/**
 * Verify repository-local Markdown links without making network requests.
 *
 * External URLs are intentionally skipped: CI should not fail because an
 * upstream website is temporarily unavailable. Local documentation links are
 * deterministic and catch renamed component guides or incorrect relative paths.
 */
import { existsSync, readdirSync, readFileSync } from 'node:fs'
import { dirname, extname, resolve } from 'node:path'

const root = resolve(process.argv[2] ?? new URL('../../..', import.meta.url).pathname)
const ignoredDirectories = new Set([
  '.agents',
  '.codex',
  '.git',
  'dist',
  'node_modules',
  'target',
  'vendor',
])
const markdownFiles = []

function collect(directory) {
  for (const entry of readdirSync(directory, { withFileTypes: true })) {
    if (entry.isDirectory() && ignoredDirectories.has(entry.name)) continue
    const path = resolve(directory, entry.name)
    if (entry.isDirectory()) collect(path)
    else if (extname(entry.name).toLowerCase() === '.md') markdownFiles.push(path)
  }
}

collect(root)

const failures = []
const markdownLink = /\[[^\]]*\]\(([^)]+)\)/g
for (const file of markdownFiles) {
  const source = readFileSync(file, 'utf8')
  for (const match of source.matchAll(markdownLink)) {
    const rawTarget = match[1].trim().replace(/^<|>$/g, '')
    if (!rawTarget || rawTarget.startsWith('#') || /^[a-z][a-z+.-]*:/i.test(rawTarget)) continue

    // The project does not currently use titled local links. Splitting here
    // still handles the conventional `(path "title")` form if one is added.
    const target = decodeURI(rawTarget.split(/\s+["']/)[0].split('#')[0])
    if (!target) continue
    const destination = resolve(dirname(file), target)
    if (!existsSync(destination)) failures.push(`${file}: ${rawTarget}`)
  }
}

if (failures.length > 0) {
  console.error(`Broken local documentation links:\n${failures.join('\n')}`)
  process.exitCode = 1
} else {
  console.log(`Checked ${markdownFiles.length} Markdown files; local links are valid.`)
}