// metrics.js — client-side filtering + hand-rolled SVG line charts for the
// metrics page. No deps. Reads /metrics.json (list of sidecar-JSON contents),
// filters by dataset + algorithm, and overlays every matching run on three
// plots: frame-to-frame travel, vs-initial travel, kNN retention.

const SVG_NS = "http://www.w3.org/2000/svg";

// Qualitative palette — defined as CSS custom properties on :root (and
// overridden under [data-theme="dark"]) so the theme toggle automatically
// swaps plot colours. Read fresh on every render.
function getPalette() {
  const cs = getComputedStyle(document.documentElement);
  const out = [];
  for (let i = 1; i <= 8; i++) {
    const v = cs.getPropertyValue(`--plot-${i}`).trim();
    if (v) out.push(v);
  }
  return out.length ? out : ["#1f4e5f"];
}

const state = {
  raw: [],
  // Multi-select: membership = "this value is currently enabled". Empty
  // set = nothing shows (matches "none" toggle). Both default to all
  // values on load so the initial view matches what a user expects.
  datasets: new Set(),
  algorithms: new Set(),
  datasetsAll: [],
  algorithmsAll: [],
  stat: "mean",
  // Runs the user has clicked in the legend to isolate. Empty = show all.
  selected: new Set(),
};

const shortGen = (p) => (p || "").split(".").pop();
const shortEmb = (p) => (p || "").split(".").pop();

function runLabel(r) {
  const m = r.meta || {};
  return `${shortEmb(m.embedder)} · ${shortGen(m.generator_path)} · N${m.num_points} T${m.num_timesteps} J${m.jitter_scale} s${m.seed}`;
}

function runKey(r) {
  return r.filename;
}

async function init() {
  const resp = await fetch("/metrics.json");
  state.raw = await resp.json();

  populateFilters();
  wireEvents();
  document.addEventListener("themechange", render);
  render();
}

function populateFilters() {
  const datasets = new Set();
  const algos = new Set();
  for (const r of state.raw) {
    datasets.add(shortGen(r.meta?.generator_path));
    algos.add(shortEmb(r.meta?.embedder));
  }
  state.datasetsAll = [...datasets].filter(Boolean).sort();
  state.algorithmsAll = [...algos].filter(Boolean).sort();
  // Default to everything enabled.
  state.datasets = new Set(state.datasetsAll);
  state.algorithms = new Set(state.algorithmsAll);
  renderChips();
  document.getElementById("total-count").textContent = state.raw.length;
}

function renderChips() {
  paintChips("flt-dataset", state.datasetsAll, state.datasets);
  paintChips("flt-algo", state.algorithmsAll, state.algorithms);
}

function paintChips(containerId, values, selectedSet) {
  const el = document.getElementById(containerId);
  el.innerHTML = "";

  for (const v of values) {
    const b = document.createElement("button");
    b.type = "button";
    b.className = "chip" + (selectedSet.has(v) ? " is-on" : "");
    b.setAttribute("aria-pressed", selectedSet.has(v) ? "true" : "false");
    b.dataset.value = v;
    b.dataset.role = "value";
    b.textContent = v;
    el.appendChild(b);
  }

  for (const [role, label] of [["all", "all"], ["none", "none"]]) {
    const b = document.createElement("button");
    b.type = "button";
    b.className = "chip chip-meta";
    b.dataset.role = role;
    b.textContent = label;
    el.appendChild(b);
  }
}

function wireEvents() {
  const bindChipRow = (containerId, selectedSet, allList) => {
    document.getElementById(containerId).addEventListener("click", (e) => {
      const btn = e.target.closest(".chip");
      if (!btn) return;
      const role = btn.dataset.role;
      if (role === "value") {
        const v = btn.dataset.value;
        if (selectedSet.has(v)) selectedSet.delete(v);
        else selectedSet.add(v);
      } else if (role === "all") {
        for (const v of allList) selectedSet.add(v);
      } else if (role === "none") {
        selectedSet.clear();
      }
      renderChips();
      render();
    });
  };
  bindChipRow("flt-dataset", state.datasets, state.datasetsAll);
  bindChipRow("flt-algo", state.algorithms, state.algorithmsAll);

