import { BadRequestException, ConflictException, ForbiddenException, Injectable, NotFoundException } from '@nestjs/common';
import { Prisma } from '@prisma/client';
import * as bcrypt from 'bcrypt';
import { AuthUser } from '../auth/auth.types';
import { PermissionsService } from '../auth/permissions.service';
import {
  buildDualDailyActivitySeries,
  startOfLocalDay,
} from '../common/daily-activity';
import { PrismaService } from '../prisma/prisma.service';
import { CreateCustomerDto } from './dto/create-customer.dto';
import { ListCustomersDto } from './dto/list-customers.dto';
import { SearchCustomersDto } from './dto/search-customers.dto';
import { UpdateCustomerDto } from './dto/update-customer.dto';

type CustomerListRow = {
  id: bigint;
  cellNumber: string;
  firstName: string | null;
  lastName: string | null;
  email: string | null;
  createdAt: Date;
  isEnabled: boolean;
};

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

  async list(
    businessIdRaw: string,
    query: ListCustomersDto,
    actor: AuthUser,
  ) {
    const businessId = BigInt(businessIdRaw);
    await this.assertPermission(businessId, actor.id, 'orders.read');

    const page = query.page ?? 1;
    const pageSize = Math.min(Math.max(query.pageSize ?? 24, 1), 100);
    const skip = (page - 1) * pageSize;

    const nameLike = query.name?.trim() ? `%${query.name.trim()}%` : null;
    const cellLike = query.cellNumber?.trim() ? `%${query.cellNumber.trim()}%` : null;

    const where = Prisma.sql`
      WHERE bc.business_id = ${businessId}
      ${nameLike ? Prisma.sql`
        AND (
          u.first_name ILIKE ${nameLike}
          OR u.last_name ILIKE ${nameLike}
          OR (COALESCE(u.first_name, '') || ' ' || COALESCE(u.last_name, '')) ILIKE ${nameLike}
        )
      ` : Prisma.empty}
      ${cellLike ? Prisma.sql`AND u.cell_number ILIKE ${cellLike}` : Prisma.empty}
    `;

    const [items, totalRow] = await Promise.all([
      this.prisma.$queryRaw<CustomerListRow[]>(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",
          bc.created_at AS "createdAt",
          bc.is_enabled AS "isEnabled"
        FROM business_customers bc
        JOIN users u ON u.id = bc.user_id
        ${where}
        ORDER BY bc.created_at DESC
        LIMIT ${pageSize} OFFSET ${skip}
      `),
      this.prisma.$queryRaw<{ total: number }[]>(Prisma.sql`
        SELECT COUNT(*)::int AS "total"
        FROM business_customers bc
        JOIN users u ON u.id = bc.user_id
        ${where}
      `),
    ]);

    return {
      items: items.map((user) => ({
        id: user.id.toString(),
        cellNumber: user.cellNumber,
        firstName: user.firstName,
        lastName: user.lastName,
        email: user.email,
        label: this.formatLabel(user),
        createdAt: user.createdAt.toISOString(),
        isEnabled: user.isEnabled,
      })),
      total: totalRow[0]?.total ?? 0,
      page,
      pageSize,
    };
  }

  /** Lightweight daily registration + active-login counts for dashboard charts. */
  async dailyActivity(
    businessIdRaw: string,
    daysRaw: number | undefined,
    actor: AuthUser,
  ) {
    const businessId = BigInt(businessIdRaw);
    await this.assertPermission(businessId, actor.id, 'orders.read');

    const days = Math.min(Math.max(daysRaw ?? 30, 1), 90);
    const from = startOfLocalDay(days - 1);

    const [registeredRows, activeRows] = await Promise.all([
      this.prisma.$queryRaw<{ day: Date; count: number }[]>(
        Prisma.sql`
          SELECT created_at::date AS day,
                 COUNT(*)::int AS count
          FROM business_customers
          WHERE business_id = ${businessId}
            AND created_at >= ${from}
          GROUP BY 1
          ORDER BY 1
        `,
      ),
      this.prisma.$queryRaw<{ day: Date; count: number }[]>(
        Prisma.sql`
          SELECT u.last_login_at::date AS day,
                 COUNT(*)::int AS count
          FROM business_customers bc
          JOIN users u ON u.id = bc.user_id
          WHERE bc.business_id = ${businessId}
            AND u.last_login_at IS NOT NULL
            AND u.last_login_at >= ${from}
          GROUP BY 1
          ORDER BY 1
        `,
      ),
    ]);

    return buildDualDailyActivitySeries(days, registeredRows, activeRows);
  }

  async search(
    businessIdRaw: string,
    query: SearchCustomersDto,
    actor: AuthUser,
  ) {
    const businessId = BigInt(businessIdRaw);
    await this.assertPermission(businessId, actor.id, 'orders.create');

    const q = query.q.trim();
    const limit = Math.min(Math.max(query.limit ?? 20, 1), 50);
    const like = `%${q}%`;

