import { test } from 'node:test';
import assert from 'node:assert/strict';
import { execFileSync } from 'node:child_process';
import { existsSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { mergeBranch, mergeWorktreeDirFor } from '../src/executor/merge.js';

function gitSync(cwd: string, args: string[]): string {
  return execFileSync('git', args, { cwd, encoding: 'utf8' });
}

/** /tmp 下建一个带 1 个 commit 的真实 git repo（main 分支） */
function makeRepo(): string {
  const repo = mkdtempSync(join(tmpdir(), 'maestro-merge-repo-'));
  gitSync(repo, ['init', '-b', 'main']);
  gitSync(repo, ['config', 'user.name', 'maestro-test']);
  gitSync(repo, ['config', 'user.email', 'test@maestro.local']);
  writeFileSync(join(repo, 'README.md'), '# demo\n');
  gitSync(repo, ['add', '-A']);
  gitSync(repo, ['commit', '-m', 'init']);
  return repo;
}

function commitFile(repo: string, file: string, content: string, msg: string): void {
  writeFileSync(join(repo, file), content);
  gitSync(repo, ['add', '-A']);
  gitSync(repo, ['commit', '-m', msg]);
}

/** 每个用例独立的 dataDir + repo，t.after 收尾（不碰 ~/.maestro） */
function setup(t: { after: (fn: () => void) => void }): string {
  const dataDir = mkdtempSync(join(tmpdir(), 'maestro-merge-data-'));
  const prevDataDir = process.env.MAESTRO_DATA_DIR;
  process.env.MAESTRO_DATA_DIR = dataDir;
  const repo = makeRepo();
  t.after(() => {
    if (prevDataDir === undefined) delete process.env.MAESTRO_DATA_DIR;
    else process.env.MAESTRO_DATA_DIR = prevDataDir;
    rmSync(dataDir, { recursive: true, force: true });
    rmSync(repo, { recursive: true, force: true });
  });
  return repo;
}

/** 临时合并 worktree 已彻底清理：目录不存在 + git worktree list 无 _merge */
function assertMergeWorktreeCleaned(repo: string, taskId: string): void {
  assert.ok(!existsSync(mergeWorktreeDirFor(taskId)), '临时合并 worktree 目录应被删除');
  const list = gitSync(repo, ['worktree', 'list']);
  assert.ok(!list.includes('_merge'), `git worktree list 不应再含 _merge：${list}`);
}

test('mergeBranch：可 ff 的分支也产出 --no-ff 合并提交，main 前进、临时 worktree 清理', async (t) => {
  const repo = setup(t);
  gitSync(repo, ['checkout', '-b', 'maestro/tsk_ff']);
  commitFile(repo, 'a.txt', 'A\n', 'maestro(tsk_ff): add a');
  gitSync(repo, ['switch', '--detach']);                 // 让 main 不被任何工作区检出

  const r = await mergeBranch(repo, 'maestro/tsk_ff', 'main', 'tsk_ff');
  assert.equal(r.ok, true, r.error);
  assert.ok(r.mergeCommit);
  assert.equal(gitSync(repo, ['rev-parse', 'main']).trim(), r.mergeCommit);
  // --no-ff：合并提交有 2 个父
  const parents = gitSync(repo, ['rev-list', '--parents', '-n', '1', 'main']).trim().split(/\s+/);
  assert.equal(parents.length, 3, '应是双亲合并提交（--no-ff）');
  assert.match(gitSync(repo, ['log', '-1', '--format=%s', 'main']), /merge: maestro\/tsk_ff \[tsk_ff\]/);
  assert.equal(gitSync(repo, ['show', 'main:a.txt']), 'A\n');
  assertMergeWorktreeCleaned(repo, 'tsk_ff');
});

test('mergeBranch：分叉历史（非 ff）无冲突合并成功，两边改动都在', async (t) => {
  const repo = setup(t);
  gitSync(repo, ['checkout', '-b', 'maestro/tsk_div']);
  commitFile(repo, 'b.txt', 'B\n', 'maestro(tsk_div): add b');
  gitSync(repo, ['checkout', 'main']);
  commitFile(repo, 'c.txt', 'C\n', 'main: add c');       // main 也前进 → 分叉
  gitSync(repo, ['switch', '--detach']);

