;
    countDistinct(col, vals);
    return col;
  }

  /* number? */
  var nums = new Array(vals.length), nOK = 0, pct = 0;
  for (i = 0; i < vals.length; i++) {
    var n = vals[i] === '' ? NaN : parseNum(vals[i]);
    nums[i] = n;
    if (isFinite(n)) { nOK++; if (isPct(vals[i])) pct++; }
  }
  if (nonEmpty > 0 && nOK / nonEmpty >= 0.8) {
    col.type = 'number'; col.nums = nums;
    var mn = Infinity, mx = -Infinity, uniq = {}, uniqN = 0, allInt = true;
    for (i = 0; i < nums.length; i++) {
      if (!isFinite(nums[i])) continue;
      if (nums[i] < mn) mn = nums[i];
      if (nums[i] > mx) mx = nums[i];
      if (!Number.isInteger(nums[i])) allInt = false;
      if (!uniq[nums[i]]) { uniq[nums[i]] = 1; uniqN++; }
    }
    col.min = mn; col.max = mx; col.distinctCount = uniqN;
    col.unit = pct === nOK && nOK > 0 ? '%' : '';
    col.idLike = allInt && uniqN === nOK && nOK > 3 && (mx - mn + 1 === nOK || /^(id|index|idx|no|num|rank|row)$/i.test(name));
    col.bad = nonEmpty - nOK;
    return col;
  }

  col.type = 'text';
  countDistinct(col, vals);
  col.bad = 0;
  return col;
}
function countDistinct(col, vals) {
  var map = new Map(), i;
  for (i = 0; i < vals.length; i++) {
    if (vals[i] === '') continue;
    map.set(vals[i], (map.get(vals[i]) || 0) + 1);
  }
  col.counts = map;
  col.distinctCount = map.size;
  col.order = Array.from(map.keys());
}

/* ============================ chart model ============================ */
var PALETTE = ['--s1', '--s2', '--s3', '--s4', '--s5', '--s6'];
var MAX_SERIES = 6;

function autoPick(parsed) {
  var cols = parsed.cols, rows = parsed.rows, n = rows.length;
  var nums = cols.filter(function (c) { return c.type === 'number'; });
  var plainNums = nums.filter(function (c) { return !c.idLike; });
  var dates = cols.filter(function (c) { return c.type === 'date'; });
  var texts = cols.filter(function (c) { return c.type === 'text'; });
  if (!nums.length) return null;
  var yPool = plainNums.length ? plainNums : nums;
  /* a column that never changes makes a useless axis — skip it if we have a choice */
  var varied = yPool.filter(function (c) { return isFinite(c.min) && c.min !== c.max; });
  if (varied.length) yPool = varied;
  var y = yPool[0], x = null, type = 'bar';

  var groupCands = texts.concat(dates).filter(function (c) {
    return c.distinctCount >= 2 && c.distinctCount <= 12 && c.distinctCount < n;
  });
  var idLikeText = texts.filter(function (c) { return c.distinctCount >= n * 0.9 && n > 3; })[0];

  if (dates.length) {
    x = dates[0]; type = 'line';
  } else if (idLikeText && yPool.length >= 2) {
    x = yPool[0]; y = yPool[1]; type = 'scatter';
  } else if (groupCands.length) {
    x = groupCands[0]; type = 'bar';
  } else if (yPool.length >= 2) {
    x = yPool[0]; y = yPool[1]; type = 'scatter';
  } else {
    /* last resort: any other column that actually has values in it */
    var rest = cols.filter(function (c) { return c !== y; });
    x = rest.filter(function (c) {
      return c.type === 'number' ? isFinite(c.min) : c.distinctCount > 0;
    })[0] || rest[0] || cols[0];
    /* a numeric X is a continuous axis — 50 ids side by side as bars is not a chart */
    type = x.type === 'date' ? 'line' : x.type !== 'number' ? 'bar' : x.idLike ? 'line' : 'scatter';
  }
  var g = groupCands.filter(function (c) {
    return c !== x && c !== y && c.distinctCount >= 2 && c.distinctCount <= MAX_SERIES;
  })[0] || null;
  return { x: x.name, y: y.name, g: g ? g.name : '', type: type };
}

function colByName(parsed, name) {
  if (!name) return null;
  for (var i = 0; i < parsed.cols.length; i++) if (parsed.cols[i].name === name) return parsed.cols[i];
  return null;
}
function rawX(col, i) {
  if (col.type === 'date') return col.times[i];
  if (col.type === 'number') return col.nums[i];
  return col.values[i];
}
function xLabelOf(col, v, sameYear) {
  if (col.type === 'date') return fmtDate(v, sameYear, col.prec);
  if (col.type === 'number') return fmtVal(v);
  return String(v);
}

function buildModel(parsed, xName, yName, gName, type) {
  var xCol = colByName(parsed, xName), yCol = colByName(parsed, yName), gCol = colByName(parsed, gName);
  if (!xCol || !yCol) return null;
  var rows = parsed.rows, i;

  /* series keys, in stable first-seen order — colour follows the entity */
  var keys = [], keyIdx = new Map();
  if (gCol) {
    var counts = [];
    gCol.counts.forEach(function (c, kk) { counts.push([kk, c]); });
    counts.sort(function (a, b) { return b[1] - a[1]; });
    var keep = new Set(counts.slice(0, MAX_SERIES).map(function (p) { return p[0]; }));
    var order = gCol.type === 'date'
      ? gCol.order.slice().sort(function (a, b) {
          var pa = parseDate(a, gCol.dayFirst), pb = parseDate(b, gCol.dayFirst);
          return ((pa && pa.t) || 0) - ((pb && pb.t) || 0);
        })
      : gCol.order;
    for (i = 0; i < order.length; i++) if (keep.has(order[i])) keys.push(order[i]);
    if (counts.length > MAX_SERIES && keys.indexOf('Other') < 0) keys.push('Other');
  } else {
    keys.push(yCol.name);
  }
  for (i = 0; i < keys.length; i++) keyIdx.set(keys[i], i);

  var folded = gCol ? Math.max(0, gCol.distinctCount - MAX_SERIES) : 0;
  var xKind = type === 'bar' ? 'ordinal'
    : xCol.type === 'date' ? 'time'
      : xCol.type === 'number' ? 'linear' : 'ordinal';

  /* collect usable rows */
  var pts = [], dropped = 0, xvalsSeen = new Map();
  for (i = 0; i < rows.length; i++) {
    var yv = yCol.type === 'number' ? yCol.nums[i] : parseNum(yCol.values[i]);
    var xv = rawX(xCol, i);
    var xOK = xCol.type === 'text' ? String(xv) !== '' : isFinite(xv);
    if (!isFinite(yv) || !xOK) { dropped++; continue; }
    var gk = yCol.name;
    if (gCol) {
      var gv = gCol.values[i];
      if (gv === '') { dropped++; continue; }
      gk = keyIdx.has(gv) ? gv : 'Other';
    }
    if (!xvalsSeen.has(String(xv))) xvalsSeen.set(String(xv), xv);
    pts.push({ x: xv, y: yv, k: gk });
  }
  if (!pts.length) return { empty: true, xCol: xCol, yCol: yCol, gCol: gCol, type: type, dropped: dropped };

  /* ordinal categories */
  var cats = null, catIdx = null, sameYear = true;
  if (xCol.type === 'date') {
    var yrs = new Set();
    for (i = 0; i < pts.length; i++) yrs.add(new Date(pts[i].x).getUTCFullYear());
    sameYear = yrs.size === 1;
  }
  if (xKind === 'ordinal') {
    cats = Array.from(xvalsSeen.values());
    if (xCol.type === 'date' || xCol.type === 'number') cats.sort(function (a, b) { return a - b; });
    catIdx = new Map();
    for (i = 0; i < cats.length; i++) catIdx.set(String(cats[i]), i);
  }

