import {
  Injectable,
  UnauthorizedException,
  ConflictException,
  BadRequestException,
  Inject,
} from "@nestjs/common";
import { JwtService } from "@nestjs/jwt";
import { ConfigService } from "@nestjs/config";
import * as bcrypt from "bcrypt";
import { UsersService } from "../users/users.service";
import { MappingsService } from "../mappings/mappings.service";
import { WhmcsService } from "../vendors/whmcs/whmcs.service";
import { SalesforceService } from "../vendors/salesforce/salesforce.service";
import { AuditService, AuditAction } from "../common/audit/audit.service";
import { TokenBlacklistService } from "./services/token-blacklist.service";
import { SignupDto } from "./dto/signup.dto";
import { LinkWhmcsDto } from "./dto/link-whmcs.dto";
import { SetPasswordDto } from "./dto/set-password.dto";
import { getErrorMessage } from "../common/utils/error.util";
import { Logger } from "nestjs-pino";
import { EmailService } from "../common/email/email.service";
import { User as SharedUser } from "@customer-portal/shared";
import type { User as PrismaUser } from "@prisma/client";
import type { Request } from "express";
import { WhmcsClientResponse } from "../vendors/whmcs/types/whmcs-api.types";

@Injectable()
export class AuthService {
  private readonly MAX_LOGIN_ATTEMPTS = 5;
  private readonly LOCKOUT_DURATION_MINUTES = 15;

  constructor(
    private usersService: UsersService,
    private mappingsService: MappingsService,
    private jwtService: JwtService,
    private configService: ConfigService,
    private whmcsService: WhmcsService,
    private salesforceService: SalesforceService,
    private auditService: AuditService,
    private tokenBlacklistService: TokenBlacklistService,
    private emailService: EmailService,
    @Inject(Logger) private readonly logger: Logger
  ) {}

  async signup(signupData: SignupDto, request?: Request) {
    const {
      email,
      password,
      firstName,
      lastName,
      company,
      phone,
      sfNumber,
      address,
      nationality,
      dateOfBirth,
      gender,
    } = signupData;

    // Enhanced input validation
    this.validateSignupData(signupData);

    // Check if user already exists
    const existingUser: PrismaUser | null = await this.usersService.findByEmailInternal(email);
    if (existingUser) {
      await this.auditService.logAuthEvent(
        AuditAction.SIGNUP,
        undefined,
        { email, reason: "User already exists" },
        request,
        false,
        "User with this email already exists"
      );
      throw new ConflictException("User with this email already exists");
    }

    // Hash password with environment-based configuration
    const saltRoundsConfig = this.configService.get<string | number>("BCRYPT_ROUNDS", 12);
    const saltRounds =
      typeof saltRoundsConfig === "string" ? Number(saltRoundsConfig) : saltRoundsConfig;
    const passwordHash = await bcrypt.hash(password, saltRounds);

    try {
      // 0. Lookup Salesforce Account by Customer Number (SF Number)
      const sfAccount: { id: string } | null =
        await this.salesforceService.findAccountByCustomerNumber(sfNumber);
      if (!sfAccount) {
        throw new BadRequestException(
          `Salesforce account not found for Customer Number: ${sfNumber}`
        );
      }

      // 1. Create user in portal
      const user: SharedUser = await this.usersService.create({
        email,
        passwordHash,
        firstName,
        lastName,
        company,
        phone,
        emailVerified: false,
        failedLoginAttempts: 0,
        lockedUntil: null,
        lastLoginAt: null,
      });

