/* manimo playground — loads every per-paper manifest from data/ and renders the gallery of testers.
 * Each paper is themed with the SAME palette as its video; each animated concept gets its interactive
 * tester (from MANIMO.registry, by primitive) so you can run the very computation the video explains.
 *
 * One click → the whole paper plays: a "Play all" bar walks every concept in storyboard order, scrolls
 * to it, lights it up, runs its animation to completion, then advances — a web mirror of the Manim video
 * (same params, same math, same order), so the page and the video tell the identical story. */
(function () {
  const k = MANIMO.kit;
  const DEFAULT_THEME = { bg: "#0E1116", ink: "#E8EDF3", muted: "#8B95A1", accent: "#58A6FF", accent2: "#BC8CFF" };

  async function getJSON(url) { const r = await fetch(url, { cache: "no-store" }); if (!r.ok) throw new Error(url + " " + r.status); return r.json(); }

  function applyTheme(node, theme) {
    const t = Object.assign({}, DEFAULT_THEME, theme || {});
    node.style.setProperty("--bg", t.bg); node.style.setProperty("--ink", t.ink);
    node.style.setProperty("--muted", t.muted); node.style.setProperty("--accent", t.accent);
    node.style.setProperty("--accent2", t.accent2); node.style.setProperty("--card", k.mix(t.bg, t.ink, 0.06));
    return t;
  }

  function widgetFor(concept) {
    return MANIMO.registry[concept.widget] || MANIMO.registry[concept.primitive] || MANIMO.registry["_generic"];
  }

  // ── Fullscreen + "theater" big-screen mode ─────────────────────────────────────────────────────
  // Play-all enters a theater layout (nav/topbar fold away, the playing card fills the screen so the
  // animation is large and legible) and best-effort requests real OS fullscreen. Theater is a CSS class
  // so it still applies when the Fullscreen API is blocked (e.g. the "#play" autostart has no user
  // gesture); fullscreen, when granted, just makes it edge-to-edge.
  function fsElement() { return document.fullscreenElement || document.webkitFullscreenElement || null; }
  function requestFS() {
    const el = document.documentElement;
    const fn = el.requestFullscreen || el.webkitRequestFullscreen || el.msRequestFullscreen;
    if (!fn) return;
    try { const r = fn.call(el); if (r && r.catch) r.catch(() => {}); } catch (e) { /* blocked → theater still applies */ }
  }
  function exitFS() {
    if (!fsElement()) return;
    const fn = document.exitFullscreen || document.webkitExitFullscreen || document.msExitFullscreen;
    if (!fn) return;
    try { const r = fn.call(document); if (r && r.catch) r.catch(() => {}); } catch (e) { /* noop */ }
  }

  // ── Narration: give the playground a VOICE with the browser's built-in speech synthesis (no files,
  // no deps — the buildless way to add audio). Each concept's plain-language explainer is spoken as it
  // plays. Triggered by the Play-all click (a real user gesture) so browsers allow it; the autostart
  // "#play" link may be muted by autoplay policy, exactly like the fullscreen request. ──
  const SPEECH = (typeof window !== "undefined" && window.speechSynthesis) || null;
  let narrOn = !!SPEECH;
  function pickVoice() {
    if (!SPEECH) return null;
    const vs = SPEECH.getVoices() || [];
    return vs.find((v) => /^en[-_]?US/i.test(v.lang)) || vs.find((v) => /^en/i.test(v.lang)) || vs[0] || null;
  }
  function speak(text, onEnd) {
    if (!SPEECH || !narrOn || !text) { if (onEnd) onEnd(); return; }
    try {
      SPEECH.cancel();                                   // never let two lines overlap
      const u = new SpeechSynthesisUtterance(String(text).replace(/\s+/g, " ").trim().slice(0, 320));
      const v = pickVoice(); if (v) { u.voice = v; u.lang = v.lang; }
      u.rate = 0.98; u.pitch = 1.0;
      if (onEnd) { u.onend = onEnd; u.onerror = onEnd; }  // tell the transport when the spoken line finishes
      SPEECH.speak(u);
    } catch (e) { if (onEnd) onEnd(); }                  // speech blocked → don't stall the sequence
  }
  function hush() { if (SPEECH) { try { SPEECH.cancel(); } catch (e) { /* noop */ } } }
  if (SPEECH) { try { SPEECH.getVoices(); SPEECH.addEventListener("voiceschanged", () => {}); } catch (e) { /* noop */ } }

