import {
  BadRequestException,
  ConflictException,
  ForbiddenException,
  Injectable,
  NotFoundException,
  ServiceUnavailableException,
} from '@nestjs/common';
import { Prisma } from '@prisma/client';
import * as bcrypt from 'bcrypt';
import { AuthUser, ASSIGNABLE_GLOBAL_ROLES } from '../auth/auth.types';
import { PermissionsService } from '../auth/permissions.service';
import { SmsService } from '../auth/sms.service';
import { PrismaService } from '../prisma/prisma.service';
import { AdminResetPasswordDto } from './dto/admin-reset-password.dto';
import { CreateUserDto } from './dto/create-user.dto';
import { ListUsersDto } from './dto/list-users.dto';
import { SearchUsersDto } from './dto/search-users.dto';
import { SendUserMessageDto } from './dto/send-user-message.dto';
import { UpdateUserDto } from './dto/update-user.dto';
import { UpdateUserRoleDto } from './dto/update-user-role.dto';

type UserListRow = {
  id: bigint;
  firstName: string | null;
  lastName: string | null;
  firstNameEn: string | null;
  lastNameEn: string | null;
  cellNumber: string;
  roles: string | null;
  roleSlug: string | null;
  businesses: string | null;
  businessMemberId: bigint | null;
  isBusinessOwner: boolean | null;
  teamRole: string | null;
  createdAt: Date;
  isActive: boolean;
};

/**
 * ILIKE patterns so local Iranian input (09…) matches stored E.164 (+98…).
 * `09024300` must match `+989024300340`; short fragments like `4300` still match.
 */
function cellNumberLikePatterns(input: string): string[] {
  const trimmed = input.trim();
  if (!trimmed) return [];

  const patterns = new Set<string>();
  patterns.add(`%${trimmed}%`);

  const digits = trimmed.replace(/\D/g, '');
  if (!digits) return [...patterns];

  patterns.add(`%${digits}%`);

  let rest = digits;
  if (rest.startsWith('00')) rest = rest.slice(2);

  if (rest.startsWith('98')) {
    patterns.add(`%+${rest}%`);
    const national = rest.slice(2);
    if (national) {
      patterns.add(`%0${national}%`);
      patterns.add(`%${national}%`);
    }
  } else if (rest.startsWith('0')) {
    const national = rest.slice(1);
    if (national) {
      patterns.add(`%+98${national}%`);
      patterns.add(`%98${national}%`);
    }
  } else if (rest.startsWith('9')) {
    patterns.add(`%+98${rest}%`);
    patterns.add(`%98${rest}%`);
    patterns.add(`%0${rest}%`);
  }

  return [...patterns];
}

function cellNumberIlikeFilter(input: string | undefined): Prisma.Sql {
  const patterns = cellNumberLikePatterns(input ?? '');
  if (!patterns.length) return Prisma.empty;
  return Prisma.sql`AND (${Prisma.join(
    patterns.map((pattern) => Prisma.sql`u.cell_number ILIKE ${pattern}`),
    ' OR ',
  )})`;
}

@Injectable()
export class UsersService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly permissions: PermissionsService,
    private readonly sms: SmsService,
  ) {}

  private async assertSuperAdmin(actor: AuthUser) {
    if (!(await this.permissions.isSuperAdmin(actor.id))) {
      throw new ForbiddenException('Super admin access required');
    }
  }

  async updateRole(userIdRaw: string, dto: UpdateUserRoleDto, actor: AuthUser) {
    await this.assertSuperAdmin(actor);

    const userId = BigInt(userIdRaw);
    if (userId === actor.id && dto.roleSlug !== 'super_admin') {
      throw new BadRequestException('You cannot change your own role');
    }

    const user = await this.prisma.user.findUnique({ where: { id: userId } });
    if (!user || !user.isActive) {
      throw new NotFoundException('User not found');
    }

    const targetRole = await this.prisma.role.findUnique({
      where: { slug: dto.roleSlug },
    });
    if (!targetRole) {
      throw new BadRequestException('Invalid role');
    }

    const replaceableRoles = await this.prisma.role.findMany({
      where: { slug: { in: [...ASSIGNABLE_GLOBAL_ROLES] } },
      select: { id: true },
    });
    const replaceableRoleIds = replaceableRoles.map((role) => role.id);

    await this.prisma.$transaction(async (tx) => {
      await tx.userRole.deleteMany({
        where: {
          userId,
          roleId: { in: replaceableRoleIds },
        },
      });

      await tx.userRole.create({
        data: {
          userId,
          roleId: targetRole.id,
        },
      });

