import {
  BadRequestException,
  ConflictException,
  HttpException,
  HttpStatus,
  Injectable,
  Logger,
  UnauthorizedException,
} from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { JwtService } from '@nestjs/jwt';
import { InjectRepository } from '@nestjs/typeorm';
import * as bcrypt from 'bcrypt';
import { Repository, IsNull } from 'typeorm';
import { Customer } from '../customers/entities/customer.entity';
import { Salon } from '../salons/entities/salon.entity';
import { ProvincesService } from '../provinces/provinces.service';
import { SmsService } from '../sms/sms.service';
import { SalonSubscription } from '../subscriptions/entities/salon-subscription.entity';
import { SalonSubscriptionsService } from '../subscriptions/salon-subscriptions.service';
import { UserRole } from '../users/enums/user-role.enum';
import { User } from '../users/entities/user.entity';
import { UsersService } from '../users/users.service';
import { VerifyAdminOtpDto } from './dto/verify-admin-otp.dto';
import { VerifyOtpDto } from './dto/verify-otp.dto';
import { VerifySalonOtpDto } from './dto/verify-salon-otp.dto';
import { Otp } from './entities/otp.entity';
import { RefreshToken } from './entities/refresh-token.entity';
import { AuthUser } from './interfaces/auth-user.interface';
import { JwtPayload } from './interfaces/jwt-payload.interface';

export interface AuthTokensResponse {
  accessToken: string;
  refreshToken: string;
  user: {
    id: string;
    firstName: string;
    lastName: string;
    mobile: string;
    role: UserRole;
  };
}

export interface SalonAuthResponse extends AuthTokensResponse {
  salon?: Salon;
}

export interface MeResponse {
  user: AuthTokensResponse['user'];
  salons?: Salon[];
  activeSubscription?: SalonSubscription | null;
}

@Injectable()
export class AuthService {
  private readonly logger = new Logger(AuthService.name);
  private readonly otpLength: number;
  private readonly otpExpiresInMinutes: number;
  private readonly otpSalonSignupExpiresInMinutes: number;
  private readonly otpMaxAttempts: number;
  private readonly otpCooldownSeconds: number;
  private readonly refreshExpiresIn: string;

  constructor(
    @InjectRepository(Otp)
    private readonly otpRepository: Repository<Otp>,
    @InjectRepository(RefreshToken)
    private readonly refreshTokenRepository: Repository<RefreshToken>,
    @InjectRepository(Customer)
    private readonly customersRepository: Repository<Customer>,
    @InjectRepository(Salon)
    private readonly salonsRepository: Repository<Salon>,
    private readonly provincesService: ProvincesService,
    private readonly usersService: UsersService,
    private readonly salonSubscriptionsService: SalonSubscriptionsService,
    private readonly smsService: SmsService,
    private readonly jwtService: JwtService,
    private readonly configService: ConfigService,
  ) {
    this.otpLength = parseInt(
      this.configService.get<string>('OTP_LENGTH') ?? '5',
      10,
    );
    this.otpExpiresInMinutes = parseInt(
      this.configService.get<string>('OTP_EXPIRES_IN_MINUTES') ?? '5',
      10,
    );
    this.otpSalonSignupExpiresInMinutes = parseInt(
      this.configService.get<string>('OTP_SALON_SIGNUP_EXPIRES_IN_MINUTES') ??
        '15',
      10,
    );
    this.otpMaxAttempts = parseInt(
      this.configService.get<string>('OTP_MAX_ATTEMPTS') ?? '5',
      10,
    );
    this.otpCooldownSeconds = parseInt(
      this.configService.get<string>('OTP_COOLDOWN_SECONDS') ?? '60',
      10,
    );
    this.refreshExpiresIn =
      this.configService.get<string>('JWT_REFRESH_EXPIRES_IN') ?? '7d';
  }

  async requestOtp(mobile: string): Promise<{ message: string; code?: string }> {
    const code = await this.sendOtp(mobile, this.otpExpiresInMinutes);
    return this.buildOtpRequestResponse(code);
  }

