import type { MedusaRequest, MedusaResponse } from "@medusajs/framework";
import {
  ContainerRegistrationKeys,
  QueryContext,
} from "@medusajs/framework/utils";
import {
  MEILISEARCH_MODULE,
  type MeiliSearchService,
} from "@rokmohar/medusa-plugin-meilisearch";

// Las rutas /store/meilisearch/* que trae el plugin (ver ADR 0006 nota de
// implementacion) no devuelven facetDistribution -- necesitamos esta
// ruta propia para pedirlo explicitamente via additionalOptions.facets,
// que el servicio del plugin reenvia tal cual al cliente Meilisearch.
const FACETS = ["category", "collection", "brand", "ageRange"];

// Mismos campos que ya usa el storefront contra /store/products
// (workloads/ecommerce/lib/headless/providers/medusa.ts) -- una vez que
// Meilisearch nos da los ids candidatos, volvemos a Medusa via
// query.graph para precio/inventario reales, nunca confiamos en el
// valor indexado (puede tener unos segundos de retraso respecto al
// evento de sincronizacion).
const PRODUCT_FIELDS = [
  "id",
  "handle",
  "title",
  "subtitle",
  "description",
  "thumbnail",
  "external_id",
  "metadata",
  "images.url",
  "tags.value",
  "categories.name",
  "collection.title",
  "variants.id",
  "variants.title",
  "variants.sku",
  "variants.manage_inventory",
  "variants.allow_backorder",
  "variants.inventory_quantity",
  "variants.calculated_price.calculated_amount",
  "variants.calculated_price.original_amount",
  "variants.calculated_price.currency_code",
  "variants.options.value",
  "variants.options.option.title",
];

function stringParam(
  query: MedusaRequest["query"],
  name: string,
): string | undefined {
  const value = query[name];
  return typeof value === "string" && value.length > 0 ? value : undefined;
}

function numberParam(
  query: MedusaRequest["query"],
  name: string,
): number | undefined {
  const value = stringParam(query, name);
  if (!value) return undefined;
  const parsed = Number(value);
  return Number.isFinite(parsed) ? parsed : undefined;
}

// Meilisearch usa comillas dobles para valores de filtro con espacios;
// escapamos las que vengan en el propio valor para no romper la sintaxis.
function escapeFilterValue(value: string): string {
  return value.replace(/\\/g, "\\\\").replace(/"/g, '\\"');
}

export async function GET(req: MedusaRequest, res: MedusaResponse) {
  const meilisearchService = req.scope.resolve<MeiliSearchService>(
    MEILISEARCH_MODULE,
  );
  const query = req.scope.resolve(ContainerRegistrationKeys.QUERY);

  const q = stringParam(req.query, "q") ?? "";
  const limit = numberParam(req.query, "limit") ?? 24;
  const offset = numberParam(req.query, "offset") ?? 0;
  // calculated_price exige region_id/currency_code en el contexto de
  // pricing o query.graph tira "Method calculatePrices requires
  // currency_code in the pricing context" (mismo error que ya rompio el
  // job de sync -- ver medusa-config.ts). El storefront ya manda
  // region_id contra /store/products (medusa.ts, regionId()); esta ruta
  // espera el mismo query param.
  const regionId = stringParam(req.query, "region_id");

  const filterParts: string[] = [];
  for (const facet of ["category", "collection", "brand", "ageRange"]) {
    const value = stringParam(req.query, facet);
    if (value) {
      filterParts.push(`${facet} = "${escapeFilterValue(value)}"`);
    }
  }
  const minPrice = numberParam(req.query, "minPrice");
  const maxPrice = numberParam(req.query, "maxPrice");
  if (typeof minPrice === "number") filterParts.push(`price >= ${minPrice}`);
  if (typeof maxPrice === "number") filterParts.push(`price <= ${maxPrice}`);

  const indexes = await meilisearchService.getIndexesByType("products");

  if (indexes.length === 0) {
    // Meilisearch no configurado o el indice "products" esta
    // deshabilitado -- degradar a "sin resultados" en vez de 500, el
    // frontend cae de nuevo a su propio filtrado si esta ruta falla.
    res.json({ products: [], facetDistribution: {}, count: 0, limit, offset });
    return;
  }

  const results = await Promise.all(
    indexes.map((indexKey) =>
      meilisearchService.search(indexKey, q, {
        filter: filterParts.length ? filterParts.join(" AND ") : undefined,
        paginationOptions: { limit, offset },
        additionalOptions: { facets: FACETS },
      }),
    ),
  );

  const hits = results.flatMap((result) => result.hits);
  const totalCount = results.reduce(
    (sum, result) => sum + result.estimatedTotalHits,
    0,
  );

  const facetDistribution: Record<string, Record<string, number>> = {};
  for (const result of results) {
    const resultFacets = (
      result as unknown as {
        facetDistribution?: Record<string, Record<string, number>>;
      }
    ).facetDistribution;
    if (!resultFacets) continue;
    for (const [facet, values] of Object.entries(resultFacets)) {
      facetDistribution[facet] ??= {};
      for (const [value, count] of Object.entries(values)) {
        facetDistribution[facet][value] =
          (facetDistribution[facet][value] ?? 0) + count;
      }
    }
  }

  const productIds = hits.map((hit) => (hit as { id: string }).id);

  if (productIds.length === 0) {
    res.json({ products: [], facetDistribution, count: 0, limit, offset });
    return;
  }

  // calculatePrices exige currency_code en el contexto -- no alcanza con
  // region_id solo (a diferencia de /store/products nativo, que lo
  // resuelve el middleware setPricingContext; esta ruta no pasa por esa
  // cadena). Resolvemos la moneda real de la region en vez de asumir COP
  // fijo, por si el catalogo suma otra region/moneda mas adelante.
  let currencyCode: string | undefined;
  if (regionId) {
    const { data: regions = [] } = await query.graph({
      entity: "region",
      fields: ["id", "currency_code"],
      filters: { id: regionId },
    });
    currencyCode = regions[0]?.currency_code;
  }

  const { data: products = [] } = await query.graph({
    entity: "product",
    fields: PRODUCT_FIELDS,
    filters: { id: productIds },
    context:
      regionId && currencyCode
        ? {
            variants: {
              calculated_price: QueryContext({
                region_id: regionId,
                currency_code: currencyCode,
              }),
            },
          }
        : {},
  });

  // Preserva el ranking de relevancia de Meilisearch -- query.graph no
  // garantiza el mismo orden que la busqueda.
  const orderedProducts = [...products].sort(
    (a, b) => productIds.indexOf(a.id) - productIds.indexOf(b.id),
  );

  res.json({
    products: orderedProducts,
    facetDistribution,
    count: totalCount,
    limit,
    offset,
  });
}