import { execFileSync } from 'node:child_process'
import { existsSync, promises as fsp, readFileSync, realpathSync, rmSync, writeFileSync } from 'node:fs'
import * as os from 'node:os'
import * as path from 'node:path'
import { afterEach, describe, expect, it } from 'vitest'
import { addDetachedWorktree, fastForwardWorktree, fetchPullRequestHead } from '../../src/git/worktree'

const gitEnv: NodeJS.ProcessEnv = {
  ...process.env,
  GIT_CONFIG_NOSYSTEM: '1',
  GIT_CONFIG_GLOBAL: '/dev/null',
  GIT_TERMINAL_PROMPT: '0',
  GIT_AUTHOR_NAME: 'review-test',
  GIT_AUTHOR_EMAIL: 'review@test.local',
  GIT_COMMITTER_NAME: 'review-test',
  GIT_COMMITTER_EMAIL: 'review@test.local',
}

function git(cwd: string, args: string[]): string {
  return execFileSync('git', ['-C', cwd, ...args], { encoding: 'utf8', env: gitEnv }).trim()
}

function commit(cwd: string, file: string, content: string): string {
  writeFileSync(path.join(cwd, file), content)
  git(cwd, ['add', file])
  git(cwd, ['commit', '-m', `edit ${file}`])
  return git(cwd, ['rev-parse', 'HEAD'])
}

interface Fixture { root: string, peer: string, repo: string, worktree: string }

/** origin（bare）上有 main，同事把 PR 的提交推到 Gitea 给 PR 留的 refs/pull/7/head；repo 是审查方的 clone，本机没有 PR 的分支。 */
async function setup(): Promise<Fixture> {
  const root = realpathSync(await fsp.mkdtemp(path.join(os.tmpdir(), 'sw-review-')))
  const origin = path.join(root, 'origin.git')
  git(root, ['init', '--bare', '-b', 'main', origin])
  const peer = path.join(root, 'peer')
  git(root, ['clone', origin, peer])
  commit(peer, 'README.md', 'hello\n')
  git(peer, ['push', '-u', 'origin', 'main'])
  git(peer, ['checkout', '-b', 'feature/x'])
  commit(peer, 'x.txt', 'x1\n')
  git(peer, ['push', 'origin', 'HEAD:refs/pull/7/head'])
  const repo = path.join(root, 'repo')
  git(root, ['clone', origin, repo])
  return { root, peer, repo, worktree: path.join(root, 'wt', 'repo', 'review-6') }
}

/** 同事在 PR 上又推了一个提交 */
function pushToPullRequest(fx: Fixture, content: string): string {
  const sha = commit(fx.peer, 'x.txt', content)
  git(fx.peer, ['push', 'origin', 'HEAD:refs/pull/7/head'])
  return sha
}

let fx: Fixture | undefined
afterEach(() => {
  if (fx)
    rmSync(fx.root, { recursive: true, force: true })
  fx = undefined
})

async function reviewWorktree(fixture: Fixture): Promise<string> {
  await fetchPullRequestHead(fixture.repo, 7)
  const head = git(fixture.peer, ['rev-parse', 'HEAD'])
  await addDetachedWorktree({ workspaceRoot: fixture.repo, worktreePath: fixture.worktree, commit: head })
  return head
}

describe('审查用的 worktree', () => {
  it('从 refs/pull/<n>/head 拉 PR 的提交，建一个停在它上面、不挂分支的 worktree（父目录不在也建）', async () => {
    fx = await setup()
    const head = await reviewWorktree(fx)
    expect(readFileSync(path.join(fx.worktree, 'x.txt'), 'utf8')).toBe('x1\n')
    expect(git(fx.worktree, ['rev-parse', 'HEAD'])).toBe(head)
    expect(git(fx.worktree, ['rev-parse', '--abbrev-ref', 'HEAD'])).toBe('HEAD')
    expect(git(fx.repo, ['branch', '--list'])).not.toContain('feature/x')
  })