  document.querySelectorAll('input[name="stat"]').forEach((el) => {
    el.addEventListener("change", (e) => {
      if (e.target.checked) { state.stat = e.target.value; render(); }
    });
  });
}

function matchesFilters(r) {
  const m = r.meta || {};
  if (!state.datasets.has(shortGen(m.generator_path))) return false;
  if (!state.algorithms.has(shortEmb(m.embedder))) return false;
  return true;
}

function filtered() {
  // Legend lists every run passing the dropdown filters. If the user has
  // clicked any legend rows, plots restrict to those; legend still shows
  // the full filtered set so you can toggle more in/out.
  return state.raw.filter(matchesFilters);
}

function plotted(runs) {
  if (state.selected.size === 0) return runs;
  return runs.filter((r) => state.selected.has(runKey(r)));
}

function render() {
  const runs = filtered();
  document.getElementById("match-count").textContent = runs.length;

  const empty = document.getElementById("empty");
  empty.hidden = state.raw.length !== 0;

  // Prune selections that no longer match the filters so the plots don't
  // stay empty when the user narrows the dataset/algo dropdowns.
  const visibleKeys = new Set(runs.map(runKey));
  for (const k of state.selected) {
    if (!visibleKeys.has(k)) state.selected.delete(k);
  }

  // Stable colour assignment per legend row (across the full filtered set),
  // so toggling selection doesn't shuffle colours.
  const palette = getPalette();
  const colored = runs.map((r, i) => ({
    run: r,
    color: palette[i % palette.length],
    selected: state.selected.has(runKey(r)),
  }));
  const forPlot = state.selected.size === 0 ? colored : colored.filter((c) => c.selected);

  const onPick = (key) => {
    if (state.selected.has(key)) state.selected.delete(key);
    else state.selected.add(key);
    render();
  };

  renderLineChart(
    document.getElementById("plot-ff"),
    forPlot.map(({ run, color }) => ({
      key: runKey(run),
      label: runLabel(run),
      color,
      points: (run.travel?.frame_to_frame || []).map((row) => [row.t, row[state.stat]]),
    })),
    { yLabel: "distance", xLabel: "t", onPick }
  );

  renderLineChart(
    document.getElementById("plot-vi"),
    forPlot.map(({ run, color }) => ({
      key: runKey(run),
      label: runLabel(run),
      color,
      points: (run.travel?.vs_initial || []).map((row) => [row.t, row[state.stat]]),
    })),
    { yLabel: "distance", xLabel: "t", onPick }
  );

  renderLineChart(
    document.getElementById("plot-knn"),
    forPlot.map(({ run, color }) => ({
      key: runKey(run),
      label: runLabel(run),
      color,
      points: (run.knn_retention || []).map((row) => [row.t, row.mean]),
    })),
    { yLabel: "retention", xLabel: "t", yMin: 0, yMax: 1, onPick }
  );

  renderLegend(colored);
}

function renderLegend(colored) {
  const el = document.getElementById("legend");
  el.innerHTML = "";
  if (!colored.length) return;

  const hasSelection = state.selected.size > 0;

  if (hasSelection) {
    const clear = document.createElement("button");
    clear.type = "button";
    clear.className = "legend-clear";
    clear.textContent = `clear selection (${state.selected.size})`;
    clear.addEventListener("click", () => {
      state.selected.clear();
      render();
    });
    el.appendChild(clear);
  }

  for (const { run, color, selected } of colored) {
    const row = document.createElement("button");
    row.type = "button";
    row.className = "legend-row" + (selected ? " is-selected" : "") +
      (hasSelection && !selected ? " is-dim" : "");
    row.setAttribute("aria-pressed", selected ? "true" : "false");
    row.innerHTML = `
      <span class="swatch" style="background:${color}"></span>
      <span class="lbl">${runLabel(run)}</span>
      <span class="fn">${run.filename}</span>
    `;
    row.addEventListener("click", () => {
      const k = runKey(run);
      if (state.selected.has(k)) state.selected.delete(k);
      else state.selected.add(k);
      render();
    });
    el.appendChild(row);
  }
}

