import { BadRequestException, Injectable } from "@nestjs/common";
// eslint-disable-next-line import/no-named-as-default
import Decimal from "decimal.js";
import { QueryRunner } from "typeorm";

import { InvoiceMessage } from "../../../common/enums/message.enum";
import { DiscountRepository } from "../../discounts/repositories/discount.repository";
import { SubscriptionPlan } from "../../subscriptions/entities/subscription.entity";
import { RoleEnum } from "../../users/enums/role.enum";
import { PaginationUtils } from "../../utils/providers/pagination.utils";
import { ApplyDiscountDto } from "../DTO/apply-discount-invoice.dto";
import { CreateInvoiceDto } from "../DTO/create-invoice.dto";
import { InvoicesSearchQueryDto, UserInvoicesSearchQueryDto } from "../DTO/invoices-search-query.dto";
import { Invoice } from "../entities/invoice.entity";
import { InvoiceStatus } from "../enums/invoice-status.enum";
// import { InvoiceItemsRepository } from "../repositories/invoice-items.repository";
import { InvoicesRepository } from "../repositories/invoices.repository";

@Injectable()
export class InvoicesService {
  constructor(
    private readonly invoiceRepository: InvoicesRepository,
    private readonly discountRepository: DiscountRepository,
    // private readonly invoiceItemsRepository: InvoiceItemsRepository,
  ) {}

  ///********************************** */

  async createInvoiceAdmin(createDto: CreateInvoiceDto) {
    //
    const invoiceItems = createDto.items.map((item) => {
      return {
        name: item.name,
        count: item.count,
        unitPrice: item.unitPrice,
        discount: item.discount || 0,
        totalPrice: item.unitPrice * item.count - (item.unitPrice * item.count * item.discount) / 100,
      };
    });
    //
    const totalPrice = invoiceItems.reduce((sum, item) => new Decimal(item.totalPrice).add(sum), new Decimal(0));
    const tax = totalPrice.mul(0.1);
    //
    const dueDate = new Date();
    dueDate.setDate(dueDate.getDate() + 5);
    //
    const invoice = this.invoiceRepository.create({
      user: { id: createDto.userId },
      totalPrice: totalPrice.toNumber(),
      items: invoiceItems,
      tax: tax.toNumber(),
      dueDate,
    });
    //
    await this.invoiceRepository.save(invoice);
    //TODO: notify user

    return {
      message: InvoiceMessage.CREATED,
      invoice,
    };
  }

  ///********************************** */

  async createInvoiceForSubscription(userId: string, plan: SubscriptionPlan, dueDate: Date, queryRunner: QueryRunner) {
    const invoiceItems = [
      { name: plan.service.name, count: 1, unitPrice: plan.price, discount: 0, subscriptionPlan: plan, totalPrice: plan.price },
    ];
    const invoice = queryRunner.manager.create(Invoice, {
      totalPrice: plan.price,
      user: { id: userId },
      status: InvoiceStatus.PAID,
      paidAt: new Date(),
      dueDate,
      items: invoiceItems,
    });
    //
    await queryRunner.manager.save(Invoice, invoice);
    return invoice;
  }

  ///********************************** */

  async getInvoices(queryDto: InvoicesSearchQueryDto) {
    const { limit, skip } = PaginationUtils(queryDto);

    const queryBuilder = this.invoiceRepository.createQueryBuilder("invoice");

    queryBuilder
      .leftJoinAndSelect("invoice.user", "user")
      .leftJoinAndSelect("invoice.items", "items")
      .leftJoinAndSelect("items.subscriptionPlan", "subscriptionPlan", "subscriptionPlan.id IS NOT NULL")
      .leftJoinAndSelect("subscriptionPlan.service", "service", "subscriptionPlan.id IS NOT NULL");

    if (queryDto.q) {
      queryBuilder
        .orWhere("user.firstName ILIKE :search", { search: `%${queryDto.q}%` })
        .orWhere("user.lastName ILIKE :search", { search: `%${queryDto.q}%` })
        .orWhere("user.email ILIKE :search", { search: `%${queryDto.q}%` });
    }

    if (queryDto.status) {
      queryBuilder.andWhere("invoice.status = :status", { status: queryDto.status });
    }

    if (queryDto.userId) {
      queryBuilder.andWhere("invoice.user.id = :userId", { userId: queryDto.userId });
    }