    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 business_customers bc
      JOIN users u ON u.id = bc.user_id
      WHERE bc.business_id = ${businessId}
        AND bc.is_enabled = TRUE
        AND u.is_active = TRUE
        AND (
          u.cell_number ILIKE ${like}
          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.toString(),
        cellNumber: user.cellNumber,
        firstName: user.firstName,
        lastName: user.lastName,
        email: user.email,
        label: this.formatLabel(user),
      })),
    };
  }

  async create(
    businessIdRaw: string,
    dto: CreateCustomerDto,
    actor: AuthUser,
  ) {
    const businessId = BigInt(businessIdRaw);
    await this.assertPermission(businessId, actor.id, 'orders.create');

    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 membership = 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() },
        });
      }

      const link = 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, link };
    });

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

    return {
      id: user.id.toString(),
      cellNumber: user.cellNumber,
      firstName: user.firstName,
      lastName: user.lastName,
      email: user.email,
      label: this.formatLabel(user),
      createdAt: membership.link.createdAt.toISOString(),
      isEnabled: membership.link.isEnabled,
      isVerified: verifiedAt !== null,
      role: 'customer',
    };
  }

  async update(
    businessIdRaw: string,
    userIdRaw: string,
    dto: UpdateCustomerDto,
    actor: AuthUser,
  ) {
    const businessId = BigInt(businessIdRaw);
    const userId = BigInt(userIdRaw);
    await this.assertPermission(businessId, actor.id, 'orders.update');

    const membership = await this.prisma.businessCustomer.findUnique({
      where: {
        businessId_userId: { businessId, userId },
      },
      include: { user: true },
    });

    if (!membership) {
      throw new NotFoundException('Customer not found for this business');
    }

    if (dto.isEnabled !== undefined) {
      await this.prisma.businessCustomer.update({
        where: { id: membership.id },
        data: { isEnabled: dto.isEnabled },
      });
    }

    const hasProfileUpdate =
      dto.firstName !== undefined ||
      dto.lastName !== undefined ||
      dto.email !== undefined ||
      dto.cellNumber !== undefined;

    if (hasProfileUpdate) {
      const user = membership.user;

      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');
        }
      }

      await this.prisma.user.update({
        where: { id: userId },
        data: {
          firstName: dto.firstName?.trim(),
          lastName: dto.lastName?.trim(),
          email: dto.email !== undefined ? dto.email.trim() || null : undefined,
          cellNumber: dto.cellNumber?.trim(),
        },
      });
    }

    const refreshed = await this.prisma.businessCustomer.findUnique({
      where: { id: membership.id },
      include: { user: true },
    });

    if (!refreshed) {
      throw new NotFoundException('Customer not found for this business');
    }

    const user = refreshed.user;
    return {
      id: user.id.toString(),
      cellNumber: user.cellNumber,
      firstName: user.firstName,
      lastName: user.lastName,
      email: user.email,
      label: this.formatLabel(user),
      isEnabled: refreshed.isEnabled,
    };
  }

  async remove(businessIdRaw: string, userIdRaw: string, actor: AuthUser) {
    const businessId = BigInt(businessIdRaw);
    const userId = BigInt(userIdRaw);
    await this.assertPermission(businessId, actor.id, 'orders.update');

    const membership = await this.prisma.businessCustomer.findUnique({
      where: {
        businessId_userId: { businessId, userId },
      },
    });

    if (!membership) {
      throw new NotFoundException('Customer not found for this business');
    }

    await this.prisma.businessCustomer.delete({
      where: { id: membership.id },
    });

    return { success: true };
  }

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

  private async assertPermission(
    businessId: bigint,
    userId: bigint,
    permission: string,
  ) {
    const allowed = await this.permissions.hasBusinessPermission(
      userId,
      businessId,
      permission,
    );

    if (!allowed) {
      throw new ForbiddenException(
        `Missing permission: ${permission} for this business`,
      );
    }
  }
}