// ---------- SVG line chart -------------------------------------------------

function renderLineChart(container, series, opts = {}) {
  container.innerHTML = "";

  const W = 720, H = 240;
  // left gutter fits (from outer to inner): y-label column (~16px) +
  // breathing (~10px) + widest tick label (~30px) + tick gap (6px).
  const PAD = { top: 12, right: 16, bottom: 28, left: 62 };

  const allPts = series.flatMap((s) => s.points).filter((p) => Number.isFinite(p[0]) && Number.isFinite(p[1]));
  const hasData = allPts.length > 0;

  const svg = document.createElementNS(SVG_NS, "svg");
  svg.setAttribute("viewBox", `0 0 ${W} ${H}`);
  svg.setAttribute("role", "img");
  svg.classList.add("chart");

  if (!hasData) {
    const t = text(W / 2, H / 2, "no data", "empty");
    t.setAttribute("text-anchor", "middle");
    svg.appendChild(t);
    container.appendChild(svg);
    return;
  }

  const xs = allPts.map((p) => p[0]);
  const ys = allPts.map((p) => p[1]);
  const xMin = Math.min(...xs), xMax = Math.max(...xs);
  let yMin = opts.yMin !== undefined ? opts.yMin : Math.min(0, Math.min(...ys));
  let yMax = opts.yMax !== undefined ? opts.yMax : Math.max(...ys);
  if (yMax === yMin) yMax = yMin + 1;

  const xPx = (x) => PAD.left + ((x - xMin) / Math.max(1, xMax - xMin)) * (W - PAD.left - PAD.right);
  const yPx = (y) => H - PAD.bottom - ((y - yMin) / (yMax - yMin)) * (H - PAD.top - PAD.bottom);

  // gridlines (4 horizontal ticks)
  const nTicks = 4;
  for (let i = 0; i <= nTicks; i++) {
    const yVal = yMin + ((yMax - yMin) * i) / nTicks;
    const y = yPx(yVal);
    const gl = document.createElementNS(SVG_NS, "line");
    gl.setAttribute("x1", PAD.left);
    gl.setAttribute("x2", W - PAD.right);
    gl.setAttribute("y1", y);
    gl.setAttribute("y2", y);
    gl.classList.add("grid");
    svg.appendChild(gl);

    const lbl = text(PAD.left - 6, y + 3.5, fmtTick(yVal), "axis");
    lbl.setAttribute("text-anchor", "end");
    svg.appendChild(lbl);
  }

  // x-axis ticks (at integer t, max ~8 labels)
  const xSpan = Math.max(1, xMax - xMin);
  const everyX = Math.max(1, Math.ceil(xSpan / 8));
  for (let x = Math.ceil(xMin); x <= xMax; x += everyX) {
    const px = xPx(x);
    const tick = document.createElementNS(SVG_NS, "line");
    tick.setAttribute("x1", px); tick.setAttribute("x2", px);
    tick.setAttribute("y1", H - PAD.bottom); tick.setAttribute("y2", H - PAD.bottom + 3);
    tick.classList.add("axis-tick");
    svg.appendChild(tick);

    const lbl = text(px, H - PAD.bottom + 14, String(x), "axis");
    lbl.setAttribute("text-anchor", "middle");
    svg.appendChild(lbl);
  }

  // axis lines
  const xAxis = document.createElementNS(SVG_NS, "line");
  xAxis.setAttribute("x1", PAD.left); xAxis.setAttribute("x2", W - PAD.right);
  xAxis.setAttribute("y1", H - PAD.bottom); xAxis.setAttribute("y2", H - PAD.bottom);
  xAxis.classList.add("axis"); svg.appendChild(xAxis);

  // y/x labels
  if (opts.yLabel) {
    const cx = 10;
    const cy = PAD.top + (H - PAD.top - PAD.bottom) / 2;
    const g = document.createElementNS(SVG_NS, "g");
    g.setAttribute("transform", `translate(${cx} ${cy}) rotate(-90)`);
    const lbl = document.createElementNS(SVG_NS, "text");
    lbl.setAttribute("text-anchor", "middle");
    lbl.setAttribute("dominant-baseline", "middle");
    lbl.classList.add("axis-label");
    lbl.textContent = opts.yLabel;
    g.appendChild(lbl);
    svg.appendChild(g);
  }
  if (opts.xLabel) {
    const lbl = text(W - PAD.right, H - 6, opts.xLabel, "axis-label");
    lbl.setAttribute("text-anchor", "end");
    svg.appendChild(lbl);
  }