  /* series buckets */
  var series = keys.map(function (kk, idx) {
    return {
      name: String(kk), key: String(kk),
      colorVar: (kk === 'Other' && folded) ? '--s-other' : PALETTE[idx % PALETTE.length],
      shape: idx % 6, points: [], visible: true
    };
  });
  var sIdx = new Map();
  for (i = 0; i < series.length; i++) sIdx.set(series[i].key, i);

  var aggregated = false;
  if (type === 'scatter') {
    for (i = 0; i < pts.length; i++) {
      var s0 = series[sIdx.get(pts[i].k)];
      var px = xKind === 'ordinal' ? catIdx.get(String(pts[i].x)) : pts[i].x;
      s0.points.push({ x: px, y: pts[i].y, xr: pts[i].x });
    }
  } else {
    var acc = new Map();
    for (i = 0; i < pts.length; i++) {
      var key = pts[i].k + '\u0000' + String(pts[i].x);
      var a = acc.get(key);
      if (a) { a.sum += pts[i].y; a.n++; aggregated = true; }
      else acc.set(key, { sum: pts[i].y, n: 1, k: pts[i].k, x: pts[i].x });
    }
    acc.forEach(function (a) {
      var s1 = series[sIdx.get(a.k)];
      var px2 = xKind === 'ordinal' ? catIdx.get(String(a.x)) : a.x;
      s1.points.push({ x: px2, y: a.sum / a.n, xr: a.x });
    });
    for (i = 0; i < series.length; i++) series[i].points.sort(function (a, b) { return a.x - b.x; });
  }

  return {
    type: type, xCol: xCol, yCol: yCol, gCol: gCol, xKind: xKind, cats: cats,
    sameYear: sameYear, series: series, aggregated: aggregated, folded: folded,
    dropped: dropped, plotted: pts.length, yDec: decimalsOf(yCol)
  };
}

function niceTicks(min, max, target) {
  if (!isFinite(min) || !isFinite(max)) return { ticks: [0], step: 1 };
  if (min === max) { var pad = Math.abs(min) * 0.2 || 1; min -= pad; max += pad; }
  var span = max - min;
  var raw = span / Math.max(1, target);
  var mag = Math.pow(10, Math.floor(Math.log10(raw)));
  var norm = raw / mag, step;
  if (norm <= 1) step = 1; else if (norm <= 2) step = 2; else if (norm <= 2.5) step = 2.5;
  else if (norm <= 5) step = 5; else step = 10;
  step = +(step * mag).toPrecision(12);
  if (!isFinite(step) || step <= 0) return { ticks: [min, max], step: (max - min) || 1 };
  function build(st) {
    var a = [], start = Math.ceil(min / st - 1e-9) * st;
    for (var v = start; v <= max + st * 1e-9 && a.length < 64; v += st) a.push(Math.abs(v) < st * 1e-9 ? 0 : +v.toFixed(10));
    return a;
  }
  var out = build(step);
  /* a two-line grid reads as no grid — step down once when the ladder lands too coarse */
  if (out.length < 3) {
    var finer = +(step / 2).toPrecision(12);
    if (finer > 0) { var o2 = build(finer); if (o2.length >= 3) { out = o2; step = finer; } }
  }
  return { ticks: out, step: step };
}

/* ============================ canvas rendering ============================ */
var cv = $('cv'), ctx = cv.getContext('2d');
var W = 0, H = 0, geo = null, anim = { raf: 0, p: 1 };
var reduce = window.matchMedia ? window.matchMedia('(prefers-reduced-motion: reduce)') : { matches: false };
var MONO = 'ui-monospace, "SF Mono", Menlo, Consolas, monospace';
var SANS = 'system-ui, -apple-system, "Segoe UI", sans-serif';

function cssVar(name) {
  return getComputedStyle(document.documentElement).getPropertyValue(name).trim() || '#888888';
}
function themeColors() {
  var c = { ink: cssVar('--ink'), muted: cssVar('--muted'), grid: cssVar('--line'), surface: cssVar('--surface'), accent: cssVar('--accent') };
  c.series = {};
  for (var i = 0; i < PALETTE.length; i++) c.series[PALETTE[i]] = cssVar(PALETTE[i]);
  c.series['--s-other'] = cssVar('--s-other');
  return c;
}
function sizeCanvas() {
  var r = cv.getBoundingClientRect();
  W = Math.max(200, r.width); H = Math.max(160, r.height);
  var dpr = Math.min(3, window.devicePixelRatio || 1);
  cv.width = Math.round(W * dpr); cv.height = Math.round(H * dpr);
  ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
}
function n2(v) { return Math.round(v * 100) / 100; }
function shapePath(i, cx, cy, r) {
  cx = n2(cx); cy = n2(cy); r = n2(r);
  var s, a, b;
  switch (i % 6) {
    case 1: s = n2(r * 0.92); return 'M ' + (cx - s) + ' ' + (cy - s) + ' H ' + (cx + s) + ' V ' + (cy + s) + ' H ' + (cx - s) + ' Z';
    case 2: return 'M ' + cx + ' ' + n2(cy - r * 1.18) + ' L ' + n2(cx + r * 1.08) + ' ' + n2(cy + r * 0.78) + ' L ' + n2(cx - r * 1.08) + ' ' + n2(cy + r * 0.78) + ' Z';
    case 3: return 'M ' + cx + ' ' + n2(cy - r * 1.25) + ' L ' + n2(cx + r * 1.25) + ' ' + cy + ' L ' + cx + ' ' + n2(cy + r * 1.25) + ' L ' + n2(cx - r * 1.25) + ' ' + cy + ' Z';
    case 4: return 'M ' + cx + ' ' + n2(cy + r * 1.18) + ' L ' + n2(cx + r * 1.08) + ' ' + n2(cy - r * 0.78) + ' L ' + n2(cx - r * 1.08) + ' ' + n2(cy - r * 0.78) + ' Z';
    case 5:
      a = n2(r * 0.44); b = n2(r * 1.2);
      return 'M ' + (cx - a) + ' ' + (cy - b) + ' H ' + (cx + a) + ' V ' + (cy - a) + ' H ' + (cx + b) + ' V ' + (cy + a) +
        ' H ' + (cx + a) + ' V ' + (cy + b) + ' H ' + (cx - a) + ' V ' + (cy + a) + ' H ' + (cx - b) + ' V ' + (cy - a) + ' H ' + (cx - a) + ' Z';
    default: return 'M ' + (cx - r) + ' ' + cy + ' a ' + r + ' ' + r + ' 0 1 0 ' + n2(2 * r) + ' 0 a ' + r + ' ' + r + ' 0 1 0 ' + n2(-2 * r) + ' 0 Z';
  }
}
function drawShape(i, cx, cy, r, fill, ring, ringW) {
  var p = new Path2D(shapePath(i, cx, cy, r));
  if (ring) { ctx.lineWidth = ringW || 2; ctx.strokeStyle = ring; ctx.stroke(p); }
  ctx.fillStyle = fill; ctx.fill(p);
}
function roundedTop(x, y, w, h, r) {
  r = Math.max(0, Math.min(r, w / 2, Math.abs(h)));
  ctx.beginPath();
  if (h >= 0) {
    var yt2 = y - h;
    ctx.moveTo(x, y); ctx.lineTo(x, yt2 + r);
    ctx.quadraticCurveTo(x, yt2, x + r, yt2); ctx.lineTo(x + w - r, yt2);
    ctx.quadraticCurveTo(x + w, yt2, x + w, yt2 + r); ctx.lineTo(x + w, y); ctx.closePath();
  } else {
    var yb = y - h;
    ctx.moveTo(x, y); ctx.lineTo(x, yb - r);
    ctx.quadraticCurveTo(x, yb, x + r, yb); ctx.lineTo(x + w - r, yb);
    ctx.quadraticCurveTo(x + w, yb, x + w, yb - r); ctx.lineTo(x + w, y); ctx.closePath();
  }
  ctx.fill();
}

function render(model, hover, p) {
  ctx.clearRect(0, 0, W, H);
  geo = null;
  if (!model || model.empty) return;
  var C = themeColors();
  var vis = model.series.filter(function (s) { return s.visible && s.points.length; });
  if (!vis.length) {
    ctx.font = '13px ' + SANS; ctx.fillStyle = C.muted; ctx.textAlign = 'center'; ctx.textBaseline = 'middle';
    ctx.fillText('every series is hidden — switch one back on below', W / 2, H / 2);
    return;
  }

