import { BadRequestException, Injectable, NotFoundException } from '@nestjs/common';
import { Prisma } from '@prisma/client';
import { PrismaService } from '../../prisma/prisma.service';
import { TableService } from '../admin-table/table.service';
import type { TableQueryDto } from '../admin-table/table-query.dto';

/**
 * Branch stock allocations — legacy views/invoice/* ("فاکتور انتقال"), served by
 * BranchController as `branch/product`:
 *   POST   branch/product/table  -> the grid
 *   POST   branch/product        -> create  { branch_id, products: [id...] }
 *   GET    branch/product/{id}   -> one allocation
 *   DELETE branch/product/{id}   -> delete
 *
 * Despite the screen being labelled an invoice, it is not a sales document: it
 * records which products head office allocated to a branch, and who did it.
 */
@Injectable()
export class AdminInvoicesService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly table: TableService,
  ) {}

  private static readonly ALLOWED = [
    'id',
    'note',
    'createdAt',
    'branchId',
    'branch.name',
    'allocatorAdminUser.fullName',
    // legacy filter keys
    'name',
    'caj',
  ];

  private static readonly FIELD_ALIASES: Record<string, string> = {
    name: 'branch.name',
    caj: 'createdAt',
    'allocator_user.name': 'allocatorAdminUser.fullName',
  };

  /** Legacy `POST branch/product/table`. */
  async list(query: TableQueryDto) {
    this.table.assertNotExport(query);

    const mapField = (f?: string) => (f ? (AdminInvoicesService.FIELD_ALIASES[f] ?? f) : f);
    const aliased: TableQueryDto = {
      ...query,
      filters: (query.filters ?? []).map((f) => ({ ...f, field: mapField(f.field) })),
      order: query.order
        ? `${query.order.startsWith('-') ? '-' : '+'}${mapField(query.order.replace(/^[+-]/, ''))}`
        : undefined,
    };

    const { where, orderBy, skip, take, page, limit } = this.table.build(aliased, {
      searchable: ['note', 'branch.name'],
      allowed: AdminInvoicesService.ALLOWED,
      defaultOrderBy: { createdAt: 'desc' },
    });

    const [rows, total] = await Promise.all([
      this.prisma.branchAllocation.findMany({
        where: where as Prisma.BranchAllocationWhereInput,
        orderBy: orderBy as Prisma.BranchAllocationOrderByWithRelationInput,
        skip,
        take,
        include: {
          branch: true,
          allocatorAdminUser: true,
          items: { include: { product: true } },
        },
      }),
      this.prisma.branchAllocation.count({ where: where as Prisma.BranchAllocationWhereInput }),
    ]);

    return this.table.respond(rows.map((r) => this.toRow(r)), total, query, page, limit);
  }

  private toRow(
    a: Prisma.BranchAllocationGetPayload<{
      include: {
        branch: true;
        allocatorAdminUser: true;
        items: { include: { product: true } };
      };
    }>,
  ) {
    const sumWeight = a.items.reduce(
      (sum, it) => sum.add(it.weightGrams ?? new Prisma.Decimal(0)),
      new Prisma.Decimal(0),
    );

    return {
      id: a.id,
      // legacy column key is `name` — the receiving branch
      name: a.branch.name,
      branch_id: a.branchId,
      branch: { id: a.branch.id, name: a.branch.name },
      sum_weight: sumWeight,
      count_item: a.items.length,
      note: a.note,
      allocator_user: a.allocatorAdminUser
        ? { id: a.allocatorAdminUser.id, name: a.allocatorAdminUser.fullName }
        : null,
      caj: a.createdAt,
      products: a.items.map((it) => ({
        id: it.productId,
        pid: it.productId,
        title: it.product.title,
        product_code: it.product.productCode,
        grams: it.weightGrams,
      })),
    };
  }

  /** Legacy `GET branch/product/{id}`. */
  async findOne(id: string) {
    const a = await this.prisma.branchAllocation.findUnique({
      where: { id },
      include: {
        branch: true,
        allocatorAdminUser: true,
        items: { include: { product: true } },
      },
    });
    if (!a) throw new NotFoundException('فاکتور یافت نشد');
    return this.toRow(a);
  }

