alert.go

package kapacitor

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	html "html/template"
	"log"
	"net"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"sync"
	text "text/template"
	"time"

	"github.com/influxdata/influxdb/influxql"
	imodels "github.com/influxdata/influxdb/models"
	"github.com/influxdata/kapacitor/expvar"
	"github.com/influxdata/kapacitor/models"
	"github.com/influxdata/kapacitor/pipeline"
	"github.com/influxdata/kapacitor/tick/stateful"
)

const (
	statsAlertsTriggered = "alerts_triggered"
	statsOKsTriggered    = "oks_triggered"
	statsInfosTriggered  = "infos_triggered"
	statsWarnsTriggered  = "warns_triggered"
	statsCritsTriggered  = "crits_triggered"
)

// The newest state change is weighted 'weightDiff' times more than oldest state change.
const weightDiff = 1.5

// Maximum weight applied to newest state change.
const maxWeight = 1.2

type AlertHandler func(ad *AlertData)

type AlertLevel int

const (
	OKAlert AlertLevel = iota
	InfoAlert
	WarnAlert
	CritAlert
)

func (l AlertLevel) String() string {
	switch l {
	case OKAlert:
		return "OK"
	case InfoAlert:
		return "INFO"
	case WarnAlert:
		return "WARNING"
	case CritAlert:
		return "CRITICAL"
	default:
		panic("unknown AlertLevel")
	}
}

func (l AlertLevel) MarshalText() ([]byte, error) {
	return []byte(l.String()), nil
}

func (l *AlertLevel) UnmarshalText(text []byte) error {
	s := string(text)
	switch s {
	case "OK":
		*l = OKAlert
	case "INFO":
		*l = InfoAlert
	case "WARNING":
		*l = WarnAlert
	case "CRITICAL":
		*l = CritAlert
	default:
		return fmt.Errorf("unknown AlertLevel %s", s)
	}
	return nil
}

type AlertData struct {
	ID       string          `json:"id"`
	Message  string          `json:"message"`
	Details  string          `json:"details"`
	Time     time.Time       `json:"time"`
	Duration time.Duration   `json:"duration"`
	Level    AlertLevel      `json:"level"`
	Data     influxql.Result `json:"data"`

	// Info for custom templates
	info detailsInfo
}

type AlertNode struct {
	node
	a           *pipeline.AlertNode
	endpoint    string
	handlers    []AlertHandler
	levels      []stateful.Expression
	scopePools  []stateful.ScopePool
	states      map[models.GroupID]*alertState
	idTmpl      *text.Template
	messageTmpl *text.Template
	detailsTmpl *html.Template

	alertsTriggered *expvar.Int
	oksTriggered    *expvar.Int
	infosTriggered  *expvar.Int
	warnsTriggered  *expvar.Int
	critsTriggered  *expvar.Int

	bufPool sync.Pool

	levelResets  []stateful.Expression
	lrScopePools []stateful.ScopePool
}

// Create a new  AlertNode which caches the most recent item and exposes it over the HTTP API.
func newAlertNode(et *ExecutingTask, n *pipeline.AlertNode, l *log.Logger) (an *AlertNode, err error) {
	an = &AlertNode{
		node: node{Node: n, et: et, logger: l},
		a:    n,
	}
	an.node.runF = an.runAlert

	// Create buffer pool for the templates
	an.bufPool = sync.Pool{
		New: func() interface{} {
			return new(bytes.Buffer)
		},
	}

	// Parse templates
	an.idTmpl, err = text.New("id").Parse(n.Id)
	if err != nil {
		return nil, err
	}

	an.messageTmpl, err = text.New("message").Parse(n.Message)
	if err != nil {
		return nil, err
	}

	an.detailsTmpl, err = html.New("details").Funcs(html.FuncMap{
		"json": func(v interface{}) html.JS {

			tmpBuffer := an.bufPool.Get().(*bytes.Buffer)
			defer func() {
				tmpBuffer.Reset()
				an.bufPool.Put(tmpBuffer)
			}()

			json.NewEncoder(tmpBuffer).Encode(v)

			return html.JS(tmpBuffer.String())
		},
	}).Parse(n.Details)
	if err != nil {
		return nil, err
	}

