// Which umtool report-video project is an article's video.
//
// Two ways, in order:
//
//   1. The manifest says so: a top-level `"article": "<site>/<report>"` in
//      video.manifest.json. build-video.mjs never reads top-level keys it does
//      not know (it reads `generatedBy` no more than this), so the key costs
//      the render nothing. A manifest that names an article is linked to it
//      and to nothing else.
//   2. The slug matches: the manifest's `slug` (else the project directory's
//      name) is the report id, `polemic-<id>`, or the id without `polemic-` --
//      and the project lives in the same workspace as the article's draft
//      (lib/articles/sources.mjs). A UNIQUE match is linked; two or more are
//      only "possible", and the page says so rather than picking one.
//
// Plain ESM, so `umtool notes` can name an article's video too.
import { readFile } from "node:fs/promises";
import os from "node:os";
import path from "node:path";
import { REPORTS_ROOT } from "../paths.mjs";
import { projectRefs } from "../projects/core.mjs";
import { kindLinksArticles } from "../projects/kinds.mjs";
import { idKeys } from "./sources.mjs";

const CACHE_MS = 30_000;
/** @type {Map<string, { at: number, value: Promise<any[]> }>} */
const cache = new Map();

/** `~/x` back to an absolute path. */
export function untildify(p) {
  if (typeof p !== "string") return p;
  return p === "~" || p.startsWith("~/") ? path.join(/* turbopackIgnore: true */ os.homedir(), p.slice(2)) : p;
}

/**
 * Every report-video project with what linking needs from its manifest:
 * `{ id, dir, name, slug, article, generatedBy, title }`.
 *
 * @param {string} [reportsRoot]
 */
export function videoProjects(reportsRoot = REPORTS_ROOT) {
  const hit = cache.get(reportsRoot);
  if (hit && Date.now() - hit.at < CACHE_MS) return hit.value;
  const value = (async () => {
    const out = [];
    for (const p of await projectRefs(reportsRoot)) {
      if (!kindLinksArticles(p.kind)) continue;
      let m = {};
      try {
        m = JSON.parse(await readFile(/* turbopackIgnore: true */ path.join(/* turbopackIgnore: true */ p.dir, "video.manifest.json"), "utf8"));
      } catch {
        // a project with no readable manifest still links by its directory name
      }
      out.push({
        id: p.id,
        dir: p.dir,
        name: p.name,
        slug: typeof m.slug === "string" && m.slug ? m.slug : p.name,
        article: typeof m.article === "string" ? m.article : null,
        generatedBy: typeof m.generatedBy === "string" ? m.generatedBy : null,
        title: typeof m.title === "string" ? m.title : p.name,
      });
    }
    return out.sort((a, b) => a.id.localeCompare(b.id));
  })();
  cache.set(reportsRoot, { at: Date.now(), value });
  value.catch(() => cache.delete(reportsRoot));
  return value;
}

export function clearLinksCache() {
  cache.clear();
}

const inside = (root, p) => p === root || p.startsWith(root + path.sep);

/**
 * The projects linked to one article: `{ linked, possible, how }`.
 *
 * @param {string} siteId
 * @param {string} reportId
 * @param {{ reportsRoot?: string, workspace?: string | null, projects?: any[] }} [opts]
 *   `workspace` is the article's workspace dir (sourceFor's, `~` allowed); without
 *   one, slug matches are only ever "possible".
 */
export async function linkedProjects(siteId, reportId, { reportsRoot = REPORTS_ROOT, workspace = null, projects } = {}) {
  const all = projects ?? (await videoProjects(reportsRoot));
  const key = `${siteId}/${reportId}`;
  const declared = all.filter((p) => p.article === key);
  if (declared.length) return { linked: declared, possible: [], how: "manifest names the article" };

  const keys = idKeys(reportId);
  // A manifest that names a DIFFERENT article is never a slug match.
  const bySlug = all.filter((p) => !p.article && keys.has(p.slug));
  const ws = workspace ? untildify(workspace) : null;
  const inWs = ws ? bySlug.filter((p) => inside(ws, p.dir)) : [];
  if (inWs.length === 1) return { linked: inWs, possible: [], how: `slug ${inWs[0].slug} in the article's workspace` };
  const possible = inWs.length > 1 ? inWs : bySlug;
  return { linked: [], possible, how: possible.length ? `${possible.length} project(s) share the slug` : "no project" };
}