  /**
   * Legacy `POST branch/product` with `{ branch_id, products: [id...] }`.
   *
   * Each product's current lightest variant weight is snapshotted, so a later
   * catalog edit does not silently rewrite what this document says was moved.
   */
  async create(data: { branch_id?: string; products?: string[]; note?: string }, actorId: string) {
    const branchId = String(data.branch_id ?? '');
    if (!branchId) throw new BadRequestException('شعبه انتخاب نشده است');

    const branch = await this.prisma.branch.findUnique({ where: { id: branchId } });
    if (!branch) throw new NotFoundException('شعبه یافت نشد');

    const productIds = [...new Set((data.products ?? []).map((p) => String(p)).filter(Boolean))];
    if (productIds.length === 0) throw new BadRequestException('هیچ محصولی انتخاب نشده است');

    const products = await this.prisma.product.findMany({
      where: { id: { in: productIds } },
      include: { variants: { where: { isActive: true } } },
    });
    if (products.length !== productIds.length) {
      throw new BadRequestException('برخی از محصولات انتخاب‌شده یافت نشدند');
    }

    const allocation = await this.prisma.branchAllocation.create({
      data: {
        branchId,
        allocatorAdminUserId: actorId,
        note: data.note ?? null,
        items: {
          create: products.map((p) => ({
            productId: p.id,
            weightGrams: p.variants.length
              ? p.variants.reduce(
                  (min, v) => (v.rashWeightGrams.lt(min) ? v.rashWeightGrams : min),
                  p.variants[0].rashWeightGrams,
                )
              : null,
          })),
        },
      },
    });

    return this.findOne(allocation.id);
  }

  /** Legacy `PUT branch/product/{id}` — the edit screen replaces the product set. */
  async update(id: string, data: { branch_id?: string; products?: string[]; note?: string }) {
    const existing = await this.prisma.branchAllocation.findUnique({ where: { id } });
    if (!existing) throw new NotFoundException('فاکتور یافت نشد');

    if (data.branch_id) {
      const branch = await this.prisma.branch.findUnique({
        where: { id: String(data.branch_id) },
      });
      if (!branch) throw new NotFoundException('شعبه یافت نشد');
    }

    if (Array.isArray(data.products)) {
      const productIds = [...new Set(data.products.map((p) => String(p)).filter(Boolean))];
      if (productIds.length === 0) {
        throw new BadRequestException('هیچ محصولی انتخاب نشده است');
      }
      const products = await this.prisma.product.findMany({
        where: { id: { in: productIds } },
        include: { variants: { where: { isActive: true } } },
      });

      await this.prisma.$transaction([
        this.prisma.branchAllocationItem.deleteMany({ where: { allocationId: id } }),
        this.prisma.branchAllocationItem.createMany({
          data: products.map((p) => ({
            allocationId: id,
            productId: p.id,
            weightGrams: p.variants.length
              ? p.variants.reduce(
                  (min, v) => (v.rashWeightGrams.lt(min) ? v.rashWeightGrams : min),
                  p.variants[0].rashWeightGrams,
                )
              : null,
          })),
          skipDuplicates: true,
        }),
      ]);
    }

    await this.prisma.branchAllocation.update({
      where: { id },
      data: {
        ...(data.branch_id ? { branchId: String(data.branch_id) } : {}),
        ...(data.note !== undefined ? { note: data.note } : {}),
      },
    });

    return this.findOne(id);
  }

  /** Legacy `DELETE branch/product/{id}`. Items cascade. */
  async remove(id: string) {
    const a = await this.prisma.branchAllocation.findUnique({ where: { id } });
    if (!a) throw new NotFoundException('فاکتور یافت نشد');
    await this.prisma.branchAllocation.delete({ where: { id } });
    return { success: true };
  }

  /** Legacy `GET branch/list` — the branch picker for the invoice form. */
  async branchList() {
    const rows = await this.prisma.branch.findMany({
      where: { isActive: true },
      orderBy: { name: 'asc' },
      select: { id: true, name: true },
    });
    return rows;
  }
}