	// Construct alert handlers
	an.handlers = make([]AlertHandler, 0)

	for _, post := range n.PostHandlers {
		post := post
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handlePost(post, ad) })
	}

	for _, tcp := range n.TcpHandlers {
		tcp := tcp
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleTcp(tcp, ad) })
	}

	for _, email := range n.EmailHandlers {
		email := email
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleEmail(email, ad) })
	}
	if len(n.EmailHandlers) == 0 && (et.tm.SMTPService != nil && et.tm.SMTPService.Global()) {
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleEmail(&pipeline.EmailHandler{}, ad) })
	}
	// If email has been configured with state changes only set it.
	if et.tm.SMTPService != nil &&
		et.tm.SMTPService.Global() &&
		et.tm.SMTPService.StateChangesOnly() {
		n.IsStateChangesOnly = true
	}

	for _, exec := range n.ExecHandlers {
		exec := exec
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleExec(exec, ad) })
	}

	for _, log := range n.LogHandlers {
		log := log
		if !filepath.IsAbs(log.FilePath) {
			return nil, fmt.Errorf("alert log path must be absolute: %s is not absolute", log.FilePath)
		}
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleLog(log, ad) })
	}

	for _, vo := range n.VictorOpsHandlers {
		vo := vo
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleVictorOps(vo, ad) })
	}
	if len(n.VictorOpsHandlers) == 0 && (et.tm.VictorOpsService != nil && et.tm.VictorOpsService.Global()) {
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleVictorOps(&pipeline.VictorOpsHandler{}, ad) })
	}

	for _, pd := range n.PagerDutyHandlers {
		pd := pd
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handlePagerDuty(pd, ad) })
	}
	if len(n.PagerDutyHandlers) == 0 && (et.tm.PagerDutyService != nil && et.tm.PagerDutyService.Global()) {
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handlePagerDuty(&pipeline.PagerDutyHandler{}, ad) })
	}

	for _, sensu := range n.SensuHandlers {
		sensu := sensu
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleSensu(sensu, ad) })
	}

	for _, slack := range n.SlackHandlers {
		slack := slack
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleSlack(slack, ad) })
	}
	if len(n.SlackHandlers) == 0 && (et.tm.SlackService != nil && et.tm.SlackService.Global()) {
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleSlack(&pipeline.SlackHandler{}, ad) })
	}
	// If slack has been configured with state changes only set it.
	if et.tm.SlackService != nil &&
		et.tm.SlackService.Global() &&
		et.tm.SlackService.StateChangesOnly() {
		n.IsStateChangesOnly = true
	}

	for _, telegram := range n.TelegramHandlers {
		telegram := telegram
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleTelegram(telegram, ad) })
	}
	if len(n.TelegramHandlers) == 0 && (et.tm.TelegramService != nil && et.tm.TelegramService.Global()) {
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleTelegram(&pipeline.TelegramHandler{}, ad) })
	}
	// If telegram has been configured with state changes only set it.
	if et.tm.TelegramService != nil &&
		et.tm.TelegramService.Global() &&
		et.tm.TelegramService.StateChangesOnly() {
		n.IsStateChangesOnly = true
	}

	for _, hipchat := range n.HipChatHandlers {
		hipchat := hipchat
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleHipChat(hipchat, ad) })
	}
	if len(n.HipChatHandlers) == 0 && (et.tm.HipChatService != nil && et.tm.HipChatService.Global()) {
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleHipChat(&pipeline.HipChatHandler{}, ad) })
	}
	// If HipChat has been configured with state changes only set it.
	if et.tm.HipChatService != nil &&
		et.tm.HipChatService.Global() &&
		et.tm.HipChatService.StateChangesOnly() {
		n.IsStateChangesOnly = true
	}

	for _, alerta := range n.AlertaHandlers {
		// Validate alerta templates
		rtmpl, err := text.New("resource").Parse(alerta.Resource)
		if err != nil {
			return nil, err
		}
		evtmpl, err := text.New("event").Parse(alerta.Event)
		if err != nil {
			return nil, err
		}
		etmpl, err := text.New("environment").Parse(alerta.Environment)
		if err != nil {
			return nil, err
		}
		gtmpl, err := text.New("group").Parse(alerta.Group)
		if err != nil {
			return nil, err
		}
		vtmpl, err := text.New("value").Parse(alerta.Value)
		if err != nil {
			return nil, err
		}
		ai := alertaHandler{
			AlertaHandler:   alerta,
			resourceTmpl:    rtmpl,
			eventTmpl:       evtmpl,
			environmentTmpl: etmpl,
			groupTmpl:       gtmpl,
			valueTmpl:       vtmpl,
		}
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleAlerta(ai, ad) })
	}

	for _, og := range n.OpsGenieHandlers {
		og := og
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleOpsGenie(og, ad) })
	}
	if len(n.OpsGenieHandlers) == 0 && (et.tm.OpsGenieService != nil && et.tm.OpsGenieService.Global()) {
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleOpsGenie(&pipeline.OpsGenieHandler{}, ad) })
	}

	for _, talk := range n.TalkHandlers {
		talk := talk
		an.handlers = append(an.handlers, func(ad *AlertData) { an.handleTalk(talk, ad) })
	}