  async requestAdminOtp(
    mobile: string,
  ): Promise<{ message: string; code?: string }> {
    await this.ensureAdminMobile(mobile);
    return this.requestOtp(mobile);
  }

  async checkSalonMobile(
    mobile: string,
  ): Promise<{ isRegistered: boolean }> {
    await this.ensureSalonMobileCanProceed(mobile);
    const isRegistered = await this.isSalonOwnerRegistered(mobile);
    return { isRegistered };
  }

  async requestSalonOtp(mobile: string): Promise<{
    message: string;
    isRegistered: boolean;
    expiresInSeconds: number;
    code?: string;
  }> {
    await this.ensureSalonMobileCanProceed(mobile);
    const isRegistered = await this.isSalonOwnerRegistered(mobile);
    const expiresInMinutes = isRegistered
      ? this.otpExpiresInMinutes
      : this.otpSalonSignupExpiresInMinutes;

    const code = await this.sendOtp(mobile, expiresInMinutes);

    return {
      ...this.buildOtpRequestResponse(code),
      isRegistered,
      expiresInSeconds: expiresInMinutes * 60,
    };
  }

  async verifySalonOtp(dto: VerifySalonOtpDto): Promise<SalonAuthResponse> {
    await this.consumeOtp(dto.mobile, dto.code);

    const existingUser = await this.usersService.findByMobile(dto.mobile);

    if (existingUser) {
      if (existingUser.role !== UserRole.SALON) {
        throw new ConflictException(
          'This mobile is already registered with another account type',
        );
      }

      return this.issueTokens(existingUser);
    }

    return this.registerSalonOwner(dto);
  }

  private async sendOtp(
    mobile: string,
    expiresInMinutes: number,
  ): Promise<string> {
    const recentOtp = await this.otpRepository.findOne({
      where: { mobile, verified: false },
      order: { createdAt: 'DESC' },
    });

    if (recentOtp) {
      const cooldownEnd =
        recentOtp.createdAt.getTime() + this.otpCooldownSeconds * 1000;
      if (Date.now() < cooldownEnd) {
        throw new HttpException(
          'Please wait before requesting a new OTP',
          HttpStatus.TOO_MANY_REQUESTS,
        );
      }
    }

    await this.otpRepository.delete({ mobile, verified: false });

    const code = this.generateOtpCode();
    const hashedCode = await bcrypt.hash(code, 10);
    const expiresAt = new Date(Date.now() + expiresInMinutes * 60 * 1000);

    await this.otpRepository.save({
      mobile,
      code: hashedCode,
      expiresAt,
    });

    const sent = await this.smsService.sendSms(mobile, `کد ورود: ${code}`);

    if (!sent && !this.shouldExposeOtpInResponse()) {
      throw new BadRequestException('Failed to send OTP');
    }

    if (this.shouldExposeOtpInResponse()) {
      this.logger.debug(`OTP for ${mobile}: ${code}`);
    }

    return code;
  }

  private shouldExposeOtpInResponse(): boolean {
    return this.configService.get<string>('NODE_ENV') !== 'production';
  }

  private buildOtpRequestResponse(code: string): {
    message: string;
    code?: string;
  } {
    return {
      message: 'OTP sent',
      ...(this.shouldExposeOtpInResponse() ? { code } : {}),
    };
  }

  private async consumeOtp(mobile: string, code: string): Promise<void> {
    const otp = await this.otpRepository.findOne({
      where: { mobile, verified: false },
      order: { createdAt: 'DESC' },
    });

    if (!otp) {
      throw new UnauthorizedException('Invalid or expired OTP');
    }

    if (otp.expiresAt < new Date()) {
      throw new UnauthorizedException('Invalid or expired OTP');
    }

    if (otp.attempts >= this.otpMaxAttempts) {
      throw new UnauthorizedException('Too many failed attempts');
    }

    const isValid = await bcrypt.compare(code, otp.code);
    if (!isValid) {
      otp.attempts += 1;
      await this.otpRepository.save(otp);
      throw new UnauthorizedException('Invalid or expired OTP');
    }

