/* Seed/live persistence.
 * data/scene.json       — committed seed (survives in git)
 * data/live/scene.live.json — runtime edits, volume-mounted in Docker, survives redeploys
 */
const fs = require('fs');
const path = require('path');

const DATA = path.join(__dirname, '..', 'data');
const LIVE_DIR = process.env.LIVE_DIR || path.join(DATA, 'live');
const SEED = path.join(DATA, 'scene.json');
const LIVE = path.join(LIVE_DIR, 'scene.live.json');
const PLAYLIST_LIVE = path.join(LIVE_DIR, 'playlist.live.json');
const MODELS_LIVE = path.join(LIVE_DIR, 'models.live.json');
const MODELS_SEED = path.join(DATA, 'models.json');
const CHARS_LIVE = path.join(LIVE_DIR, 'characters.live.json');
const LANDING_LIVE = path.join(LIVE_DIR, 'landing.live.json');

/* Named layouts: each is a self-contained { name, scene, playlist } saved under
 * layouts/<slug>.json. layouts.index.json tracks the list + which slug is active.
 * The active layout's scene/playlist are mirrored into scene.live.json /
 * playlist.live.json so viewers and the playlist engine need no changes. */
const LAYOUTS_DIR = path.join(LIVE_DIR, 'layouts');
const LAYOUTS_INDEX = path.join(LIVE_DIR, 'layouts.index.json');

fs.mkdirSync(LIVE_DIR, { recursive: true });
fs.mkdirSync(LAYOUTS_DIR, { recursive: true });

function slugify(name) {
  const s = String(name || '').toLowerCase().trim()
    .replace(/[^a-z0-9]+/g, '-').replace(/^-+|-+$/g, '').slice(0, 60);
  return s || 'layout';
}

function readJSON(p, fallback) {
  try { return JSON.parse(fs.readFileSync(p, 'utf8')); } catch { return fallback; }
}
function writeJSON(p, obj) {
  fs.writeFileSync(p, JSON.stringify(obj, null, 2));
}

let scene = readJSON(LIVE, null) || readJSON(SEED, { anchors: [], buildings: [], spawns: [], paths: [], world: { units: 'cm' } });
let ghosts = readJSON(path.join(DATA, 'ghosts.json'), []);
let gradients = readJSON(path.join(DATA, 'gradients.json'), {});
let models = readJSON(MODELS_LIVE, null) || readJSON(MODELS_SEED, { models: [] });
/* characters: per-ghost visual overrides keyed by ghost id, plus defaults.
 * { defaults: {...}, byId: { 'mad-fenton': { modelId, opacity, topColor, bottomColor,
 *   faceTextureUrl, torsoTextureUrl, heightCm, scale } } } */
let characters = readJSON(CHARS_LIVE, null) || { defaults: {}, byId: {} };

/* landing: end-user facing start screen + details page. All text is editable except
 * that the disclaimer is ALWAYS rendered (wording editable, presence is not). */
const LANDING_DEFAULTS = {
  title: 'NEWBURY NIGHTS',
  subtitle: 'Point your phone at the Newbury Crests to reveal the hidden side of the town.',
  logoUrl: '',
  backgroundUrl: '',
  startButton: 'Start Ghost Watching',
  detailsButton: 'About this build',
  detailsTitle: 'About Newbury Nights',
  detailsMarkdown: 'Write about your build here.\n\nUse **bold**, *italic*, and blank lines for paragraphs.',
  disclaimer: 'Fan-made tribute experience. Not affiliated with, sponsored, or endorsed by the LEGO Group. LEGO® and Hidden Side™ are trademarks of the LEGO Group.',
  accent: '#51eaf1',
  textColor: '#e8ecff',
  overlay: 0.55,
};
let landing = Object.assign({}, LANDING_DEFAULTS, readJSON(LANDING_LIVE, null) || {});

const listeners = [];

/* ---------- named layouts ---------- */
function readLayoutIndex() {
  const idx = readJSON(LAYOUTS_INDEX, null);
  if (idx && Array.isArray(idx.layouts)) return idx;
  return { layouts: [], activeSlug: null };
}
function writeLayoutIndex(idx) { writeJSON(LAYOUTS_INDEX, idx); }
function layoutPath(slug) { return path.join(LAYOUTS_DIR, `${slug}.json`); }

function listLayouts() {
  const idx = readLayoutIndex();
  return { layouts: idx.layouts, activeSlug: idx.activeSlug };
}

/* Snapshot the CURRENT live scene + playlist under a name. Overwrites if the
 * slug already exists (same name). Returns the updated index. */
function saveLayout(name, playlistCfg) {
  const slug = slugify(name);
  const record = {
    name: String(name || slug),
    slug,
    scene,
    playlist: playlistCfg || readJSON(PLAYLIST_LIVE, null) || readJSON(path.join(DATA, 'playlist.json'), {}),
    savedAt: Date.now(),
  };
  writeJSON(layoutPath(slug), record);
  const idx = readLayoutIndex();
  if (!idx.layouts.some(l => l.slug === slug)) idx.layouts.push({ slug, name: record.name });
  else idx.layouts = idx.layouts.map(l => l.slug === slug ? { slug, name: record.name } : l);
  idx.activeSlug = slug;
  writeLayoutIndex(idx);
  return listLayouts();
}