      // 2. Create client in WHMCS
      // Prepare WHMCS custom fields (IDs configurable via env)
      const customerNumberFieldId = this.configService.get<string>(
        "WHMCS_CUSTOMER_NUMBER_FIELD_ID",
        "198"
      );
      const dobFieldId = this.configService.get<string>("WHMCS_DOB_FIELD_ID");
      const genderFieldId = this.configService.get<string>("WHMCS_GENDER_FIELD_ID");
      const nationalityFieldId = this.configService.get<string>("WHMCS_NATIONALITY_FIELD_ID");

      const customfields: Record<string, string> = {};
      if (customerNumberFieldId) customfields[customerNumberFieldId] = sfNumber;
      if (dobFieldId && dateOfBirth) customfields[dobFieldId] = dateOfBirth;
      if (genderFieldId && gender) customfields[genderFieldId] = gender;
      if (nationalityFieldId && nationality) customfields[nationalityFieldId] = nationality;

      const whmcsClient: { clientId: number } = await this.whmcsService.addClient({
        firstname: firstName,
        lastname: lastName,
        email,
        companyname: company || "",
        phonenumber: phone || "",
        address1: address?.line1,
        city: address?.city,
        state: address?.state,
        postcode: address?.postalCode,
        country: address?.country,
        password2: password, // WHMCS requires plain password for new clients
        customfields,
      });

      // 3. Store ID mappings
      await this.mappingsService.createMapping({
        userId: user.id,
        whmcsClientId: whmcsClient.clientId,
        sfAccountId: sfAccount.id,
      });

      // Log successful signup
      await this.auditService.logAuthEvent(
        AuditAction.SIGNUP,
        user.id,
        { email, whmcsClientId: whmcsClient.clientId },
        request,
        true
      );

      // Generate JWT token
      const tokens = this.generateTokens(user);

      return {
        user: this.sanitizeUser(user),
        ...tokens,
      };
    } catch (error) {
      // Log failed signup
      await this.auditService.logAuthEvent(
        AuditAction.SIGNUP,
        undefined,
        { email, error: getErrorMessage(error) },
        request,
        false,
        getErrorMessage(error)
      );

      // TODO: Implement rollback logic if any step fails
      this.logger.error("Signup error", { error: getErrorMessage(error) });
      throw new BadRequestException("Failed to create user account");
    }
  }

  async login(
    user: {
      id: string;
      email: string;
      role?: string;
      passwordHash?: string | null;
      failedLoginAttempts?: number | null;
      lockedUntil?: Date | null;
    },
    request?: Request
  ) {
    // Update last login time and reset failed attempts
    await this.usersService.update(user.id, {
      lastLoginAt: new Date(),
      failedLoginAttempts: 0,
      lockedUntil: null,
    });

    // Log successful login
    await this.auditService.logAuthEvent(
      AuditAction.LOGIN_SUCCESS,
      user.id,
      { email: user.email },
      request,
      true
    );

    const tokens = this.generateTokens(user);
    return {
      user: this.sanitizeUser(user),
      ...tokens,
    };
  }

  async linkWhmcsUser(linkData: LinkWhmcsDto, _request?: Request) {
    const { email, password } = linkData;

    // Check if user already exists in portal
    const existingUser: PrismaUser | null = await this.usersService.findByEmailInternal(email);
    if (existingUser) {
      // If user exists but has no password (abandoned during setup), allow them to continue
      if (!existingUser.passwordHash) {
        this.logger.log(
          `User ${email} exists but has no password - allowing password setup to continue`
        );
        return {
          user: this.sanitizeUser(existingUser),
          needsPasswordSet: true,
        };
      } else {
        throw new ConflictException(
          "User already exists in portal and has completed setup. Please use the login page."
        );
      }
    }

    try {
      // 1. First, find the client by email using GetClientsDetails directly
      let clientDetails: WhmcsClientResponse["client"];
      try {
        clientDetails = await this.whmcsService.getClientDetailsByEmail(email);
      } catch (error) {
        this.logger.warn(`WHMCS client lookup failed for email ${email}`, {
          error: getErrorMessage(error),
        });
        throw new UnauthorizedException("WHMCS client not found with this email address");
      }

