// memory.js — "The Oracle's Memory" (upgrade #5).
//
// Local-first persistence: session resurrection (last channel / volume / modes),
// per-channel rolling uptime history (feeds the guide reliability glyphs and
// auto-skip), and pinned channels. Everything in localStorage, namespaced.

const NS = 'orb.';
const K = {
  settings: NS + 'settings',
  health: NS + 'health',
  pins: NS + 'pins',
};
const HISTORY_DECAY = 0.85; // exponential weighting toward recent samples

function read(key, fallback) {
  try { const v = localStorage.getItem(key); return v ? JSON.parse(v) : fallback; }
  catch { return fallback; }
}
function write(key, val) {
  try { localStorage.setItem(key, JSON.stringify(val)); } catch { /* quota / private mode */ }
}

class OracleMemory {
  constructor() {
    this.settings = read(K.settings, {
      lastChannelId: null,
      volume: 1,
      muted: false,
      modes: { theater: false, dim: false, ambient: false },
    });
    /** @type {Object<string,{score:number,samples:number,last:string,ts:number}>} */
    this.health = read(K.health, {});
    this.pins = new Set(read(K.pins, []));
  }

  // ---- session resurrection ----
  get lastChannelId() { return this.settings.lastChannelId; }
  rememberChannel(id) { this.settings.lastChannelId = id; this._saveSettings(); }
  rememberVolume(volume, muted) {
    this.settings.volume = volume; this.settings.muted = muted; this._saveSettings();
  }
  rememberModes(modes) { this.settings.modes = { ...modes }; this._saveSettings(); }
  _saveSettings() { write(K.settings, this.settings); }

  // ---- uptime history (fed by health probes) ----
  /** @param {string} id @param {'live'|'degraded'|'dead'} state */
  recordHealth(id, state) {
    const ok = state === 'live' ? 1 : state === 'degraded' ? 0.5 : 0;
    const prev = this.health[id];
    const score = prev ? prev.score * HISTORY_DECAY + ok * (1 - HISTORY_DECAY) : ok;
    this.health[id] = {
      score,
      samples: (prev?.samples || 0) + 1,
      last: state,
      ts: Date.now(),
    };
    this._healthDirty = true;
    this._scheduleHealthSave();
  }
  _scheduleHealthSave() {
    if (this._healthT) return;
    this._healthT = setTimeout(() => { this._healthT = 0; write(K.health, this.health); }, 1500);
  }
  /** @returns {{score:number,samples:number,last:string,ts:number}|null} */
  reliability(id) { return this.health[id] || null; }
  isKnownDead(id) { return this.health[id]?.last === 'dead'; }

  // ---- pins ----
  isPinned(id) { return this.pins.has(id); }
  togglePin(id) {
    this.pins.has(id) ? this.pins.delete(id) : this.pins.add(id);
    write(K.pins, [...this.pins]);
    return this.pins.has(id);
  }
  pinned() { return [...this.pins]; }
}

export const memory = new OracleMemory();