  // The water-drop flow rail: a glowing teardrop descends a vertical stream, one station per slide. On each
  // slide the drop FALLS to that slide's station (a gravity-eased transition), LANDS with a ripple while
  // the slide's video plays, then falls on to the next — a literal "water flowing down the page, pausing
  // to explain each slide, playing its video, then falling to the next". The fill above the drop = progress.
  function buildFlow(n) {
    const TOP = 4, BOT = 96, FALL_MS = 720;              // FALL_MS must match the CSS .flow-drop transition
    const yOf = (i) => (n <= 1 ? 50 : TOP + (BOT - TOP) * (i / (n - 1)));
    const stream = k.el("div", { class: "flow-stream" });
    const fillv = k.el("div", { class: "flow-fill" });
    const ripple = k.el("div", { class: "flow-ripple" });
    const drop = k.el("div", { class: "flow-drop" }, [k.el("div", { class: "bulb" })]);
    const rail = k.el("div", { class: "flowrail", "aria-hidden": "true" }, [stream, fillv]);
    const stations = [];
    for (let i = 0; i < n; i++) {
      const st = k.el("i", { class: "flow-station" });
      st.style.top = yOf(i) + "%";
      stations.push(st); rail.appendChild(st);
    }
    rail.appendChild(ripple); rail.appendChild(drop);
    let landT = null, postT = null;
    function clear() { if (landT) clearTimeout(landT); if (postT) clearTimeout(postT); landT = postT = null; }
    return {
      el: rail,
      to(i) {                                            // drop falls to slide i, then lands + ripples
        const y = yOf(i);
        clear();
        drop.classList.add("falling");
        drop.style.top = y + "%";
        fillv.style.height = Math.max(0, y - TOP) + "%";
        ripple.style.top = y + "%";
        stations.forEach((s, j) => { s.classList.toggle("done", j < i); s.classList.toggle("active", j === i); });
        landT = setTimeout(() => {
          drop.classList.remove("falling"); drop.classList.add("land");
          ripple.classList.remove("go"); void ripple.offsetWidth; ripple.classList.add("go");  // restart ripple
          postT = setTimeout(() => drop.classList.remove("land"), 520);
        }, FALL_MS);
      },
      reset() {
        clear();
        drop.classList.remove("falling", "land"); drop.style.top = TOP + "%";
        fillv.style.height = "0%";
        stations.forEach((s) => s.classList.remove("done", "active"));
      },
      atTop: TOP,
    };
  }

