// backend/src/modules/auth/auth.service.ts
import {
  Injectable,
  UnauthorizedException,
  BadRequestException,
  ConflictException,
  InternalServerErrorException
} from '@nestjs/common';
import { JwtService } from '@nestjs/jwt';
import { ConfigService } from '@nestjs/config';
import * as bcrypt from 'bcrypt';
import { PrismaService } from '../../../prisma/prisma.service';
import { LoginDto } from './dto/login.dto';
import { RegisterDto } from './dto/register.dto';
import { CreateOrganizationDto } from './dto/create-organization.dto';
import { JwtPayload } from './interfaces/jwt-payload.interface';

const ALL_PERMISSIONS = [
  'TAB_TODAY_READ',
  'TAB_TODAY_EDIT',
  'TAB_PATIENTS_READ',
  'TAB_PATIENTS_EDIT',
  'TAB_APPOINTMENTS_READ',
  'TAB_APPOINTMENTS_EDIT',
  'TAB_STAFF_READ',
  'TAB_STAFF_EDIT',
  'TAB_LAB_READ',
  'TAB_LAB_EDIT',
  'TAB_BILLING_READ',
  'TAB_BILLING_EDIT',
  'TAB_REPORTS_READ',
  'TAB_REPORTS_EDIT',
];

@Injectable()
export class AuthService {
  constructor(
    private prisma: PrismaService,
    private jwtService: JwtService,
    private configService: ConfigService,
  ) { }

  /**
   * Validate user credentials (used by LocalStrategy)
   * @param email - User's email
   * @param password - User's password
   * @returns User object without passwordHash or null if invalid
   */
  async validateUser(email: string, password: string): Promise<any> {
    try {
      const user = await this.prisma.user.findUnique({
        where: { email },
        include: {
          memberships: {
            include: {
              organization: {
                include: {
                  type: true, // Include organization type (CLINIC/LAB)
                  plan: true,
                }
              },
              permissions: {
                include: {
                  permission: true, // Include permission details
                },
              },
            },
          },
        },
      });

      if (!user) {
        return null;
      }

      // Check if user has a password (might be OAuth only, but we're not using OAuth)
      if (!user.passwordHash) {
        return null;
      }

      const isPasswordValid = await bcrypt.compare(password, user.passwordHash);
      if (!isPasswordValid) {
        return null;
      }

      // Remove sensitive data
      const { passwordHash, ...result } = user;
      return result;
    } catch (error) {
      throw new InternalServerErrorException('Error validating user');
    }
  }

  /**
   * Login user and generate tokens
   * @param loginDto - Login credentials (email, password)
   * @param user - Validated user object from LocalStrategy
   * @returns Access token, refresh token, user info, and organizations
   */
  async login(loginDto: LoginDto, user: any) {
    try {
      // Generate access token (short-lived)
      const accessPayload: JwtPayload = {
        sub: user.id,
        email: user.email,
        type: 'access'
      };

      // Generate refresh token (long-lived)
      const refreshPayload: JwtPayload = {
        sub: user.id,
        email: user.email,
        type: 'refresh'
      };

      const [accessToken, refreshToken] = await Promise.all([
        this.jwtService.signAsync(accessPayload, {
          secret: this.configService.get('JWT_SECRET'),
          expiresIn: this.configService.get('JWT_EXPIRES_IN'),
        }),
        this.jwtService.signAsync(refreshPayload, {
          secret: this.configService.get('JWT_REFRESH_SECRET'),
          expiresIn: this.configService.get('JWT_REFRESH_EXPIRES_IN'),
        }),
      ]);

      // Store session in database
      await this.prisma.session.create({
        data: {
          userId: user.id,
          token: accessToken,
          refreshToken: refreshToken,
          expiresAt: new Date(Date.now() + 30 * 24 * 60 * 60 * 1000), // 30 days
        },
      });