	// Parse level expressions
	an.levels = make([]stateful.Expression, CritAlert+1)
	an.scopePools = make([]stateful.ScopePool, CritAlert+1)

	an.levelResets = make([]stateful.Expression, CritAlert+1)
	an.lrScopePools = make([]stateful.ScopePool, CritAlert+1)

	if n.Info != nil {
		statefulExpression, expressionCompileError := stateful.NewExpression(n.Info.Expression)
		if expressionCompileError != nil {
			return nil, fmt.Errorf("Failed to compile stateful expression for info: %s", expressionCompileError)
		}

		an.levels[InfoAlert] = statefulExpression
		an.scopePools[InfoAlert] = stateful.NewScopePool(stateful.FindReferenceVariables(n.Info.Expression))
		if n.InfoReset != nil {
			lstatefulExpression, lexpressionCompileError := stateful.NewExpression(n.InfoReset.Expression)
			if lexpressionCompileError != nil {
				return nil, fmt.Errorf("Failed to compile stateful expression for infoReset: %s", lexpressionCompileError)
			}
			an.levelResets[InfoAlert] = lstatefulExpression
			an.lrScopePools[InfoAlert] = stateful.NewScopePool(stateful.FindReferenceVariables(n.InfoReset.Expression))
		}
	}

	if n.Warn != nil {
		statefulExpression, expressionCompileError := stateful.NewExpression(n.Warn.Expression)
		if expressionCompileError != nil {
			return nil, fmt.Errorf("Failed to compile stateful expression for warn: %s", expressionCompileError)
		}
		an.levels[WarnAlert] = statefulExpression
		an.scopePools[WarnAlert] = stateful.NewScopePool(stateful.FindReferenceVariables(n.Warn.Expression))
		if n.WarnReset != nil {
			lstatefulExpression, lexpressionCompileError := stateful.NewExpression(n.WarnReset.Expression)
			if lexpressionCompileError != nil {
				return nil, fmt.Errorf("Failed to compile stateful expression for warnReset: %s", lexpressionCompileError)
			}
			an.levelResets[WarnAlert] = lstatefulExpression
			an.lrScopePools[WarnAlert] = stateful.NewScopePool(stateful.FindReferenceVariables(n.WarnReset.Expression))
		}
	}

	if n.Crit != nil {
		statefulExpression, expressionCompileError := stateful.NewExpression(n.Crit.Expression)
		if expressionCompileError != nil {
			return nil, fmt.Errorf("Failed to compile stateful expression for crit: %s", expressionCompileError)
		}
		an.levels[CritAlert] = statefulExpression
		an.scopePools[CritAlert] = stateful.NewScopePool(stateful.FindReferenceVariables(n.Crit.Expression))
		if n.CritReset != nil {
			lstatefulExpression, lexpressionCompileError := stateful.NewExpression(n.CritReset.Expression)
			if lexpressionCompileError != nil {
				return nil, fmt.Errorf("Failed to compile stateful expression for critReset: %s", lexpressionCompileError)
			}
			an.levelResets[CritAlert] = lstatefulExpression
			an.lrScopePools[CritAlert] = stateful.NewScopePool(stateful.FindReferenceVariables(n.CritReset.Expression))
		}
	}

	// Setup states
	if n.History < 2 {
		n.History = 2
	}
	an.states = make(map[models.GroupID]*alertState)

	// Configure flapping
	if n.UseFlapping {
		if n.FlapLow > 1 || n.FlapHigh > 1 {
			return nil, errors.New("alert flap thresholds are percentages and should be between 0 and 1")
		}
	}

	return
}

func (a *AlertNode) runAlert([]byte) error {
	a.alertsTriggered = &expvar.Int{}
	a.statMap.Set(statsAlertsTriggered, a.alertsTriggered)

	a.oksTriggered = &expvar.Int{}
	a.statMap.Set(statsOKsTriggered, a.oksTriggered)

	a.infosTriggered = &expvar.Int{}
	a.statMap.Set(statsInfosTriggered, a.infosTriggered)

	a.warnsTriggered = &expvar.Int{}
	a.statMap.Set(statsWarnsTriggered, a.warnsTriggered)

	a.critsTriggered = &expvar.Int{}
	a.statMap.Set(statsCritsTriggered, a.critsTriggered)