  it('目录被手动删掉后同一路径能再建', async () => {
    fx = await setup()
    await reviewWorktree(fx)
    rmSync(fx.worktree, { recursive: true, force: true })
    await reviewWorktree(fx)
    expect(existsSync(path.join(fx.worktree, 'x.txt'))).toBe(true)
  })
})

describe('把 worktree 快进到 PR 最新的提交', () => {
  it('同事在 PR 上又推了提交、工作副本干净：快进过去', async () => {
    fx = await setup()
    await reviewWorktree(fx)
    const latest = pushToPullRequest(fx, 'x2\n')
    await fetchPullRequestHead(fx.repo, 7)
    expect(await fastForwardWorktree(fx.worktree, latest)).toBe('updated')
    expect(git(fx.worktree, ['rev-parse', 'HEAD'])).toBe(latest)
    expect(readFileSync(path.join(fx.worktree, 'x.txt'), 'utf8')).toBe('x2\n')
  })

  it('已经在最新的提交上：不动', async () => {
    fx = await setup()
    const head = await reviewWorktree(fx)
    expect(await fastForwardWorktree(fx.worktree, head)).toBe('current')
  })

  it('只有未跟踪的文件：照样快进，文件留着', async () => {
    fx = await setup()
    await reviewWorktree(fx)
    writeFileSync(path.join(fx.worktree, 'notes.txt'), 'mine\n')
    const latest = pushToPullRequest(fx, 'x2\n')
    await fetchPullRequestHead(fx.repo, 7)
    expect(await fastForwardWorktree(fx.worktree, latest)).toBe('updated')
    expect(readFileSync(path.join(fx.worktree, 'notes.txt'), 'utf8')).toBe('mine\n')
  })

  it('有没提交的改动：不动，改动留着', async () => {
    fx = await setup()
    const head = await reviewWorktree(fx)
    writeFileSync(path.join(fx.worktree, 'x.txt'), 'local edit\n')
    const latest = pushToPullRequest(fx, 'x2\n')
    await fetchPullRequestHead(fx.repo, 7)
    expect(await fastForwardWorktree(fx.worktree, latest)).toBe('dirty')
    expect(git(fx.worktree, ['rev-parse', 'HEAD'])).toBe(head)
    expect(readFileSync(path.join(fx.worktree, 'x.txt'), 'utf8')).toBe('local edit\n')
  })

  it('本地另有提交、PR 也往前走了：快进不了，不动', async () => {
    fx = await setup()
    await reviewWorktree(fx)
    const local = commit(fx.worktree, 'local.txt', 'local\n')
    const latest = pushToPullRequest(fx, 'x2\n')
    await fetchPullRequestHead(fx.repo, 7)
    expect(await fastForwardWorktree(fx.worktree, latest)).toBe('diverged')
    expect(git(fx.worktree, ['rev-parse', 'HEAD'])).toBe(local)
  })

  it('目录不是工作副本的根（只是仓库里的普通目录）：报错，外面的仓库不动', async () => {
    fx = await setup()
    await fetchPullRequestHead(fx.repo, 7)
    const latest = git(fx.peer, ['rev-parse', 'HEAD'])
    const before = git(fx.repo, ['rev-parse', 'HEAD'])
    const inside = path.join(fx.repo, 'review-6')
    await fsp.mkdir(inside)
    await expect(fastForwardWorktree(inside, latest)).rejects.toThrow('不是 git 工作副本的根目录')
    expect(git(fx.repo, ['rev-parse', 'HEAD'])).toBe(before)
  })

  it('本地在 PR 最新的提交之上还有提交：已经含着它，不动', async () => {
    fx = await setup()
    const head = await reviewWorktree(fx)
    const local = commit(fx.worktree, 'local.txt', 'local\n')
    expect(await fastForwardWorktree(fx.worktree, head)).toBe('current')
    expect(git(fx.worktree, ['rev-parse', 'HEAD'])).toBe(local)
  })
})