      // Transform memberships to include organization info and permissions
      const organizations = user.memberships?.map(membership => ({
        id: membership.organization.id,
        name: membership.organization.name,
        type: membership.organization.type.name, // 'CLINIC' or 'LAB'
        isOwner: membership.isOwner,
        permissions: membership.isOwner
          ? ALL_PERMISSIONS
          : membership.permissions?.map(p => p.permission.name) || [],
        plan: membership.organization.plan
          ? {
              name: membership.organization.plan.name,
              maxUsers: membership.organization.plan.maxUsers,
            }
          : undefined,
      })) || [];

      return {
        success: true,
        data: {
          accessToken,
          refreshToken,
          user: {
            id: user.id,
            email: user.email,
            name: user.name,
          },
          organizations,
        },
      };
    } catch (error) {
      //throw new InternalServerErrorException('Login failed');
      console.error('🔥 LOGIN ERROR FULL:', error);
      throw error;
    }
  }

  /**
   * Register a new user
   * @param registerDto - Registration data (email, password, name)
   * @returns Created user info without password
   */
  async register(registerDto: RegisterDto) {
    const { email, password, name, organizationName, organizationEmail, organizationType } = registerDto;

    // 1. Check existing user
    const existingUser = await this.prisma.user.findUnique({
      where: { email },
    });

    if (existingUser) {
      throw new ConflictException('User already exists. Please login and create a new organization from your account.');
    }

    // 2. Hash password
    const hashedPassword = await bcrypt.hash(password, 10);

    // 3. Transaction (IMPORTANT)
    const result = await this.prisma.$transaction(async (tx) => {
      // Create user
      const user = await tx.user.create({
        data: {
          email,
          passwordHash: hashedPassword,
          name,
          trialUsedAt: new Date(),
        },
      });

      // Create organization
      const organization = await tx.organization.create({
        data: {
          name: organizationName,
          email: organizationEmail,

          owner: {
            connect: { id: user.id },
          },

          plan: {
            connect: { name: 'trial' }, // make sure this exists in DB
          },

          type: {
            connect: {
              name: organizationType, // 'CLINIC' | 'LAB'
            },
          },
        },
      });

      // Create membership (owner)
      await tx.membership.create({
        data: {
          userId: user.id,
          organizationId: organization.id,
          isOwner: true,
        },
      });

      return { user, organization };
    });

    // 4. Generate tokens (reuse login logic)
    const validatedUser = await this.validateUser(email, password);

    if (!validatedUser) {
      throw new UnauthorizedException('Auto-login failed');
    }

    return this.login({ email, password } as any, validatedUser);
  }

  async createOrganization(userId: string, dto: CreateOrganizationDto) {
    const owner = await this.prisma.user.findUnique({
      where: { id: userId },
      select: { id: true, trialUsedAt: true },
    });

    if (!owner) {
      throw new UnauthorizedException('User not found');
    }

    const planName = dto.planName?.trim() || 'Small';
    const effectivePlanName = owner.trialUsedAt ? planName : 'trial';

    const organization = await this.prisma.$transaction(async (tx) => {
      const createdOrganization = await tx.organization.create({
        data: {
          name: dto.organizationName,
          email: dto.organizationEmail,
          owner: {
            connect: { id: userId },
          },
          plan: {
            connect: { name: effectivePlanName },
          },
          type: {
            connect: { name: dto.organizationType },
          },
        },
      });

      await tx.membership.create({
        data: {
          userId,
          organizationId: createdOrganization.id,
          isOwner: true,
        },
      });

      if (!owner.trialUsedAt) {
        await tx.user.update({
          where: { id: userId },
          data: { trialUsedAt: new Date() },
        });
      }

      return createdOrganization;
    });

    return {
      success: true,
      data: {
        organization: {
          id: organization.id,
          name: organization.name,
          email: organization.email,
        },
      },
    };
  }