      if (dto.roleSlug === 'business_owner') {
        await tx.user.update({
          where: { id: userId },
          data: { cellVerifiedAt: user.cellVerifiedAt ?? new Date() },
        });
      }
    });

    const userRoles = await this.prisma.userRole.findMany({
      where: { userId },
      include: { role: true },
    });

    return {
      id: userId,
      role: dto.roleSlug,
      roles: userRoles.map((entry) => entry.role.slug),
    };
  }

  async list(query: ListUsersDto, actor: AuthUser) {
    await this.assertSuperAdmin(actor);

    const page = query.page ?? 1;
    const pageSize = query.pageSize ?? 24;
    const skip = (page - 1) * pageSize;

    const nameLike = query.name?.trim() ? `%${query.name.trim()}%` : null;
    const roleSlug = query.role?.trim() || null;
    const businessId = query.businessId ?? null;
    const membership = query.membership ?? null;

    const where = Prisma.sql`
      WHERE 1=1
      ${nameLike ? Prisma.sql`
        AND (
          u.first_name ILIKE ${nameLike}
          OR u.last_name ILIKE ${nameLike}
          OR u.first_name_en ILIKE ${nameLike}
          OR u.last_name_en ILIKE ${nameLike}
          OR (COALESCE(u.first_name, '') || ' ' || COALESCE(u.last_name, '')) ILIKE ${nameLike}
          OR (COALESCE(u.first_name_en, '') || ' ' || COALESCE(u.last_name_en, '')) ILIKE ${nameLike}
        )
      ` : Prisma.empty}
      ${cellNumberIlikeFilter(query.cellNumber)}
      ${roleSlug ? Prisma.sql`
        AND EXISTS (
          SELECT 1
          FROM user_roles ur
          JOIN roles r ON r.id = ur.role_id
          WHERE ur.user_id = u.id AND r.slug = ${roleSlug}
        )
      ` : Prisma.empty}
      ${businessId && membership === 'staff' ? Prisma.sql`
        AND EXISTS (
          SELECT 1
          FROM business_users bu
          WHERE bu.user_id = u.id AND bu.business_id = ${businessId}
        )
      ` : Prisma.empty}
      ${businessId && membership === 'all' ? Prisma.sql`
        AND EXISTS (
          SELECT 1
          FROM (
            SELECT user_id FROM business_users WHERE business_id = ${businessId}
            UNION
            SELECT user_id FROM business_customers WHERE business_id = ${businessId}
          ) ub
          WHERE ub.user_id = u.id
        )
      ` : Prisma.empty}
    `;

    const [items, totalRow] = await Promise.all([
      this.prisma.$queryRaw<UserListRow[]>(Prisma.sql`
        SELECT
          u.id AS "id",
          u.first_name AS "firstName",
          u.last_name AS "lastName",
          u.first_name_en AS "firstNameEn",
          u.last_name_en AS "lastNameEn",
          u.cell_number AS "cellNumber",
          u.created_at AS "createdAt",
          u.is_active AS "isActive",
          roles.roles AS "roles",
          global_role.slug AS "roleSlug",
          biz.businesses AS "businesses",
          biz_member.member_id AS "businessMemberId",
          biz_member.is_owner AS "isBusinessOwner",
          biz_member.team_slug AS "teamRole"
        FROM users u
        LEFT JOIN LATERAL (
          SELECT string_agg(DISTINCT r.name, ', ' ORDER BY r.name) AS roles
          FROM user_roles ur
          JOIN roles r ON r.id = ur.role_id
          WHERE ur.user_id = u.id
        ) roles ON TRUE
        LEFT JOIN LATERAL (
          SELECT r.slug
          FROM user_roles ur
          JOIN roles r ON r.id = ur.role_id
          WHERE ur.user_id = u.id
            AND r.slug IN (${Prisma.join([...ASSIGNABLE_GLOBAL_ROLES])})
          ORDER BY r.name
          LIMIT 1
        ) global_role ON TRUE
        LEFT JOIN LATERAL (
          SELECT string_agg(DISTINCT b.name, ', ' ORDER BY b.name) AS businesses
          FROM (
            SELECT business_id FROM business_users WHERE user_id = u.id
            UNION
            SELECT business_id FROM business_customers WHERE user_id = u.id
          ) ub
          JOIN businesses b ON b.id = ub.business_id
        ) biz ON TRUE
        ${businessId ? Prisma.sql`
          LEFT JOIN LATERAL (
            SELECT bu.id AS member_id, bu.is_owner, r.slug AS team_slug
            FROM business_users bu
            LEFT JOIN roles r ON r.id = bu.role_id
            WHERE bu.user_id = u.id AND bu.business_id = ${businessId}
            LIMIT 1
          ) biz_member ON TRUE
        ` : Prisma.sql`
          LEFT JOIN LATERAL (
            SELECT NULL::bigint AS member_id, NULL::boolean AS is_owner, NULL::text AS team_slug
          ) biz_member ON TRUE
        `}
        ${where}
        ORDER BY u.created_at DESC
        LIMIT ${pageSize} OFFSET ${skip}
      `),
      this.prisma.$queryRaw<{ total: number }[]>(Prisma.sql`
        SELECT COUNT(*)::int AS "total"
        FROM users u
        ${where}
      `),
    ]);