  /* ---- domains ---- */
  var ymin = Infinity, ymax = -Infinity, xmin = Infinity, xmax = -Infinity, i, j, s, pt;
  for (i = 0; i < vis.length; i++) for (j = 0; j < vis[i].points.length; j++) {
    pt = vis[i].points[j];
    if (pt.y < ymin) ymin = pt.y;
    if (pt.y > ymax) ymax = pt.y;
    if (pt.x < xmin) xmin = pt.x;
    if (pt.x > xmax) xmax = pt.x;
  }
  var bar = model.type === 'bar';
  if (bar) { if (ymin > 0) ymin = 0; if (ymax < 0) ymax = 0; }
  if (ymin === ymax) { var e = Math.abs(ymin) * 0.15 || 1; ymin -= e; ymax += e; }
  else if (!bar) { var padY = (ymax - ymin) * 0.08; ymin -= padY; ymax += padY; }
  var yt = niceTicks(ymin, ymax, H < 260 ? 4 : 5);
  if (yt.ticks.length) {
    ymin = Math.min(ymin, yt.ticks[0]);
    ymax = Math.max(ymax, yt.ticks[yt.ticks.length - 1]);
  }

  /* ---- paddings ---- */
  ctx.font = '11px ' + MONO;
  var labW = 0;
  for (i = 0; i < yt.ticks.length; i++) labW = Math.max(labW, ctx.measureText(fmtTick(yt.ticks[i], yt.step)).width);
  var padL = Math.ceil(labW) + 12, padT = 12, padB = 42, padR = 14;

  var endLabels = model.type === 'line' && vis.length <= 4 && W >= 440;
  if (endLabels) {
    ctx.font = '11px ' + SANS;
    var endW = 0;
    for (i = 0; i < vis.length; i++) endW = Math.max(endW, ctx.measureText(vis[i].name).width);
    padR += Math.min(endW + 18, 110);
  }
  var plotW = W - padL - padR, plotH = H - padT - padB;
  if (plotW < 90) { endLabels = false; padR = 14; plotW = W - padL - padR; }

  var ordinal = model.xKind === 'ordinal';
  var nCats = ordinal ? model.cats.length : 0;
  var band = ordinal ? plotW / Math.max(1, nCats) : 0;
  function X(v) {
    if (ordinal) return padL + band * (v + 0.5);
    if (xmax === xmin) return padL + plotW / 2;
    return padL + (v - xmin) / (xmax - xmin) * plotW;
  }
  function Y(v) { return padT + plotH - (v - ymin) / (ymax - ymin) * plotH; }

  /* ---- gridlines + y ticks ---- */
  ctx.strokeStyle = C.grid; ctx.lineWidth = 1;
  ctx.font = '11px ' + MONO; ctx.fillStyle = C.muted; ctx.textAlign = 'right'; ctx.textBaseline = 'middle';
  for (i = 0; i < yt.ticks.length; i++) {
    var gy = Math.round(Y(yt.ticks[i])) + 0.5;
    ctx.beginPath(); ctx.moveTo(padL, gy); ctx.lineTo(padL + plotW, gy); ctx.stroke();
    ctx.fillText(fmtTick(yt.ticks[i], yt.step), padL - 8, gy);
  }

  /* ---- x ticks ---- */
  var xticks = [], lb;
  if (ordinal) {
    ctx.font = '11px ' + MONO;
    /* sample the widths — measuring every category costs a frame on wide files */
    var maxW = 0, sampleStep = Math.max(1, Math.ceil(nCats / 120));
    for (i = 0; i < nCats; i += sampleStep) {
      lb = xLabelOf(model.xCol, model.cats[i], model.sameYear);
      maxW = Math.max(maxW, ctx.measureText(lb).width);
    }
    var fit = Math.max(1, Math.floor(plotW / (maxW + 14)));
    var stepC = Math.ceil(nCats / fit);
    for (i = 0; i < nCats; i += stepC) xticks.push({ px: X(i), label: xLabelOf(model.xCol, model.cats[i], model.sameYear) });
  } else if (model.xKind === 'linear') {
    var want1 = Math.max(2, Math.min(7, Math.floor(plotW / 74)));
    var xt = niceTicks(xmin, xmax, want1);
    for (i = 0; i < xt.ticks.length; i++) {
      if (xt.ticks[i] < xmin - 1e-9 || xt.ticks[i] > xmax + 1e-9) continue;
      xticks.push({ px: X(xt.ticks[i]), label: fmtTick(xt.ticks[i], xt.step) });
    }
  } else {
    var ded = xValueList(model);   /* cached + deduped per visibility signature */
    var want2 = Math.max(2, Math.min(7, Math.floor(plotW / 74)));
    var stepT = Math.max(1, Math.ceil(ded.length / want2));
    for (i = 0; i < ded.length; i += stepT) xticks.push({ px: X(ded[i].x), label: xLabelOf(model.xCol, ded[i].x, model.sameYear) });
  }
  ctx.fillStyle = C.muted; ctx.textAlign = 'center'; ctx.textBaseline = 'top'; ctx.font = '11px ' + MONO;
  for (i = 0; i < xticks.length; i++) {
    var halfW = ctx.measureText(xticks[i].label).width / 2;
    ctx.fillText(xticks[i].label, Math.min(W - 3 - halfW, Math.max(3 + halfW, xticks[i].px)), padT + plotH + 8);
  }
  ctx.strokeStyle = C.grid; ctx.beginPath();
  ctx.moveTo(padL, Math.round(padT + plotH) + 0.5); ctx.lineTo(padL + plotW, Math.round(padT + plotH) + 0.5); ctx.stroke();
  ctx.fillStyle = C.muted; ctx.font = '10.5px ' + MONO; ctx.textBaseline = 'alphabetic';
  ctx.fillText(model.xCol.name, padL + plotW / 2, H - 6);