  // The "Play all" transport: drives every concept's player in order, like scrubbing through the video —
  // but paced for a human: each concept settles into view, plays, then HOLDS so you can take it all in.
  function buildTransport(players) {
    const SETTLE_MS = 650;   // let the scroll + spotlight land before the animation starts
    const HOLD_MS = 2000;    // comprehension pause after each concept finishes, before advancing
    let running = false, cancelled = false, idx = -1, timer = null, speechTimer = null;
    const fill = k.el("i", { class: "fill" });
    const rail = k.el("div", { class: "rail" }, [fill]);
    const caption = k.el("span", { class: "cap" }, ["Press play to watch + hear the whole paper, step by step — full screen, narrated."]);
    const count = k.el("span", { class: "count" }, ["0 / " + players.length]);
    const playBtn = k.el("button", { class: "btn play", onclick: start }, ["▶  Play all"]);
    const stopBtn = k.el("button", { class: "btn ghost", onclick: stop }, ["⏹  Stop"]);
    stopBtn.disabled = true;
    const muteBtn = k.el("button", { class: "btn ghost mute", onclick: toggleNarr, title: "Narration on/off" }, [narrOn ? "🔊" : "🔇"]);
    if (!SPEECH) { muteBtn.disabled = true; muteBtn.title = "Narration not supported in this browser"; }
    const bar = k.el("div", { class: "transport" }, [
      k.el("div", { class: "tbtns" }, [playBtn, stopBtn, muteBtn]),
      k.el("div", { class: "tmeta" }, [k.el("div", { class: "caprow" }, [caption, count]), rail]),
    ]);
    const flow = buildFlow(players.length);              // the descending water-drop, one station per slide
    bar.appendChild(flow.el);                            // position:fixed → floats over the theater stage

    function toggleNarr() {
      narrOn = !narrOn;
      muteBtn.textContent = narrOn ? "🔊" : "🔇";
      hush();                                              // stop any browser TTS
      document.querySelectorAll("video.manim-hero").forEach((v) => { v.muted = !narrOn; });  // mute/unmute clip audio
    }
    function clearTimer() { if (timer) { clearTimeout(timer); timer = null; } if (speechTimer) { clearTimeout(speechTimer); speechTimer = null; } }
    function later(fn, ms) { clearTimer(); timer = setTimeout(fn, ms); }
    function progress(done) { fill.style.width = (players.length ? (100 * done / players.length) : 0) + "%"; }
    function spotlight(i) {
      players.forEach((p, j) => p.card.classList.toggle("playing", i === j));
      if (i >= 0 && players[i]) players[i].card.scrollIntoView({ behavior: "smooth", block: "center" });
    }
    function enterTheater() { document.body.classList.add("theater"); requestFS(); }
    function exitTheater() { document.body.classList.remove("theater"); exitFS(); }
    function teardown(msg, ok) {
      running = false; cancelled = false; idx = -1; clearTimer(); hush();
      playBtn.disabled = false; stopBtn.disabled = true;
      players.forEach((p) => p.card.classList.remove("playing"));
      flow.reset();
      exitTheater();
      caption.textContent = msg; caption.classList.toggle("ok", !!ok);
    }
    function step() {
      if (!running || cancelled) return;
      idx++;
      if (idx >= players.length) { progress(players.length); teardown("Finished — that's the whole paper. ▶ replay or edit any input.", true); return; }
      const p = players[idx];
      caption.classList.remove("ok");
      caption.textContent = "Now playing — " + p.name;
      count.textContent = (idx + 1) + " / " + players.length;
      progress(idx);
      spotlight(idx);                                    // light it up + scroll, THEN settle before playing
      flow.to(idx);                                      // the drop falls to this slide + lands with a ripple