    if (queryDto.serviceId) {
      queryBuilder.andWhere("subscriptionPlan.serviceId = :serviceId", { serviceId: queryDto.serviceId });
    }

    queryBuilder.orderBy("invoice.createdAt", "DESC");
    queryBuilder.skip(skip);
    queryBuilder.take(limit);

    const [invoices, count] = await queryBuilder.getManyAndCount();

    return {
      invoices,
      count,
      paginate: true,
    };
  }

  //*********************************** */

  async getInvoiceById(invoiceId: string, role: RoleEnum, userId: string) {
    let invoice: Invoice | null;

    if (role === RoleEnum.ADMIN) {
      invoice = await this.invoiceRepository.findOne({
        where: { id: invoiceId },
        relations: { items: { subscriptionPlan: true }, user: true },
      });
    } else {
      invoice = await this.invoiceRepository.findOne({
        where: { id: invoiceId, user: { id: userId } },
        relations: { items: { subscriptionPlan: true } },
      });
    }

    if (!invoice) throw new BadRequestException(InvoiceMessage.NOT_FOUND_BY_ID);

    return {
      invoice,
    };
  }

  //*********************************** */

  async getUserInvoices(queryDto: UserInvoicesSearchQueryDto, userId: string) {
    const { limit, skip } = PaginationUtils(queryDto);

    const queryBuilder = this.invoiceRepository.createQueryBuilder("invoice");

    queryBuilder
      .andWhere("invoice.user.id = :userId", { userId: userId })
      .leftJoinAndSelect("invoice.items", "items")
      .leftJoinAndSelect("items.subscriptionPlan", "subscriptionPlan", "subscriptionPlan.id IS NOT NULL")
      .leftJoinAndSelect("subscriptionPlan.service", "service", "subscriptionPlan.id IS NOT NULL");

    if (queryDto.status) {
      queryBuilder.andWhere("invoice.status = :status", { status: queryDto.status });
    }

    queryBuilder.orderBy("invoice.createdAt", "DESC").skip(skip).take(limit);

    const [invoices, count] = await queryBuilder.getManyAndCount();

    return {
      invoices,
      count,
      paginate: true,
    };
  }

  //*********************************** */

  async applyDiscount(invoiceId: string, applyDiscountDto: ApplyDiscountDto) {
    const invoice = await this.invoiceRepository.findOneBy({ id: invoiceId });
    if (!invoice) throw new BadRequestException(InvoiceMessage.NOT_FOUND_BY_ID);

    const discount = await this.discountRepository.findOne({
      where: { code: applyDiscountDto.discountCode, isActive: true },
      relations: ["subscriptionPlans", "users"],
    });
    if (!discount) {
      throw new BadRequestException(`Discount with code ${applyDiscountDto.discountCode} not found or inactive`);
    }

    if (discount.subscriptionPlans && discount.subscriptionPlans.length > 0) {
      const isApplicable = invoice.items.some((item) => {
        const subscriptionPlan = item.subscriptionPlan;
        if (!subscriptionPlan) return false;
        return discount.subscriptionPlans.some((plan) => plan.id === subscriptionPlan.id);
      });
      if (!isApplicable) {
        throw new BadRequestException("This discount is not applicable to any subscription plan in the invoice.");
      }
    }

    if (discount.users && discount.users.length > 0) {
      if (!invoice.user || !discount.users.some((user) => user.id === invoice.user.id)) {
        throw new BadRequestException("This discount is not applicable for this user.");
      }
    }

    invoice.discount = discount;
    await this.invoiceRepository.save(invoice);

    return { invoice };
  }

  async calculateFinalPrice(invoiceId: string): Promise<Decimal> {
    const invoice = await this.invoiceRepository.findOneBy({ id: invoiceId });
    if (!invoice) throw new BadRequestException(InvoiceMessage.NOT_FOUND_BY_ID);

    let discountValue = new Decimal(0);
    if (invoice.discount) {
      if (invoice.discount.calculationType === "PERCENTAGE") {
        discountValue = invoice.totalPrice.mul(invoice.discount.amount).div(100);
      } else if (invoice.discount.calculationType === "FIXED") {
        discountValue = new Decimal(invoice.discount.amount);
      }
    }
    return invoice.totalPrice.minus(discountValue);
  }
}