import { test } from 'node:test'
import assert from 'node:assert/strict'
import fs from 'node:fs'
import os from 'node:os'
import path from 'node:path'
import { execFileSync } from 'node:child_process'

import { createCheckpoint, restoreCheckpoint, listCheckpoints, isGitRepo, dirtySubmodules } from '../src/checkpoint.mjs'

function git(project, args) {
  return execFileSync('git', ['-c', 'user.email=t@t', '-c', 'user.name=t', ...args], { cwd: project, encoding: 'utf8' })
}

function tempRepo() {
  const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'kilo-cp-'))
  git(dir, ['init', '-q'])
  fs.writeFileSync(path.join(dir, 'tracked.txt'), 'one\n')
  git(dir, ['add', '.'])
  git(dir, ['commit', '-qm', 'init'])
  return dir
}

test('createCheckpoint captures a patch and untracked list', () => {
  const project = tempRepo()
  const runDir = path.join(project, 'run')
  fs.appendFileSync(path.join(project, 'tracked.txt'), 'two\n')
  fs.writeFileSync(path.join(project, 'new.txt'), 'untracked\n')
  const cp = createCheckpoint(project, runDir, 'before iteration 1', { id: 'iter-01' })
  assert.equal(cp.id, 'iter-01')
  assert.ok(cp.patchBytes > 0)
  assert.ok(cp.untracked.includes('new.txt'))
  assert.ok(fs.existsSync(cp.patchFile))
  assert.equal(listCheckpoints(runDir).length, 1)
})

test('restoreCheckpoint reverts tracked edits and removes new untracked files', () => {
  const project = tempRepo()
  const runDir = path.join(project, 'run')
  const cp = createCheckpoint(project, runDir, 'before iteration 1', { id: 'iter-01' })
  fs.writeFileSync(path.join(project, 'tracked.txt'), 'changed\n')
  fs.writeFileSync(path.join(project, 'created-later.txt'), 'junk\n')
  const res = restoreCheckpoint(project, cp)
  assert.equal(res.ok, true)
  assert.equal(fs.readFileSync(path.join(project, 'tracked.txt'), 'utf8'), 'one\n')
  assert.equal(fs.existsSync(path.join(project, 'created-later.txt')), false)
})

test('restoreCheckpoint keeps untracked files that existed at checkpoint time', () => {
  const project = tempRepo()
  const runDir = path.join(project, 'run')
  fs.writeFileSync(path.join(project, 'preexisting.txt'), 'keep me\n')
  const cp = createCheckpoint(project, runDir, 'before iteration 1', { id: 'iter-01' })
  fs.writeFileSync(path.join(project, 'later.txt'), 'junk\n')
  restoreCheckpoint(project, cp)
  assert.equal(fs.existsSync(path.join(project, 'preexisting.txt')), true)
  assert.equal(fs.existsSync(path.join(project, 'later.txt')), false)
})

test('restoreCheckpoint reproduces pre-existing changes captured at checkpoint time', () => {
  const project = tempRepo()
  const runDir = path.join(project, 'run')
  fs.writeFileSync(path.join(project, 'tracked.txt'), 'one\npreexisting\n')
  const cp = createCheckpoint(project, runDir, 'before iteration 1', { id: 'iter-01' })
  fs.writeFileSync(path.join(project, 'tracked.txt'), 'totally different\n')
  const res = restoreCheckpoint(project, cp)
  assert.equal(res.ok, true)
  assert.equal(fs.readFileSync(path.join(project, 'tracked.txt'), 'utf8'), 'one\npreexisting\n')
})

test('checkpoint helpers are no-ops outside a git repository', () => {
  const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'kilo-nogit-'))
  assert.equal(isGitRepo(dir), false)
  assert.equal(createCheckpoint(dir, path.join(dir, 'run'), 'x'), null)
})

test('restoreCheckpoint refuses to run when a submodule is dirty', () => {
  const project = tempRepo()
  const sub = path.join(project, 'sub')
  fs.mkdirSync(sub)
  git(sub, ['init', '-q'])
  fs.writeFileSync(path.join(sub, 'x.txt'), 'a\n')
  git(sub, ['add', '.'])
  git(sub, ['commit', '-qm', 'sub init'])
  fs.writeFileSync(
    path.join(project, '.gitmodules'),
    `[submodule "sub"]\n\tpath = sub\n\turl = ./sub\n`,
  )
  git(project, ['add', '.gitmodules'])
  git(project, ['commit', '-qm', 'add submodule'])
  // Dirty the submodule pointer by committing inside it and staging the pointer.
  fs.appendFileSync(path.join(sub, 'x.txt'), 'b\n')
  git(sub, ['commit', '-qam', 'sub change'])
  git(project, ['add', 'sub'])
  assert.deepEqual(dirtySubmodules(project), ['sub'])
  const cp = createCheckpoint(project, path.join(project, 'run'), 'before iteration 1', { id: 'iter-01' })
  const res = restoreCheckpoint(project, cp)
  assert.equal(res.ok, false)
  assert.match(res.error, /submodule/i)
})