    otp.verified = true;
    await this.otpRepository.save(otp);
  }

  private async isSalonOwnerRegistered(mobile: string): Promise<boolean> {
    const user = await this.usersService.findByMobile(mobile);
    return user?.role === UserRole.SALON;
  }

  private async ensureSalonMobileCanProceed(mobile: string): Promise<void> {
    const user = await this.usersService.findByMobile(mobile);

    if (user && user.role !== UserRole.SALON) {
      throw new ConflictException(
        'This mobile is already registered with another account type',
      );
    }
  }

  private async ensureAdminMobile(mobile: string): Promise<void> {
    const user = await this.usersService.findByMobile(mobile);

    if (!user || user.role !== UserRole.ADMIN) {
      throw new BadRequestException('این شماره ادمین نیست');
    }
  }

  private async registerSalonOwner(
    dto: VerifySalonOtpDto,
  ): Promise<SalonAuthResponse> {
    this.validateSalonSignupFields(dto);
    await this.validateSalonLocation(dto.salonProvinceId!, dto.salonCityId!);

    const user = await this.usersService.create({
      firstName: dto.firstName!,
      lastName: dto.lastName!,
      mobile: dto.mobile,
      role: UserRole.SALON,
    });

    const salon = await this.salonsRepository.save({
      name: dto.salonName!,
      description: dto.salonDescription ?? null,
      address: dto.salonAddress!,
      phone: dto.salonPhone!,
      provinceId: dto.salonProvinceId!,
      cityId: dto.salonCityId!,
      ownerId: user.id,
    });

    const tokens = await this.issueTokens(user);
    return { ...tokens, salon };
  }

  private validateSalonSignupFields(dto: VerifySalonOtpDto): void {
    const requiredFields: Array<keyof VerifySalonOtpDto> = [
      'firstName',
      'lastName',
      'salonName',
      'salonAddress',
      'salonPhone',
      'salonProvinceId',
      'salonCityId',
    ];

    const missingFields = requiredFields.filter((field) => !dto[field]);

    if (missingFields.length > 0) {
      throw new BadRequestException(
        `Missing required fields for salon registration: ${missingFields.join(', ')}`,
      );
    }
  }

  private async validateSalonLocation(
    provinceId: string,
    cityId: string,
  ): Promise<void> {
    const city = await this.provincesService.findCity(provinceId, cityId);
    if (!city) {
      throw new BadRequestException('شهر انتخاب‌شده با استان مطابقت ندارد');
    }
  }

  async verifyOtp(dto: VerifyOtpDto): Promise<AuthTokensResponse> {
    await this.consumeOtp(dto.mobile, dto.code);

    const user = await this.resolveUserForLogin(dto);
    return this.issueTokens(user);
  }

  async verifyAdminOtp(dto: VerifyAdminOtpDto): Promise<AuthTokensResponse> {
    await this.ensureAdminMobile(dto.mobile);
    await this.consumeOtp(dto.mobile, dto.code);

    const user = await this.usersService.findByMobile(dto.mobile);
    if (!user || user.role !== UserRole.ADMIN) {
      throw new BadRequestException('این شماره ادمین نیست');
    }

    return this.issueTokens(user);
  }

  async refresh(refreshToken: string): Promise<AuthTokensResponse> {
    const storedTokens = await this.refreshTokenRepository.find({
      where: { revokedAt: IsNull() },
      relations: { user: true },
    });

    let matchedToken: RefreshToken | null = null;
    for (const stored of storedTokens) {
      if (await bcrypt.compare(refreshToken, stored.tokenHash)) {
        if (stored.expiresAt < new Date()) {
          throw new UnauthorizedException('Invalid refresh token');
        }
        matchedToken = stored;
        break;
      }
    }

    if (!matchedToken) {
      throw new UnauthorizedException('Invalid refresh token');
    }

    matchedToken.revokedAt = new Date();
    await this.refreshTokenRepository.save(matchedToken);

