// The song kind, read cheaply.
//
// The RICH read is lib/browse.ts's readSong(): verdict tallies against thumb
// aliases, plan provenance, spec validation, the accepted-cover set. That stays
// where it is and the project page still uses it. This is the index's version --
// two readdirs and one small JSON -- because `umtool ls` has to work from a
// terminal with no server, and because the index pays this per project.
import { readdir, readFile, stat } from "node:fs/promises";
import path from "node:path";
/** This kind's registry id. The one place the string lives. */
export const SONG_KIND = "song";

// The cut list is FIXED, not derived from the directory: mortal-kombat and
// mario-rpg have no vertical.mp4, and a scan-derived list would render those
// songs as complete. A hole in the deliverable set is information.
//
// Defined here rather than in lib/browse.ts so the CLI and the app share one
// list; lib/browse.ts re-exports it.
export const CUT_NAMES = ["wide", "wide-short", "vertical", "vertical-short"];

const MEDIA_RE = /\.(mp4|mkv|webm|mov|m4v)$/i;

const stat0 = (p) => stat(p).then((s) => s, () => null);

const listMediaIn = (dir) =>
  readdir(dir, { withFileTypes: true }).then(
    (es) => es.filter((e) => e.isFile() && MEDIA_RE.test(e.name) && !e.name.startsWith(".")).map((e) => e.name),
    () => [],
  );

export async function songSignature(dir) {
  const [d, v] = await Promise.all([stat0(dir), stat0(path.join(dir, "verdicts.json"))]);
  return [Math.round(d?.mtimeMs ?? 0), Math.round(v?.mtimeMs ?? 0), v?.size ?? 0].join(":");
}

export async function summariseSong(ctx) {
  const { dir, name } = ctx;
  const [top, variants, readme, verdicts] = await Promise.all([
    listMediaIn(dir),
    listMediaIn(path.join(dir, "variants")),
    readFile(path.join(dir, "README.md"), "utf8").catch(() => null),
    readFile(path.join(dir, "verdicts.json"), "utf8").then(
      (t) => JSON.parse(t),
      () => ({}),
    ),
  ]);

  const bases = new Set(top.map((n) => n.replace(MEDIA_RE, "")));
  const present = CUT_NAMES.filter((c) => bases.has(c));
  const missing = CUT_NAMES.filter((c) => !bases.has(c));

  const counts = { keep: 0, reject: 0, undecided: 0 };
  const all = [...top, ...variants.map((n) => path.posix.join("variants", n))];
  for (const rel of all) {
    const v = verdicts[rel]?.verdict;
    counts[v === "keep" || v === "reject" ? v : "undecided"] += 1;
  }

  let newest = 0;
  // The shipped cuts' bytes, for the dashboard's deliverables count. Variants
  // are not deliverables, so they are not summed.
  let finalBytes = 0;
  for (const rel of all) {
    const st = await stat0(path.join(dir, rel));
    if (!st) continue;
    newest = Math.max(newest, st.mtimeMs);
    if (!rel.startsWith("variants/")) finalBytes += st.size;
  }

  const title = readme?.match(/^#\s+(.+)$/m)?.[1]?.trim() ?? name;
  const state = present.length === 0 ? "draft" : present.length === CUT_NAMES.length ? "shipped" : "built";

  const facts = [
    `${present.length}/${CUT_NAMES.length} cuts`,
    `${variants.length} variant${variants.length === 1 ? "" : "s"}`,
  ];
  if (counts.undecided) facts.push(`${counts.undecided} undecided`);

  return {
    title,
    subtitle: missing.length ? `no ${missing.join(", ")}` : null,
    state,
    newestMtimeMs: newest,
    facts,
    flags: [],
    posterRel: present.length ? `${present[0]}.mp4` : null,
    haystack: [ctx.id, title, ...bases].join(" ").toLowerCase(),
    attrs: {
      song: name,
      cuts: String(present.length),
      variants: String(variants.length),
      keep: String(counts.keep),
      reject: String(counts.reject),
      undecided: String(counts.undecided),
      ...(present.length ? { "final-bytes": String(finalBytes) } : {}),
      // Omitted entirely when the set is complete: a hole in the deliverables
      // is information, and its ABSENCE has to be readable as "nothing missing"
      // rather than as an empty list.
      ...(missing.length ? { missing: missing.join(",") } : {}),
    },
    counts,
    present,
    missing,
    variantCount: variants.length,
  };
}