    return {
      items,
      total: totalRow[0]?.total ?? 0,
      page,
      pageSize,
    };
  }

  async create(dto: CreateUserDto, actor: AuthUser) {
    await this.assertSuperAdmin(actor);

    const businessId = BigInt(dto.businessId);
    const business = await this.prisma.business.findUnique({
      where: { id: businessId },
    });

    if (!business?.isActive) {
      throw new NotFoundException('Business not found');
    }

    const customerRole = await this.prisma.role.findUnique({
      where: { slug: 'customer' },
    });

    if (!customerRole) {
      throw new Error('Customer role is missing. Run database migrations first.');
    }

    const existingUser = await this.prisma.user.findUnique({
      where: { cellNumber: dto.cellNumber },
      include: {
        businessCustomers: { where: { businessId } },
      },
    });

    if (existingUser?.businessCustomers.length) {
      throw new ConflictException('User is already a customer of this business');
    }

    if (existingUser) {
      const staffMembership = await this.prisma.businessUser.findUnique({
        where: {
          businessId_userId: { businessId, userId: existingUser.id },
        },
      });
      if (staffMembership) {
        throw new ConflictException('User is already staff of this business');
      }
    }

    if (!existingUser && !dto.password) {
      throw new BadRequestException('password is required for new users');
    }

    const passwordHash = existingUser
      ? existingUser.passwordHash
      : await bcrypt.hash(dto.password!, 10);

    const user = await this.prisma.$transaction(async (tx) => {
      const account =
        existingUser ??
        (await tx.user.create({
          data: {
            cellNumber: dto.cellNumber,
            passwordHash,
            email: dto.email,
            firstName: dto.firstName,
            lastName: dto.lastName,
            cellVerifiedAt: new Date(),
          },
        }));

      if (existingUser && !existingUser.cellVerifiedAt) {
        await tx.user.update({
          where: { id: account.id },
          data: { cellVerifiedAt: new Date() },
        });
      }

      await tx.businessCustomer.create({
        data: {
          businessId,
          userId: account.id,
        },
      });

      const hasCustomerRole = await tx.userRole.findUnique({
        where: {
          userId_roleId: {
            userId: account.id,
            roleId: customerRole.id,
          },
        },
      });

      if (!hasCustomerRole) {
        await tx.userRole.create({
          data: {
            userId: account.id,
            roleId: customerRole.id,
          },
        });
      }

      return account;
    });

    const verifiedAt = user.cellVerifiedAt ?? new Date();

    return {
      id: user.id,
      cellNumber: user.cellNumber,
      firstName: user.firstName,
      lastName: user.lastName,
      email: user.email,
      cellVerifiedAt: verifiedAt,
      isVerified: verifiedAt !== null,
      businessId,
      role: 'customer',
    };
  }

  async search(query: SearchUsersDto, actor: AuthUser) {
    await this.assertSuperAdmin(actor);

    const q = query.q.trim();
    const limit = Math.min(Math.max(query.limit ?? 20, 1), 50);
    const like = `%${q}%`;
    const cellPatterns = cellNumberLikePatterns(q);
    const cellMatch = Prisma.join(
      cellPatterns.map((pattern) => Prisma.sql`u.cell_number ILIKE ${pattern}`),
      ' OR ',
    );

    const items = await this.prisma.$queryRaw<
      {
        id: bigint;
        cellNumber: string;
        firstName: string | null;
        lastName: string | null;
        email: string | null;
      }[]
    >(Prisma.sql`
      SELECT
        u.id AS "id",
        u.cell_number AS "cellNumber",
        u.first_name AS "firstName",
        u.last_name AS "lastName",
        u.email AS "email"
      FROM users u
      WHERE u.is_active = TRUE
        AND (
          ${cellMatch}
          OR u.first_name ILIKE ${like}
          OR u.last_name ILIKE ${like}
          OR u.email ILIKE ${like}
          OR (COALESCE(u.first_name, '') || ' ' || COALESCE(u.last_name, '')) ILIKE ${like}
        )
      ORDER BY u.first_name ASC NULLS LAST, u.last_name ASC NULLS LAST
      LIMIT ${limit}
    `);