  /* ---- marks ---- */
  var hoverIdx = (hover && hover.kind === 'x' && hover.cat != null) ? hover.cat : -1;
  if (bar) {
    var slots = vis.length, gap = 2;
    var inner = Math.min(band * 0.8, 26 * slots + gap * (slots - 1));
    var bw = Math.max(1.5, (inner - gap * (slots - 1)) / slots);
    if (hoverIdx >= 0) {
      ctx.globalAlpha = 0.5; ctx.fillStyle = C.grid;
      ctx.fillRect(padL + band * hoverIdx, padT, band, plotH); ctx.globalAlpha = 1;
    }
    for (i = 0; i < vis.length; i++) {
      s = vis[i]; ctx.fillStyle = C.series[s.colorVar];
      for (j = 0; j < s.points.length; j++) {
        pt = s.points[j];
        var bx = padL + band * (pt.x + 0.5) - inner / 2 + i * (bw + gap);
        var y0 = Y(0);
        roundedTop(bx, y0, bw, (y0 - Y(pt.y)) * p, 4);
      }
    }
  } else if (model.type === 'line') {
    ctx.save();
    ctx.beginPath(); ctx.rect(padL - 8, 0, plotW * p + 16, H); ctx.clip();
    ctx.lineJoin = 'round'; ctx.lineCap = 'round'; ctx.lineWidth = 2;
    var total = 0;
    for (i = 0; i < vis.length; i++) {
      s = vis[i]; total += s.points.length;
      ctx.strokeStyle = C.series[s.colorVar];
      ctx.beginPath();
      for (j = 0; j < s.points.length; j++) {
        pt = s.points[j];
        if (j === 0) ctx.moveTo(X(pt.x), Y(pt.y)); else ctx.lineTo(X(pt.x), Y(pt.y));
      }
      ctx.stroke();
    }
    if (total <= 300) for (i = 0; i < vis.length; i++) {
      s = vis[i];
      for (j = 0; j < s.points.length; j++) drawShape(s.shape, X(s.points[j].x), Y(s.points[j].y), 4, C.series[s.colorVar], C.surface, 2);
    }
    ctx.restore();
  } else {
    ctx.globalAlpha = p;
    for (i = 0; i < vis.length; i++) {
      s = vis[i];
      var many = s.points.length > 400;
      for (j = 0; j < s.points.length; j++) {
        pt = s.points[j];
        drawShape(s.shape, X(pt.x), Y(pt.y), 4.5 * (0.4 + 0.6 * p), C.series[s.colorVar], many ? null : C.surface, 2);
      }
    }
    ctx.globalAlpha = 1;
  }

  /* ---- direct labels ---- */
  if (p >= 1 && endLabels) {
    var lab = [];
    for (i = 0; i < vis.length; i++) {
      s = vis[i];
      if (!s.points.length) continue;
      var last = s.points[s.points.length - 1];
      lab.push({ y: Y(last.y), x: X(last.x), name: s.name, cvar: C.series[s.colorVar] });
    }
    lab.sort(function (a, b) { return a.y - b.y; });
    var collide = false;
    for (i = 1; i < lab.length; i++) if (lab[i].y - lab[i - 1].y < 14) collide = true;
    if (!collide) {
      ctx.font = '11px ' + SANS; ctx.textAlign = 'left'; ctx.textBaseline = 'middle';
      for (i = 0; i < lab.length; i++) {
        var lx = Math.min(lab[i].x + 8, padL + plotW + 8);
        ctx.strokeStyle = lab[i].cvar; ctx.lineWidth = 2;
        ctx.beginPath(); ctx.moveTo(lx, lab[i].y); ctx.lineTo(lx + 10, lab[i].y); ctx.stroke();
        ctx.fillStyle = C.ink;
        ctx.fillText(lab[i].name, lx + 15, lab[i].y);
      }
    }
  }
  if (p >= 1 && bar && vis.length === 1) {
    ctx.font = '11px ' + MONO; ctx.textAlign = 'center'; ctx.textBaseline = 'bottom'; ctx.fillStyle = C.ink;
    s = vis[0];
    var fits = true;
    for (j = 0; j < s.points.length; j++) if (ctx.measureText(fmtY(s.points[j].y, model.yDec)).width + 8 > band) fits = false;
    if (fits) for (j = 0; j < s.points.length; j++) {
      pt = s.points[j];
      ctx.fillText(fmtY(pt.y, model.yDec), padL + band * (pt.x + 0.5), Y(pt.y) + (pt.y < 0 ? 15 : -6));
    }
  }

  /* ---- hover overlay ---- */
  if (hover && p >= 1) {
    if (hover.kind === 'x') {
      if (!bar && hover.x != null) {
        var hx = Math.round(X(hover.x)) + 0.5;
        ctx.save();
        ctx.globalAlpha = 0.5; ctx.strokeStyle = C.muted; ctx.lineWidth = 1;
        ctx.beginPath();
        ctx.moveTo(hx, padT); ctx.lineTo(hx, padT + plotH);
        ctx.stroke(); ctx.restore();
      }
      for (i = 0; i < hover.marks.length; i++) {
        var mk = hover.marks[i];
        if (bar) {
          var hbx = padL + band * (mk.x + 0.5) - inner / 2 + mk.si * (bw + gap);
          ctx.lineWidth = 2; ctx.strokeStyle = C.ink;
          ctx.strokeRect(hbx - 1.5, Math.min(Y(0), Y(mk.y)) - 1.5, bw + 3, Math.abs(Y(mk.y) - Y(0)) + 3);
        } else {
          drawShape(mk.shape, X(mk.x), Y(mk.y), 5.5, C.series[mk.colorVar], C.surface, 2.5);
        }
      }
    } else if (hover.kind === 'pt' && hover.mark) {
      drawShape(hover.mark.shape, X(hover.mark.x), Y(hover.mark.y), 6.5, C.series[hover.mark.colorVar], C.surface, 2.5);
    }
  }

  geo = {
    padL: padL, padT: padT, padR: padR, plotW: plotW, plotH: plotH, band: band,
    X: X, Y: Y, ordinal: ordinal, vis: vis, bar: bar, nCats: nCats
  };
}

function animateIn() {
  if (anim.raf) { cancelAnimationFrame(anim.raf); anim.raf = 0; }
  if (reduce.matches) { anim.p = 1; draw(); return; }
  var t0 = 0, dur = 340;
  anim.p = 0;
  anim.raf = requestAnimationFrame(function step(now) {
    if (!t0) t0 = now;
    var k = Math.min(1, (now - t0) / dur);
    anim.p = 1 - Math.pow(1 - k, 3);
    draw();
    anim.raf = k < 1 ? requestAnimationFrame(step) : 0;
  });
}
function draw() { render(state.model, state.hover, anim.p); }

/* ============================ state + UI ============================ */
var state = {
  parsed: null, model: null, x: '', y: '', g: '', type: 'line',
  manual: { x: false, y: false, g: false, type: false },
  hidden: Object.create(null), hover: null, showTable: false, keyIdx: -1
};

var elCsv = $('csv'), elIssues = $('issues'), elCols = $('cols'), elFacts = $('facts');
var okPill = $('okPill'), warnPill = $('warnPill'), elLegend = $('legend'), elTip = $('tip');
var selX = $('selX'), selY = $('selY'), selG = $('selG'), autoflag = $('autoflag');
var chartArea = $('chartArea'), chartErr = $('chartErr'), errTitle = $('errTitle'), errBody = $('errBody');
var chartTitle = $('chartTitle'), chartNote = $('chartNote'), live = $('live');
var tableBtn = $('tableBtn'), tablebox = $('tablebox');

function colDetail(col) {
  if (col.type === 'number') {
    if (!isFinite(col.min)) return 'no values';
    return fmtVal(col.min) + '–' + fmtVal(col.max) + (col.unit || '');
  }
  if (col.type === 'date') return fmtDateFull(col.min, col.prec) + ' → ' + fmtDateFull(col.max, col.prec);
  return col.distinctCount + ' distinct';
}

function renderStatus(parsed, ms) {
  clear(elIssues);
  if (!parsed.ok) {
    okPill.hidden = true; warnPill.hidden = true;
    elFacts.textContent = '';
    return;
  }
  okPill.hidden = false;
  var facts = document.createDocumentFragment();
  function fact(v, unit) {
    var sp = el('span');
    sp.appendChild(el('b', null, v));
    sp.appendChild(document.createTextNode(' ' + unit));
    facts.appendChild(sp);
    facts.appendChild(document.createTextNode(' · '));
  }
  fact(parsed.rows.length.toLocaleString('en-US'), parsed.rows.length === 1 ? 'row' : 'rows');
  fact(String(parsed.cols.length), 'columns');
  var dn = parsed.delim === '\t' ? 'tab' : parsed.delim === ',' ? 'comma' : parsed.delim === ';' ? 'semicolon' : 'pipe';
  facts.appendChild(el('span', null, dn + '-separated'));
  facts.appendChild(document.createTextNode(' · '));
  fact(ms.toFixed(ms < 10 ? 1 : 0), 'ms');
  facts.removeChild(facts.lastChild);
  clear(elFacts);
  elFacts.appendChild(facts);

