import { Injectable, UnauthorizedException, Inject } from '@nestjs/common';
import { IAuthService } from '../interfaces/auth-service.interface';
import { LoggerService } from '../services/logger.service';

@Injectable()
export class LoginUserCommand {
  constructor(
    @Inject('IAuthService')
    private readonly authService: IAuthService,
    @Inject(LoggerService)
    private readonly logger: LoggerService,
  ) {}

  async execute(username: string, password: string): Promise<string> {
    try {
      this.logger.log(`Login attempt for user: ${username}`, LoginUserCommand.name);

      // Validate input parameters
      this.validateInput(username, password);

      const token = await this.authService.authenticate(username, password);

      if (!token) {
        this.logger.warn(`Authentication failed for user: ${username}`, LoginUserCommand.name);
        throw new UnauthorizedException('Invalid username or password');
      }

      this.logger.log(`Successfully authenticated user: ${username}`, LoginUserCommand.name);
      return token;
    } catch (error) {
      if (error instanceof UnauthorizedException) {
        throw error;
      }

      this.logger.error(`Failed to login user ${username}: ${error.message}`, undefined, LoginUserCommand.name);
      throw new Error(`Failed to login: ${error.message}`);
    }
  }

  private validateInput(username: string, password: string): void {
    if (!username || username.trim().length === 0) {
      throw new Error('Username cannot be empty');
    }

    if (!password || password.trim().length === 0) {
      throw new Error('Password cannot be empty');
    }
  }
}