	switch a.Wants() {
	case pipeline.StreamEdge:
		for p, ok := a.ins[0].NextPoint(); ok; p, ok = a.ins[0].NextPoint() {
			a.timer.Start()
			var currentLevel AlertLevel
			if state, ok := a.states[p.Group]; ok {
				currentLevel = state.currentLevel()
			}
			l := a.determineLevel(p.Time, p.Fields, p.Tags, currentLevel)
			state := a.updateState(p.Time, l, p.Group)
			if (a.a.UseFlapping && state.flapping) || (a.a.IsStateChangesOnly && !state.changed && !state.expired) {
				a.timer.Stop()
				continue
			}
			// send alert if we are not OK or we are OK and state changed (i.e recovery)
			if l != OKAlert || state.changed {
				batch := models.Batch{
					Name:   p.Name,
					Group:  p.Group,
					ByName: p.Dimensions.ByName,
					Tags:   p.Tags,
					Points: []models.BatchPoint{models.BatchPointFromPoint(p)},
				}
				state.triggered(p.Time)
				// Suppress the recovery event.
				if a.a.NoRecoveriesFlag && l == OKAlert {
					a.timer.Stop()
					continue
				}
				duration := state.duration()
				ad, err := a.alertData(p.Name, p.Group, p.Tags, p.Fields, l, p.Time, duration, batch)
				if err != nil {
					return err
				}
				a.handleAlert(ad)
				if a.a.LevelTag != "" || a.a.IdTag != "" {
					p.Tags = p.Tags.Copy()
					if a.a.LevelTag != "" {
						p.Tags[a.a.LevelTag] = l.String()
					}
					if a.a.IdTag != "" {
						p.Tags[a.a.IdTag] = ad.ID
					}
				}
				if a.a.LevelField != "" || a.a.IdField != "" || a.a.DurationField != "" || a.a.MessageField != "" {
					p.Fields = p.Fields.Copy()
					if a.a.LevelField != "" {
						p.Fields[a.a.LevelField] = l.String()
					}
					if a.a.MessageField != "" {
						p.Fields[a.a.MessageField] = ad.Message
					}
					if a.a.IdField != "" {
						p.Fields[a.a.IdField] = ad.ID
					}
					if a.a.DurationField != "" {
						p.Fields[a.a.DurationField] = int64(duration)
					}
				}
				a.timer.Pause()
				for _, child := range a.outs {
					err := child.CollectPoint(p)
					if err != nil {
						return err
					}
				}
				a.timer.Resume()
			}
			a.timer.Stop()
		}
	case pipeline.BatchEdge:
		for b, ok := a.ins[0].NextBatch(); ok; b, ok = a.ins[0].NextBatch() {
			a.timer.Start()
			if len(b.Points) == 0 {
				a.timer.Stop()
				continue
			}
			// Keep track of lowest level for any point
			lowestLevel := CritAlert
			// Keep track of highest level and point
			highestLevel := OKAlert
			var highestPoint *models.BatchPoint

			for i, p := range b.Points {
				var currentLevel AlertLevel
				if state, ok := a.states[b.Group]; ok {
					currentLevel = state.currentLevel()
				}
				l := a.determineLevel(p.Time, p.Fields, p.Tags, currentLevel)
				if l < lowestLevel {
					lowestLevel = l
				}
				if l > highestLevel || highestPoint == nil {
					highestLevel = l
					highestPoint = &b.Points[i]
				}
			}

			// Default the determined level to lowest.
			l := lowestLevel
			// Update determined level to highest if we don't care about all
			if !a.a.AllFlag {
				l = highestLevel
			}
			// Create alert Data
			t := highestPoint.Time
			if a.a.AllFlag || l == OKAlert {
				t = b.TMax
			}

			// Update state
			state := a.updateState(t, l, b.Group)
			// Trigger alert if:
			//  l == OK and state.changed (aka recovery)
			//    OR
			//  l != OK and flapping/statechanges checkout
			if state.changed && l == OKAlert ||
				(l != OKAlert &&
					!((a.a.UseFlapping && state.flapping) ||
						(a.a.IsStateChangesOnly && !state.changed && !state.expired))) {
				state.triggered(t)
				// Suppress the recovery event.
				if a.a.NoRecoveriesFlag && l == OKAlert {
					a.timer.Stop()
					continue
				}

