/**
 * Persistence.js
 * Handles asynchronous saving and loading using IndexedDB.
 * Manages both Active Runs and Persistent Roster data.
 */
const DB_NAME = "AetherShardsDB";
const RUN_STORE = "Runs";
const ROSTER_STORE = "Roster";
const VERSION = 2; // Bumped version to add Roster store

export class Persistence {
  constructor() {
    this.db = null;
  }

  async init() {
    return new Promise((resolve, reject) => {
      const request = indexedDB.open(DB_NAME, VERSION);

      request.onerror = (e) => reject("DB Error: " + e.target.error);

      request.onupgradeneeded = (e) => {
        const db = e.target.result;

        // Create Runs Store if missing
        if (!db.objectStoreNames.contains(RUN_STORE)) {
          db.createObjectStore(RUN_STORE, { keyPath: "id" });
        }

        // Create Roster Store if missing
        if (!db.objectStoreNames.contains(ROSTER_STORE)) {
          db.createObjectStore(ROSTER_STORE, { keyPath: "id" });
        }
      };

      request.onsuccess = (e) => {
        this.db = e.target.result;
        resolve();
      };
    });
  }

  // --- RUN DATA ---

  async saveRun(runData) {
    if (!this.db) await this.init();
    return this._put(RUN_STORE, { ...runData, id: "active_run" });
  }

  async loadRun() {
    if (!this.db) await this.init();
    return this._get(RUN_STORE, "active_run");
  }

  async clearRun() {
    if (!this.db) await this.init();
    return this._delete(RUN_STORE, "active_run");
  }

  // --- ROSTER DATA ---

  async saveRoster(rosterData) {
    if (!this.db) await this.init();
    // Wrap the raw data object in an ID for storage
    return this._put(ROSTER_STORE, { id: "player_roster", data: rosterData });
  }

  async loadRoster() {
    if (!this.db) await this.init();
    const result = await this._get(ROSTER_STORE, "player_roster");
    return result ? result.data : null;
  }

  // --- INTERNAL HELPERS ---

  _put(storeName, item) {
    return new Promise((resolve, reject) => {
      const tx = this.db.transaction([storeName], "readwrite");
      const store = tx.objectStore(storeName);
      const req = store.put(item);
      req.onsuccess = () => resolve();
      req.onerror = () => reject(req.error);
    });
  }

  _get(storeName, key) {
    return new Promise((resolve, reject) => {
      const tx = this.db.transaction([storeName], "readonly");
      const store = tx.objectStore(storeName);
      const req = store.get(key);
      req.onsuccess = () => resolve(req.result);
      req.onerror = () => reject(req.error);
    });
  }

  _delete(storeName, key) {
    return new Promise((resolve, reject) => {
      const tx = this.db.transaction([storeName], "readwrite");
      const store = tx.objectStore(storeName);
      const req = store.delete(key);
      req.onsuccess = () => resolve();
      req.onerror = () => reject(req.error);
    });
  }
}