/**
 * ============================================================================
 * GAME DATA MANAGER - Global persistent state management
 * ============================================================================
 *
 * Singleton that manages all persistent game state across scenes:
 * - Numeric stats (HP, score, love points, money)
 * - Boolean flags (chapter completed, item obtained, choice made)
 * - Inventory items
 * - Chapter progress
 * - Ending determination
 *
 * Data persists across scene transitions because the singleton lives
 * in module scope (not tied to any scene lifecycle).
 * Optionally saves/loads from localStorage for cross-session persistence.
 *
 * USAGE:
 *   const gd = GameDataManager.getInstance();
 *
 *   // Set values
 *   gd.set('playerHP', 100);
 *   gd.addTo('score', 50);
 *   gd.setFlag('chapter1_complete', true);
 *
 *   // Get values
 *   const hp = gd.get('playerHP', 100);  // default 100
 *   const done = gd.getFlag('chapter1_complete');
 *
 *   // Inventory
 *   gd.addItem('health_potion');
 *   gd.hasItem('health_potion');  // true
 *
 *   // Save/Load
 *   gd.saveToStorage('my_game_save');
 *   gd.loadFromStorage('my_game_save');
 *
 *   // Ending
 *   const ending = gd.determineEnding(endingRules);
 */

export interface EndingRule {
  /** Ending scene key */
  endingKey: string;
  /** Condition function -- first matching rule wins */
  condition: (data: GameDataManager) => boolean;
  /** Priority (higher = checked first) */
  priority?: number;
}

export class GameDataManager {
  // Singleton pattern
  private static instance: GameDataManager;

  private numericData: Map<string, number> = new Map();
  private flagData: Map<string, boolean> = new Map();
  private inventory: Set<string> = new Set();
  private choiceHistory: Map<string, string> = new Map();

  private constructor() {}

  static getInstance(): GameDataManager {
    if (!GameDataManager.instance) {
      GameDataManager.instance = new GameDataManager();
    }
    return GameDataManager.instance;
  }

  // -- Numeric Data --

  /** Set a numeric value. */
  set(key: string, value: number): void {
    this.numericData.set(key, value);
  }

  /** Get a numeric value with optional default. */
  get(key: string, defaultValue: number = 0): number {
    return this.numericData.get(key) ?? defaultValue;
  }

  /** Add to a numeric value. */
  addTo(key: string, amount: number): number {
    const current = this.get(key);
    const newValue = current + amount;
    this.set(key, newValue);
    return newValue;
  }

  // -- Flags --

  /** Set a boolean flag. */
  setFlag(key: string, value: boolean): void {
    this.flagData.set(key, value);
  }

  /** Get a boolean flag. */
  getFlag(key: string): boolean {
    return this.flagData.get(key) ?? false;
  }

  // -- Inventory --

  /** Add an item to inventory. */
  addItem(itemId: string): void {
    this.inventory.add(itemId);
  }

  /** Remove an item from inventory. */
  removeItem(itemId: string): boolean {
    return this.inventory.delete(itemId);
  }

  /** Check if player has an item. */
  hasItem(itemId: string): boolean {
    return this.inventory.has(itemId);
  }

  /** Get all inventory items. */
  getInventory(): string[] {
    return [...this.inventory];
  }

  // -- Choice History --

  /** Record a choice the player made. */
  recordChoice(choiceId: string, selectedOption: string): void {
    this.choiceHistory.set(choiceId, selectedOption);
  }

  /** Get what the player chose for a given choice. */
  getChoice(choiceId: string): string | undefined {
    return this.choiceHistory.get(choiceId);
  }

  // -- Ending Determination --

  /**
   * Evaluate ending rules and return the matching ending key.
   * Rules are sorted by priority (highest first).
   */
  determineEnding(rules: EndingRule[]): string | undefined {
    const sorted = [...rules].sort(
      (a, b) => (b.priority ?? 0) - (a.priority ?? 0),
    );
    for (const rule of sorted) {
      if (rule.condition(this)) {
        return rule.endingKey;
      }
    }
    return undefined;
  }

  // -- Persistence --

  /** Save all data to localStorage. */
  saveToStorage(slotName: string): void {
    try {
      const data = {
        numeric: Object.fromEntries(this.numericData),
        flags: Object.fromEntries(this.flagData),
        inventory: [...this.inventory],
        choices: Object.fromEntries(this.choiceHistory),
      };
      localStorage.setItem(slotName, JSON.stringify(data));
    } catch (e) {
      console.warn('[GameDataManager] Failed to save:', e);
    }
  }

  /** Load data from localStorage. Returns true if data was loaded. */
  loadFromStorage(slotName: string): boolean {
    try {
      const raw = localStorage.getItem(slotName);
      if (!raw) return false;
      const data = JSON.parse(raw);
      if (data.numeric) {
        this.numericData = new Map(Object.entries(data.numeric));
      }
      if (data.flags) {
        this.flagData = new Map(Object.entries(data.flags));
      }
      if (data.inventory) {
        this.inventory = new Set(data.inventory);
      }
      if (data.choices) {
        this.choiceHistory = new Map(Object.entries(data.choices));
      }
      return true;
    } catch (e) {
      console.warn('[GameDataManager] Failed to load:', e);
      return false;
    }
  }

  /** Reset all data to defaults. */
  reset(): void {
    this.numericData.clear();
    this.flagData.clear();
    this.inventory.clear();
    this.choiceHistory.clear();
  }
}