      // 2. Validate the password using ValidateLogin
      try {
        this.logger.debug(`About to validate WHMCS password for ${email}`);
        const validateResult = await this.whmcsService.validateLogin(email, password);
        this.logger.debug("WHMCS validation successful", { email });
        if (!validateResult || !validateResult.userId) {
          throw new UnauthorizedException("Invalid WHMCS credentials");
        }
      } catch (error) {
        this.logger.debug("WHMCS validation failed", { email, error: getErrorMessage(error) });
        throw new UnauthorizedException("Invalid WHMCS password");
      }

      // 3. Extract Customer Number from field ID 198
      const customerNumberField = clientDetails.customfields?.find(field => field.id === 198);
      const customerNumber = customerNumberField?.value?.trim();

      if (!customerNumber) {
        throw new BadRequestException(
          `Customer Number not found in WHMCS custom field 198. Please contact support.`
        );
      }

      this.logger.log(
        `Found Customer Number: ${customerNumber} for WHMCS client ${clientDetails.id}`
      );

      // 3. Find existing Salesforce account using Customer Number
      const sfAccount: { id: string } | null =
        await this.salesforceService.findAccountByCustomerNumber(customerNumber);
      if (!sfAccount) {
        throw new BadRequestException(
          `Salesforce account not found for Customer Number: ${customerNumber}. Please contact support.`
        );
      }

      // 4. Create portal user (without password initially)
      const user: SharedUser = await this.usersService.create({
        email,
        passwordHash: null, // No password hash - will be set when user sets password
        firstName: clientDetails.firstname || "",
        lastName: clientDetails.lastname || "",
        company: clientDetails.companyname || "",
        phone: clientDetails.phonenumber || "",
        emailVerified: true, // WHMCS users are pre-verified
      });

      // 5. Store ID mappings
      await this.mappingsService.createMapping({
        userId: user.id,
        whmcsClientId: clientDetails.id,
        sfAccountId: sfAccount.id,
      });

      return {
        user: this.sanitizeUser(user),
        needsPasswordSet: true,
      };
    } catch (error) {
      this.logger.error("WHMCS linking error", { error: getErrorMessage(error) });
      if (error instanceof BadRequestException || error instanceof UnauthorizedException) {
        throw error;
      }
      throw new BadRequestException("Failed to link WHMCS account");
    }
  }

  async checkPasswordNeeded(email: string) {
    const user: PrismaUser | null = await this.usersService.findByEmailInternal(email);
    if (!user) {
      return { needsPasswordSet: false, userExists: false };
    }

    return {
      needsPasswordSet: !user.passwordHash,
      userExists: true,
      email: user.email,
    };
  }

  async setPassword(setPasswordData: SetPasswordDto, _request?: Request) {
    const { email, password } = setPasswordData;

    const user: PrismaUser | null = await this.usersService.findByEmailInternal(email);
    if (!user) {
      throw new UnauthorizedException("User not found");
    }

    // Check if user needs to set password (linked users have null password hash)
    if (user.passwordHash) {
      throw new BadRequestException("User already has a password set");
    }

    // Hash new password
    const saltRounds = 12; // Use a fixed safe value
    const passwordHash = await bcrypt.hash(password, saltRounds);

    // Update user with new password
    const updatedUser: SharedUser = await this.usersService.update(user.id, {
      passwordHash,
    });

    // Generate tokens
    const tokens = this.generateTokens(updatedUser);

    return {
      user: this.sanitizeUser(updatedUser),
      ...tokens,
    };
  }

  async validateUser(
    email: string,
    password: string,
    _request?: Request
  ): Promise<PrismaUser | null> {
    const user: PrismaUser | null = await this.usersService.findByEmailInternal(email);

    if (!user) {
      await this.auditService.logAuthEvent(
        AuditAction.LOGIN_FAILED,
        undefined,
        { email, reason: "User not found" },
        _request,
        false,
        "User not found"
      );
      return null;
    }

