package dept

import (
	"context"
	"errors"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"perms-system-server/internal/testutil"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// TC-0759: M-5 修复实战回归 —— UpdateWithOptLock 在 10 个 goroutine 同时写同一行时,
// 必须精确有 **1 个成功、9 个 ErrUpdateConflict**。
// 旧实现依赖应用层 "先读后写", 高并发下两个 goroutine 都拿到 UpdateTime=t0 就都会写入成功
// (最后一个覆盖前一个, 数据静默丢失). 新实现 WHERE updateTime=? 才更新, affected=0 即冲突。
// 这是"真实并发"断言, 不是 mock, 踩在实际 MySQL 上, 为乐观锁修复提供最强的防退化护栏。
func TestSysDeptModel_UpdateWithOptLock_ConcurrentSingleWinner(t *testing.T) {
	ctx := context.Background()
	conn := testutil.GetTestSqlConn()
	m := NewSysDeptModel(conn, testutil.GetTestCacheConf(), testutil.GetTestCachePrefix())

	base := time.Now().Unix()
	row := &SysDept{
		ParentId:   0,
		Name:       "dept_optlock_" + testutil.UniqueId(),
		Path:       "/optlock/" + testutil.UniqueId() + "/",
		Sort:       10,
		Remark:     "orig",
		Status:     1,
		CreateTime: base,
		UpdateTime: base,
	}
	res, err := m.Insert(ctx, row)
	require.NoError(t, err)
	id, err := res.LastInsertId()
	require.NoError(t, err)
	tbl := m.TableName()
	t.Cleanup(func() { testutil.CleanTable(ctx, conn, tbl, id) })

	const workers = 10
	var (
		wg        sync.WaitGroup
		success   int32
		conflicts int32
		other     int32
		start     = make(chan struct{})
	)

	for i := 0; i < workers; i++ {
		wg.Add(1)
		go func(idx int) {
			defer wg.Done()
			<-start
			err := m.UpdateWithOptLock(ctx, &SysDept{
				Id:         id,
				ParentId:   0,
				Name:       row.Name,
				Path:       row.Path,
				Sort:       int64(idx),
				Remark:     "w" + testutil.UniqueId(),
				DeptType:   "NORMAL",
				Status:     1,
				CreateTime: base,
				UpdateTime: base + int64(idx+1),
			}, base)
			switch {
			case err == nil:
				atomic.AddInt32(&success, 1)
			case errors.Is(err, ErrUpdateConflict):
				atomic.AddInt32(&conflicts, 1)
			default:
				atomic.AddInt32(&other, 1)
				t.Errorf("unexpected error: %v", err)
			}
		}(i)
	}

	close(start)
	wg.Wait()

	assert.Equal(t, int32(1), atomic.LoadInt32(&success),
		"M-5: 10 个并发写必须且仅有 1 个成功, 实际 %d", success)
	assert.Equal(t, int32(workers-1), atomic.LoadInt32(&conflicts),
		"M-5: 其余 goroutine 必须全部得到 ErrUpdateConflict (无声覆盖即 BUG)")
	assert.Equal(t, int32(0), atomic.LoadInt32(&other),
		"不应出现除成功/冲突外的其他错误")

	after, err := m.FindOne(ctx, id)
	require.NoError(t, err)
	assert.NotEqual(t, base, after.UpdateTime,
		"成功的那一个必须把 UpdateTime 推进, DB 里不允许停留在初值")
	assert.Equal(t, "orig", row.Remark)
	assert.NotEqual(t, "orig", after.Remark, "胜出者必须把 Remark 更新为 w*")
}