import { spawnSync } from "node:child_process";
import { existsSync, readdirSync, readFileSync } from "node:fs";
import { dirname, join, resolve } from "node:path";
import { fileURLToPath } from "node:url";

export const root = resolve(dirname(fileURLToPath(import.meta.url)), "..");
export const talksDir = join(root, "talks");
export const templateDir = join(root, "template");
export const distDir = join(root, "dist");

/** Every directory in talks/ that has a slides.md, with its frontmatter title/date/video. */
export function listTalks() {
  return readdirSync(talksDir, { withFileTypes: true })
    .filter((d) => d.isDirectory() && existsSync(join(talksDir, d.name, "slides.md")))
    .map((d) => {
      const entry = join(talksDir, d.name, "slides.md");
      const headmatter = readFileSync(entry, "utf8").match(/^---\n([\s\S]*?)\n---/)?.[1] ?? "";
      const field = (name) => {
        const raw = headmatter.match(new RegExp(`^${name}:\\s*(.+)$`, "m"))?.[1].trim();
        if (raw?.startsWith('"')) return JSON.parse(raw);
        return raw?.replace(/^'(.*)'$/, "$1");
      };
      // `video` is optional — the recording's URL, once there is one.
      const video = field("video");
      if (video && !/^https?:\/\//.test(video)) {
        console.error(`talks/${d.name}: video must be an http(s) URL, got "${video}"`);
        process.exit(1);
      }
      return { slug: d.name, entry, title: field("title") ?? d.name, date: field("date"), video };
    })
    .sort((a, b) => (b.date ?? "").localeCompare(a.date ?? "") || a.slug.localeCompare(b.slug));
}

/** Resolve a talk from a CLI arg; falls back to the only talk, else exits with the list. */
export function pickTalk(slug) {
  const talks = listTalks();
  const talk = slug ? talks.find((t) => t.slug === slug) : talks.length === 1 ? talks[0] : undefined;
  if (talk) return talk;
  console.error(slug ? `No talk named "${slug}".` : "Which talk?");
  console.error(talks.map((t) => `  ${t.slug}`).join("\n"));
  process.exit(1);
}

export function slidev(args) {
  const { status } = spawnSync(join(root, "node_modules/.bin/slidev"), args, { cwd: root, stdio: "inherit" });
  if (status !== 0) process.exit(status ?? 1);
}