      // A slide is finished only when BOTH its animation has played out AND its spoken explanation has
      // been said in full — whichever takes longer. That's the fix for the "cut short" feeling: narration
      // (~8–12s/concept) used to be chopped off when the shorter visual + hold advanced the slide.
      let visualDone = false, speechDone = false, advanced = false, narrated = false;
      function advance() {
        if (advanced || !running || cancelled || !visualDone || !speechDone) return;
        advanced = true;
        caption.textContent = "Take it in — " + p.name;
        later(step, narrated ? 800 : HOLD_MS);           // narration already gave dwell time; else a full hold
      }
      function onSpeechEnd() {
        if (speechDone) return;
        speechDone = true;
        if (speechTimer) { clearTimeout(speechTimer); speechTimer = null; }
        advance();
      }
      // Clip slides carry their own baked-in Kokoro narration on the video's audio track; only fall back to
      // the browser's Web Speech voice for concepts with NO clip (e.g. pipeline runs without rendered clips).
      if (narrOn && SPEECH && !p.hasClip && (p.say || p.name)) {
        narrated = true;
        speak(p.say || p.name, onSpeechEnd);
        const words = String(p.say || p.name).split(/\s+/).length;
        speechTimer = setTimeout(onSpeechEnd, Math.min(24000, words * 430 + 4000));  // safety if no 'end' event
      } else {
        speechDone = true;
      }
      later(() => {
        if (!running || cancelled) return;
        try {
          p.player.reset();
          p.player.play(() => { if (!running || cancelled) return; visualDone = true; progress(idx + 1); advance(); });
        } catch (e) { visualDone = true; progress(idx + 1); advance(); }
      }, SETTLE_MS);
    }
    function start() {
      if (running) return;
      running = true; cancelled = false; idx = -1;
      playBtn.disabled = true; stopBtn.disabled = false;
      caption.classList.remove("ok");
      enterTheater();                                    // go big-screen the instant Play all is pressed
      flow.reset();                                      // drop at the top of the stream, ready to fall
      step();
    }
    function stop() {
      if (!running) return;
      cancelled = true; clearTimer();
      if (idx >= 0 && players[idx]) { try { players[idx].player.stop(); } catch (e) { /* noop */ } }
      teardown("Stopped. ▶ Play all to watch it again.", false);
    }
    // Exiting fullscreen (ESC) while playing ends the run cleanly and drops the theater layout.
    const onFsChange = () => { if (!fsElement() && running) stop(); };
    document.addEventListener("fullscreenchange", onFsChange);
    document.addEventListener("webkitfullscreenchange", onFsChange);
    bar.start = start;     // expose so a "#play" link can auto-run the whole paper
    return bar;
  }

  // A connector strip drawn between two interconnected cards: the upstream value flows into this one.
  function connector(key, fromTitle) {
    return k.el("div", { class: "flowlink" }, [
      k.el("span", { class: "flow-dot" }, []),
      k.el("span", { class: "flow-var" }, [key]),
      k.el("span", { class: "flow-txt" }, ["flows in from " + fromTitle]),
    ]);
  }

  // Drive a Manim-clip <video> as a transport "player": play it to the end, then signal done. Robust to a
  // missing/blocked clip (resolves anyway) so a broken clip can never stall the Play-all sequence.
  function videoPlayer(video) {
    let cap = null;
    const clearCap = () => { if (cap) { clearTimeout(cap); cap = null; } };
    return {
      play(done) {
        const finish = () => { clearCap(); video.onended = null; video.onerror = null; if (done) done(); };
        try {
          try { video.currentTime = 0; } catch (e) { /* not seekable yet */ }
          video.onended = finish;
          video.onerror = finish;
          // play WITH sound (the narration is baked into the clip); if the browser blocks unmuted autoplay,
          // retry muted so the visual still runs (narration just won't be heard on that strict browser).
          const attempt = (muted) => {
            video.muted = muted;
            const pr = video.play();
            if (pr && pr.catch) pr.catch(() => (muted ? finish() : attempt(true)));
          };
          attempt(!narrOn);
          cap = setTimeout(finish, 60000);                 // hard safety cap so a stuck clip never hangs
        } catch (e) { finish(); }
      },
      stop() { clearCap(); try { video.pause(); } catch (e) { /* noop */ } },
      reset() { clearCap(); try { video.pause(); video.currentTime = 0; } catch (e) { /* noop */ } },
    };
  }

  function renderPaper(main, manifest) {
    k.clear(main);
    MANIMO.bus.clear();                  // fresh data bus per paper; widgets re-wire as they mount in order
    const theme = applyTheme(main, manifest.theme);
    main.appendChild(k.el("div", { class: "paper-head" }, [
      k.el("h1", null, [manifest.title || "Paper"]),
      k.el("p", { class: "sub" }, [manifest.subtitle || ""]),
    ]));
    const concepts = manifest.concepts || [];
    if (!concepts.length) { main.appendChild(k.el("p", { class: "empty" }, ["No animated concepts in this paper."])); return; }

