import { readFile } from 'node:fs/promises'
import path from 'node:path'
import { fileURLToPath } from 'node:url'
import test from 'brittle'
import b4a from 'b4a'

const __dirname = path.dirname(fileURLToPath(import.meta.url))
const AsyncFunction = Object.getPrototypeOf(async function () {}).constructor

async function loadMvBin() {
  const runtime = await readFile(
    path.join(__dirname, '../lib/runtime.js'),
    'utf8'
  )
  const body = await readFile(path.join(__dirname, '../src/mv.js'), 'utf8')
  return new AsyncFunction(
    'ctx',
    'argv',
    `${runtime}\n${body}\nif (typeof run === 'function') return await run(ctx, argv)\n`
  )
}

test('/bin/mv cross-drive failure injection preserves source and exits non-zero', async (t) => {
  const run = await loadMvBin()
  const errors = []
  let sourceRemoved = false
  const writes = []
  const ctx = {
    b4a,
    exitCode: 0,
    console: {
      log() {},
      error(msg) {
        errors.push(String(msg))
      }
    },
    vfs: {
      resolveLogical(p) {
        return String(p)
      },
      async lstat(p) {
        if (p === '/mnt/a/file.txt') return { type: 'file' }
        return null
      },
      async stat() {
        return null
      },
      async readFile(p) {
        if (p === '/mnt/a/file.txt') return b4a.from('payload')
        return null
      },
      async writeFile(p, buf) {
        writes.push([String(p), b4a.toString(buf)])
        if (String(p).startsWith('/mnt/b/')) {
          const e = new Error('EXDEV: cross-device link not permitted')
          e.code = 'EXDEV'
          throw e
        }
      },
      async unlink() {},
      async rm(p) {
        if (p === '/mnt/a/file.txt') sourceRemoved = true
      },
      async readdir() {
        return []
      },
      async mkdir() {}
    }
  }

  await run(ctx, ['mv', '/mnt/a/file.txt', '/mnt/b/file.txt'])
  t.is(ctx.exitCode, 1)
  t.absent(sourceRemoved, 'source should remain when cross-drive write fails')
  t.ok(errors.some((m) => m.includes('EXDEV')))
  t.ok(
    writes.some((w) => w[0].startsWith('/mnt/b/.bare-os-mv-tmp.')),
    'staging write attempted on destination drive'
  )
})