package model

import (
	"strings"
	"time"

	"gorm.io/gorm"
)

const (
	RuleCoverAll = iota
	RuleCoverIgnoreAll
)

type NResult struct {
	N uint64
}

type Rule struct {
	// 指标类型，cpu、memory、swap、disk、net_in_speed、net_out_speed
	// net_all_speed、transfer_in、transfer_out、transfer_all、offline
	// transfer_in_cycle、transfer_out_cycle、transfer_all_cycle
	Type          string          `json:"type,omitempty"`
	Min           uint64          `json:"min,omitempty"`            // 最小阈值 (百分比、字节 kb ÷ 1024)
	Max           uint64          `json:"max,omitempty"`            // 最大阈值 (百分比、字节 kb ÷ 1024)
	CycleStart    time.Time       `json:"cycle_start,omitempty"`    // 流量统计的开始时间
	CycleInterval uint64          `json:"cycle_interval,omitempty"` // 流量统计周期
	Duration      uint64          `json:"duration,omitempty"`       // 持续时间 (秒)
	Cover         uint64          `json:"cover,omitempty"`          // 覆盖范围 RuleCoverAll/IgnoreAll
	Ignore        map[uint64]bool `json:"ignore,omitempty"`         // 覆盖范围的排除

	// 只作为缓存使用，记录下次该检测的时间
	NextTransferAt  map[uint64]time.Time   `json:"-"`
	LastCycleStatus map[uint64]interface{} `json:"-"`
}

func percentage(used, total uint64) uint64 {
	if total == 0 {
		return 0
	}
	return used * 100 / total
}

// Snapshot 未通过规则返回 struct{}{}, 通过返回 nil
func (u *Rule) Snapshot(server *Server, db *gorm.DB) interface{} {
	// 监控全部但是排除了此服务器
	if u.Cover == RuleCoverAll && u.Ignore[server.ID] {
		return nil
	}
	// 忽略全部但是指定监控了此服务器
	if u.Cover == RuleCoverIgnoreAll && !u.Ignore[server.ID] {
		return nil
	}

	// 循环区间流量检测 · 短期无需重复检测
	if u.IsTransferDurationRule() && u.NextTransferAt[server.ID].After(time.Now()) {
		return u.LastCycleStatus[server.ID]
	}

	var src uint64

	switch u.Type {
	case "cpu":
		src = uint64(server.State.CPU)
	case "memory":
		src = percentage(server.State.MemUsed, server.Host.MemTotal)
	case "swap":
		src = percentage(server.State.SwapUsed, server.Host.SwapTotal)
	case "disk":
		src = percentage(server.State.DiskUsed, server.Host.DiskTotal)
	case "net_in_speed":
		src = server.State.NetInSpeed
	case "net_out_speed":
		src = server.State.NetOutSpeed
	case "net_all_speed":
		src = server.State.NetOutSpeed + server.State.NetOutSpeed
	case "transfer_in":
		src = server.State.NetInTransfer
	case "transfer_out":
		src = server.State.NetOutTransfer
	case "transfer_all":
		src = server.State.NetOutTransfer + server.State.NetInTransfer
	case "offline":
		if server.LastActive.IsZero() {
			src = 0
		} else {
			src = uint64(server.LastActive.Unix())
		}
	case "transfer_in_cycle":
		src = server.State.NetInTransfer - uint64(server.PrevHourlyTransferIn)
		if u.CycleInterval != 1 {
			var res NResult
			db.Model(&Transfer{}).Select("SUM(`in`) AS n").Where("created_at > ? AND server_id = ?", u.GetTransferDurationStart(), server.ID).Scan(&res)
			src += res.N
		}
	case "transfer_out_cycle":
		src = server.State.NetOutTransfer - uint64(server.PrevHourlyTransferOut)
		if u.CycleInterval != 1 {
			var res NResult
			db.Model(&Transfer{}).Select("SUM(`out`) AS n").Where("created_at > ? AND server_id = ?", u.GetTransferDurationStart(), server.ID).Scan(&res)
			src += res.N
		}
	case "transfer_all_cycle":
		src = server.State.NetOutTransfer - uint64(server.PrevHourlyTransferOut) + server.State.NetInTransfer - uint64(server.PrevHourlyTransferIn)
		if u.CycleInterval != 1 {
			var res NResult
			db.Model(&Transfer{}).Select("SUM(`in`+`out`) AS n").Where("created_at > ?  AND server_id = ?", u.GetTransferDurationStart(), server.ID).Scan(&res)
			src += res.N
		}
	}

	// 循环区间流量检测 · 更新下次需要检测时间
	if u.IsTransferDurationRule() {
		seconds := 1800 * time.Duration(((u.Max - src) / u.Max))
		if seconds < 180 {
			seconds = 180
		}
		if u.NextTransferAt == nil {
			u.NextTransferAt = make(map[uint64]time.Time)
		}
		if u.LastCycleStatus == nil {
			u.LastCycleStatus = make(map[uint64]interface{})
		}
		u.NextTransferAt[server.ID] = time.Now().Add(time.Duration(time.Second * seconds))
		if (u.Max > 0 && src > u.Max) || (u.Min > 0 && src < u.Min) {
			u.LastCycleStatus[server.ID] = struct{}{}
		} else {
			u.LastCycleStatus[server.ID] = nil
		}
	}

	if u.Type == "offline" && uint64(time.Now().Unix())-src > 6 {
		return struct{}{}
	} else if (u.Max > 0 && src > u.Max) || (u.Min > 0 && src < u.Min) {
		return struct{}{}
	}

	return nil
}

func (rule Rule) IsTransferDurationRule() bool {
	return strings.HasSuffix(rule.Type, "_cycle")
}

func (rule Rule) GetTransferDurationStart() time.Time {
	interval := 3600 * int64(rule.CycleInterval)
	return time.Unix(rule.CycleStart.Unix()+(time.Now().Unix()-rule.CycleStart.Unix())/interval*interval, 0)
}