package service

import (
	"log"
	"time"

	"gorm.io/gorm"

	"github.com/wangjia/jiu/backend/internal/model"
)

// sessionCleanupInterval 清理任务执行周期。
const sessionCleanupInterval = 24 * time.Hour

// StartSessionCleanup 启动后台清理 goroutine：启动即跑一次，之后每 24h 跑一次。
// 删除已撤销/已过期的会话行与过旧的失败登录记录，防止表无限膨胀、IP/UA 长期滞留。
// retentionDays<=0 时视为关闭清理（直接返回，不启动 goroutine）。
func StartSessionCleanup(db *gorm.DB, retentionDays int) {
	if retentionDays <= 0 {
		log.Printf("[cleanup] session cleanup disabled (retention_days=%d)", retentionDays)
		return
	}
	go func() {
		cleanupOnce(db, retentionDays)
		ticker := time.NewTicker(sessionCleanupInterval)
		defer ticker.Stop()
		for range ticker.C {
			cleanupOnce(db, retentionDays)
		}
	}()
}

// cleanupOnce 执行一轮清理，返回各表删除行数（供测试断言）。
func cleanupOnce(db *gorm.DB, retentionDays int) (sessions, attempts int64) {
	cutoff := time.Now().AddDate(0, 0, -retentionDays)

	r1 := db.Where(
		"(revoked_at IS NOT NULL AND revoked_at < ?) OR (refresh_exp_at IS NOT NULL AND refresh_exp_at < ?)",
		cutoff, cutoff,
	).Delete(&model.UserSession{})
	if r1.Error != nil {
		log.Printf("[cleanup] purge user_sessions failed: %v", r1.Error)
	}

	r2 := db.Where("created_at < ?", cutoff).Delete(&model.LoginAttempt{})
	if r2.Error != nil {
		log.Printf("[cleanup] purge login_attempts failed: %v", r2.Error)
	}

	if r1.RowsAffected > 0 || r2.RowsAffected > 0 {
		log.Printf("[cleanup] purged %d sessions, %d login_attempts (older than %dd)",
			r1.RowsAffected, r2.RowsAffected, retentionDays)
	}
	return r1.RowsAffected, r2.RowsAffected
}