/**
 * transcript.js — Transcript Logger for The Matrix.
 *
 * Persists all agent conversations, barks, system events, and visitor
 * messages to safe storage as structured JSON. Provides download as
 * plaintext (.txt) or JSON (.json) via the HUD controls.
 *
 * Architecture:
 *   - `logEntry()` is called from ui.js on every appendChatMessage
 *   - Entries stored via storage.js under 'matrix:transcript'
 *   - Rolling buffer of MAX_ENTRIES to prevent storage bloat
 *   - Download buttons injected into the HUD
 *
 * Resolves Issue #54
 */

import { getItem as _getItem, setItem as _setItem } from './storage.js';

const STORAGE_KEY = 'matrix:transcript';
const MAX_ENTRIES = 500;

/** @type {Array<TranscriptEntry>} */
let entries = [];

/** @type {HTMLElement|null} */
let $controls = null;

/**
 * @typedef {Object} TranscriptEntry
 * @property {number} ts — Unix timestamp (ms)
 * @property {string} iso — ISO 8601 timestamp
 * @property {string} agent — Agent label (TIMMY, PERPLEXITY, SYS, YOU, etc.)
 * @property {string} text — Message content
 * @property {string} [type] — Entry type: chat, bark, system, visitor
 */

/* ── Public API ── */

export function initTranscript() {
  loadFromStorage();
  buildControls();
}

/**
 * Log a chat/bark/system entry to the transcript.
 * Called from ui.js appendChatMessage.
 *
 * @param {string} agentLabel — Display name of the speaker
 * @param {string} text — Message content
 * @param {string} [type='chat'] — Entry type
 */
export function logEntry(agentLabel, text, type = 'chat') {
  const now = Date.now();
  const entry = {
    ts: now,
    iso: new Date(now).toISOString(),
    agent: agentLabel,
    text: text,
    type: type,
  };

  entries.push(entry);

  // Trim rolling buffer
  if (entries.length > MAX_ENTRIES) {
    entries = entries.slice(-MAX_ENTRIES);
  }

  saveToStorage();
  updateBadge();
}

/**
 * Get a copy of all transcript entries.
 * @returns {TranscriptEntry[]}
 */
export function getTranscript() {
  return [...entries];
}

/**
 * Clear the transcript.
 */
export function clearTranscript() {
  entries = [];
  saveToStorage();
  updateBadge();
}

export function disposeTranscript() {
  // Nothing to dispose — DOM controls persist across context loss
}

/* ── Storage ── */

function loadFromStorage() {
  try {
    const raw = _getItem(STORAGE_KEY);
    if (!raw) return;
    const parsed = JSON.parse(raw);
    if (Array.isArray(parsed)) {
      entries = parsed.filter(e =>
        e && typeof e.ts === 'number' && typeof e.agent === 'string'
      );
    }
  } catch {
    entries = [];
  }
}

function saveToStorage() {
  try {
    _setItem(STORAGE_KEY, JSON.stringify(entries));
  } catch { /* quota exceeded — silent */ }
}

/* ── Download ── */

function downloadAsText() {
  if (entries.length === 0) return;

  const lines = entries.map(e => {
    const time = new Date(e.ts).toLocaleTimeString('en-US', { hour12: false });
    return `[${time}] ${e.agent}: ${e.text}`;
  });

  const header = `THE MATRIX — Transcript\n` +
    `Exported: ${new Date().toISOString()}\n` +
    `Entries: ${entries.length}\n` +
    `${'─'.repeat(50)}\n`;

  download(header + lines.join('\n'), 'matrix-transcript.txt', 'text/plain');
}

function downloadAsJson() {
  if (entries.length === 0) return;

  const data = {
    export_time: new Date().toISOString(),
    entry_count: entries.length,
    entries: entries,
  };

  download(JSON.stringify(data, null, 2), 'matrix-transcript.json', 'application/json');
}

function download(content, filename, mimeType) {
  const blob = new Blob([content], { type: mimeType });
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = filename;
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  URL.revokeObjectURL(url);
}

/* ── HUD Controls ── */

function buildControls() {
  $controls = document.getElementById('transcript-controls');
  if (!$controls) return;

  $controls.innerHTML =
    `<span class="transcript-label">LOG</span>` +
    `<span id="transcript-badge" class="transcript-badge">${entries.length}</span>` +
    `<button class="transcript-btn" id="transcript-dl-txt" title="Download as text">TXT</button>` +
    `<button class="transcript-btn" id="transcript-dl-json" title="Download as JSON">JSON</button>` +
    `<button class="transcript-btn transcript-btn-clear" id="transcript-clear" title="Clear transcript">✕</button>`;

  // Wire up buttons (pointer-events: auto on the container)
  $controls.querySelector('#transcript-dl-txt').addEventListener('click', downloadAsText);
  $controls.querySelector('#transcript-dl-json').addEventListener('click', downloadAsJson);
  $controls.querySelector('#transcript-clear').addEventListener('click', () => {
    clearTranscript();
  });
}

function updateBadge() {
  const badge = document.getElementById('transcript-badge');
  if (badge) badge.textContent = entries.length;
}