import type { IStatePersistenceConfig, IAppUIState } from '../../interfaces/appconfig.js';

/**
 * Manager for persisting and restoring UI state
 */
export class StateManager {
  private config: Required<IStatePersistenceConfig>;
  private memoryStorage: Map<string, string> = new Map();

  constructor(config: IStatePersistenceConfig = { enabled: false }) {
    this.config = {
      enabled: config.enabled,
      storageKey: config.storageKey || 'dees-appui-state',
      storage: config.storage || 'localStorage',
      persist: {
        mainMenuCollapsed: true,
        secondaryMenuCollapsed: true,
        selectedView: true,
        secondaryMenuSelection: true,
        collapsedGroups: true,
        ...config.persist,
      },
    };
  }

  /**
   * Check if state persistence is enabled
   */
  public isEnabled(): boolean {
    return this.config.enabled;
  }

  /**
   * Save current UI state
   */
  public save(state: Partial<IAppUIState>): void {
    if (!this.config.enabled) return;

    const existingState = this.load() || {};
    const newState: IAppUIState = {
      ...existingState,
      timestamp: Date.now(),
    };

    // Only save what's configured
    if (this.config.persist.selectedView && state.currentViewId !== undefined) {
      newState.currentViewId = state.currentViewId;
    }
    if (this.config.persist.mainMenuCollapsed && state.mainMenuCollapsed !== undefined) {
      newState.mainMenuCollapsed = state.mainMenuCollapsed;
    }
    if (this.config.persist.secondaryMenuCollapsed && state.secondaryMenuCollapsed !== undefined) {
      newState.secondaryMenuCollapsed = state.secondaryMenuCollapsed;
    }
    if (this.config.persist.secondaryMenuSelection && state.secondaryMenuSelectedKey !== undefined) {
      newState.secondaryMenuSelectedKey = state.secondaryMenuSelectedKey;
    }
    if (this.config.persist.collapsedGroups && state.collapsedGroups !== undefined) {
      newState.collapsedGroups = state.collapsedGroups;
    }

    this.setItem(this.config.storageKey, JSON.stringify(newState));
  }

  /**
   * Load persisted UI state
   */
  public load(): IAppUIState | null {
    if (!this.config.enabled) return null;

    try {
      const data = this.getItem(this.config.storageKey);
      if (!data) return null;
      return JSON.parse(data) as IAppUIState;
    } catch (e) {
      console.warn('Failed to load UI state:', e);
      return null;
    }
  }

  /**
   * Clear persisted state
   */
  public clear(): void {
    this.removeItem(this.config.storageKey);
  }

  /**
   * Check if state exists
   */
  public hasState(): boolean {
    return this.getItem(this.config.storageKey) !== null;
  }

  /**
   * Get state age in milliseconds
   */
  public getStateAge(): number | null {
    const state = this.load();
    if (!state?.timestamp) return null;
    return Date.now() - state.timestamp;
  }

  /**
   * Update specific state properties
   */
  public update(updates: Partial<IAppUIState>): void {
    const currentState = this.load() || {};
    this.save({ ...currentState, ...updates });
  }

  /**
   * Get the storage key being used
   */
  public getStorageKey(): string {
    return this.config.storageKey;
  }

  // Storage abstraction methods

  private getItem(key: string): string | null {
    switch (this.config.storage) {
      case 'localStorage':
        try {
          return localStorage.getItem(key);
        } catch {
          return null;
        }
      case 'sessionStorage':
        try {
          return sessionStorage.getItem(key);
        } catch {
          return null;
        }
      case 'memory':
        return this.memoryStorage.get(key) || null;
      default:
        return null;
    }
  }

  private setItem(key: string, value: string): void {
    switch (this.config.storage) {
      case 'localStorage':
        try {
          localStorage.setItem(key, value);
        } catch (e) {
          console.warn('Failed to save to localStorage:', e);
        }
        break;
      case 'sessionStorage':
        try {
          sessionStorage.setItem(key, value);
        } catch (e) {
          console.warn('Failed to save to sessionStorage:', e);
        }
        break;
      case 'memory':
        this.memoryStorage.set(key, value);
        break;
    }
  }

  private removeItem(key: string): void {
    switch (this.config.storage) {
      case 'localStorage':
        try {
          localStorage.removeItem(key);
        } catch {
          // Ignore
        }
        break;
      case 'sessionStorage':
        try {
          sessionStorage.removeItem(key);
        } catch {
          // Ignore
        }
        break;
      case 'memory':
        this.memoryStorage.delete(key);
        break;
    }
  }
}