				duration := state.duration()
				ad, err := a.alertData(b.Name, b.Group, b.Tags, highestPoint.Fields, l, t, duration, b)
				if err != nil {
					return err
				}
				a.handleAlert(ad)
				// Update tags or fields for Level property
				if a.a.LevelTag != "" ||
					a.a.LevelField != "" ||
					a.a.IdTag != "" ||
					a.a.IdField != "" ||
					a.a.DurationField != "" ||
					a.a.MessageField != "" {
					for i := range b.Points {
						if a.a.LevelTag != "" || a.a.IdTag != "" {
							b.Points[i].Tags = b.Points[i].Tags.Copy()
							if a.a.LevelTag != "" {
								b.Points[i].Tags[a.a.LevelTag] = l.String()
							}
							if a.a.IdTag != "" {
								b.Points[i].Tags[a.a.IdTag] = ad.ID
							}
						}
						if a.a.LevelField != "" || a.a.IdField != "" || a.a.DurationField != "" || a.a.MessageField != "" {
							b.Points[i].Fields = b.Points[i].Fields.Copy()
							if a.a.LevelField != "" {
								b.Points[i].Fields[a.a.LevelField] = l.String()
							}
							if a.a.MessageField != "" {
								b.Points[i].Fields[a.a.MessageField] = ad.Message
							}
							if a.a.IdField != "" {
								b.Points[i].Fields[a.a.IdField] = ad.ID
							}
							if a.a.DurationField != "" {
								b.Points[i].Fields[a.a.DurationField] = int64(duration)
							}
						}
					}
					if a.a.LevelTag != "" || a.a.IdTag != "" {
						b.Tags = b.Tags.Copy()
						if a.a.LevelTag != "" {
							b.Tags[a.a.LevelTag] = l.String()
						}
						if a.a.IdTag != "" {
							b.Tags[a.a.IdTag] = ad.ID
						}
					}
				}
				a.timer.Pause()
				for _, child := range a.outs {
					err := child.CollectBatch(b)
					if err != nil {
						return err
					}
				}
				a.timer.Resume()
			}
			a.timer.Stop()
		}
	}
	return nil
}

func (a *AlertNode) handleAlert(ad *AlertData) {
	a.alertsTriggered.Add(1)
	switch ad.Level {
	case OKAlert:
		a.oksTriggered.Add(1)
	case InfoAlert:
		a.infosTriggered.Add(1)
	case WarnAlert:
		a.warnsTriggered.Add(1)
	case CritAlert:
		a.critsTriggered.Add(1)
	}
	a.logger.Printf("D! %v alert triggered id:%s msg:%s data:%v", ad.Level, ad.ID, ad.Message, ad.Data.Series[0])
	for _, h := range a.handlers {
		h(ad)
	}
}

func (a *AlertNode) determineLevel(now time.Time, fields models.Fields, tags map[string]string, currentLevel AlertLevel) AlertLevel {
	if higherLevel, found := a.findFirstMatchLevel(CritAlert, currentLevel-1, now, fields, tags); found {
		return higherLevel
	}
	if rse := a.levelResets[currentLevel]; rse != nil {
		if pass, err := EvalPredicate(rse, a.lrScopePools[currentLevel], now, fields, tags); err != nil {
			a.logger.Printf("E! error evaluating reset expression for current level %v: %s", currentLevel, err)
		} else if !pass {
			return currentLevel
		}
	}
	if newLevel, found := a.findFirstMatchLevel(currentLevel, OKAlert, now, fields, tags); found {
		return newLevel
	}
	return OKAlert
}

func (a *AlertNode) findFirstMatchLevel(start AlertLevel, stop AlertLevel, now time.Time, fields models.Fields, tags map[string]string) (AlertLevel, bool) {
	if stop < OKAlert {
		stop = OKAlert
	}
	for l := start; l > stop; l-- {
		se := a.levels[l]
		if se == nil {
			continue
		}
		if pass, err := EvalPredicate(se, a.scopePools[l], now, fields, tags); err != nil {
			a.logger.Printf("E! error evaluating expression for level %v: %s", AlertLevel(l), err)
			continue
		} else if pass {
			return AlertLevel(l), true
		}
	}
	return OKAlert, false
}

func (a *AlertNode) batchToResult(b models.Batch) influxql.Result {
	row := models.BatchToRow(b)
	r := influxql.Result{
		Series: imodels.Rows{row},
	}
	return r
}

func (a *AlertNode) alertData(
	name string,
	group models.GroupID,
	tags models.Tags,
	fields models.Fields,
	level AlertLevel,
	t time.Time,
	d time.Duration,
	b models.Batch,
) (*AlertData, error) {
	id, err := a.renderID(name, group, tags)
	if err != nil {
		return nil, err
	}
	msg, details, info, err := a.renderMessageAndDetails(id, name, t, group, tags, fields, level)
	if err != nil {
		return nil, err
	}
	ad := &AlertData{
		ID:       id,
		Message:  msg,
		Details:  details,
		Time:     t,
		Duration: d,
		Level:    level,
		Data:     a.batchToResult(b),
		info:     info,
	}
	return ad, nil
}

type alertState struct {
	history  []AlertLevel
	idx      int
	flapping bool
	changed  bool
	// Time when first alert was triggered
	firstTriggered time.Time
	// Time when last alert was triggered.
	// Note: Alerts are not triggered for every event.
	lastTriggered time.Time
	expired       bool
}