  /**
   * Get user profile with all memberships and permissions
   * @param userId - User ID from JWT token
   * @returns User profile with organizations and permissions
   */
  async getProfile(userId: string) {
    try {
      const user = await this.prisma.user.findUnique({
        where: { id: userId },
        include: {
          memberships: {
            include: {
              organization: {
                include: {
                  type: true,
                  plan: true,
                },
              },
              permissions: {
                include: {
                  permission: true,
                },
              },
            },
          },
        },
      });

      if (!user) {
        throw new UnauthorizedException('User not found');
      }

      const { passwordHash, ...result } = user;

      // Transform memberships for frontend consumption
      const organizations = user.memberships?.map(membership => ({
        id: membership.organization.id,
        name: membership.organization.name,
        type: membership.organization.type.name,
        isOwner: membership.isOwner,
        permissions: membership.isOwner
          ? ALL_PERMISSIONS
          : membership.permissions?.map(p => p.permission.name) || [],
        plan: membership.organization.plan
          ? {
              name: membership.organization.plan.name,
              maxUsers: membership.organization.plan.maxUsers,
            }
          : undefined,
      })) || [];

      return {
        success: true,
        data: {
          ...result,
          organizations,
        },
      };
    } catch (error) {
      throw new InternalServerErrorException('Failed to get profile');
    }
  }

  /**
   * Logout user by invalidating their session
   * @param token - Access token to invalidate
   * @returns Success message
   */
  async logout(token: string) {
    try {
      await this.prisma.session.deleteMany({
        where: { token },
      });

      return {
        success: true,
        message: 'Logged out successfully',
      };
    } catch (error) {
      throw new InternalServerErrorException('Logout failed');
    }
  }

  /**
   * Refresh access token using refresh token
   * @param refreshToken - Valid refresh token
   * @returns New access token
   */
  async refreshToken(refreshToken: string) {
    try {
      // Verify the refresh token
      const payload = await this.jwtService.verifyAsync(refreshToken, {
        secret: this.configService.get('jwt.refreshSecret'),
      });

      // Ensure this is a refresh token
      if (payload.type !== 'refresh') {
        throw new UnauthorizedException('Invalid token type');
      }

      // Find session with this refresh token
      const session = await this.prisma.session.findFirst({
        where: {
          refreshToken,
          expiresAt: { gt: new Date() }
        },
        include: {
          user: {
            include: {
              memberships: {
                include: {
                  organization: {
                    include: {
                      type: true,
                      plan: true,
                    },
                  },
                  permissions: {
                    include: {
                      permission: true,
                    },
                  },
                },
              },
            },
          },
        },
      });

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

      // Generate new access token
      const newAccessPayload: JwtPayload = {
        sub: session.user.id,
        email: session.user.email,
        type: 'access',
      };

      const newAccessToken = await this.jwtService.signAsync(newAccessPayload, {
        secret: this.configService.get('jwt.secret'),
        expiresIn: this.configService.get('jwt.expiresIn'),
      });

      // Update session with new access token
      await this.prisma.session.update({
        where: { id: session.id },
        data: {
          token: newAccessToken,
          expiresAt: new Date(Date.now() + 7 * 24 * 60 * 60 * 1000), // 7 days
        },
      });

      // Transform memberships for response
      const organizations = session.user.memberships?.map(membership => ({
        id: membership.organization.id,
        name: membership.organization.name,
        type: membership.organization.type.name,
        isOwner: membership.isOwner,
        permissions: membership.isOwner
          ? ALL_PERMISSIONS
          : membership.permissions?.map(p => p.permission.name) || [],
        plan: membership.organization.plan
          ? {
              name: membership.organization.plan.name,
              maxUsers: membership.organization.plan.maxUsers,
            }
          : undefined,
      })) || [];

      return {
        success: true,
        data: {
          accessToken: newAccessToken,
          user: {
            id: session.user.id,
            email: session.user.email,
            name: session.user.name,
          },
          organizations,
        },
      };
    } catch (error) {
      if (error.name === 'JsonWebTokenError' || error.name === 'TokenExpiredError') {
        throw new UnauthorizedException('Invalid or expired refresh token');
      }
      throw new UnauthorizedException('Refresh token failed');
    }
  }

