/**
 * Signup with Email Use Case
 *
 * Creates a new user account with email and password.
 */

import type { IUserRepository, StoredUser } from '../../domain/repositories/IUserRepository';
import type { AuthenticatedUser } from '../ports/IdentityProviderPort';
import type { IdentitySessionPort } from '../ports/IdentitySessionPort';
import { Result } from '@core/shared/application/Result';
import type { ApplicationErrorCode } from '@core/shared/errors/ApplicationErrorCode';
import type { UseCaseOutputPort, Logger } from '@core/shared/application';

export type SignupWithEmailInput = {
  email: string;
  password: string;
  displayName: string;
};

export type SignupWithEmailResult = {
  sessionToken: string;
  userId: string;
  displayName: string;
  email: string;
  createdAt: Date;
  isNewUser: boolean;
};

export type SignupWithEmailErrorCode =
  | 'INVALID_EMAIL_FORMAT'
  | 'WEAK_PASSWORD'
  | 'INVALID_DISPLAY_NAME'
  | 'EMAIL_ALREADY_EXISTS'
  | 'REPOSITORY_ERROR';

export type SignupWithEmailApplicationError = ApplicationErrorCode<
  SignupWithEmailErrorCode,
  { message: string }
>;

export class SignupWithEmailUseCase {
  constructor(
    private readonly userRepository: IUserRepository,
    private readonly sessionPort: IdentitySessionPort,
    private readonly logger: Logger,
    private readonly output: UseCaseOutputPort<SignupWithEmailResult>,
  ) {}

  async execute(input: SignupWithEmailInput): Promise<
    Result<void, SignupWithEmailApplicationError>
  > {
    // Validate email format
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    if (!emailRegex.test(input.email)) {
      return Result.err({
        code: 'INVALID_EMAIL_FORMAT',
        details: { message: 'Invalid email format' },
      } as SignupWithEmailApplicationError);
    }

    // Validate password strength
    if (input.password.length < 8) {
      return Result.err({
        code: 'WEAK_PASSWORD',
        details: { message: 'Password must be at least 8 characters' },
      } as SignupWithEmailApplicationError);
    }

    // Validate display name
    if (!input.displayName || input.displayName.trim().length < 2) {
      return Result.err({
        code: 'INVALID_DISPLAY_NAME',
        details: { message: 'Display name must be at least 2 characters' },
      } as SignupWithEmailApplicationError);
    }

    // Check if email already exists
    const existingUser = await this.userRepository.findByEmail(input.email);
    if (existingUser) {
      return Result.err({
        code: 'EMAIL_ALREADY_EXISTS',
        details: { message: 'An account with this email already exists' },
      } as SignupWithEmailApplicationError);
    }

    try {
      // Hash password (simple hash for demo - in production use bcrypt)
      const salt = this.generateSalt();
      const passwordHash = await this.hashPassword(input.password, salt);

      // Create user
      const userId = this.generateUserId();
      const createdAt = new Date();
      const newUser: StoredUser = {
        id: userId,
        email: input.email.toLowerCase().trim(),
        displayName: input.displayName.trim(),
        passwordHash,
        salt,
        createdAt,
      };

      await this.userRepository.create(newUser);

      // Create session
      const authenticatedUser: AuthenticatedUser = {
        id: newUser.id,
        displayName: newUser.displayName,
        email: newUser.email,
      };

      const session = await this.sessionPort.createSession(authenticatedUser);

      const result: SignupWithEmailResult = {
        sessionToken: session.token,
        userId: session.user.id,
        displayName: session.user.displayName,
        email: session.user.email ?? newUser.email,
        createdAt,
        isNewUser: true,
      };

      this.output.present(result);

      return Result.ok(undefined);
    } catch (error) {
      const message =
        error instanceof Error && error.message
          ? error.message
          : 'Failed to execute SignupWithEmailUseCase';

      this.logger.error(
        'SignupWithEmailUseCase.execute failed',
        error instanceof Error ? error : undefined,
        { input },
      );

      return Result.err({
        code: 'REPOSITORY_ERROR',
        details: { message },
      } as SignupWithEmailApplicationError);
    }
  }

  private generateSalt(): string {
    const array = new Uint8Array(16);
    if (typeof crypto !== 'undefined' && crypto.getRandomValues) {
      crypto.getRandomValues(array);
    } else {
      for (let i = 0; i < array.length; i++) {
        array[i] = Math.floor(Math.random() * 256);
      }
    }
    return Array.from(array, byte => byte.toString(16).padStart(2, '0')).join('');
  }

  private async hashPassword(password: string, salt: string): Promise<string> {
    // Simple hash for demo - in production, use bcrypt or argon2
    const data = password + salt;
    if (typeof crypto !== 'undefined' && crypto.subtle) {
      const encoder = new TextEncoder();
      const dataBuffer = encoder.encode(data);
      const hashBuffer = await crypto.subtle.digest('SHA-256', dataBuffer);
      const hashArray = Array.from(new Uint8Array(hashBuffer));
      return hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
    }
    // Fallback for environments without crypto.subtle
    let hash = 0;
    for (let i = 0; i < data.length; i++) {
      const char = data.charCodeAt(i);
      hash = ((hash << 5) - hash) + char;
      hash = hash & hash;
    }
    return Math.abs(hash).toString(16).padStart(16, '0');
  }

  private generateUserId(): string {
    if (typeof crypto !== 'undefined' && crypto.randomUUID) {
      return crypto.randomUUID();
    }
    return 'user-' + Date.now().toString(36) + Math.random().toString(36).substr(2, 9);
  }
}