import { NextResponse, type NextRequest } from "next/server";
import { isDatabaseConfigured } from "../../../../lib/server/env";
import { listMethodRecommendations } from "../../../../lib/server/methodRecommendations";
import { apiRoute } from "../../../../lib/server/apiRoute";
import { dbUnavailable, errorJson } from "../../../../lib/server/responses";
import {
  SECTION_IDS,
  type SectionId,
  parseRequestedFacetsFromSearchParams,
} from "../../../../lib/server/validation/methodFacetsSchemas";

const SECTION_SET = new Set<string>(SECTION_IDS);

/**
 * GET /api/create-flow/methods?section=<section>[&facet.*=...]
 *
 * Returns slugs + per-method match scores for one of the four card-deck
 * sections; the wizard renders by looking up the slug in the section's
 * messages file (`useMessages().create.customRule.<section>.methods`).
 *
 * See `docs/guides/template-recommendation-matrix.md` §9.2 / §10.
 */
export const GET = apiRoute(
  "createFlow.methods.get",
  async (request: NextRequest) => {
    if (!isDatabaseConfigured()) {
      return dbUnavailable();
    }

    const sectionParam = request.nextUrl.searchParams.get("section");
    if (!sectionParam || !SECTION_SET.has(sectionParam)) {
      return errorJson(
        "validation_error",
        `Unknown section. Expected one of: ${SECTION_IDS.join(", ")}`,
        400,
      );
    }
    const section = sectionParam as SectionId;

    const facets = parseRequestedFacetsFromSearchParams(
      request.nextUrl.searchParams,
    );
    const result = await listMethodRecommendations({ section, facets });
    if (!result) {
      // DB query failed; return empty so the wizard falls back to its messages
      // deck in authoring order (§10).
      return NextResponse.json({ section, methods: [] });
    }

    const methods = result.rankedSlugs.map((slug) => ({
      slug,
      matches: result.matchesBySlug[slug] ?? { score: 0, matchedFacets: [] },
    }));
    return NextResponse.json({ section, methods });
  },
);