    return this.issueTokens(matchedToken.user);
  }

  async logout(userId: string, refreshToken: string): Promise<void> {
    const storedTokens = await this.refreshTokenRepository.find({
      where: { userId, revokedAt: IsNull() },
    });

    for (const stored of storedTokens) {
      if (await bcrypt.compare(refreshToken, stored.tokenHash)) {
        stored.revokedAt = new Date();
        await this.refreshTokenRepository.save(stored);
        return;
      }
    }

    throw new UnauthorizedException('Invalid refresh token');
  }

  async getMe(authUser: AuthUser): Promise<MeResponse> {
    const user = await this.usersService.findOne(authUser.id);

    const response: MeResponse = {
      user: {
        id: user.id,
        firstName: user.firstName,
        lastName: user.lastName,
        mobile: user.mobile,
        role: user.role,
      },
    };

    if (user.role === UserRole.SALON) {
      response.salons = await this.salonsRepository.find({
        where: { ownerId: user.id },
        relations: { province: true, city: true },
        order: { createdAt: 'ASC' },
      });
      response.activeSubscription =
        await this.salonSubscriptionsService.findActiveSubscriptionForOwner(
          user.id,
        );
    }

    return response;
  }

  private async resolveUserForLogin(dto: VerifyOtpDto): Promise<User> {
    const existingUser = await this.usersService.findByMobile(dto.mobile);

    if (existingUser) {
      return existingUser;
    }

    if (!dto.role) {
      throw new BadRequestException(
        'role is required when registering a new account',
      );
    }

    return this.createUserFromOtp(dto);
  }

  private async createUserFromOtp(dto: VerifyOtpDto): Promise<User> {
    const firstName = dto.firstName ?? 'کاربر';
    const lastName = dto.lastName ?? dto.mobile.slice(-4);

    const user = await this.usersService.create({
      firstName,
      lastName,
      mobile: dto.mobile,
      role: dto.role!,
    });

    if (dto.role === UserRole.CUSTOMER) {
      const dateOfBirth = dto.dateOfBirth ?? '2000-01-01';
      const address = dto.address ?? '-';

      await this.customersRepository.save({
        userId: user.id,
        dateOfBirth,
        address,
      });
    }

    return user;
  }

  private async issueTokens(user: User): Promise<AuthTokensResponse> {
    const payload: JwtPayload = { sub: user.id, role: user.role };

    const accessToken = this.jwtService.sign(payload);
    const refreshToken = await this.createRefreshToken(user.id);

    return {
      accessToken,
      refreshToken,
      user: {
        id: user.id,
        firstName: user.firstName,
        lastName: user.lastName,
        mobile: user.mobile,
        role: user.role,
      },
    };
  }

  private async createRefreshToken(userId: string): Promise<string> {
    const refreshToken = this.jwtService.sign(
      { sub: userId },
      {
        secret: this.configService.getOrThrow<string>('JWT_REFRESH_SECRET'),
        expiresIn: this.refreshExpiresIn as `${number}d`,
      },
    );

    const tokenHash = await bcrypt.hash(refreshToken, 10);
    const expiresAt = this.parseExpiresIn(this.refreshExpiresIn);

    await this.refreshTokenRepository.save({
      userId,
      tokenHash,
      expiresAt,
    });

    return refreshToken;
  }

  private generateOtpCode(): string {
    const max = Math.pow(10, this.otpLength);
    const min = Math.pow(10, this.otpLength - 1);
    return String(Math.floor(min + Math.random() * (max - min)));
  }

  private parseExpiresIn(expiresIn: string): Date {
    const match = expiresIn.match(/^(\d+)([dhms])$/);
    if (!match) {
      return new Date(Date.now() + 7 * 24 * 60 * 60 * 1000);
    }

    const value = parseInt(match[1], 10);
    const unit = match[2];
    const multipliers: Record<string, number> = {
      s: 1000,
      m: 60 * 1000,
      h: 60 * 60 * 1000,
      d: 24 * 60 * 60 * 1000,
    };

    return new Date(Date.now() + value * multipliers[unit]);
  }
}