/**
 * run-cli — spawn a colocated CLI entry point (`index.ts`) through tsx, the way
 * the orchestrator invokes it, and parse the JSON envelope it prints.
 *
 * Why a real spawn: every scaffolder used to be tested only through
 * `generate()` with hand-filled fixtures, so `index.ts` handing the RAW spec
 * to `generate()` (Zod defaults never applied) stayed invisible to a
 * 2442-green suite. An entry test runs the documented invocation end to end.
 */
import { spawnSync } from 'node:child_process'
import { existsSync } from 'node:fs'
import { dirname, resolve } from 'node:path'
import { fileURLToPath } from 'node:url'

const here = dirname(fileURLToPath(import.meta.url))
/** Repository root (templates/skills/lib/__tests__/helpers → 5 levels up). */
export const REPO_ROOT = resolve(here, '../../../../..')
const TSX_CLI = resolve(REPO_ROOT, 'node_modules/tsx/dist/cli.mjs')

export interface CliRun {
  status: number | null
  stdout: string
  stderr: string
  /** The last JSON document on stdout (the envelope), or null when stdout is not JSON. */
  envelope: any | null
}

export function runCli(indexPath: string, args: string[], opts: { cwd?: string } = {}): CliRun {
  if (!existsSync(TSX_CLI)) throw new Error(`tsx not found at ${TSX_CLI} — run npm install`)
  const r = spawnSync(process.execPath, [TSX_CLI, indexPath, ...args], {
    cwd: opts.cwd ?? REPO_ROOT,
    encoding: 'utf-8',
    maxBuffer: 16 * 1024 * 1024,
  })
  const stdout = r.stdout ?? ''
  const start = stdout.indexOf('{')
  let envelope: any | null = null
  if (start >= 0) {
    try { envelope = JSON.parse(stdout.slice(start)) } catch { envelope = null }
  }
  return { status: r.status, stdout, stderr: r.stderr ?? '', envelope }
}