    const players = [], nodes = [], produced = {};
    concepts.forEach((c, i) => {
      const w = widgetFor(c);
      const name = c.title || c.label || w.title;
      const io = c.io || {};
      // mounting order = manifest order, so an upstream producer has already published before this mounts.
      if (io.consumes && produced[io.consumes]) nodes.push(connector(io.consumes, produced[io.consumes]));
      const card = k.el("section", { class: "card" });
      card.appendChild(k.el("div", { class: "card-h" }, [
        k.el("span", { class: "card-n" }, [String(i + 1).padStart(2, "0")]),
        k.el("span", { class: "card-t" }, [name]),
        k.el("span", { class: "tag" }, [w.title]),
      ]));
      const body = k.el("div", { class: "card-b" });
      card.appendChild(body);
      // The hero is the real Manim clip (same params as the video); the interactive widget sits below as
      // "try it yourself". Play-all plays the Manim clip; exit theater to tinker with the live widget.
      let hero = null;
      if (c.clip) {
        const video = k.el("video", {
          class: "manim-hero", src: c.clip, preload: "metadata", playsinline: "",
          controls: "", "aria-label": name + " — narrated Manim animation",
        });
        video.muted = !narrOn;                            // the Kokoro narration is baked into the clip's audio
        body.appendChild(k.el("div", { class: "hero-wrap" }, [video]));
        body.appendChild(k.el("div", { class: "tryit" }, ["try it yourself"]));
        hero = videoPlayer(video);
      }
      const stage = k.el("div", { class: "widget-body" });
      body.appendChild(stage);
      let widget = null;
      try { widget = w.mount(stage, c, theme); } catch (e) { stage.appendChild(k.el("p", { class: "err" }, ["widget error: " + e.message])); }
      if (io.produces) produced[io.produces] = name;
      const say = c.explainer ? name + ". " + c.explainer : name;   // what the narrator says for this concept
      const player = hero || (widget && typeof widget.play === "function" ? widget : null);
      if (player) players.push({ player, card, name, say, hasClip: !!hero });
      nodes.push(card);
    });

    let transport = null;
    if (players.length) { transport = buildTransport(players); main.appendChild(transport); }
    nodes.forEach((n) => main.appendChild(n));
    // shareable autoplay: opening the page at "#play" runs the whole paper on load.
    if (transport && (location.hash === "#play" || location.hash === "#autoplay")) setTimeout(transport.start, 400);
  }

  async function boot() {
    const nav = document.getElementById("nav"), main = document.getElementById("main");
    let index;
    try { index = await getJSON("data/index.json"); }
    catch (e) { main.appendChild(k.el("p", { class: "empty" }, ["No data/index.json found. Add per-paper manifests to webapp/data/ (the pipeline writes them)."])); return; }
    const papers = index.papers || [];
    if (!papers.length) { main.appendChild(k.el("p", { class: "empty" }, ["No papers yet."])); return; }
    let active = null;
    for (const entry of papers) {
      const btn = k.el("button", { class: "nav-item", onclick: async () => {
        if (active) active.classList.remove("on"); active = btn; btn.classList.add("on");
        try { renderPaper(main, await getJSON("data/" + entry.file)); }
        catch (e) { k.clear(main); main.appendChild(k.el("p", { class: "err" }, ["failed to load " + entry.file + ": " + e.message])); }
      } }, [k.el("span", { class: "nav-t" }, [entry.title || entry.file]), k.el("span", { class: "nav-s" }, [(entry.concepts || "") + (entry.concepts ? " testers" : "")])]);
      nav.appendChild(btn);
    }
    nav.firstChild.click();
  }
  document.addEventListener("DOMContentLoaded", boot);
})();