// Return the duration of the current alert state.
func (a *alertState) duration() time.Duration {
	return a.lastTriggered.Sub(a.firstTriggered)
}

// Record that the alert was triggered at time t.
func (a *alertState) triggered(t time.Time) {
	a.lastTriggered = t
	// Check if we are being triggered for first time since an OKAlert
	// If so reset firstTriggered time
	p := a.idx - 1
	if p == -1 {
		p = len(a.history) - 1
	}
	if a.history[p] == OKAlert {
		a.firstTriggered = t
	}
}

// Record an event in the alert history.
func (a *alertState) addEvent(level AlertLevel) {
	a.changed = a.history[a.idx] != level
	a.idx = (a.idx + 1) % len(a.history)
	a.history[a.idx] = level
}

// Return current level of this state
func (a *alertState) currentLevel() AlertLevel {
	return a.history[a.idx]
}

// Compute the percentage change in the alert history.
func (a *alertState) percentChange() float64 {
	l := len(a.history)
	changes := 0.0
	weight := (maxWeight / weightDiff)
	step := (maxWeight - weight) / float64(l-1)
	for i := 0; i < l-1; i++ {
		// get current index
		c := (i + a.idx) % l
		// get previous index
		p := c - 1
		// check for wrap around
		if p < 0 {
			p = l - 1
		}
		if a.history[c] != a.history[p] {
			changes += weight
		}
		weight += step
	}

	p := changes / float64(l-1)
	return p
}

func (a *AlertNode) updateState(t time.Time, level AlertLevel, group models.GroupID) *alertState {
	state, ok := a.states[group]
	if !ok {
		state = &alertState{
			history: make([]AlertLevel, a.a.History),
		}
		a.states[group] = state
	}
	state.addEvent(level)

	if a.a.UseFlapping {
		p := state.percentChange()
		if state.flapping && p < a.a.FlapLow {
			state.flapping = false
		} else if !state.flapping && p > a.a.FlapHigh {
			state.flapping = true
		}
	}
	state.expired = !state.changed && a.a.StateChangesOnlyDuration != 0 && t.Sub(state.lastTriggered) >= a.a.StateChangesOnlyDuration
	return state
}

// Type containing information available to ID template.
type idInfo struct {
	// Measurement name
	Name string

	// Task name
	TaskName string

	// Concatenation of all group-by tags of the form [key=value,]+.
	// If not groupBy is performed equal to literal 'nil'
	Group string

	// Map of tags
	Tags map[string]string
}

type messageInfo struct {
	idInfo

	// The ID of the alert.
	ID string

	// Fields of alerting data point.
	Fields map[string]interface{}

	// Alert Level, one of: INFO, WARNING, CRITICAL.
	Level string

	// Time
	Time time.Time
}

type detailsInfo struct {
	messageInfo
	// The Message of the Alert
	Message string
}

func (a *AlertNode) renderID(name string, group models.GroupID, tags models.Tags) (string, error) {
	g := string(group)
	if group == models.NilGroup {
		g = "nil"
	}
	info := idInfo{
		Name:     name,
		TaskName: a.et.Task.ID,
		Group:    g,
		Tags:     tags,
	}
	id := a.bufPool.Get().(*bytes.Buffer)
	defer func() {
		id.Reset()
		a.bufPool.Put(id)
	}()

	err := a.idTmpl.Execute(id, info)
	if err != nil {
		return "", err
	}
	return id.String(), nil
}

func (a *AlertNode) renderMessageAndDetails(id, name string, t time.Time, group models.GroupID, tags models.Tags, fields models.Fields, level AlertLevel) (string, string, detailsInfo, error) {
	g := string(group)
	if group == models.NilGroup {
		g = "nil"
	}
	minfo := messageInfo{
		idInfo: idInfo{
			Name:     name,
			TaskName: a.et.Task.ID,
			Group:    g,
			Tags:     tags,
		},
		ID:     id,
		Fields: fields,
		Level:  level.String(),
		Time:   t,
	}

	// Grab a buffer for the message template and the details template
	tmpBuffer := a.bufPool.Get().(*bytes.Buffer)
	defer func() {
		tmpBuffer.Reset()
		a.bufPool.Put(tmpBuffer)
	}()
	tmpBuffer.Reset()

	err := a.messageTmpl.Execute(tmpBuffer, minfo)
	if err != nil {
		return "", "", detailsInfo{}, err
	}

	msg := tmpBuffer.String()
	dinfo := detailsInfo{
		messageInfo: minfo,
		Message:     msg,
	}

