/*
 * build.mjs — TypeScript 编译为 ES module JavaScript
 *
 * 每个 .ts 编译为同名 .js,保留 ES module import 路径(含 .js 后缀)
 * 排除:types/(类型声明)、vendor/(第三方)、node_modules、.git、logs、assets
 */

import { build } from 'esbuild';
import { readdir } from 'fs/promises';
import path from 'path';

const SKIP_DIRS = new Set(['node_modules', 'vendor', '.git', 'logs', 'assets', 'types']);

async function walk(dir, files = []) {
  const entries = await readdir(dir, { withFileTypes: true });
  for (const e of entries) {
    if (e.isDirectory()) {
      if (SKIP_DIRS.has(e.name)) continue;
      await walk(path.join(dir, e.name), files);
    } else if (e.isFile() && e.name.endsWith('.ts') && !e.name.endsWith('.d.ts')) {
      files.push(path.join(dir, e.name));
    }
  }
  return files;
}

const files = await walk('.');
if (files.length === 0) {
  console.log('No .ts files to build.');
  process.exit(0);
}

const isWatch = process.argv.includes('--watch');

console.log(`Building ${files.length} .ts files → .js (esbuild, ESM, ES2022)...`);

if (isWatch) {
  const ctx = await (await import('esbuild')).context({
    entryPoints: files,
    outbase: '.',
    outdir: '.',
    outExtension: { '.js': '.js' },
    format: 'esm',
    target: 'es2022',
    sourcemap: false,
    logLevel: 'info',
    allowOverwrite: true,
  });
  await ctx.watch();
  console.log('Watching for changes... (Ctrl+C to exit)');
} else {
  await build({
    entryPoints: files,
    outbase: '.',
    outdir: '.',
    outExtension: { '.js': '.js' },
    format: 'esm',
    target: 'es2022',
    sourcemap: false,
    logLevel: 'info',
    allowOverwrite: true,
  });
  console.log(`Done. Built ${files.length} files.`);
}