/**
 * LDAP Authentication Strategy
 * Handles LDAP/Active Directory authentication
 *
 * Note: This is a basic implementation. For production use with actual LDAP,
 * you may need to integrate with a Deno-compatible LDAP library.
 */

import type { AuthProvider } from '../../../models/auth.provider.ts';
import type { CryptoService } from '../../crypto.service.ts';
import type {
  IExternalUserInfo,
  IConnectionTestResult,
} from '../../../interfaces/auth.interfaces.ts';
import type { IAuthStrategy } from './auth.strategy.interface.ts';

// LDAP entry type (simplified)
interface ILdapEntry {
  dn: string;
  [key: string]: unknown;
}

export class LdapStrategy implements IAuthStrategy {
  constructor(
    private provider: AuthProvider,
    private cryptoService: CryptoService
  ) {}

  /**
   * Authenticate user with LDAP credentials
   */
  public async authenticateCredentials(
    username: string,
    password: string
  ): Promise<IExternalUserInfo> {
    const config = this.provider.ldapConfig;
    if (!config) {
      throw new Error('LDAP config not found');
    }

    // Escape username to prevent LDAP injection
    const escapedUsername = this.escapeLdap(username);

    // Build user search filter
    const userFilter = config.userSearchFilter.replace('{{username}}', escapedUsername);

    // Decrypt bind password
    const bindPassword = await this.cryptoService.decrypt(config.bindPasswordEncrypted);

    // Perform LDAP authentication
    // This is a placeholder - actual implementation would use an LDAP library
    const userEntry = await this.ldapBind(
      config.serverUrl,
      config.bindDn,
      bindPassword,
      config.baseDn,
      userFilter,
      password
    );

    // Map LDAP attributes to user info
    return this.mapAttributes(userEntry);
  }

  /**
   * Test LDAP connection
   */
  public async testConnection(): Promise<IConnectionTestResult> {
    const start = Date.now();
    const config = this.provider.ldapConfig;

    if (!config) {
      return {
        success: false,
        latencyMs: Date.now() - start,
        error: 'LDAP config not found',
      };
    }

    try {
      // Decrypt bind password
      const bindPassword = await this.cryptoService.decrypt(config.bindPasswordEncrypted);

      // Test connection by binding with service account
      await this.testLdapConnection(
        config.serverUrl,
        config.bindDn,
        bindPassword,
        config.baseDn
      );

      return {
        success: true,
        latencyMs: Date.now() - start,
        serverInfo: {
          serverUrl: config.serverUrl,
          baseDn: config.baseDn,
          tlsEnabled: config.tlsEnabled,
        },
      };
    } catch (error) {
      return {
        success: false,
        latencyMs: Date.now() - start,
        error: error instanceof Error ? error.message : String(error),
      };
    }
  }

  /**
   * Escape special LDAP characters to prevent injection
   */
  private escapeLdap(value: string): string {
    return value
      .replace(/\\/g, '\\5c')
      .replace(/\*/g, '\\2a')
      .replace(/\(/g, '\\28')
      .replace(/\)/g, '\\29')
      .replace(/\x00/g, '\\00');
  }

  /**
   * Perform LDAP bind and search
   * This is a placeholder implementation - actual LDAP would require a library
   */
  private async ldapBind(
    serverUrl: string,
    bindDn: string,
    bindPassword: string,
    baseDn: string,
    userFilter: string,
    userPassword: string
  ): Promise<ILdapEntry> {
    // In a real implementation, this would:
    // 1. Connect to LDAP server
    // 2. Bind with service account (bindDn/bindPassword)
    // 3. Search for user with userFilter
    // 4. Re-bind with user's DN and password to verify
    // 5. Return user entry if successful

    // For now, we throw an error indicating LDAP needs to be configured
    // This allows the structure to be in place while the actual LDAP library
    // integration can be done separately

    console.log('[LdapStrategy] LDAP auth attempt:', {
      serverUrl,
      baseDn,
      userFilter,
    });

    throw new Error(
      'LDAP authentication is not yet fully implemented. ' +
      'Please integrate with a Deno-compatible LDAP library (e.g., ldapts via npm compatibility).'
    );
  }

  /**
   * Test LDAP connection
   */
  private async testLdapConnection(
    serverUrl: string,
    bindDn: string,
    bindPassword: string,
    baseDn: string
  ): Promise<void> {
    // Similar to ldapBind, this is a placeholder
    // Would connect and bind with service account to verify connectivity

    console.log('[LdapStrategy] Testing LDAP connection:', {
      serverUrl,
      bindDn,
      baseDn,
    });

    // For now, check if server URL is valid
    if (!serverUrl.startsWith('ldap://') && !serverUrl.startsWith('ldaps://')) {
      throw new Error('Invalid LDAP server URL. Must start with ldap:// or ldaps://');
    }

    // In a real implementation, we would actually connect here
    // For now, we just validate the configuration
    if (!bindDn || !bindPassword || !baseDn) {
      throw new Error('Missing required LDAP configuration');
    }

    // Return success for configuration validation
    // Actual connectivity test would happen with LDAP library
    console.log('[LdapStrategy] LDAP configuration is valid (actual connection test requires LDAP library)');
  }

  /**
   * Map LDAP attributes to standard user info
   */
  private mapAttributes(entry: ILdapEntry): IExternalUserInfo {
    const mapping = this.provider.attributeMapping;

    // Get external ID (typically uid or sAMAccountName)
    const externalId = String(entry[mapping.username] || entry.dn);

    // Get email
    const email = entry[mapping.email];
    if (!email || typeof email !== 'string') {
      throw new Error('Email not found in LDAP entry');
    }

    return {
      externalId,
      email,
      username: entry[mapping.username]
        ? String(entry[mapping.username])
        : undefined,
      displayName: entry[mapping.displayName]
        ? String(entry[mapping.displayName])
        : undefined,
      groups: mapping.groups
        ? this.parseGroups(entry[mapping.groups])
        : undefined,
      rawAttributes: entry as Record<string, unknown>,
    };
  }

  /**
   * Parse LDAP group membership
   */
  private parseGroups(memberOf: unknown): string[] {
    if (!memberOf) return [];

    if (Array.isArray(memberOf)) {
      return memberOf.map((dn) => this.extractCnFromDn(String(dn)));
    }

    return [this.extractCnFromDn(String(memberOf))];
  }

  /**
   * Extract CN (Common Name) from a DN (Distinguished Name)
   */
  private extractCnFromDn(dn: string): string {
    const match = dn.match(/^CN=([^,]+)/i);
    return match ? match[1] : dn;
  }
}