package controller

import (
	"fmt"
	"time"

	"ezops/model"
)

// SNMP 指标名映射（与采集模板一致）// Logan.Li
var snmpCPUMetricNames = []string{
	"h3c_cpu_usage", "hw_cpu_usage", "cisco_cpu_5min", "ruijie_cpu_usage", "inspur_cpu_usage",
}
var snmpMemMetricNames = []string{
	"h3c_mem_usage", "hw_mem_usage", "ruijie_mem_usage", "inspur_mem_usage",
}
var snmpTempMetricNames = []string{
	"h3c_temperature", "hw_temperature", "ruijie_temperature", "dell_temperature",
	"inspur_temperature", "cisco_sensor_value",
}

// checkSNMPAlerts SNMP 设备指标告警 // Logan.Li
func (e *AlertEngine) checkSNMPAlerts() {
	var rules []model.MonitorAlertRule
	e.db.Where("enabled = ? AND category = ?", true, model.MonitorAlertSNMP).Find(&rules)
	if len(rules) == 0 {
		return
	}

	var devices []model.SNMPDevice
	e.db.Where("template_id > 0").Find(&devices)
	deviceMap := make(map[uint]model.SNMPDevice, len(devices))
	for _, d := range devices {
		deviceMap[d.ID] = d
	}

	for _, rule := range rules {
		checkDevices := devices
		if rule.TargetID > 0 {
			if d, ok := deviceMap[rule.TargetID]; ok {
				checkDevices = []model.SNMPDevice{d}
			} else {
				continue
			}
		}
		for _, device := range checkDevices {
			e.evalSNMPRule(rule, device)
		}
	}
}

func (e *AlertEngine) evalSNMPRule(rule model.MonitorAlertRule, device model.SNMPDevice) {
	var value float64
	var triggered bool
	var msg string

	switch rule.Metric {
	case "snmp_offline":
		triggered = device.Status != model.SNMPDeviceOnline
		value = 1
		if triggered {
			msg = fmt.Sprintf("SNMP 设备 %s (%s) 离线或采集异常", device.Name, device.IP)
		}
	case "snmp_cpu_usage":
		value, triggered = e.evalSNMPGaugeRule(device.ID, snmpCPUMetricNames, rule)
		if triggered {
			msg = fmt.Sprintf("SNMP %s CPU %.1f%% %s %.1f%%", device.Name, value, rule.Operator, rule.Threshold)
		}
	case "snmp_mem_usage":
		value, triggered = e.evalSNMPGaugeRule(device.ID, snmpMemMetricNames, rule)
		if triggered {
			msg = fmt.Sprintf("SNMP %s 内存 %.1f%% %s %.1f%%", device.Name, value, rule.Operator, rule.Threshold)
		}
	case "snmp_temperature":
		value, triggered = e.evalSNMPGaugeRule(device.ID, snmpTempMetricNames, rule)
		if triggered {
			msg = fmt.Sprintf("SNMP %s 温度 %.1f°C %s %.1f°C", device.Name, value, rule.Operator, rule.Threshold)
		}
	case "snmp_if_in_bps":
		value, triggered = e.evalSNMPRateRule(device.ID, "if_in_octets", rule)
		if triggered {
			msg = fmt.Sprintf("SNMP %s 入流量 %.0f bps %s %.0f bps", device.Name, value, rule.Operator, rule.Threshold)
		}
	case "snmp_if_out_bps":
		value, triggered = e.evalSNMPRateRule(device.ID, "if_out_octets", rule)
		if triggered {
			msg = fmt.Sprintf("SNMP %s 出流量 %.0f bps %s %.0f bps", device.Name, value, rule.Operator, rule.Threshold)
		}
	default:
		return
	}

	if !triggered {
		return
	}
	e.fireSNMPAlert(rule, device, value, rule.Threshold, msg)
}

func (e *AlertEngine) evalSNMPGaugeRule(deviceID uint, names []string, rule model.MonitorAlertRule) (float64, bool) {
	value, ok := e.getMaxSNMPMetric(deviceID, names)
	if !ok {
		return 0, false
	}
	return value, e.compareOperator(rule.Operator, value, rule.Threshold)
}

func (e *AlertEngine) evalSNMPRateRule(deviceID uint, counterName string, rule model.MonitorAlertRule) (float64, bool) {
	value, ok := e.getSNMPCounterRate(deviceID, counterName)
	if !ok {
		return 0, false
	}
	return value, e.compareOperator(rule.Operator, value, rule.Threshold)
}

func (e *AlertEngine) getMaxSNMPMetric(deviceID uint, names []string) (float64, bool) {
	var latestTS int64
	e.db.Model(&model.SNMPMetric{}).Where("device_id = ?", deviceID).
		Select("COALESCE(MAX(timestamp), 0)").Scan(&latestTS)
	if latestTS == 0 {
		return 0, false
	}
	var metrics []model.SNMPMetric
	e.db.Where("device_id = ? AND timestamp = ? AND name IN ?", deviceID, latestTS, names).Find(&metrics)
	if len(metrics) == 0 {
		return 0, false
	}
	max := 0.0
	for _, m := range metrics {
		if m.Value > max {
			max = m.Value
		}
	}
	return max, true
}

// getSNMPCounterRate 取 counter 最近两次差分比特速率 // Logan.Li
func (e *AlertEngine) getSNMPCounterRate(deviceID uint, name string) (float64, bool) {
	var metrics []model.SNMPMetric
	e.db.Where("device_id = ? AND name = ?", deviceID, name).
		Order("timestamp DESC").Limit(2).Find(&metrics)
	if len(metrics) < 2 {
		return 0, false
	}
	cur, prev := metrics[0], metrics[1]
	dt := float64(cur.Timestamp - prev.Timestamp)
	if dt <= 0 {
		return 0, false
	}
	delta := cur.Value - prev.Value
	if delta < 0 {
		return 0, false
	}
	return (delta * 8) / dt, true
}

func (e *AlertEngine) fireSNMPAlert(rule model.MonitorAlertRule, device model.SNMPDevice, value, threshold float64, msg string) {
	tenMinAgo := time.Now().Add(-10 * time.Minute)
	var existing model.AgentAlert
	e.db.Where("rule_name = ? AND hostname = ? AND resolved = ? AND created_at > ?",
		rule.Name, device.Name, false, tenMinAgo).First(&existing)
	if existing.ID > 0 {
		return
	}
	if e.isSilenced(rule.Name, device.Name, rule.ID) {
		return
	}
	sev := rule.Severity
	if sev == "" {
		sev = "warning"
	}
	alert := model.AgentAlert{
		RuleName: rule.Name, Hostname: device.Name, Metric: rule.Metric,
		Severity: sev, Message: msg, Value: value, Threshold: threshold,
	}
	e.db.Create(&alert)
	e.notifyAlertRule("snmp", rule.Name, device.Name, rule.Metric, sev, msg, value, threshold)
	now := time.Now()
	e.db.Model(&rule).Update("last_triggered", now)
}

// isSNMPMetric 判断 AgentAlert 是否属于 SNMP // Logan.Li
func isSNMPMetric(metric string) bool {
	return len(metric) >= 5 && metric[:5] == "snmp_"
}