import PocketBase from "pocketbase";
import yaml from "js-yaml";
import configYaml from "../../config/pocketbaseConfig.yml?raw";

// Configuration type definitions
interface Config {
  api: {
    baseUrl: string;
    oauth2: {
      redirectPath: string;
      providerName: string;
    };
  };
}

// Parse YAML configuration
const config = yaml.load(configYaml) as Config;

export class Authentication {
  private pb: PocketBase;
  private static instance: Authentication;
  private authChangeCallbacks: ((isValid: boolean) => void)[] = [];
  private isUpdating: boolean = false;
  private authSyncServiceInitialized: boolean = false;

  private constructor() {
    // Use the baseUrl from the config file
    this.pb = new PocketBase(config.api.baseUrl);

    // Configure PocketBase client
    this.pb.autoCancellation(false); // Disable auto-cancellation globally

    // Listen for auth state changes
    this.pb.authStore.onChange(() => {
      if (!this.isUpdating) {
        this.notifyAuthChange();
      }
    });
  }

  /**
   * Get the singleton instance of Authentication
   */
  public static getInstance(): Authentication {
    if (!Authentication.instance) {
      Authentication.instance = new Authentication();
    }
    return Authentication.instance;
  }

  /**
   * Get the PocketBase instance
   */
  public getPocketBase(): PocketBase {
    return this.pb;
  }

  /**
   * Handle user login through OAuth2
   */
  public async login(): Promise<void> {
    try {
      const authMethods = await this.pb.collection("users").listAuthMethods();
      const oidcProvider = authMethods.oauth2?.providers?.find(
        (p: { name: string }) => p.name === config.api.oauth2.providerName,
      );

      if (!oidcProvider) {
        throw new Error("OIDC provider not found");
      }

      localStorage.setItem("provider", JSON.stringify(oidcProvider));
      const redirectUrl =
        window.location.origin + config.api.oauth2.redirectPath;
      const authUrl = oidcProvider.authURL + encodeURIComponent(redirectUrl);
      window.location.href = authUrl;
    } catch (err) {
      console.error("Authentication error:", err);
      throw err;
    }
  }

  /**
   * Handle user logout
   */
  public async logout(): Promise<void> {
    try {
      // Initialize AuthSyncService if needed (lazy loading)
      await this.initAuthSyncService();
      
      // Get AuthSyncService instance
      const { AuthSyncService } = await import('../database/AuthSyncService');
      const authSync = AuthSyncService.getInstance();
      
      // Handle data cleanup before actual logout
      await authSync.handleLogout();
      
      // Clear auth store
      this.pb.authStore.clear();
      
      console.log('Logout completed successfully with data cleanup');
    } catch (error) {
      console.error('Error during logout:', error);
      // Fallback to basic logout if sync fails
      this.pb.authStore.clear();
    }
  }

  /**
   * Check if user is currently authenticated
   */
  public isAuthenticated(): boolean {
    return this.pb.authStore.isValid;
  }

  /**
   * Get current user model
   */
  public getCurrentUser(): any {
    return this.pb.authStore.model;
  }

  /**
   * Get current user ID
   */
  public getUserId(): string | null {
    return this.pb.authStore.model?.id || null;
  }

  /**
   * Subscribe to auth state changes
   * @param callback Function to call when auth state changes
   */
  public onAuthStateChange(callback: (isValid: boolean) => void): void {
    this.authChangeCallbacks.push(callback);
    
    // Initialize AuthSyncService when first callback is registered
    if (!this.authSyncServiceInitialized && this.authChangeCallbacks.length === 1) {
      this.initAuthSyncService();
    }
  }

  /**
   * Remove auth state change subscription
   * @param callback Function to remove from subscribers
   */
  public offAuthStateChange(callback: (isValid: boolean) => void): void {
    this.authChangeCallbacks = this.authChangeCallbacks.filter(
      (cb) => cb !== callback,
    );
  }

  /**
   * Set updating state to prevent auth change notifications during updates
   */
  public setUpdating(updating: boolean): void {
    this.isUpdating = updating;
  }

  /**
   * Notify all subscribers of auth state change
   */
  private notifyAuthChange(): void {
    const isValid = this.pb.authStore.isValid;
    this.authChangeCallbacks.forEach((callback) => callback(isValid));
  }
  
  /**
   * Initialize the AuthSyncService (lazy loading)
   */
  private async initAuthSyncService(): Promise<void> {
    if (this.authSyncServiceInitialized) return;
    
    try {
      // Dynamically import AuthSyncService to avoid circular dependencies
      const { AuthSyncService } = await import('../database/AuthSyncService');
      
      // Initialize the service
      AuthSyncService.getInstance();
      
      this.authSyncServiceInitialized = true;
      console.log('AuthSyncService initialized successfully');
      
      // If user is already authenticated, trigger initial sync
      if (this.isAuthenticated()) {
        const authSync = AuthSyncService.getInstance();
        authSync.handleLogin().catch(err => {
          console.error('Error during initial data sync:', err);
        });
      }
    } catch (error) {
      console.error('Failed to initialize AuthSyncService:', error);
    }
  }
}