  /**
   * Change user password
   * @param userId - User ID
   * @param oldPassword - Current password
   * @param newPassword - New password
   * @returns Success message
   */
  async changePassword(userId: string, oldPassword: string, newPassword: string) {
    try {
      const user = await this.prisma.user.findUnique({
        where: { id: userId },
      });

      if (!user || !user.passwordHash) {
        throw new BadRequestException('User not found or invalid password method');
      }

      // Verify old password
      const isPasswordValid = await bcrypt.compare(oldPassword, user.passwordHash);
      if (!isPasswordValid) {
        throw new UnauthorizedException('Current password is incorrect');
      }

      // Hash new password
      const hashedPassword = await bcrypt.hash(newPassword, 10);

      // Update password
      await this.prisma.user.update({
        where: { id: userId },
        data: { passwordHash: hashedPassword },
      });

      // Invalidate all sessions for this user (force re-login)
      await this.prisma.session.deleteMany({
        where: { userId },
      });

      return {
        success: true,
        message: 'Password changed successfully. Please login again.',
      };
    } catch (error) {
      if (error instanceof UnauthorizedException || error instanceof BadRequestException) {
        throw error;
      }
      throw new InternalServerErrorException('Failed to change password');
    }
  }

  /**
   * Get all active sessions for a user
   * @param userId - User ID
   * @returns List of active sessions
   */
  async getUserSessions(userId: string) {
    try {
      const sessions = await this.prisma.session.findMany({
        where: {
          userId,
          expiresAt: { gt: new Date() },
        },
        orderBy: { createdAt: 'desc' },
      });

      return {
        success: true,
        data: sessions,
      };
    } catch (error) {
      throw new InternalServerErrorException('Failed to get sessions');
    }
  }

  /**
   * Revoke a specific session
   * @param userId - User ID
   * @param sessionId - Session ID to revoke
   * @returns Success message
   */
  async revokeSession(userId: string, sessionId: string) {
    try {
      await this.prisma.session.delete({
        where: {
          id: sessionId,
          userId, // Ensure session belongs to user
        },
      });

      return {
        success: true,
        message: 'Session revoked successfully',
      };
    } catch (error) {
      throw new InternalServerErrorException('Failed to revoke session');
    }
  }

  /**
   * Revoke all sessions for a user (except current)
   * @param userId - User ID
   * @param currentToken - Current access token to keep
   * @returns Success message
   */
  async revokeAllSessions(userId: string, currentToken: string) {
    try {
      await this.prisma.session.deleteMany({
        where: {
          userId,
          token: { not: currentToken }, // Keep current session
        },
      });

      return {
        success: true,
        message: 'All other sessions revoked successfully',
      };
    } catch (error) {
      throw new InternalServerErrorException('Failed to revoke sessions');
    }
  }

  /**
   * Validate token and return user
   * @param token - JWT token
   * @returns User info if token is valid
   */
  async validateToken(token: string) {
    try {
      const payload = await this.jwtService.verifyAsync(token, {
        secret: this.configService.get('jwt.secret'),
      });

      if (payload.type !== 'access') {
        throw new UnauthorizedException('Invalid token type');
      }

      const session = await this.prisma.session.findFirst({
        where: {
          token,
          expiresAt: { gt: new Date() }
        },
        include: {
          user: {
            include: {
              memberships: {
                include: {
                  organization: {
                    include: {
                      type: true,
                      plan: true,
                    },
                  },
                  permissions: {
                    include: {
                      permission: true,
                    },
                  },
                },
              },
            },
          },
        },
      });

      if (!session) {
        throw new UnauthorizedException('Session not found or expired');
      }

      const { passwordHash, ...user } = session.user;

      const organizations = session.user.memberships?.map(membership => ({
        id: membership.organization.id,
        name: membership.organization.name,
        type: membership.organization.type.name,
        isOwner: membership.isOwner,
        permissions: membership.isOwner
          ? ALL_PERMISSIONS
          : membership.permissions?.map(p => p.permission.name) || [],
        plan: membership.organization.plan
          ? {
              name: membership.organization.plan.name,
              maxUsers: membership.organization.plan.maxUsers,
            }
          : undefined,
      })) || [];