  if (parsed.skipped) {
    warnPill.hidden = false;
    warnPill.textContent = parsed.skipped + (parsed.skipped === 1 ? ' row skipped' : ' rows skipped');
  } else warnPill.hidden = true;

  for (var i = 0; i < parsed.issues.length; i++) {
    var it = parsed.issues[i];
    var li = el('li', it.kind === 'bad' ? 'bad' : null);
    li.appendChild(el('span', 'row', it.row));
    li.appendChild(el('span', null, it.text));
    elIssues.appendChild(li);
  }
}

function renderColumns(parsed) {
  clear(elCols);
  parsed.cols.forEach(function (col) {
    var b = el('button', 'colbtn');
    b.type = 'button';
    var nm = el('span', 'nm', col.name);
    var ty = el('span', 'ty ' + col.type, col.type);
    var rg = el('span', 'rng', colDetail(col));
    b.appendChild(nm); b.appendChild(ty); b.appendChild(rg);
    /* One button, one honest action. A column already carrying a role says so
       instead of offering a role it cannot take (colour-by is never the X). */
    var numCount = parsed.cols.filter(function (c) { return c.type === 'number'; }).length;
    var groupable = col.type !== 'number' && col.name !== state.x &&
      col.distinctCount >= 2 && col.distinctCount <= 12;
    var action, verb;
    if (col.name === state.g) { action = 'ungroup'; verb = 'Stop colouring by'; }
    else if (col.type === 'number') {
      if (col.name !== state.y) { action = 'y'; verb = 'Plot on the Y axis'; }
      else if (numCount > 1) { action = 'x'; verb = 'Move to the X axis'; }
      else { action = 'y'; verb = 'Already the Y axis'; }
    } else if (col.name === state.x) { action = 'x'; verb = 'Already the X axis'; }
    else if (groupable) { action = 'g'; verb = 'Colour the chart by'; }
    else { action = 'x'; verb = 'Plot on the X axis'; }
    b.title = verb + ': ' + col.name;
    b.setAttribute('aria-label', verb + ': ' + col.name + ' (' + col.type + ', ' + colDetail(col) + ')');
    var role = col.name === state.x ? 'x' : col.name === state.y ? 'y' : col.name === state.g ? 'g' : '';
    if (role) {
      b.setAttribute('data-active', role);
      b.setAttribute('aria-pressed', 'true');
      b.insertBefore(el('span', 'role', role === 'g' ? 'colour' : role.toUpperCase()), rg);
    }
    b.addEventListener('click', function () {
      if (action === 'y') setY(col.name);
      else if (action === 'x') setX(col.name);
      else if (action === 'ungroup') { state.g = ''; state.manual.g = true; state.hidden = Object.create(null); }
      else { state.g = col.name; state.manual.g = true; state.hidden = Object.create(null); }
      syncSelects(); rebuild(true);
    });
    elCols.appendChild(b);
  });
}

function fillSelect(sel, items, value) {
  clear(sel);
  items.forEach(function (it) {
    var o = document.createElement('option');
    o.value = it.value; o.textContent = it.label;
    sel.appendChild(o);
  });
  sel.value = value;
  if (sel.selectedIndex < 0 && sel.options.length) sel.selectedIndex = 0;
}
function groupCandidates(parsed) {
  return parsed.cols.filter(function (c) {
    return c.type !== 'number' && c.distinctCount >= 2 && c.distinctCount <= 12;
  });
}
function syncSelects() {
  var p = state.parsed;
  if (!p || !p.ok) return;
  fillSelect(selX, p.cols.map(function (c) { return { value: c.name, label: c.name + '  (' + c.type + ')' }; }), state.x);
  if (selX.options.length) state.x = selX.value;
  var nums = p.cols.filter(function (c) { return c.type === 'number'; });
  fillSelect(selY, nums.map(function (c) { return { value: c.name, label: c.name }; }), state.y);
  if (selY.options.length) state.y = selY.value;
  selY.disabled = nums.length === 0;
  var gs = groupCandidates(p).filter(function (c) { return c.name !== state.x; });
  fillSelect(selG, [{ value: '', label: '(nothing — one series)' }].concat(
    gs.map(function (c) { return { value: c.name, label: c.name + '  (' + c.distinctCount + ')' }; })
  ), gs.some(function (c) { return c.name === state.g; }) ? state.g : '');
  state.g = selG.value;
  selG.disabled = gs.length === 0;
  var r = document.querySelector('input[name="ctype"][value="' + state.type + '"]');
  if (r) r.checked = true;
  renderColumns(p);

  clear(autoflag);
  var manual = state.manual.x || state.manual.y || state.manual.g || state.manual.type;
  if (manual) {
    var btn = el('button', 'linkbtn', 'reset to auto-pick');
    btn.type = 'button';
    btn.addEventListener('click', function () {
      state.manual = { x: false, y: false, g: false, type: false };
      state.hidden = Object.create(null);
      applyAuto(); syncSelects(); rebuild(true);
      selX.focus();
    });
    autoflag.appendChild(el('span', null, 'manual · '));
    autoflag.appendChild(btn);
  } else {
    autoflag.textContent = 'auto-picked from the data';
  }
}

function applyAuto() {
  var p = state.parsed, a = p ? autoPick(p) : null;
  if (!a) return false;
  if (!state.manual.x || !colByName(p, state.x)) state.x = a.x;
  if (!state.manual.y || !colByName(p, state.y)) state.y = a.y;
  if (!state.manual.g || (state.g && !colByName(p, state.g))) state.g = a.g;
  if (!state.manual.type) state.type = a.type;
  return true;
}

/* When the visitor swaps the X column but has not pinned a chart type, re-derive
   the type from the new X — a line drawn across unordered categories implies an
   order that is not in the data. */
function typeForX(xCol) {
  if (!xCol) return state.type;
  if (xCol.type === 'date') return 'line';
  if (xCol.type === 'number' && !xCol.idLike) return 'scatter';
  return 'bar';
}
/* The colour-by column is dropped whenever it becomes the X column. If the
   visitor never chose it by hand, offer it back once it is legal again rather
   than silently collapsing every series into one averaged line. */
function autoGroupFor(xName, yName) {
  var p = state.parsed;
  if (!p || !p.ok) return '';
  var n = p.rows.length;
  var c = p.cols.filter(function (col) {
    return col.name !== xName && col.name !== yName && col.type !== 'number' &&
      col.distinctCount >= 2 && col.distinctCount <= MAX_SERIES && col.distinctCount < n;
  })[0];
  return c ? c.name : '';
}
/* A column plotted against itself is a 45° line that says nothing, and both
   selects can reach that state. Whichever axis the visitor just moved keeps the
   column; the other axis steps aside to the next sensible one. */
function fixAxisClash(moved) {
  var p = state.parsed;
  if (!p || !p.ok || state.x !== state.y) return;
  var i, alt;
  if (moved === 'x') {
    alt = p.cols.filter(function (c) { return c.type === 'number' && c.name !== state.x; })[0];
    if (alt) { state.y = alt.name; return; }
    alt = p.cols.filter(function (c) { return c.name !== state.y; })[0];
    if (alt) state.x = alt.name;
  } else {
    var rest = p.cols.filter(function (c) { return c.name !== state.y; });
    alt = rest.filter(function (c) { return c.type === 'date'; })[0] ||
      rest.filter(function (c) { return c.type === 'text'; })[0] || rest[0];
    if (alt) {
      state.x = alt.name;
      if (!state.manual.type) state.type = typeForX(alt);
    }
  }
}
function setX(name) {
  state.x = name;
  state.manual.x = true;
  fixAxisClash('x');
  if (!state.manual.type) state.type = typeForX(colByName(state.parsed, state.x));
  if (!state.manual.g) state.g = autoGroupFor(state.x, state.y);
}
function setY(name) {
  state.y = name;
  state.manual.y = true;
  fixAxisClash('y');
  if (!state.manual.g) state.g = autoGroupFor(state.x, state.y);
}

