#!/usr/bin/env node
/**
 * Verify a synced skills tree the way this port consumes it.
 *
 *   node dsh/sync/verify-skills.mjs <skills-dir>
 *
 * `install.sh` runs this between `sync-from-upstream.mjs` and the copy into
 * `$DSH_HOME/skills`: a tree that fails here is never installed.
 *
 * Checks, per `<skill>/SKILL.md`:
 *
 *   1. YAML frontmatter parses and carries non-empty scalar `name` and
 *      `description` — the fields the DSH skill catalog reads. The parser is
 *      the scalar one vendored from LayneChai's `parseFrontmatter` (MIT); no
 *      provider is imported, because on the DeepSeek Harness the registry
 *      belongs to the built-in `skill-filesystem`, not to this repository.
 *   2. The body carries no leftover upstream `superpowers:` namespace
 *      prefix — the port strips it during sync, and the DSH registry
 *      addresses skills by bare name.
 *   3. Every relative reference in the body resolves inside `<skills-dir>`:
 *      markdown links (`[x](../<skill>/y.md)`) and path-like inline code
 *      (`references/y.md`, `../<skill>/references/y.md`, `scripts/y`). A
 *      sibling skill's `scripts/` invocation only needs that skill directory
 *      to exist: the reduced vendor tree under `dsh/tests/fixtures/` keeps
 *      the upstream command without shipping the executable, and a mistyped
 *      skill name still fails. Names that are illustrative examples rather
 *      than real files (`scripts/tool.sh`, …) are skipped, as in the
 *      vendored reference implementation.
 *
 * The prefix check is scoped to SKILL.md bodies on purpose: reference files
 * such as `using-superpowers/references/dsh-tools.md` quote `superpowers:` in
 * prose, and that is legal — the mapping table names the upstream namespace
 * on purpose (T1.5). Fenced code blocks are treated as examples, not prose,
 * exactly as the vendored reference implementation does.
 *
 * Output: one `ok: <skill>` line per skill directory and a final
 * `verified N skills`. The first problem stops the run: `<skill>/SKILL.md:
 * <reason>` on stderr, exit 1.
 *
 * @module dsh/sync/verify-skills
 */
import { readdir, readFile, stat } from 'node:fs/promises'
import { join, resolve } from 'node:path'

const USAGE = 'usage: node dsh/sync/verify-skills.mjs <skills-dir>'

const MARKDOWN_LINK = /\[[^\]]*\]\(([^)\s]+)\)/g
const INLINE_CODE = /`([^`\n]+)`/g

/** Trailing punctuation a path picks up from the surrounding sentence. */
const TRAILING_PUNCTUATION = /[.,;:)\]]+$/

/**
 * Names that appear only as illustrative examples in prose, never as real
 * files — the same list the vendored reference implementation keeps.
 */
const ILLUSTRATIVE = new Set(['scripts/tool.sh', 'scripts/tool.js', 'scripts/helper.py', 'scripts/helper.sh'])

/**
 * Parse a scalar-only YAML frontmatter block, same rules as the vendored
 * `parseFrontmatter`: the file starts with `---`, the block ends at the first
 * line that starts with `---`, and each `key: value` line becomes a string
 * (matching quotes stripped). Anything else is left for a real YAML parser.
 *
 * @returns {{metadata: Record<string, string>, body: string} | null}
 */
function parseFrontmatter(text) {
  if (!text.startsWith('---')) return null
  const end = text.indexOf('\n---', 3)
  if (end === -1) return null
  const block = text.slice(3, end)
  const body = text.slice(end + 4).replace(/^\n+/, '')
  const metadata = {}
  for (const line of block.split('\n')) {
    const match = /^([A-Za-z][\w-]*):\s*(.*)$/.exec(line.trim())
    if (!match) continue
    let value = match[2].trim()
    if ((value.startsWith('"') && value.endsWith('"')) || (value.startsWith("'") && value.endsWith("'"))) {
      value = value.slice(1, -1)
    }
    metadata[match[1]] = value
  }
  return { metadata, body }
}

/** Map every line inside a ``` / ~~~ fence to an empty line: examples are not prose. */
function blankFences(text) {
  let fenced = false
  return text
    .split('\n')
    .map((line) => {
      if (/^\s*(```|~~~)/.test(line)) {
        fenced = !fenced
        return ''
      }
      return fenced ? '' : line
    })
    .join('\n')
}

