// zapper.js — channel tuning: number entry, OSD banner, up/down, last-channel,
// and the "Scrying Static" channel-change transition.

const ENTRY_DEBOUNCE = 1200;   // ms cable-box number accumulation
const BANNER_MS = 4000;
const STATIC_MIN = 300;        // never flash shorter than this
const STATIC_MAX = 3000;       // clear regardless after this

export class Zapper {
  /**
   * @param {object} els
   * @param {import('./player.js').Player} player
   * @param {import('./providers/source-provider.js').ChannelAggregator} agg
   * @param {{memory?:any, health?:import('./health.js').Health}} [opts]
   */
  constructor(els, player, agg, opts = {}) {
    this.els = els;
    this.player = player;
    this.agg = agg;
    this.memory = opts.memory || null;
    this.health = opts.health || null;
    this.current = null;     // current Channel
    this.previous = null;    // for last-channel toggle
    this._entry = '';
    this._entryT = 0;
    this._bannerT = 0;
    this._staticFrames = [];
    this._reduced = matchMedia('(prefers-reduced-motion: reduce)').matches;
    this._prepStatic();
    // player calls this when first fragment buffers → clear the static
    this.player.onFirstFrag = () => this._clearStatic();
  }

  // ---------- public tuning API ----------
  async tuneToNumber(n) {
    const ch = this.agg.getChannelByNumber(n);
    if (!ch) { this._flashEntry(String(n), true); return; }
    return this.tune(ch);
  }

  async tuneToIndexOffset(delta) {
    const list = this.agg.channels;
    if (!list.length) return;
    const start = this.current ? list.findIndex((c) => c.id === this.current.id) : -1;
    let idx = start;
    // Step in the requested direction, skipping channels the Oracle knows are dead.
    for (let n = 0; n < list.length; n++) {
      idx = (idx + delta + list.length) % list.length;
      const ch = list[idx];
      if (!this.health || !this.health.isKnownDead(ch.id)) return this.tune(ch);
    }
    // everything known-dead → just tune the immediate neighbour
    return this.tune(list[(start + delta + list.length) % list.length]);
  }

  async tuneLast() { if (this.previous) return this.tune(this.previous); }

  /** @param {import('./providers/source-provider.js').Channel} ch */
  async tune(ch) {
    if (!ch) return;
    if (this.current && this.current.id !== ch.id) this.previous = this.current;
    this.current = ch;
    if (this.memory) this.memory.rememberChannel(ch.id);
    if (this.health) this.health.probe(ch);   // refresh this channel's reliability
    this._showStatic();
    this._safetyClear = setTimeout(() => this._clearStatic(), STATIC_MAX);

    const handle = await this.agg.getStreamHandle(ch.id);
    if (!handle) { this.player._showNoSignal?.(); this._clearStatic(); }
    else {
      const fallbacks = (ch.streamUrls || []).slice(1);
      await this.player.play(handle, fallbacks);
    }
    this._showBanner(ch);
    this._announce(ch);
    return ch;
  }

  // ---------- number entry (incantation) ----------
  pushDigit(d) {
    this._entry = (this._entry + d).slice(-4);
    this._flashEntry(this._entry, false);
    clearTimeout(this._entryT);
    this._entryT = setTimeout(() => {
      const n = parseInt(this._entry, 10);
      this._entry = '';
      this.els.osdNumber.hidden = true;
      if (Number.isFinite(n)) this.tuneToNumber(n);
    }, ENTRY_DEBOUNCE);
  }
  _flashEntry(text, invalid) {
    this.els.osdNumber.hidden = false;
    this.els.osdNumberVal.textContent = (text + '___').slice(0, 3);
    this.els.osdNumberVal.style.color = invalid ? 'var(--ink-dim)' : '';
    if (invalid) setTimeout(() => { this.els.osdNumber.hidden = true; }, 900);
  }

  // ---------- channel banner OSD ----------
  async _showBanner(ch) {
    const e = this.els;
    e.osdNum.textContent = String(ch.number ?? '--');
    e.osdName.textContent = ch.name || '';            // textContent: untrusted-safe
    e.osdLogo.src = ch.logo || '';
    e.osdLogo.alt = '';
    e.osdNow.textContent = '';
    e.osdProgFill.style.width = '0%';
    e.osdChannel.hidden = false;
    requestAnimationFrame(() => e.osdChannel.classList.add('show'));
    clearTimeout(this._bannerT);
    this._bannerT = setTimeout(() => {
      e.osdChannel.classList.remove('show');
      setTimeout(() => { e.osdChannel.hidden = true; }, 350);
    }, BANNER_MS);

    // now-playing (best effort)
    try {
      const { now } = await this.agg.nowNext(ch.id);
      if (now && this.current && this.current.id === ch.id) {
        e.osdNow.textContent = now.title;
        const pct = Math.min(100, Math.max(0, ((Date.now() - now.start) / (now.stop - now.start)) * 100));
        e.osdProgFill.style.width = pct.toFixed(1) + '%';
      }
    } catch {}
  }

  _announce(ch) {
    // aria-live region already on osd-channel; ensure SR gets a concise message
    this.els.osdChannel.setAttribute('aria-label', `Channel ${ch.number}, ${ch.name}`);
  }

  // ---------- scrying static ----------
  _prepStatic() {
    if (this._reduced) return;
    const c = this.els.staticCanvas;
    const w = c.width = 160, h = c.height = 90;
    const ctx = c.getContext('2d');
    for (let f = 0; f < 8; f++) {
      const img = ctx.createImageData(w, h);
      for (let i = 0; i < img.data.length; i += 4) {
        const v = (Math.random() * 90) | 0;
        img.data[i] = v + (Math.random() * 80 | 0); // red-tinged
        img.data[i+1] = v * 0.3;
        img.data[i+2] = v * 0.3;
        img.data[i+3] = 255;
      }
      this._staticFrames.push(img);
    }
  }
  _showStatic() {
    const c = this.els.staticCanvas;
    this._staticShownAt = performance.now();
    if (this._reduced) {
      // reduced-motion: brief red flash instead of noise
      c.classList.add('show'); c.style.background = 'var(--red-deep)';
      return;
    }
    c.style.background = '';
    c.classList.add('show');
    const ctx = c.getContext('2d');
    let i = 0;
    clearInterval(this._staticTimer);
    this._staticTimer = setInterval(() => {
      ctx.putImageData(this._staticFrames[i++ % this._staticFrames.length], 0, 0);
    }, 1000 / 18);
  }
  _clearStatic() {
    clearTimeout(this._safetyClear);
    const elapsed = performance.now() - (this._staticShownAt || 0);
    const wait = Math.max(0, STATIC_MIN - elapsed);
    setTimeout(() => {
      clearInterval(this._staticTimer);
      this.els.staticCanvas.classList.remove('show');
    }, wait);
  }
}