	// Reuse the buffer, for the details template
	tmpBuffer.Reset()
	err = a.detailsTmpl.Execute(tmpBuffer, dinfo)
	if err != nil {
		return "", "", dinfo, err
	}

	details := tmpBuffer.String()
	return msg, details, dinfo, nil
}

//--------------------------------
// Alert handlers

func (a *AlertNode) handlePost(post *pipeline.PostHandler, ad *AlertData) {
	bodyBuffer := a.bufPool.Get().(*bytes.Buffer)
	defer func() {
		bodyBuffer.Reset()
		a.bufPool.Put(bodyBuffer)
	}()

	err := json.NewEncoder(bodyBuffer).Encode(ad)
	if err != nil {
		a.logger.Println("E! failed to marshal alert data json", err)
		return
	}

	resp, err := http.Post(post.URL, "application/json", bodyBuffer)
	if err != nil {
		a.logger.Println("E! failed to POST batch", err)
		return
	}

	if resp == nil {
		a.logger.Println("E! failed to POST batch response is nil")
		return
	}

	// close http response otherwise tcp socket will be 'ESTABLISHED' in a long time
	defer resp.Body.Close()
	return
}

func (a *AlertNode) handleTcp(tcp *pipeline.TcpHandler, ad *AlertData) {
	buf := a.bufPool.Get().(*bytes.Buffer)
	defer func() {
		buf.Reset()
		a.bufPool.Put(buf)
	}()

	err := json.NewEncoder(buf).Encode(ad)
	if err != nil {
		a.logger.Println("E! failed to marshal alert data json", err)
		return
	}

	conn, err := net.Dial("tcp", tcp.Address)
	if err != nil {
		a.logger.Println("E! failed to connect", err)
		return
	}
	defer conn.Close()

	buf.WriteByte('\n')
	conn.Write(buf.Bytes())

	return
}

func (a *AlertNode) handleEmail(email *pipeline.EmailHandler, ad *AlertData) {
	if err := a.et.tm.SMTPService.SendMail(email.ToList, ad.Message, ad.Details); err != nil {
		a.logger.Println("E! failed to send email:", err)
	}
}

func (a *AlertNode) handleExec(ex *pipeline.ExecHandler, ad *AlertData) {
	b, err := json.Marshal(ad)
	if err != nil {
		a.logger.Println("E! failed to marshal alert data json", err)
		return
	}
	cmd := exec.Command(ex.Command[0], ex.Command[1:]...)
	cmd.Stdin = bytes.NewBuffer(b)
	var out bytes.Buffer
	cmd.Stdout = &out
	cmd.Stderr = &out
	err = cmd.Run()
	if err != nil {
		a.logger.Println("E! error running alert command:", err, out.String())
		return
	}
}

func (a *AlertNode) handleLog(l *pipeline.LogHandler, ad *AlertData) {
	b, err := json.Marshal(ad)
	if err != nil {
		a.logger.Println("E! failed to marshal alert data json", err)
		return
	}
	f, err := os.OpenFile(l.FilePath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, os.FileMode(l.Mode))
	if err != nil {
		a.logger.Println("E! failed to open file for alert logging", err)
		return
	}
	defer f.Close()
	n, err := f.Write(b)
	if n != len(b) || err != nil {
		a.logger.Println("E! failed to write to file", err)
	}
	n, err = f.Write([]byte("\n"))
	if n != 1 || err != nil {
		a.logger.Println("E! failed to write to file", err)
	}
}

func (a *AlertNode) handleVictorOps(vo *pipeline.VictorOpsHandler, ad *AlertData) {
	var messageType string
	switch ad.Level {
	case OKAlert:
		messageType = "RECOVERY"
	default:
		messageType = ad.Level.String()
	}
	err := a.et.tm.VictorOpsService.Alert(
		vo.RoutingKey,
		messageType,
		ad.Message,
		ad.ID,
		ad.Time,
		ad.Data,
	)
	if err != nil {
		a.logger.Println("E! failed to send alert data to VictorOps:", err)
		return
	}
}

func (a *AlertNode) handlePagerDuty(pd *pipeline.PagerDutyHandler, ad *AlertData) {
	err := a.et.tm.PagerDutyService.Alert(
		pd.ServiceKey,
		ad.ID,
		ad.Message,
		ad.Level,
		ad.Data,
	)
	if err != nil {
		a.logger.Println("E! failed to send alert data to PagerDuty:", err)
		return
	}
}

func (a *AlertNode) handleSensu(sensu *pipeline.SensuHandler, ad *AlertData) {
	err := a.et.tm.SensuService.Alert(
		ad.ID,
		ad.Message,
		ad.Level,
	)
	if err != nil {
		a.logger.Println("E! failed to send alert data to Sensu:", err)
		return
	}
}