/* ---------------- legend ---------------- */
function swatch(series, type) {
  var svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
  svg.setAttribute('width', '16'); svg.setAttribute('height', '14'); svg.setAttribute('viewBox', '0 0 16 14');
  svg.setAttribute('aria-hidden', 'true');
  var col = cssVar(series.colorVar);
  if (type === 'bar') {
    var r = document.createElementNS('http://www.w3.org/2000/svg', 'rect');
    r.setAttribute('x', '2'); r.setAttribute('y', '2'); r.setAttribute('width', '12'); r.setAttribute('height', '10');
    r.setAttribute('rx', '2'); r.setAttribute('fill', col);
    svg.appendChild(r);
  } else {
    if (type === 'line') {
      var l = document.createElementNS('http://www.w3.org/2000/svg', 'line');
      l.setAttribute('x1', '1'); l.setAttribute('y1', '7'); l.setAttribute('x2', '15'); l.setAttribute('y2', '7');
      l.setAttribute('stroke', col); l.setAttribute('stroke-width', '2'); l.setAttribute('stroke-linecap', 'round');
      svg.appendChild(l);
    }
    var p = document.createElementNS('http://www.w3.org/2000/svg', 'path');
    p.setAttribute('d', shapePath(series.shape, 8, 7, 4));
    p.setAttribute('fill', col);
    p.setAttribute('stroke', cssVar('--surface'));
    p.setAttribute('stroke-width', '2');
    p.setAttribute('paint-order', 'stroke');
    svg.appendChild(p);
  }
  return svg;
}
function renderLegend(model) {
  clear(elLegend);
  if (!model || model.empty || model.series.length < 2) { elLegend.hidden = true; return; }
  elLegend.hidden = false;
  model.series.forEach(function (s) {
    var b = el('button');
    b.type = 'button';
    b.setAttribute('aria-pressed', s.visible ? 'true' : 'false');
    b.appendChild(swatch(s, model.type));
    b.appendChild(el('span', null, s.name));
    b.title = (s.visible ? 'Hide ' : 'Show ') + s.name;
    b.addEventListener('click', function () {
      s.visible = !s.visible;
      if (s.visible) delete state.hidden[s.key]; else state.hidden[s.key] = true;
      b.setAttribute('aria-pressed', s.visible ? 'true' : 'false');
      b.title = (s.visible ? 'Hide ' : 'Show ') + s.name;
      state.hover = null; hideTip();
      draw(); renderTable(model); updateNote();
    });
    elLegend.appendChild(b);
  });
}

/* ---------------- table view ---------------- */
function renderTable(model) {
  if (!state.showTable) { tablebox.hidden = true; return; }
  tablebox.hidden = false;
  clear(tablebox);
  if (!model || model.empty) { tablebox.appendChild(el('p', 'hint', 'nothing to tabulate')); return; }
  var vis = model.series.filter(function (s) { return s.visible && s.points.length; });
  var t = document.createElement('table'), thead = document.createElement('thead'),
    tb = document.createElement('tbody'), hr = document.createElement('tr');
  var i, j, tr, td;
  var MAXR = 250, count = 0, truncated = 0;

  if (model.type === 'scatter') {
    [model.xCol.name, model.yCol.name].concat(model.gCol ? [model.gCol.name] : []).forEach(function (h) {
      hr.appendChild(el('th', null, h));
    });
    var flat = [];
    for (i = 0; i < vis.length; i++) for (j = 0; j < vis[i].points.length; j++) flat.push({ s: vis[i], p: vis[i].points[j] });
    for (i = 0; i < flat.length; i++) {
      if (count >= MAXR) { truncated = flat.length - count; break; }
      tr = document.createElement('tr');
      tr.appendChild(el('td', null, xLabelOf(model.xCol, model.xKind === 'ordinal' ? model.cats[flat[i].p.x] : flat[i].p.xr, model.sameYear)));
      tr.appendChild(el('td', null, fmtY(flat[i].p.y, model.yDec)));
      if (model.gCol) tr.appendChild(el('td', null, flat[i].s.name));
      tb.appendChild(tr); count++;
    }
  } else {
    hr.appendChild(el('th', null, model.xCol.name));
    for (i = 0; i < vis.length; i++) hr.appendChild(el('th', null, vis[i].name));
    var xs = [];
    if (model.xKind === 'ordinal') { for (i = 0; i < model.cats.length; i++) xs.push({ k: i, raw: model.cats[i] }); }
    else {
      var seen = new Map();
      for (i = 0; i < vis.length; i++) for (j = 0; j < vis[i].points.length; j++) seen.set(vis[i].points[j].x, vis[i].points[j].xr);
      var keys = Array.from(seen.keys()).sort(function (a, b) { return a - b; });
      for (i = 0; i < keys.length; i++) xs.push({ k: keys[i], raw: seen.get(keys[i]) });
    }
    for (i = 0; i < xs.length; i++) {
      if (count >= MAXR) { truncated = xs.length - count; break; }
      tr = document.createElement('tr');
      tr.appendChild(el('td', null, xLabelOf(model.xCol, model.xKind === 'ordinal' ? xs[i].raw : xs[i].k, model.sameYear)));
      for (j = 0; j < vis.length; j++) {
        var found = null, pts = vis[j].points;
        for (var q = 0; q < pts.length; q++) if (pts[q].x === xs[i].k) { found = pts[q]; break; }
        td = el('td', null, found ? fmtY(found.y, model.yDec) : '—');
        if (!found) td.style.color = 'var(--muted)';
        tr.appendChild(td);
      }
      tb.appendChild(tr); count++;
    }
  }
  thead.appendChild(hr); t.appendChild(thead); t.appendChild(tb);
  tablebox.appendChild(t);
  if (truncated) tablebox.appendChild(el('p', 'hint', ' ' + truncated.toLocaleString('en-US') + ' more rows not shown'));
}

