#!/usr/bin/env bun
/**
 * Fetch Drizzle ORM docs directly from the docs repo (default: drizzle-team/drizzle-orm-docs).
 *
 * Strategy:
 * - Use the GitHub trees API to list files under `src/content/docs/`.
 * - Download raw files via raw.githubusercontent.com.
 * - Write them under `drizzle/` (configurable).
 *
 * Usage:
 *   bun run scripts/pull_drizzle_docs.ts [--repo drizzle-team/drizzle-orm-docs] [--branch main] [--output drizzle] [--workers 16] [--docs-prefix src/content/docs/]
 */

import { mkdir } from "node:fs/promises";

const DEFAULT_REPO = "drizzle-team/drizzle-orm-docs";
const DEFAULT_BRANCH = "main";
const DEFAULT_OUTPUT = "drizzle";
const DEFAULT_WORKERS = 16;
const DEFAULT_PREFIX = "src/content/docs/";

type Options = {
  repo: string;
  branch: string;
  output: string;
  workers: number;
  docsPrefix: string;
};

type Page = {
  path: string; // repo path, eg: src/content/docs/quick-start.mdx
  output: string; // local path, eg: drizzle/quick-start.mdx
};

const args = Bun.argv.slice(2);

function getArg(flag: string, fallback: string): string {
  const idx = args.indexOf(flag);
  if (idx !== -1 && args[idx + 1]) return args[idx + 1];
  return fallback;
}

const opts: Options = {
  repo: getArg("--repo", DEFAULT_REPO),
  branch: getArg("--branch", DEFAULT_BRANCH),
  output: getArg("--output", DEFAULT_OUTPUT),
  workers: Number(getArg("--workers", String(DEFAULT_WORKERS))),
  docsPrefix: getArg("--docs-prefix", DEFAULT_PREFIX),
};

async function fetchJson(url: string) {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`Failed to fetch ${url}: ${res.status}`);
  return res.json();
}

async function fetchText(url: string) {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`Failed to fetch ${url}: ${res.status}`);
  return res.text();
}

async function listDocsFromRepo(options: Options): Promise<Page[]> {
  const treeUrl = `https://api.github.com/repos/${options.repo}/git/trees/${options.branch}?recursive=1`;
  type GitTreeResponse = {
    tree: { path: string; type: string }[];
  };
  const data = (await fetchJson(treeUrl)) as GitTreeResponse;
  const tree = data.tree;
  if (!Array.isArray(tree)) throw new Error("Unexpected tree response");

  const pages: Page[] = [];
  for (const entry of tree) {
    if (entry.type !== "blob") continue;
    if (!entry.path.startsWith(options.docsPrefix)) continue;
    if (!entry.path.match(/\.(md|mdx|json)$/i)) continue;

    const rel = entry.path.replace(options.docsPrefix, "");
    const parts = rel.split("/");
    const filename = parts.pop() || "index";
    const dir = [opts.output, ...parts].join("/");
    const output = `${dir ? `${dir}/` : ""}${filename}`;
    pages.push({ path: entry.path, output });
  }
  return pages;
}

async function ensureDir(path: string) {
  const dir = path.split("/").slice(0, -1).join("/");
  if (!dir) return;
  await mkdir(dir, { recursive: true });
}

async function writeFile(path: string, content: string) {
  await ensureDir(path);
  await Bun.write(path, content.endsWith("\n") ? content : `${content}\n`);
}

async function pullDocs(options: Options) {
  const pages = await listDocsFromRepo(options);
  console.log(
    `Discovered ${pages.length} docs files from repo ${options.repo} @ ${options.branch} (prefix: ${options.docsPrefix}).`,
  );

  let active = 0;
  let idx = 0;
  let ok = 0;
  let skipped = 0;
  const results: Promise<void>[] = [];

  async function worker(page: Page) {
    try {
      const rawUrl = `https://raw.githubusercontent.com/${options.repo}/${options.branch}/${page.path}`;
      const content = await fetchText(rawUrl);
      await writeFile(page.output, content);
      ok++;
      console.log(`[ok] ${page.output}`);
    } catch (err) {
      skipped++;
      console.log(`[err] ${page.path}: ${(err as Error).message}`);
    }
  }

  function next(): void {
    if (idx >= pages.length) return;
    const page = pages[idx++];
    active++;
    const p = worker(page).finally(() => {
      active--;
      next();
    });
    results.push(p);
    if (active < options.workers && idx < pages.length) next();
  }

  for (let i = 0; i < options.workers && i < pages.length; i++) next();
  await Promise.all(results);
  console.log(`Done. ok=${ok} skipped=${skipped}`);
}

pullDocs(opts).catch((err) => {
  console.error(err);
  process.exit(1);
});