/* Make a saved layout active: mirror its scene into the live scene (so viewers
 * update) and return its playlist so the caller can reload the engine. */
function loadLayout(slug) {
  const rec = readJSON(layoutPath(slug), null);
  if (!rec) throw new Error('layout not found: ' + slug);
  scene = validateScene(rec.scene);
  writeJSON(LIVE, scene);
  if (rec.playlist) writeJSON(PLAYLIST_LIVE, rec.playlist);
  const idx = readLayoutIndex();
  idx.activeSlug = slug;
  writeLayoutIndex(idx);
  listeners.forEach(f => f());
  return { scene, playlist: rec.playlist || null };
}

function deleteLayout(slug) {
  try { fs.unlinkSync(layoutPath(slug)); } catch {}
  const idx = readLayoutIndex();
  idx.layouts = idx.layouts.filter(l => l.slug !== slug);
  if (idx.activeSlug === slug) idx.activeSlug = null;
  writeLayoutIndex(idx);
  return listLayouts();
}

function validateScene(s) {
  if (!s || typeof s !== 'object') throw new Error('scene must be object');
  for (const k of ['anchors', 'buildings', 'spawns']) {
    if (!Array.isArray(s[k])) throw new Error(`scene.${k} must be array`);
  }
  s.table = Object.assign({ width: 120, depth: 100, offsetX: 0, offsetZ: 0, show: true }, s.table || {});
  s.ghostHeightCm = Number(s.ghostHeightCm || 4);   // minifigure-scale default
  s.paths = Array.isArray(s.paths) ? s.paths : [];
  for (const pth of s.paths) {
    if (!pth.id) throw new Error('path.id required');
    if (!Array.isArray(pth.points) || pth.points.length < 2) throw new Error(`path ${pth.id} needs >= 2 points`);
    pth.mode = pth.mode === 'pingpong' ? 'pingpong' : 'loop';
    pth.enabled = pth.enabled !== false;
  }
  for (const a of s.anchors) {
    if (typeof a.markerId !== 'number') throw new Error('anchor.markerId required');
    if (!Array.isArray(a.position) || a.position.length !== 3) throw new Error('anchor.position [x,y,z] required');
    a.mount = a.mount || 'flat';                       // 'flat' | 'wall' | 'custom'
    a.yawDeg = Number(a.yawDeg || 0);
    a.pitchDeg = Number(a.pitchDeg || 0);
    a.rollDeg = Number(a.rollDeg || 0);
    a.sizeMM = Number(a.sizeMM || 60);                 // printed marker size
    a.enabled = a.enabled !== false;
  }
  return s;
}

module.exports = {
  getScene: () => scene,
  putScene(s) {
    scene = validateScene(s);
    writeJSON(LIVE, scene);
    listeners.forEach(f => f());
    return scene;
  },
  resetToSeed() {
    scene = readJSON(SEED, scene);
    writeJSON(LIVE, scene);
    listeners.forEach(f => f());
    return scene;
  },
  getGhosts: () => ({ ghosts, gradients }),
  getLanding: () => landing,
  putLanding(l) {
    if (!l || typeof l !== 'object') throw new Error('landing must be object');
    const next = Object.assign({}, LANDING_DEFAULTS, l);
    // disclaimer may be reworded but never emptied — it protects the project
    if (!String(next.disclaimer || '').trim()) next.disclaimer = LANDING_DEFAULTS.disclaimer;
    landing = next;
    writeJSON(LANDING_LIVE, landing);
    listeners.forEach(f => f());
    return landing;
  },
  getCharacters: () => characters,
  putCharacters(c) {
    if (!c || typeof c !== 'object') throw new Error('characters must be object');
    characters = { defaults: c.defaults || {}, byId: c.byId || {} };
    writeJSON(CHARS_LIVE, characters);
    listeners.forEach(f => f());
    return characters;
  },
  liveDir: LIVE_DIR,
  getModels: () => models,
  putModels(m) {
    if (!m || !Array.isArray(m.models)) throw new Error('models.models must be array');
    models = m; writeJSON(MODELS_LIVE, models); return models;
  },
  getPlaylistConfig: (fallback) => readJSON(PLAYLIST_LIVE, null) || readJSON(path.join(DATA, 'playlist.json'), fallback),
  putPlaylistConfig(cfg) { writeJSON(PLAYLIST_LIVE, cfg); return cfg; },
  listLayouts,
  saveLayout,
  loadLayout,
  deleteLayout,
  onChange: (f) => listeners.push(f),
};