#!/usr/bin/env bun
/**
 * Fuzzy-pick a LeetCode problem and scaffold it via leetcode-cli.
 *
 * The problem index lives in the local SQLite cache (see db.ts), refreshed at
 * most once per 24h; campaign problem descriptions from README.md are
 * backfilled into the same db on the way. Problems that already have a
 * numbered file under work/ are excluded from the picker — re-picking them
 * would only clobber the existing scaffold.
 */
import { autocomplete, cancel, isCancel, spinner } from "@clack/prompts";
import { basename, join } from "node:path";
import { fetchDescription, problemDb, readmeSlugs, type Problem } from "./db";

const ROOT = join(import.meta.dir, "..", "..");
const WORK_DIR = join(ROOT, "work");

const db = problemDb();

// ── problem index (24h TTL) ──────────────────────────────────────

if (db.indexStale()) {
  const s = spinner();
  s.start("Fetching problem index from leetcode.com");
  try {
    s.stop(`Indexed ${await db.refreshIndex()} problems`);
  } catch (err) {
    if (db.all().length === 0) {
      s.error(`Fetch failed: ${err}`);
      process.exit(1);
    }
    s.stop(`Index refresh failed (${err}) — using cached copy`);
  }
}

// ── description backfill for the campaign problems in README.md ──

const missing = db.missingDescriptions(readmeSlugs(await Bun.file(join(ROOT, "README.md")).text()));
if (missing.length > 0) {
  const s = spinner();
  s.start(`Caching ${missing.length} problem descriptions`);
  let fetched = 0;
  let failed = 0;
  await Promise.all(
    Array.from({ length: 6 }, async () => {
      for (let slug = missing.shift(); slug; slug = missing.shift()) {
        try {
          const html = await fetchDescription(slug);
          if (html !== null) db.saveDescription(slug, html);
          s.message(`Caching problem descriptions (${++fetched})`);
        } catch {
          failed++; // left NULL — retried on the next run
        }
      }
    }),
  );
  s.stop(failed ? `Cached ${fetched} descriptions (${failed} failed, will retry next run)` : `Cached ${fetched} problem descriptions`);
}

// ── exclude problems already picked or solved under work/ ────────

const done = new Set<number>();
for (const rel of new Bun.Glob("**/*.*").scanSync({ cwd: WORK_DIR })) {
  const m = basename(rel).match(/^(\d+)\./);
  if (m) done.add(Number(m[1]));
}

const problems = db.all().filter((p) => !done.has(p.id));
db.close();

const picked = await autocomplete<Problem>({
  message: "Pick a problem",
  placeholder: "Type to search by number or title...",
  maxItems: 12,
  options: problems.map((p) => ({
    value: p,
    label: `${p.id}. ${p.title}`,
    hint: p.paidOnly ? `${p.difficulty} 🔒 premium` : p.difficulty,
  })),
  filter: (search, option) => {
    const haystack = option.label!.toLowerCase();
    return search
      .toLowerCase()
      .split(/\s+/)
      .every((token) => haystack.includes(token));
  },
});

if (isCancel(picked)) {
  cancel("Nothing picked.");
  process.exit(0);
}

const proc = Bun.spawn(
  // bun installs workspace-dep bins into this package's node_modules, not the root's
  [join(import.meta.dir, "node_modules", ".bin", "leetcode"), "pick", picked.slug],
  { cwd: ROOT, stdio: ["inherit", "inherit", "inherit"] },
);
process.exit(await proc.exited);