import path from "node:path";
import { selectVariant } from "umtool-report-to-video/build-video";
import {
  decodeProjectSegment,
  deckPreviewFile,
  previewDirFor,
  rangeResponse,
  resolveReport,
} from "@/lib/report/serve.mjs";

export const dynamic = "force-dynamic";

// The deck's preview composition, served to the iframe.
//
// /api/report/chrome/files/<project>/<variant>/<file…>, where <project> is the
// project id base64url-encoded into one segment (POST /api/report/chrome/preview
// hands out the src; nothing builds it by hand). The project and the variant
// travel IN THE PATH because the composition names its assets by relative url,
// and a relative url resolved against `index.html?project=…` drops the query.
//
// This is the one report route that takes a path from the client, so it is
// confined twice: the project and the variant must be members of the server's
// own scan and list, and the file must resolve -- symlinks followed -- inside
// that cut's out/<variant>/chrome/deck-preview/. deckPreviewFile is the rule,
// and it is tested.
//
// The posts region's windows are served from the same prefix one segment
// deeper: <project>/<variant>/posts-preview-<segment>/<file…>, where <segment>
// must be an entry of this cut (previewDirFor), and the file is then confined
// to THAT window's directory by the same deckPreviewFile.

const TYPES: Record<string, string> = {
  ".html": "text/html; charset=utf-8",
  ".js": "text/javascript; charset=utf-8",
  ".mjs": "text/javascript; charset=utf-8",
  ".css": "text/css; charset=utf-8",
  ".json": "application/json",
  ".png": "image/png",
  ".jpg": "image/jpeg",
  ".jpeg": "image/jpeg",
  ".webp": "image/webp",
  ".svg": "image/svg+xml",
  ".woff2": "font/woff2",
  ".woff": "font/woff",
  ".ttf": "font/ttf",
  ".otf": "font/otf",
};

export async function GET(request: Request, ctx: { params: Promise<{ path: string[] }> }) {
  const { path: segments } = await ctx.params;
  if (!Array.isArray(segments) || segments.length < 3) return new Response("not found", { status: 404 });
  const [projectSeg, variant, ...rest] = segments;

  const projectId = decodeProjectSegment(projectSeg);
  if (!projectId) return new Response("not found", { status: 404 });
  const r = await resolveReport(projectId, variant);
  if ("error" in r) return new Response(r.error, { status: r.status });

  const ids = (selectVariant(r.manifest, r.variant).timeline ?? []).map((e: { id: string }) => e.id);
  const where = previewDirFor(r.project.dir, r.variant, rest, ids);
  if (!where) return new Response("not found", { status: 404 });
  const file = await deckPreviewFile(where.dir, where.rest);
  if (!file) return new Response("not found", { status: 404 });

  return rangeResponse(request, {
    abs: file.abs,
    size: file.size,
    headers: {
      "content-type": TYPES[path.extname(file.abs).toLowerCase()] ?? "application/octet-stream",
      "cache-control": "no-store",
      "x-content-type-options": "nosniff",
    },
  });
}