      return {
        success: true,
        data: {
          user,
          organizations,
        },
      };
    } catch (error) {
      throw new UnauthorizedException('Invalid token');
    }
  }

  async selectOrganization(userId: string, organizationId: string) {
    // 1. Verify membership
    const membership = await this.prisma.membership.findFirst({
      where: {
        userId,
        organizationId,
      },
      include: {
        user: true,
        organization: {
          include: {
            type: true,
            plan: true,
          },
        },
        permissions: {
          include: {
            permission: true,
          },
        },
      },
    });

    if (!membership) {
      throw new UnauthorizedException('Access denied to this organization');
    }

    // 2. Build payload WITH org context
    const payload = {
      sub: userId,
      email: membership.user.email,
      organizationId: membership.organizationId,
      type: 'access',
    };

    // 3. Generate new token
    const accessToken = await this.jwtService.signAsync(payload, {
      secret: this.configService.get('JWT_SECRET'),
      expiresIn: this.configService.get('JWT_EXPIRES_IN'),
    });

    // 4. Format permissions
    const permissions = membership.isOwner
      ? ALL_PERMISSIONS
      : membership.permissions.map(p => p.permission.name);

    return {
      success: true,
      data: {
        accessToken,
        organization: {
          id: membership.organization.id,
          name: membership.organization.name,
          type: membership.organization.type.name,
          isOwner: membership.isOwner,
          plan: membership.organization.plan
            ? {
                name: membership.organization.plan.name,
                maxUsers: membership.organization.plan.maxUsers,
              }
            : undefined,
        },
        permissions,
      },
    };
  }

  /**
   * Owner-only subscription / seat alerts for the current org (from JWT).
   * Used for a subtle warning indicator in the app shell (not staff-facing banners).
   */
  async getOwnerSubscriptionAlert(userId: string, organizationId: string | undefined) {
    if (!organizationId) {
      return {
        success: true,
        data: {
          showWarning: false,
          seatsLow: false,
          trialEndingSoon: false,
          trialExpired: false,
        },
      };
    }

    const membership = await this.prisma.membership.findFirst({
      where: { userId, organizationId },
      include: {
        organization: {
          include: { plan: true },
        },
      },
    });

    if (!membership || !membership.isOwner) {
      return {
        success: true,
        data: {
          showWarning: false,
          seatsLow: false,
          trialEndingSoon: false,
          trialExpired: false,
        },
      };
    }

    const org = membership.organization;
    const plan = org.plan;
    const maxUsers = plan.maxUsers;
    const seatsUsed = await this.prisma.membership.count({
      where: { organizationId: org.id },
    });

    const unlimited = maxUsers >= 999999;
    const remaining = unlimited ? Infinity : maxUsers - seatsUsed;
    const seatsLow =
      !unlimited && remaining >= 0 && remaining <= 2 && maxUsers > 0;

    let trialEndingSoon = false;
    let trialExpired = false;
    let daysUntilTrialEnd: number | null = null;
    let trialEndsAt: string | null = null;

    if (plan.name === 'trial') {
      const end = new Date(org.createdAt);
      end.setDate(end.getDate() + 30);
      trialEndsAt = end.toISOString();
      const ms = end.getTime() - Date.now();
      daysUntilTrialEnd = Math.ceil(ms / (1000 * 60 * 60 * 24));
      if (daysUntilTrialEnd <= 0) {
        trialExpired = true;
      } else if (daysUntilTrialEnd <= 7) {
        trialEndingSoon = true;
      }
    }

    const showWarning = seatsLow || trialEndingSoon || trialExpired;

    return {
      success: true,
      data: {
        showWarning,
        seatsLow,
        trialEndingSoon,
        trialExpired,
        seatsUsed,
        seatsLimit: maxUsers,
        daysUntilTrialEnd,
        trialEndsAt,
      },
    };
  }
}