/* ---------------- rebuild ---------------- */
function rebuild(animate) {
  var p = state.parsed;
  state.hover = null; hideTip(); state.keyIdx = -1;
  if (!p || !p.ok) return;
  var nums = p.cols.filter(function (c) { return c.type === 'number'; });
  if (!nums.length) {
    showError('No numeric column found',
      'Every column parsed as text or dates, so there is nothing to measure. A chart needs at least one column of numbers — check for stray units, currency symbols or a mis-detected separator.');
    return;
  }
  hideError();
  var model = buildModel(p, state.x, state.y, state.g, state.type);
  if (!model) { showError('Pick two columns', 'Choose an X and a Y column to plot.'); return; }
  for (var i = 0; i < (model.series || []).length; i++) {
    if (state.hidden[model.series[i].key]) model.series[i].visible = false;
  }
  state.model = model;

  var yName = model.yCol.name + (model.yCol.unit || '');
  chartTitle.textContent = model.empty ? 'Nothing to plot' : yName + ' by ' + model.xCol.name;
  updateNote();

  if (model.empty) {
    showError('No rows survived',
      'Every row was missing a usable value in "' + model.xCol.name + '" or "' + model.yCol.name + '". Try different columns.');
    return;
  }
  cv.setAttribute('aria-label',
    model.type + ' chart of ' + yName + ' by ' + model.xCol.name +
    (model.gCol ? ', one series per ' + model.gCol.name : '') +
    '. ' + model.plotted + ' points. Use the data table below for exact values.');

  renderLegend(model);
  renderTable(model);
  sizeCanvas();
  if (animate) animateIn(); else { anim.p = 1; draw(); }
}
function updateNote() {
  var model = state.model, p = state.parsed;
  if (!model || !p) { chartNote.textContent = ''; return; }
  var bits = [model.type];
  if (!model.empty) {
    var visN = model.series.filter(function (s) { return s.visible; }).length;
    var hidden = model.series.length - visN;
    bits.push(visN + ' series' + (hidden ? ' of ' + model.series.length : ''));
    bits.push(model.plotted.toLocaleString('en-US') + ' of ' + p.rows.length.toLocaleString('en-US') + ' rows plotted');
    if (model.aggregated) bits.push('mean per point');
    if (model.folded) bits.push(model.folded + ' small groups folded into "Other"');
  }
  chartNote.textContent = bits.join(' · ');
}
function showError(title, body) {
  errTitle.textContent = title; errBody.textContent = body;
  chartErr.hidden = false; chartArea.hidden = true;
  state.model = null;
}
function hideError() { chartErr.hidden = true; chartArea.hidden = false; }

/* ---------------- parse pipeline ---------------- */
function runParse(text, resetManual, animate) {
  var t0 = performance.now();
  var p = parseCSV(text);
  var ms = performance.now() - t0;
  state.parsed = p;
  if (resetManual) { state.manual = { x: false, y: false, g: false, type: false }; state.hidden = Object.create(null); }
  renderStatus(p, ms);
  if (!p.ok) {
    clear(elCols);
    [selX, selY, selG].forEach(function (s) { clear(s); s.disabled = true; });
    clear(autoflag);
    showError(p.fatal.title, p.fatal.body);
    return;
  }
  [selX, selY].forEach(function (s) { s.disabled = false; });
  applyAuto();
  syncSelects();
  rebuild(animate !== false);
}

/* ---------------- tooltip + hover ---------------- */
function hideTip() { elTip.classList.remove('on'); elTip.setAttribute('aria-hidden', 'true'); }
function showTip(px, py, headline, rows) {
  clear(elTip);
  elTip.appendChild(el('div', 'tx', headline));
  rows.forEach(function (r) {
    var row = el('div', 'row');
    var k = el('span', 'key');
    k.style.background = cssVar(r.colorVar);
    row.appendChild(k);
    row.appendChild(el('span', 'nm', r.name));
    row.appendChild(el('span', 'v', r.value));
    elTip.appendChild(row);
  });
  elTip.classList.add('on');
  elTip.setAttribute('aria-hidden', 'false');
  var tw = elTip.offsetWidth, th = elTip.offsetHeight;
  var left = Math.max(tw / 2 + 4, Math.min(W - tw / 2 - 4, px));
  var top = Math.max(th + 6, py - 12);
  elTip.style.left = left + 'px';
  elTip.style.top = top + 'px';
}

function visSig(model) {
  return model.series.map(function (s) { return s.visible ? 1 : 0; }).join('');
}
function xValueList(model) {
  var sig = visSig(model);
  if (model._xl && model._xlSig === sig) return model._xl;
  var vis = model.series.filter(function (s) { return s.visible && s.points.length; });
  var set = new Map(), i, j;
  for (i = 0; i < vis.length; i++) for (j = 0; j < vis[i].points.length; j++) set.set(vis[i].points[j].x, vis[i].points[j].xr);
  var keys = Array.from(set.keys()).sort(function (a, b) { return a - b; });
  model._xl = keys.map(function (k) { return { x: k, raw: set.get(k) }; });
  model._xlSig = sig;
  return model._xl;
}
function flatPoints(model) {
  var sig = visSig(model);
  if (model._fp && model._fpSig === sig) return model._fp;
  var out = [], vis = model.series.filter(function (s) { return s.visible && s.points.length; });
  for (var i = 0; i < vis.length; i++) for (var j = 0; j < vis[i].points.length; j++) out.push({ s: vis[i], p: vis[i].points[j] });
  out.sort(function (a, b) { return a.p.x - b.p.x; });
  model._fp = out; model._fpSig = sig;
  return out;
}
function hoverAtX(model, xv, raw) {
  var vis = model.series.filter(function (s) { return s.visible && s.points.length; });
  var marks = [], i, j;
  for (i = 0; i < vis.length; i++) {
    for (j = 0; j < vis[i].points.length; j++) {
      if (vis[i].points[j].x === xv) {
        marks.push({ x: xv, y: vis[i].points[j].y, colorVar: vis[i].colorVar, shape: vis[i].shape, name: vis[i].name, si: i });
        break;
      }
    }
  }
  if (!marks.length) return null;
  var label = xLabelOf(model.xCol, model.xKind === 'ordinal' ? (raw != null ? raw : model.cats[xv]) : xv, false);
  if (model.xCol.type === 'date') {
    var t = model.xKind === 'ordinal' ? (raw != null ? raw : model.cats[xv]) : xv;
    label = fmtDateFull(t, model.xCol.prec);
  }
  return { kind: 'x', cat: model.xKind === 'ordinal' ? xv : null, x: xv, marks: marks, label: label, px: geo ? geo.X(xv) : null };
}
function paintHover(h, announce) {
  state.hover = h;
  draw();
  if (!h || !geo) { hideTip(); return; }
  if (h.kind === 'x') {
    var minY = Infinity, i;
    for (i = 0; i < h.marks.length; i++) minY = Math.min(minY, geo.Y(h.marks[i].y));
    var rows = h.marks.map(function (m) {
      return { colorVar: m.colorVar, name: state.model.gCol ? m.name : state.model.yCol.name, value: fmtY(m.y, state.model.yDec) + (state.model.yCol.unit || '') };
    });
    showTip(geo.X(h.x), minY, h.label, rows);
    if (announce) live.textContent = h.label + ': ' + rows.map(function (r) { return r.name + ' ' + r.value; }).join(', ');
  } else if (h.kind === 'pt') {
    var m = h.mark;
    var head = state.model.xCol.name + ' ' + xLabelOf(state.model.xCol, state.model.xKind === 'ordinal' ? state.model.cats[m.x] : m.x, false);
    showTip(geo.X(m.x), geo.Y(m.y), head, [{
      colorVar: m.colorVar,
      name: state.model.gCol ? m.name : state.model.yCol.name,
      value: fmtY(m.y, state.model.yDec) + (state.model.yCol.unit || '')
    }]);
    if (announce) live.textContent = head + ', ' + m.name + ' ' + fmtY(m.y, state.model.yDec);
  }
}