    // Check if account is locked
    if (user.lockedUntil && user.lockedUntil > new Date()) {
      await this.auditService.logAuthEvent(
        AuditAction.LOGIN_FAILED,
        user.id,
        { email, reason: "Account locked" },
        _request,
        false,
        "Account is locked"
      );
      return null;
    }

    if (!user.passwordHash) {
      await this.auditService.logAuthEvent(
        AuditAction.LOGIN_FAILED,
        user.id,
        { email, reason: "No password set" },
        _request,
        false,
        "No password set"
      );
      return null;
    }

    try {
      const isPasswordValid = await bcrypt.compare(password, user.passwordHash);

      if (isPasswordValid) {
        return user;
      } else {
        // Increment failed login attempts
        await this.handleFailedLogin(user, _request);
        return null;
      }
    } catch (error) {
      this.logger.error("Password validation error", { email, error: getErrorMessage(error) });
      await this.auditService.logAuthEvent(
        AuditAction.LOGIN_FAILED,
        user.id,
        { email, error: getErrorMessage(error) },
        _request,
        false,
        getErrorMessage(error)
      );
      return null;
    }
  }

  private async handleFailedLogin(user: PrismaUser, _request?: Request): Promise<void> {
    const newFailedAttempts = (user.failedLoginAttempts || 0) + 1;
    let lockedUntil = null;
    let isAccountLocked = false;

    // Lock account if max attempts reached
    if (newFailedAttempts >= this.MAX_LOGIN_ATTEMPTS) {
      lockedUntil = new Date();
      lockedUntil.setMinutes(lockedUntil.getMinutes() + this.LOCKOUT_DURATION_MINUTES);
      isAccountLocked = true;
    }

    await this.usersService.update(user.id, {
      failedLoginAttempts: newFailedAttempts,
      lockedUntil,
    });

    // Log failed login
    await this.auditService.logAuthEvent(
      AuditAction.LOGIN_FAILED,
      user.id,
      {
        email: user.email,
        failedAttempts: newFailedAttempts,
        lockedUntil: lockedUntil?.toISOString(),
      },
      _request,
      false,
      "Invalid password"
    );

    // Log account lock if applicable
    if (isAccountLocked) {
      await this.auditService.logAuthEvent(
        AuditAction.ACCOUNT_LOCKED,
        user.id,
        {
          email: user.email,
          lockDuration: this.LOCKOUT_DURATION_MINUTES,
          lockedUntil: lockedUntil?.toISOString(),
        },
        _request,
        false,
        `Account locked for ${this.LOCKOUT_DURATION_MINUTES} minutes`
      );
    }
  }

  async logout(userId: string, token: string, _request?: Request): Promise<void> {
    // Blacklist the token
    await this.tokenBlacklistService.blacklistToken(token);

    await this.auditService.logAuthEvent(AuditAction.LOGOUT, userId, {}, _request, true);
  }

  // Helper methods
  private generateTokens(user: { id: string; email: string; role?: string }) {
    const payload = { email: user.email, sub: user.id, role: user.role };
    return {
      access_token: this.jwtService.sign(payload),
    };
  }

  private sanitizeUser<
    T extends {
      id: string;
      email: string;
      role?: string;
      passwordHash?: string | null;
      failedLoginAttempts?: number | null;
      lockedUntil?: Date | null;
    },
  >(user: T): Omit<T, "passwordHash" | "failedLoginAttempts" | "lockedUntil"> {
    const {
      passwordHash: _passwordHash,
      failedLoginAttempts: _failedLoginAttempts,
      lockedUntil: _lockedUntil,
      ...sanitizedUser
    } = user as T & {
      passwordHash?: string | null;
      failedLoginAttempts?: number | null;
      lockedUntil?: Date | null;
    };
    return sanitizedUser;
  }

  /**
   * Create SSO link to WHMCS for general access
   */
  async createSsoLink(
    userId: string,
    destination?: string
  ): Promise<{ url: string; expiresAt: string }> {
    try {
      // Production-safe logging - no sensitive data
      this.logger.log("Creating SSO link request");