    return {
      items: items.map((user) => ({
        id: user.id,
        cellNumber: user.cellNumber,
        firstName: user.firstName,
        lastName: user.lastName,
        email: user.email,
        label: this.formatLabel(user),
      })),
    };
  }

  async update(userIdRaw: string, dto: UpdateUserDto, actor: AuthUser) {
    await this.assertSuperAdmin(actor);

    const userId = BigInt(userIdRaw);
    const user = await this.prisma.user.findUnique({ where: { id: userId } });
    if (!user) {
      throw new NotFoundException('User not found');
    }

    if (dto.cellNumber && dto.cellNumber !== user.cellNumber) {
      const existing = await this.prisma.user.findUnique({
        where: { cellNumber: dto.cellNumber },
      });
      if (existing && existing.id !== userId) {
        throw new BadRequestException('Cell number is already in use');
      }
    }

    const isBusinessOwner =
      Boolean(
        await this.prisma.businessUser.findFirst({
          where: { userId, isOwner: true },
          select: { id: true },
        }),
      ) ||
      Boolean(
        await this.prisma.userRole.findFirst({
          where: { userId, role: { slug: 'business_owner' } },
          select: { id: true },
        }),
      );

    const updated = await this.prisma.user.update({
      where: { id: userId },
      data: {
        firstName: dto.firstName?.trim(),
        lastName: dto.lastName?.trim(),
        firstNameEn:
          dto.firstNameEn !== undefined ? dto.firstNameEn.trim() || null : undefined,
        lastNameEn:
          dto.lastNameEn !== undefined ? dto.lastNameEn.trim() || null : undefined,
        email: dto.email !== undefined ? dto.email.trim() || null : undefined,
        cellNumber: dto.cellNumber?.trim(),
        ...(isBusinessOwner
          ? { cellVerifiedAt: user.cellVerifiedAt ?? new Date() }
          : {}),
      },
    });

    return {
      id: updated.id,
      firstName: updated.firstName,
      lastName: updated.lastName,
      firstNameEn: updated.firstNameEn,
      lastNameEn: updated.lastNameEn,
      email: updated.email,
      cellNumber: updated.cellNumber,
    };
  }

  async resetPassword(userIdRaw: string, dto: AdminResetPasswordDto, actor: AuthUser) {
    await this.assertSuperAdmin(actor);

    const userId = BigInt(userIdRaw);
    const user = await this.prisma.user.findUnique({ where: { id: userId } });
    if (!user) {
      throw new NotFoundException('User not found');
    }

    const passwordHash = await bcrypt.hash(dto.newPassword, 10);
    await this.prisma.user.update({
      where: { id: userId },
      data: { passwordHash },
    });

    return { message: 'Password reset successfully' };
  }

  async remove(userIdRaw: string, actor: AuthUser) {
    await this.assertSuperAdmin(actor);

    const userId = BigInt(userIdRaw);
    if (userId === actor.id) {
      throw new BadRequestException('You cannot remove your own account');
    }

    const user = await this.prisma.user.findUnique({ where: { id: userId } });
    if (!user) {
      throw new NotFoundException('User not found');
    }

    await this.prisma.user.update({
      where: { id: userId },
      data: { isActive: false },
    });

    return { message: 'User removed' };
  }

  async sendMessage(userIdRaw: string, dto: SendUserMessageDto, actor: AuthUser) {
    await this.assertSuperAdmin(actor);

    const userId = BigInt(userIdRaw);
    const user = await this.prisma.user.findUnique({ where: { id: userId } });
    if (!user) {
      throw new NotFoundException('User not found');
    }

    if (!this.sms.isEnabled()) {
      return {
        enabled: false,
        message: 'SMS is disabled. Message was not sent.',
      };
    }

    try {
      await this.sms.sendMessage(user.cellNumber, dto.message.trim());
    } catch {
      throw new ServiceUnavailableException('SMS provider is not configured yet');
    }

    return {
      enabled: true,
      message: 'Message sent successfully',
    };
  }

  private formatLabel(user: {
    firstName: string | null;
    lastName: string | null;
    cellNumber: string;
  }): string {
    const name = [user.firstName, user.lastName].filter(Boolean).join(' ').trim();
    return name ? `${name} (${user.cellNumber})` : user.cellNumber;
  }
}