  // lines
  const drawn = [];
  for (const s of series) {
    const pts = s.points.filter((p) => Number.isFinite(p[0]) && Number.isFinite(p[1]));
    if (!pts.length) continue;
    const d = pts.map((p, i) => `${i === 0 ? "M" : "L"}${xPx(p[0]).toFixed(2)},${yPx(p[1]).toFixed(2)}`).join(" ");
    const path = document.createElementNS(SVG_NS, "path");
    path.setAttribute("d", d);
    path.setAttribute("stroke", s.color);
    path.setAttribute("fill", "none");
    path.setAttribute("stroke-width", "1.5");
    path.setAttribute("stroke-linejoin", "round");
    path.setAttribute("stroke-linecap", "round");
    path.classList.add("series");
    const nativeTitle = document.createElementNS(SVG_NS, "title");
    nativeTitle.textContent = s.label;
    path.appendChild(nativeTitle);
    svg.appendChild(path);
    drawn.push({ key: s.key, label: s.label, color: s.color, pts, d, path });
  }

  // Hover affordances. A single transparent overlay rect captures all
  // pointer events over the plot area; we find the nearest line
  // mathematically. More robust than per-line stroke hit-testing. All
  // styling is applied inline so it doesn't depend on stylesheet caching.
  if (getComputedStyle(container).position === "static") {
    container.style.position = "relative";
  }

  const marker = document.createElementNS(SVG_NS, "circle");
  marker.setAttribute("r", "3.5");
  marker.setAttribute("stroke-width", "2");
  marker.setAttribute("fill", "#ffffff");
  marker.setAttribute("pointer-events", "none");
  marker.style.display = "none";
  svg.appendChild(marker);

  const tooltip = document.createElement("div");
  Object.assign(tooltip.style, {
    position: "absolute",
    pointerEvents: "none",
    zIndex: "4",
    display: "none",
    minWidth: "180px",
    maxWidth: "320px",
    padding: "6px 9px",
    background: "var(--panel, #ffffff)",
    color: "var(--ink, #111)",
    border: "1px solid var(--rule-2, #bbb)",
    borderLeft: "3px solid var(--ink, #111)",
    boxShadow: "0 4px 14px rgba(0, 0, 0, 0.14)",
    fontSize: "12px",
    lineHeight: "1.3",
    left: "0",
    top: "0",
  });
  const ttLabel = document.createElement("div");
  Object.assign(ttLabel.style, {
    fontWeight: "600",
    whiteSpace: "nowrap",
    overflow: "hidden",
    textOverflow: "ellipsis",
  });
  const ttValues = document.createElement("div");
  Object.assign(ttValues.style, {
    fontFamily: "var(--mono, ui-monospace, monospace)",
    opacity: "0.75",
    marginTop: "2px",
  });
  tooltip.appendChild(ttLabel);
  tooltip.appendChild(ttValues);

  const dimOthers = (active) => {
    for (const o of drawn) {
      if (o === active) {
        o.path.style.opacity = "1";
        o.path.style.strokeWidth = "2.25";
      } else {
        o.path.style.opacity = "0.18";
        o.path.style.strokeWidth = "";
      }
    }
  };
  const clearDim = () => {
    for (const o of drawn) {
      o.path.style.opacity = "";
      o.path.style.strokeWidth = "";
    }
  };

  // Interpolate a series' y at a given data-x; also return the nearest
  // actual data point (for marker placement + tooltip value readout).
  const seriesYAt = (pts, x) => {
    if (!pts.length) return null;
    if (x <= pts[0][0]) return { y: pts[0][1], pt: pts[0] };
    if (x >= pts[pts.length - 1][0]) {
      const last = pts[pts.length - 1];
      return { y: last[1], pt: last };
    }
    for (let i = 1; i < pts.length; i++) {
      const a = pts[i - 1], b = pts[i];
      if (x >= a[0] && x <= b[0]) {
        const span = b[0] - a[0];
        const t = span === 0 ? 0 : (x - a[0]) / span;
        const y = a[1] + t * (b[1] - a[1]);
        const pt = Math.abs(x - a[0]) < Math.abs(x - b[0]) ? a : b;
        return { y, pt };
      }
    }
    return { y: pts[pts.length - 1][1], pt: pts[pts.length - 1] };
  };

