/* ============================================================
 * Diablo2D — save.js : localStorage persistence layer
 * ============================================================ */
'use strict';

window.D2 = window.D2 || {};
(function (D2) {

  const PREFIX = 'd2d.';
  const SAVE_VERSION = 3;

  let storageOk = true;
  try {
    localStorage.setItem(PREFIX + '__probe', '1');
    localStorage.removeItem(PREFIX + '__probe');
  } catch (e) {
    storageOk = false;
  }

  function get(key, fallback = null) {
    if (!storageOk) return fallback;
    try {
      const raw = localStorage.getItem(PREFIX + key);
      if (raw == null) return fallback;
      return JSON.parse(raw);
    } catch (e) {
      console.warn('[save] corrupt entry', key, e);
      return fallback;
    }
  }

  function set(key, value) {
    if (!storageOk) return false;
    try {
      localStorage.setItem(PREFIX + key, JSON.stringify(value));
      return true;
    } catch (e) {
      console.error('[save] write failed', e);
      return false;
    }
  }

  function remove(key) {
    if (!storageOk) return;
    try { localStorage.removeItem(PREFIX + key); } catch (e) {}
  }

  function hasMeta() {
    return !!get('meta', null);
  }

  function writeMeta(meta) {
    meta.version = SAVE_VERSION;
    meta.savedAt = Date.now();
    set('meta', meta);
  }

  function readMeta() {
    return get('meta', null);
  }

  function wipeAll() {
    remove('meta');
    remove('char');
    remove('world');
    remove('settings');
  }

  /* full snapshot: meta + char + world */
  function serializeSnapshot() {
    return JSON.stringify({
      v: SAVE_VERSION,
      meta: readMeta(),
      char: get('char'),
      world: get('world'),
    });
  }

  function restoreSnapshot(text) {
    try {
      const obj = JSON.parse(text);
      if (!obj || typeof obj !== 'object' || !obj.char) return false;
      if (obj.meta) set('meta', obj.meta);
      if (obj.char) set('char', obj.char);
      if (obj.world) set('world', obj.world);
      return true;
    } catch (e) {
      return false;
    }
  }

  D2.save = {
    version: SAVE_VERSION,
    get storageOk() { return storageOk; },
    KEY: { META: 'meta', CHAR: 'char', WORLD: 'world', SETTINGS: 'settings' },
    get, set, remove,
    hasMeta, writeMeta, readMeta,
    wipeAll,
    serializeSnapshot, restoreSnapshot,
  };
})(window.D2);