cv.addEventListener('pointermove', function (ev) {
  var model = state.model;
  if (!model || model.empty || !geo || anim.p < 1) return;
  var r = cv.getBoundingClientRect();
  var mx = ev.clientX - r.left, my = ev.clientY - r.top;
  if (mx < geo.padL - 12 || mx > geo.padL + geo.plotW + 12 || my > geo.padT + geo.plotH + 8) { state.hover = null; hideTip(); draw(); return; }
  if (model.type === 'scatter') {
    var best = null, bd = 44 * 44;
    var fp = flatPoints(model);
    for (var i = 0; i < fp.length; i++) {
      var dx = geo.X(fp[i].p.x) - mx, dy = geo.Y(fp[i].p.y) - my, d = dx * dx + dy * dy;
      if (d < bd) { bd = d; best = fp[i]; }
    }
    if (!best) { state.hover = null; hideTip(); draw(); return; }
    paintHover({ kind: 'pt', mark: { x: best.p.x, y: best.p.y, colorVar: best.s.colorVar, shape: best.s.shape, name: best.s.name } }, false);
  } else {
    var xs = xValueList(model);
    if (!xs.length) return;
    var bi = 0, bdist = Infinity;
    for (var k = 0; k < xs.length; k++) {
      var dd = Math.abs(geo.X(xs[k].x) - mx);
      if (dd < bdist) { bdist = dd; bi = k; }
    }
    state.keyIdx = bi;
    var h = hoverAtX(model, xs[bi].x, xs[bi].raw);
    paintHover(h, false);
  }
});
cv.addEventListener('pointerleave', function () { state.hover = null; hideTip(); draw(); });
cv.addEventListener('keydown', function (ev) {
  var model = state.model;
  if (!model || model.empty) return;
  var list = model.type === 'scatter' ? flatPoints(model) : xValueList(model);
  if (!list.length) return;
  var k = ev.key, handled = true;
  if (k === 'ArrowRight' || k === 'ArrowDown') state.keyIdx = Math.min(list.length - 1, state.keyIdx + 1);
  else if (k === 'ArrowLeft' || k === 'ArrowUp') state.keyIdx = state.keyIdx <= 0 ? 0 : state.keyIdx - 1;
  else if (k === 'Home') state.keyIdx = 0;
  else if (k === 'End') state.keyIdx = list.length - 1;
  else if (k === 'Escape') { state.keyIdx = -1; state.hover = null; hideTip(); draw(); live.textContent = ''; }
  else handled = false;
  if (!handled) return;
  ev.preventDefault();
  if (state.keyIdx < 0) return;
  if (model.type === 'scatter') {
    var it = list[state.keyIdx];
    paintHover({ kind: 'pt', mark: { x: it.p.x, y: it.p.y, colorVar: it.s.colorVar, shape: it.s.shape, name: it.s.name } }, true);
  } else {
    paintHover(hoverAtX(model, list[state.keyIdx].x, list[state.keyIdx].raw), true);
  }
});
cv.addEventListener('blur', function () { state.hover = null; hideTip(); draw(); });

/* ---------------- controls ---------------- */
selX.addEventListener('change', function () { setX(selX.value); syncSelects(); rebuild(true); });
selY.addEventListener('change', function () { setY(selY.value); syncSelects(); rebuild(true); });
selG.addEventListener('change', function () {
  state.g = selG.value; state.manual.g = true; state.hidden = Object.create(null);
  syncSelects(); rebuild(true);
});
Array.prototype.forEach.call(document.querySelectorAll('input[name="ctype"]'), function (r) {
  r.addEventListener('change', function () {
    if (!r.checked) return;
    state.type = r.value; state.manual.type = true;
    syncSelects(); rebuild(true);
  });
});
tableBtn.addEventListener('click', function () {
  state.showTable = !state.showTable;
  tableBtn.setAttribute('aria-expanded', state.showTable ? 'true' : 'false');
  tableBtn.textContent = state.showTable ? 'hide data table' : 'show data table';
  renderTable(state.model);
});

/* ---------------- input: typing, samples, files, drop ---------------- */
var sampleBtns = document.querySelectorAll('[data-sample]');
function markSample(name) {
  Array.prototype.forEach.call(sampleBtns, function (o) {
    o.setAttribute('aria-pressed', o.getAttribute('data-sample') === name ? 'true' : 'false');
  });
}
var typeTimer = 0;
elCsv.addEventListener('input', function () {
  markSample('');
  clearTimeout(typeTimer);
  typeTimer = setTimeout(function () { runParse(elCsv.value, true, false); }, 220);
});
Array.prototype.forEach.call(sampleBtns, function (b) {
  b.addEventListener('click', function () {
    var name = b.getAttribute('data-sample');
    elCsv.value = SAMPLES[name];
    markSample(name);
    runParse(elCsv.value, true, true);
  });
});
var drop = $('drop'), fileInput = $('file');
$('pickFile').addEventListener('click', function () { fileInput.click(); });
fileInput.addEventListener('change', function () {
  if (fileInput.files && fileInput.files[0]) readFile(fileInput.files[0]);
  fileInput.value = '';
});
function fileStatus(msg) {
  okPill.hidden = true; warnPill.hidden = true;
  clear(elIssues);
  elFacts.textContent = msg;
}
function readFile(f) {
  markSample('');
  if (f.size > 5e6) {
    elCsv.value = '';
    fileStatus('file too big — not read');
    showError('That file is too big', 'This demo reads files up to 5 MB in the browser. "' + f.name + '" is ' + (f.size / 1e6).toFixed(1) + ' MB.');
    return;
  }
  fileStatus('reading ' + f.name + '…');
  var fr = new FileReader();
  fr.onload = function () { elCsv.value = String(fr.result || ''); runParse(elCsv.value, true, true); };
  fr.onerror = function () {
    fileStatus('could not read ' + f.name);
    showError('Could not read that file', 'The browser refused to read "' + f.name + '".');
  };
  fr.readAsText(f);
}
['dragenter', 'dragover'].forEach(function (t) {
  drop.addEventListener(t, function (ev) { ev.preventDefault(); drop.classList.add('over'); });
});
['dragleave', 'dragend'].forEach(function (t) {
  drop.addEventListener(t, function () { drop.classList.remove('over'); });
});
drop.addEventListener('drop', function (ev) {
  ev.preventDefault();
  drop.classList.remove('over');
  var dt = ev.dataTransfer;
  if (!dt) return;
  if (dt.files && dt.files[0]) readFile(dt.files[0]);
  else {
    var txt = dt.getData('text');
    if (txt) { elCsv.value = txt; markSample(''); runParse(txt, true, true); }
  }
});
document.addEventListener('dragover', function (ev) { ev.preventDefault(); });
document.addEventListener('drop', function (ev) { ev.preventDefault(); });

/* ---------------- theme + resize ---------------- */
window.addEventListener('message', function (ev) {
  var d = ev.data;
  if (d && d.type === 'sloprun:theme' && (d.theme === 'light' || d.theme === 'dark')) {
    document.documentElement.setAttribute('data-theme', d.theme);
    repaintTheme();
  }
});
function repaintTheme() {
  draw();
  if (state.model) renderLegend(state.model);
}
/* the canvas is not CSS — it has to be told when the palette moves under it,
   including when the host flips data-theme on <html> without a message */
if (window.MutationObserver) {
  new MutationObserver(repaintTheme).observe(document.documentElement, {
    attributes: true, attributeFilter: ['data-theme']
  });
}
if (window.matchMedia) {
  var mq = window.matchMedia('(prefers-color-scheme: dark)');
  if (mq.addEventListener) mq.addEventListener('change', repaintTheme);
  else if (mq.addListener) mq.addListener(repaintTheme);
  if (reduce.addEventListener) reduce.addEventListener('change', function () { anim.p = 1; draw(); });
}
var rzTimer = 0;
function onResize() {
  cancelAnimationFrame(rzTimer);
  rzTimer = requestAnimationFrame(function () {
    state.hover = null; hideTip();
    sizeCanvas();
    if (!anim.raf) anim.p = 1;   /* don't cut the entrance animation short */
    draw();
  });
}
if (window.ResizeObserver) new ResizeObserver(onResize).observe($('plotwrap'));
else window.addEventListener('resize', onResize);

/* ---------------- boot ---------------- */
elCsv.value = SAMPLES.weather;
markSample('weather');
runParse(elCsv.value, true, true);
})();
</script>
</body>
</html>