  const r = await mergeBranch(repo, 'maestro/tsk_div', 'main', 'tsk_div');
  assert.equal(r.ok, true, r.error);
  assert.equal(gitSync(repo, ['rev-parse', 'main']).trim(), r.mergeCommit);
  assert.equal(gitSync(repo, ['show', 'main:b.txt']), 'B\n');
  assert.equal(gitSync(repo, ['show', 'main:c.txt']), 'C\n');
  assertMergeWorktreeCleaned(repo, 'tsk_div');
});

test('mergeBranch：冲突 → 返回错误含冲突文件列表，main 与用户分支均无损，临时 worktree 清理', async (t) => {
  const repo = setup(t);
  gitSync(repo, ['checkout', '-b', 'maestro/tsk_cf']);
  commitFile(repo, 'README.md', '# demo\nbranch version\n', 'maestro(tsk_cf): edit readme');
  gitSync(repo, ['checkout', 'main']);
  commitFile(repo, 'README.md', '# demo\nmain version\n', 'main: edit readme');
  gitSync(repo, ['switch', '--detach']);
  const mainBefore = gitSync(repo, ['rev-parse', 'main']).trim();
  const branchBefore = gitSync(repo, ['rev-parse', 'maestro/tsk_cf']).trim();

  const r = await mergeBranch(repo, 'maestro/tsk_cf', 'main', 'tsk_cf');
  assert.equal(r.ok, false);
  assert.match(r.error ?? '', /README\.md/, `错误应含冲突文件列表：${r.error}`);
  // 双方无损
  assert.equal(gitSync(repo, ['rev-parse', 'main']).trim(), mainBefore, 'main 应无损');
  assert.equal(gitSync(repo, ['rev-parse', 'maestro/tsk_cf']).trim(), branchBefore, '用户分支应无损');
  assertMergeWorktreeCleaned(repo, 'tsk_cf');
});

test('mergeBranch：分支不存在（已删）→ 明确错误', async (t) => {
  const repo = setup(t);
  gitSync(repo, ['switch', '--detach']);
  const r = await mergeBranch(repo, 'maestro/tsk_gone', 'main', 'tsk_gone');
  assert.equal(r.ok, false);
  assert.match(r.error ?? '', /分支不存在/);
});

test('mergeBranch：defaultBranch 正被工作区检出 → 失败且不动用户检出', async (t) => {
  const repo = setup(t);                                  // main 仍在主工作区检出
  gitSync(repo, ['branch', 'maestro/tsk_co']);            // 分支存在但 main 被占用
  const mainBefore = gitSync(repo, ['rev-parse', 'main']).trim();

  const r = await mergeBranch(repo, 'maestro/tsk_co', 'main', 'tsk_co');
  assert.equal(r.ok, false);
  assert.match(r.error ?? '', /检出/, `应提示 defaultBranch 被检出：${r.error}`);
  assert.equal(gitSync(repo, ['rev-parse', 'main']).trim(), mainBefore);
  assert.equal(gitSync(repo, ['rev-parse', '--abbrev-ref', 'HEAD']).trim(), 'main', '用户检出不应被切走');
  assertMergeWorktreeCleaned(repo, 'tsk_co');
});

test('mergeBranch：重复合并（分支已在 main 里）→ ok，不新建提交', async (t) => {
  const repo = setup(t);
  gitSync(repo, ['checkout', '-b', 'maestro/tsk_re']);
  commitFile(repo, 'd.txt', 'D\n', 'maestro(tsk_re): add d');
  gitSync(repo, ['switch', '--detach']);

  const first = await mergeBranch(repo, 'maestro/tsk_re', 'main', 'tsk_re');
  assert.equal(first.ok, true, first.error);
  const second = await mergeBranch(repo, 'maestro/tsk_re', 'main', 'tsk_re');
  assert.equal(second.ok, true, second.error);
  assert.equal(second.mergeCommit, first.mergeCommit, '重复合并不应产生新提交（Already up to date）');
  assertMergeWorktreeCleaned(repo, 'tsk_re');
});