import { BadRequestException, Injectable, NotFoundException } from '@nestjs/common';
import { PrismaService } from '../../prisma/prisma.service';
import { AccountingHooksService } from '../accounting-sync/accounting-hooks.service';
import { CatalogCacheService } from './catalog-cache.service';

@Injectable()
export class CatalogService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly accounting: AccountingHooksService,
    private readonly catalogCache: CatalogCacheService,
  ) {}

  /** Served from CatalogCacheService; see there for what invalidates it. */
  listProducts() {
    return this.catalogCache.get(() => this.buildProductList());
  }

  private async buildProductList() {
    const products = await this.prisma.product.findMany({
      // D27 — a product with no image is never shown in the app. Products now
      // also arrive from the accounting software, which carries no pictures;
      // they appear once an admin photographs them.
      where: { isActive: true, images: { some: {} } },
      include: {
        // Only orderable variants reach the storefront. An inactive one used to
        // be listed and then rejected by getVariantOrThrow at checkout, so the
        // customer could pick a chip and get a 404 on the order.
        variants: {
          where: { isActive: true },
          // Each variant carries its own gallery picture, so the app can render
          // the chip without a second request per variant.
          include: { image: true },
        },
        // Explicit order: the UI treats images[0] as the product's main photo,
        // which is only meaningful if the rows come back sorted.
        images: { orderBy: { sortOrder: 'asc' } },
        category: true,
        brand: true,
        collections: { include: { collection: true } },
      },
    });

    const stockBlocked = await this.accounting.stockBlocker();
    const out = [];
    for (const p of products) {
      const { accountingStockWeight, accountingStockCount, accountingStockAt, ...product } = p;
      // D27 — out of stock in the accounting software: every variant reads as
      // qty 0, which the apps already render as «ناموجود» and refuse to add to
      // the cart unless it is a pre-order variant. The stock figures themselves
      // stay server-side; this endpoint is public.
      const blocked = stockBlocked({ accountingStockWeight, accountingStockCount, accountingStockAt });
      out.push(blocked ? { ...product, variants: product.variants.map((v) => (v.isPreOrder ? v : { ...v, qty: 0 })) } : product);
    }
    return out;
  }

  async getVariantOrThrow(variantId: string) {
    const variant = await this.prisma.productVariant.findUnique({
      where: { id: variantId },
      include: {
        product: {
          select: {
            id: true,
            accountingStockWeight: true,
            accountingStockCount: true,
            accountingStockAt: true,
            _count: { select: { images: true } },
          },
        },
      },
    });
    if (!variant || !variant.isActive) {
      throw new NotFoundException(`Product variant ${variantId} not found or inactive`);
    }
    // The same two rules the listing applies, so a stale client cannot order
    // around them.
    if (variant.product._count.images === 0) {
      throw new BadRequestException('این محصول هنوز تصویر ندارد و قابل سفارش نیست');
    }
    // Live from the accounting software at order time; on no answer the last
    // stored figure decides (liveStock).
    if (!variant.isPreOrder && (await this.accounting.stockBlocked(await this.accounting.liveStock(variant.product)))) {
      throw new BadRequestException('این محصول در انبار موجود نیست');
    }
    const { product: _product, ...plain } = variant;
    return plain;
  }
}