package service

import (
	"context"
	"log/slog"
	"time"

	"git.lzcwy.cn/zhengchiliu/zt-closet-backend/global"
	"git.lzcwy.cn/zhengchiliu/zt-closet-backend/internal/mysqldao"
)

// AI 推荐每次生成都会落一条 status=3（待用户保存）的穿搭：
// 用户不调用 /ai-recommend/save 就会长期堆积在 outfits / outfit_items 中，
// 并且会出现在 GET /outfit 列表里。这里按保留期兜底清理，连同明细一起软删除。
const (
	// aiUnsavedOutfitRetention 未保存 AI 穿搭的保留时长。
	aiUnsavedOutfitRetention = 7 * 24 * time.Hour

	// aiUnsavedOutfitCleanupInterval 清理任务执行间隔。
	aiUnsavedOutfitCleanupInterval = time.Hour

	// aiUnsavedOutfitCleanupBatch 单批清理条数，避免长事务持锁。
	aiUnsavedOutfitCleanupBatch = 500

	// aiUnsavedOutfitCleanupMaxRounds 单次执行的最大批次轮数，防止一次跑太久。
	aiUnsavedOutfitCleanupMaxRounds = 20
)

// StartAIOutfitCleanupScheduler 启动「未保存 AI 穿搭」清理定时任务：
// 启动后立即执行一次，之后每小时执行一次。
func StartAIOutfitCleanupScheduler() {
	go func() {
		slog.Info("ai unsaved outfit cleanup scheduler started",
			"interval", aiUnsavedOutfitCleanupInterval.String(),
			"retention", aiUnsavedOutfitRetention.String(),
		)
		for {
			func() {
				defer func() {
					if r := recover(); r != nil {
						slog.Error("ai unsaved outfit cleanup panic", "recover", r)
					}
				}()
				runAIOutfitCleanup()
			}()
			time.Sleep(aiUnsavedOutfitCleanupInterval)
		}
	}()
}

// runAIOutfitCleanup 清理超过保留期仍未保存的 AI 穿搭。
// 条件更新天然幂等，多实例并发执行无害，无需分布式锁。
func runAIOutfitCleanup() {
	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
	defer cancel()

	ctx, span := global.Tracer.Start(ctx, "scheduler.AIOutfitCleanup")
	defer span.End()

	deadline := time.Now().Add(-aiUnsavedOutfitRetention).Unix()
	dao := mysqldao.NewOutfitDao()

	var total int64
	for round := 0; round < aiUnsavedOutfitCleanupMaxRounds; round++ {
		affected, err := dao.OutfitCleanupExpiredUnsavedAI(ctx, deadline, aiUnsavedOutfitCleanupBatch)
		if err != nil {
			slog.ErrorContext(ctx, "cleanup unsaved ai outfits failed", "error", err, "cleaned", total)
			return
		}
		total += affected
		if affected < aiUnsavedOutfitCleanupBatch {
			break
		}
	}

	if total > 0 {
		slog.InfoContext(ctx, "cleaned unsaved ai outfits",
			"count", total,
			"retention_hours", int(aiUnsavedOutfitRetention.Hours()),
		)
	} else {
		slog.DebugContext(ctx, "ai outfit cleanup: nothing to clean")
	}
}