import {
  ShortlistError,
  addPick,
  createShortlist,
  deleteShortlist,
  exportJson,
  exportMarkdown,
  isShortlistBody,
  listShortlists,
  noteShortlist,
  readShortlist,
  removePick,
  renameShortlist,
  reorderShortlist,
} from "@/lib/shortlist";

export const dynamic = "force-dynamic";

// The shortlists.
//
//   GET                        every list, as summaries
//   GET ?list=<slug>           one list, in full
//   GET ?list=<slug>&format=md the same list for a person to read
//   GET ?list=<slug>&format=json  THE EXPORT -- what a renderer consumes
//   POST <ShortlistBody>       create · add · remove · note · reorder · rename · delete
//
// The two export formats answer different questions and neither is the other's
// pretty-printing: the JSON is an ordered list of absolute episode windows on
// the same timeline as wav48/ and media/, and the markdown is what you paste
// into a note six weeks later to remember why these forty moments.

const noStore = { "cache-control": "no-store" };

export async function GET(request: Request) {
  const url = new URL(request.url);
  const slug = url.searchParams.get("list");
  if (!slug) {
    return Response.json({ lists: await listShortlists() }, { headers: noStore });
  }

  const list = await readShortlist(slug);
  if (!list) return Response.json({ error: `no shortlist called ${slug}` }, { status: 404 });

  const format = url.searchParams.get("format");
  // An EXPORT is a file, so it is served as one. Handing it back inline would
  // make the obvious next step "select all and copy", which loses the order to
  // whatever the clipboard does with a wrapped line.
  if (format === "md") {
    return new Response(exportMarkdown(list), {
      headers: {
        ...noStore,
        "content-type": "text/markdown; charset=utf-8",
        "content-disposition": `attachment; filename="${slug}.md"`,
      },
    });
  }
  if (format === "json") {
    return new Response(JSON.stringify(exportJson(list), null, 1), {
      headers: {
        ...noStore,
        "content-type": "application/json; charset=utf-8",
        "content-disposition": `attachment; filename="${slug}.json"`,
      },
    });
  }

  return Response.json({ list }, { headers: noStore });
}

export async function POST(request: Request) {
  let body: unknown;
  try {
    body = await request.json();
  } catch {
    return Response.json({ error: "bad json" }, { status: 400 });
  }
  if (!isShortlistBody(body)) {
    return Response.json({ error: "not a shortlist op" }, { status: 400 });
  }

  try {
    switch (body.op) {
      case "create":
        return Response.json(
          { ok: true, list: await createShortlist(body.name, body.note) },
          { headers: noStore },
        );
      case "add":
        return Response.json(
          { ok: true, list: await addPick(body.list, body.pick) },
          { headers: noStore },
        );
      case "remove":
        return Response.json(
          { ok: true, list: await removePick(body.list, body.id) },
          { headers: noStore },
        );
      case "note":
        return Response.json(
          { ok: true, list: await noteShortlist(body.list, body.note, body.id) },
          { headers: noStore },
        );
      case "reorder":
        return Response.json(
          { ok: true, list: await reorderShortlist(body.list, body.ids) },
          { headers: noStore },
        );
      case "rename":
        return Response.json(
          { ok: true, list: await renameShortlist(body.list, body.name) },
          { headers: noStore },
        );
      case "delete":
        return Response.json(
          { ok: true, ...(await deleteShortlist(body.list)) },
          { headers: noStore },
        );
    }
  } catch (e) {
    if (e instanceof ShortlistError) {
      return Response.json({ error: e.message }, { status: e.status });
    }
    return Response.json({ error: "could not write the shortlist" }, { status: 500 });
  }
}