/** True when a markdown link target names no in-tree file to resolve. */
function isExternal(target) {
  return target.startsWith('#') || target.startsWith('/') || /^[a-z][a-z0-9+.-]*:/i.test(target)
}

async function statOrNull(path) {
  return stat(path).catch(() => null)
}

async function exists(path) {
  return Boolean(await statOrNull(path))
}

async function isDirectory(path) {
  return Boolean((await statOrNull(path))?.isDirectory())
}

/**
 * Classify one whitespace-separated token of an inline code span.
 *
 * `file` — a path that must resolve; `sibling-script` — a `../<skill>/scripts/`
 * invocation, where only the skill directory has to exist (see the header).
 *
 * @returns {{kind: 'file' | 'sibling-script', path: string} | null}
 */
function inlineReference(token) {
  if (/^(?:references|scripts)\//.test(token)) return { kind: 'file', path: token }
  if (!token.startsWith('../')) return null
  const parts = token.split('/')
  const scripts = parts.indexOf('scripts')
  if (scripts > 0) return { kind: 'sibling-script', path: parts.slice(0, scripts).join('/') }
  return { kind: 'file', path: token }
}

function fail(skill, reason) {
  console.error(`${skill}/SKILL.md: ${reason}`)
  process.exit(1)
}

/** Verify one `<skillsRoot>/<skill>/SKILL.md`; exits the process on the first problem. */
async function verifySkill(skillsRoot, skill) {
  const skillDir = join(skillsRoot, skill)
  const skillFile = join(skillDir, 'SKILL.md')

  let text
  try {
    text = await readFile(skillFile, 'utf8')
  } catch (error) {
    fail(skill, `cannot read SKILL.md (${error?.code ?? error})`)
  }

  const parsed = parseFrontmatter(text)
  if (parsed === null) fail(skill, 'missing YAML frontmatter')
  if (!parsed.metadata.name) fail(skill, 'empty name in frontmatter')
  if (!parsed.metadata.description) fail(skill, 'empty description in frontmatter')

  // The body is a suffix of the file, so the number of newlines before it is
  // the line offset: report file lines, not body lines, to the operator.
  const lineOffset = (text.slice(0, text.length - parsed.body.length).match(/\n/g) ?? []).length

  const lines = blankFences(parsed.body).split('\n')
  for (const [index, line] of lines.entries()) {
    const lineNumber = lineOffset + index + 1

    if (line.includes('superpowers:')) {
      fail(skill, `leftover superpowers: namespace prefix in body (line ${lineNumber})`)
    }

    for (const match of line.matchAll(MARKDOWN_LINK)) {
      const target = match[1]
      if (isExternal(target)) continue
      if (!(await exists(resolve(skillDir, target.replace(/[?#].*$/, ''))))) {
        fail(skill, `dangling relative reference: ${target} (line ${lineNumber})`)
      }
    }

    for (const code of line.matchAll(INLINE_CODE)) {
      for (const raw of code[1].split(/\s+/)) {
        const token = raw.replace(TRAILING_PUNCTUATION, '')
        if (token === '' || ILLUSTRATIVE.has(token)) continue
        const reference = inlineReference(token)
        if (reference === null) continue
        const target = resolve(skillDir, reference.path)
        const resolved = reference.kind === 'sibling-script' ? await isDirectory(target) : await exists(target)
        if (!resolved) fail(skill, `dangling relative reference: ${token} (line ${lineNumber})`)
      }
    }
  }
}

async function main() {
  if (process.argv.length > 3) {
    console.error(USAGE)
    process.exit(2)
  }
  const arg = process.argv[2]
  if (!arg) {
    console.error(USAGE)
    process.exit(2)
  }

  const skillsRoot = resolve(arg)
  if (!(await isDirectory(skillsRoot))) {
    console.error(`${skillsRoot}: not a skills directory`)
    process.exit(1)
  }

  const skills = (await readdir(skillsRoot, { withFileTypes: true }))
    .filter((entry) => entry.isDirectory())
    .map((entry) => entry.name)
    .sort()

  for (const skill of skills) await verifySkill(skillsRoot, skill)

  for (const skill of skills) console.log(`ok: ${skill}`)
  console.log(`verified ${skills.length} skills`)
}

main().catch((error) => {
  console.error(`\n[FAIL] unexpected error: ${error?.stack ?? error}\n`)
  process.exit(1)
})