package database

import (
	"fmt"
	"strings"

	"gorm.io/gorm"
)

// DriverName 从 GORM 连接获取驱动名（sqlite / mysql / postgres）// Logan.Li
func DriverName(db *gorm.DB) string {
	if db == nil || db.Dialector == nil {
		return "mysql"
	}
	name := strings.ToLower(db.Dialector.Name())
	switch {
	case strings.Contains(name, "sqlite"):
		return "sqlite"
	case strings.Contains(name, "postgres"):
		return "postgres"
	default:
		return "mysql"
	}
}

// HourBucketExpr 按小时分桶表达式（跨 SQLite / MySQL）// Logan.Li
func HourBucketExpr(driver string) string {
	switch driver {
	case "sqlite":
		return "cast(strftime('%s', report_time) as integer) / 3600"
	default:
		return "UNIX_TIMESTAMP(report_time) DIV 3600"
	}
}

// CleanupAgentReportsSQL 清理 7 天前 Agent 上报 // Logan.Li
func CleanupAgentReportsSQL(driver string) string {
	switch driver {
	case "sqlite":
		return "DELETE FROM monitor_agent_reports WHERE report_time < datetime('now', '-7 days')"
	default:
		return "DELETE FROM monitor_agent_reports WHERE report_time < DATE_SUB(NOW(), INTERVAL 7 DAY)"
	}
}

// CleanupSNMPMetricsSQL 清理超期 SNMP 采集指标 // Logan.Li
func CleanupSNMPMetricsSQL(driver string, retentionDays int) string {
	if retentionDays <= 0 {
		retentionDays = 7
	}
	switch driver {
	case "sqlite":
		return fmt.Sprintf(
			"DELETE FROM monitor_snmp_samples WHERE timestamp < CAST(strftime('%%s', 'now', '-%d days') AS INTEGER)",
			retentionDays,
		)
	default:
		return fmt.Sprintf(
			"DELETE FROM monitor_snmp_samples WHERE timestamp < UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL %d DAY))",
			retentionDays,
		)
	}
}