/* 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');

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

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: [] });

const listeners = [];

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.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 }),
  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; },
  onChange: (f) => listeners.push(f),
};