      // Get WHMCS client ID from user mapping
      const mapping = await this.mappingsService.findByUserId(userId);

      if (!mapping?.whmcsClientId) {
        this.logger.warn("SSO link creation failed: No WHMCS mapping found");
        throw new UnauthorizedException("WHMCS client mapping not found");
      }

      // Create SSO token using custom redirect for better compatibility
      const ssoDestination = "sso:custom_redirect";
      const ssoRedirectPath = destination || "clientarea.php";

      const result = await this.whmcsService.createSsoToken(
        mapping.whmcsClientId,
        ssoDestination,
        ssoRedirectPath
      );

      this.logger.log("SSO link created successfully");

      return result;
    } catch (error) {
      // Production-safe error logging - no sensitive data or stack traces
      this.logger.error("SSO link creation failed", {
        errorType: error instanceof Error ? error.constructor.name : "Unknown",
        message: getErrorMessage(error),
      });
      throw error;
    }
  }

  async requestPasswordReset(email: string): Promise<void> {
    const user = await this.usersService.findByEmailInternal(email);
    // Always act as if successful to avoid account enumeration
    if (!user) {
      return;
    }

    // Create a short-lived signed token (JWT) containing user id and purpose
    const token = this.jwtService.sign(
      { sub: user.id, purpose: "password_reset" },
      { expiresIn: "15m" }
    );

    const appBase = this.configService.get<string>("APP_BASE_URL", "http://localhost:3000");
    const resetUrl = `${appBase}/auth/reset-password?token=${encodeURIComponent(token)}`;
    const templateId = this.configService.get<string>("EMAIL_TEMPLATE_RESET");

    if (templateId) {
      await this.emailService.sendEmail({
        to: email,
        subject: "Reset your password",
        templateId,
        dynamicTemplateData: { resetUrl },
      });
    } else {
      await this.emailService.sendEmail({
        to: email,
        subject: "Reset your Assist Solutions password",
        html: `
          <p>We received a request to reset your password.</p>
          <p><a href="${resetUrl}">Click here to reset your password</a>. This link expires in 15 minutes.</p>
          <p>If you didn't request this, you can safely ignore this email.</p>
        `,
      });
    }
  }

  async resetPassword(token: string, newPassword: string) {
    try {
      const payload = this.jwtService.verify<{ sub: string; purpose: string }>(token);
      if (payload.purpose !== "password_reset") {
        throw new BadRequestException("Invalid token");
      }

      const user = await this.usersService.findById(payload.sub);
      if (!user) throw new BadRequestException("Invalid token");

      const saltRoundsConfig = this.configService.get<string | number>("BCRYPT_ROUNDS", 12);
      const saltRounds =
        typeof saltRoundsConfig === "string" ? Number(saltRoundsConfig) : saltRoundsConfig;
      const passwordHash = await bcrypt.hash(newPassword, saltRounds);

      const updatedUser = await this.usersService.update(user.id, { passwordHash });
      const tokens = this.generateTokens(updatedUser);

      return {
        user: this.sanitizeUser(updatedUser),
        ...tokens,
      };
    } catch (error) {
      this.logger.error("Reset password failed", { error: getErrorMessage(error) });
      throw new BadRequestException("Invalid or expired token");
    }
  }

  private validateSignupData(signupData: SignupDto) {
    const { email, password, firstName, lastName } = signupData;

    if (!email || !password || !firstName || !lastName) {
      throw new BadRequestException(
        "Email, password, firstName, and lastName are required for signup."
      );
    }

    if (!email.includes("@")) {
      throw new BadRequestException("Invalid email address.");
    }

    if (password.length < 8) {
      throw new BadRequestException("Password must be at least 8 characters long.");
    }

    // Password must contain at least one uppercase letter, one lowercase letter, and one number
    if (!/(?=.*[a-z])(?=.*[A-Z])(?=.*\d)/.test(password)) {
      throw new BadRequestException(
        "Password must contain at least one uppercase letter, one lowercase letter, and one number."
      );
    }
  }
}