#!/usr/bin/env node
/**
 * CI: spot-check markdown links to repo-relative paths (../ or ./ from each file).
 *
 * Skips `packages/bare-os-seeder/kernel/**`: it is a byte-identical copy of `kernel/`
 * (see verify-kernel-seeder-parity.mjs). Links in those files are validated from the
 * canonical `kernel/**` paths only.
 */
import fs from 'node:fs'
import path from 'node:path'
import process from 'node:process'
import { fileURLToPath } from 'node:url'

const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..')

const GLOBS = [
  'docs',
  'handbook',
  'developer-guide',
  'scripts',
  'users-manual',
  'packages',
  'kernel',
]

const ROOT_MD_FILES = ['README.md', 'DOCUMENTATION.md', 'PEAR-RUN.md']

/** Copied into `kernel/lib/bare/README.md`; links are relative to that path. */
const SKIP_FILES = new Set(['packages/bare-os-bare-libs/README.kernel-lib-bare.md'])

function isSkippedPath(relFromRoot) {
  const norm = relFromRoot.split(path.sep).join('/')
  return norm === 'packages/bare-os-seeder/kernel' || norm.startsWith('packages/bare-os-seeder/kernel/')
}

/**
 * @param {string} dir
 * @returns {string[]}
 */
function walkMd(dir) {
  const abs = path.join(root, dir)
  if (!fs.existsSync(abs)) return []
  /** @type {string[]} */
  const out = []
  const st = fs.statSync(abs)
  if (st.isFile() && abs.endsWith('.md')) {
    out.push(abs)
    return out
  }
  if (!st.isDirectory()) return out
  for (const ent of fs.readdirSync(abs, { withFileTypes: true })) {
    if (ent.name === 'node_modules' || ent.name === '.git') continue
    const p = path.join(abs, ent.name)
    const relFromRoot = p.slice(root.length + 1)
    if (isSkippedPath(relFromRoot)) continue
    if (ent.isDirectory()) out.push(...walkMd(relFromRoot))
    else if (ent.isFile() && ent.name.endsWith('.md')) out.push(p)
  }
  return out
}

/**
 * @param {string} file
 * @param {string[]} errors
 */
function collectMdLinkErrors(file, errors) {
  const rel = path.relative(root, file)
  if (SKIP_FILES.has(rel.split(path.sep).join('/')) || isSkippedPath(rel)) return
  const text = fs.readFileSync(file, 'utf8')
  const re = /\]\(([^)#\s]+\.md)(#[^)]*)?\)/g
  let m
  while ((m = re.exec(text))) {
    const target = m[1]
    if (target.startsWith('http')) continue
    const resolved = path.normalize(path.join(path.dirname(file), target))
    if (!fs.existsSync(resolved)) {
      errors.push(
        `${path.relative(root, file)} → missing ${path.relative(root, resolved)}`
      )
    }
  }
}

function main() {
  /** @type {string[]} */
  const errors = []
  for (const g of GLOBS) {
    for (const file of walkMd(g)) {
      collectMdLinkErrors(file, errors)
    }
  }
  for (const name of ROOT_MD_FILES) {
    const file = path.join(root, name)
    if (fs.existsSync(file)) collectMdLinkErrors(file, errors)
  }
  if (errors.length) {
    console.error('verify-doc-links: broken relative .md links:')
    for (const e of errors.slice(0, 80)) console.error(' ', e)
    if (errors.length > 80) console.error(`  … and ${errors.length - 80} more`)
    process.exit(1)
  }
  console.log('verify-doc-links: OK')
}

main()