  const overlay = document.createElementNS(SVG_NS, "rect");
  overlay.setAttribute("x", "0");
  overlay.setAttribute("y", "0");
  overlay.setAttribute("width", W);
  overlay.setAttribute("height", H);
  overlay.setAttribute("fill", "transparent");
  overlay.setAttribute("pointer-events", "all");
  overlay.style.cursor = "crosshair";

  let activeDs = null;
  const hideHover = () => {
    if (!activeDs) return;
    clearDim();
    marker.style.display = "none";
    tooltip.style.display = "none";
    overlay.style.cursor = "crosshair";
    activeDs = null;
  };

  overlay.addEventListener("pointermove", (e) => {
    const svgRect = svg.getBoundingClientRect();
    const vbX = ((e.clientX - svgRect.left) / svgRect.width) * W;
    const vbY = ((e.clientY - svgRect.top) / svgRect.height) * H;
    // Outside the inner plot area? Release.
    if (vbX < PAD.left || vbX > W - PAD.right || vbY < PAD.top || vbY > H - PAD.bottom) {
      hideHover();
      return;
    }
    const dataX = xMin + ((vbX - PAD.left) / (W - PAD.left - PAD.right)) * (xMax - xMin);

    // Nearest line to the cursor, measured in *pixels* on the y axis at the
    // cursor's x. A proximity threshold keeps the tooltip quiet in empty
    // regions of the chart.
    let best = null;
    let bestDist = Infinity;
    for (const ds of drawn) {
      const hit = seriesYAt(ds.pts, dataX);
      if (!hit) continue;
      const distPx = Math.abs(yPx(hit.y) - vbY);
      if (distPx < bestDist) {
        bestDist = distPx;
        best = { ds, pt: hit.pt };
      }
    }
    if (!best || bestDist > 40) {
      hideHover();
      return;
    }

    const { ds, pt } = best;
    if (activeDs !== ds) {
      activeDs = ds;
      dimOthers(ds);
      marker.setAttribute("stroke", ds.color);
      marker.style.display = "";
      tooltip.style.display = "block";
      tooltip.style.borderLeftColor = ds.color;
      overlay.style.cursor = typeof opts.onPick === "function" ? "pointer" : "crosshair";
    }
    marker.setAttribute("cx", xPx(pt[0]).toFixed(2));
    marker.setAttribute("cy", yPx(pt[1]).toFixed(2));
    ttLabel.textContent = ds.label;
    ttValues.textContent = `t=${pt[0]} · ${fmtTick(pt[1])}`;

    const cRect = container.getBoundingClientRect();
    const ttW = tooltip.offsetWidth || 200;
    const ttH = tooltip.offsetHeight || 44;
    let left = e.clientX - cRect.left + 12;
    let top = e.clientY - cRect.top + 12;
    if (left + ttW > cRect.width - 4) left = e.clientX - cRect.left - ttW - 12;
    if (top + ttH > cRect.height - 4) top = e.clientY - cRect.top - ttH - 12;
    if (left < 4) left = 4;
    if (top < 4) top = 4;
    tooltip.style.left = left + "px";
    tooltip.style.top = top + "px";
  });
  overlay.addEventListener("pointerleave", hideHover);
  overlay.addEventListener("click", () => {
    if (activeDs && typeof opts.onPick === "function" && activeDs.key != null) {
      opts.onPick(activeDs.key);
    }
  });
  svg.appendChild(overlay);

  container.appendChild(svg);
  container.appendChild(tooltip);
}

function text(x, y, str, cls) {
  const el = document.createElementNS(SVG_NS, "text");
  el.setAttribute("x", x);
  el.setAttribute("y", y);
  if (cls) el.classList.add(cls);
  el.textContent = str;
  return el;
}

function fmtTick(v) {
  const abs = Math.abs(v);
  if (abs === 0) return "0";
  if (abs < 0.01) return v.toExponential(1);
  if (abs < 1) return v.toFixed(3);
  if (abs < 10) return v.toFixed(2);
  if (abs < 100) return v.toFixed(1);
  return v.toFixed(0);
}

init();