func (a *AlertNode) handleSlack(slack *pipeline.SlackHandler, ad *AlertData) {
	err := a.et.tm.SlackService.Alert(
		slack.Channel,
		ad.Message,
		slack.Username,
		slack.IconEmoji,
		ad.Level,
	)
	if err != nil {
		a.logger.Println("E! failed to send alert data to Slack:", err)
		return
	}
}

func (a *AlertNode) handleTelegram(telegram *pipeline.TelegramHandler, ad *AlertData) {
	err := a.et.tm.TelegramService.Alert(
		telegram.ChatId,
		telegram.ParseMode,
		ad.Message,
		telegram.IsDisableWebPagePreview,
		telegram.IsDisableNotification,
	)
	if err != nil {
		a.logger.Println("E! failed to send alert data to Telegram:", err)
		return
	}
}

func (a *AlertNode) handleHipChat(hipchat *pipeline.HipChatHandler, ad *AlertData) {
	err := a.et.tm.HipChatService.Alert(
		hipchat.Room,
		hipchat.Token,
		ad.Message,
		ad.Level,
	)
	if err != nil {
		a.logger.Println("E! failed to send alert data to HipChat:", err)
		return
	}
}

type alertaHandler struct {
	*pipeline.AlertaHandler

	resourceTmpl    *text.Template
	eventTmpl       *text.Template
	environmentTmpl *text.Template
	valueTmpl       *text.Template
	groupTmpl       *text.Template
}

func (a *AlertNode) handleAlerta(alerta alertaHandler, ad *AlertData) {
	var severity string

	switch ad.Level {
	case OKAlert:
		severity = "ok"
	case InfoAlert:
		severity = "informational"
	case WarnAlert:
		severity = "warning"
	case CritAlert:
		severity = "critical"
	default:
		severity = "indeterminate"
	}
	var buf bytes.Buffer
	err := alerta.resourceTmpl.Execute(&buf, ad.info)
	if err != nil {
		a.logger.Printf("E! failed to evaluate Alerta Resource template %s", alerta.Resource)
		return
	}
	resource := buf.String()
	buf.Reset()

	type eventData struct {
		idInfo
		ID string
	}
	data := eventData{
		idInfo: ad.info.messageInfo.idInfo,
		ID:     ad.ID,
	}
	err = alerta.eventTmpl.Execute(&buf, data)
	if err != nil {
		a.logger.Printf("E! failed to evaluate Alerta Event template %s", alerta.Event)
		return
	}
	event := buf.String()
	buf.Reset()

	err = alerta.environmentTmpl.Execute(&buf, ad.info)
	if err != nil {
		a.logger.Printf("E! failed to evaluate Alerta Environment template %s", alerta.Environment)
		return
	}
	environment := buf.String()
	buf.Reset()

	err = alerta.groupTmpl.Execute(&buf, ad.info)
	if err != nil {
		a.logger.Printf("E! failed to evaluate Alerta Group template %s", alerta.Group)
		return
	}
	group := buf.String()
	buf.Reset()

	err = alerta.valueTmpl.Execute(&buf, ad.info)
	if err != nil {
		a.logger.Printf("E! failed to evaluate Alerta Value template %s", alerta.Value)
		return
	}
	value := buf.String()

	service := alerta.Service
	if len(alerta.Service) == 0 {
		service = []string{ad.info.Name}
	}

	err = a.et.tm.AlertaService.Alert(
		alerta.Token,
		resource,
		event,
		environment,
		severity,
		group,
		value,
		ad.Message,
		alerta.Origin,
		service,
		ad.Data,
	)
	if err != nil {
		a.logger.Println("E! failed to send alert data to Alerta:", err)
		return
	}
}

func (a *AlertNode) handleOpsGenie(og *pipeline.OpsGenieHandler, ad *AlertData) {
	var messageType string
	switch ad.Level {
	case OKAlert:
		messageType = "RECOVERY"
	default:
		messageType = ad.Level.String()
	}

	err := a.et.tm.OpsGenieService.Alert(
		og.TeamsList,
		og.RecipientsList,
		messageType,
		ad.Message,
		ad.ID,
		ad.Time,
		ad.Data,
	)
	if err != nil {
		a.logger.Println("E! failed to send alert data to OpsGenie:", err)
		return
	}
}

func (a *AlertNode) handleTalk(talk *pipeline.TalkHandler, ad *AlertData) {
	err := a.et.tm.TalkService.Alert(
		ad.ID,
		ad.Message,
	)
	if err != nil {
		a.logger.Println("E! failed to send alert data to Talk:", err)
		return
	}
}