package notifiers

import (
	"encoding/json"
	"time"

	"github.com/grafana/grafana/pkg/bus"
	"github.com/grafana/grafana/pkg/log"
	"github.com/grafana/grafana/pkg/metrics"
	m "github.com/grafana/grafana/pkg/models"
	"github.com/grafana/grafana/pkg/services/alerting"
	"github.com/grafana/grafana/pkg/setting"
)

func init() {
	alerting.RegisterNotifier(&alerting.NotifierPlugin{
		Type:        "slack",
		Name:        "Slack",
		Description: "Sends notifications using Grafana server configured STMP settings",
		Factory:     NewSlackNotifier,
		OptionsTemplate: `
      <h3 class="page-heading">Slack settings</h3>
      <div class="gf-form max-width-30">
        <span class="gf-form-label width-6">Url</span>
        <input type="text" required class="gf-form-input max-width-30" ng-model="ctrl.model.settings.url" placeholder="Slack incoming webhook url"></input>
      </div>
      <div class="gf-form max-width-30">
        <span class="gf-form-label width-6">Recipient</span>
        <input type="text"
          class="gf-form-input max-width-30"
          ng-model="ctrl.model.settings.recipient"
          data-placement="right">
        </input>
        <info-popover mode="right-absolute">
          Override default channel or user, use #channel-name or @username
        </info-popover>
      </div>
      <div class="gf-form max-width-30">
        <span class="gf-form-label width-6">Mention</span>
        <input type="text"
          class="gf-form-input max-width-30"
          ng-model="ctrl.model.settings.mention"
          data-placement="right">
        </input>
        <info-popover mode="right-absolute">
          Mention a user or a group using @ when notifying in a channel
        </info-popover>
      </div>
    `,
	})

}

func NewSlackNotifier(model *m.AlertNotification) (alerting.Notifier, error) {
	url := model.Settings.Get("url").MustString()
	if url == "" {
		return nil, alerting.ValidationError{Reason: "Could not find url property in settings"}
	}

	recipient := model.Settings.Get("recipient").MustString()
	mention := model.Settings.Get("mention").MustString()

	return &SlackNotifier{
		NotifierBase: NewNotifierBase(model.Id, model.IsDefault, model.Name, model.Type, model.Settings),
		Url:          url,
		Recipient:    recipient,
		Mention:      mention,
		log:          log.New("alerting.notifier.slack"),
	}, nil
}

type SlackNotifier struct {
	NotifierBase
	Url       string
	Recipient string
	Mention   string
	log       log.Logger
}

func (this *SlackNotifier) Notify(evalContext *alerting.EvalContext) error {
	this.log.Info("Executing slack notification", "ruleId", evalContext.Rule.Id, "notification", this.Name)
	metrics.M_Alerting_Notification_Sent_Slack.Inc(1)

	ruleUrl, err := evalContext.GetRuleUrl()
	if err != nil {
		this.log.Error("Failed get rule link", "error", err)
		return err
	}

	fields := make([]map[string]interface{}, 0)
	fieldLimitCount := 4
	for index, evt := range evalContext.EvalMatches {
		fields = append(fields, map[string]interface{}{
			"title": evt.Metric,
			"value": evt.Value,
			"short": true,
		})
		if index > fieldLimitCount {
			break
		}
	}

	if evalContext.Error != nil {
		fields = append(fields, map[string]interface{}{
			"title": "Error message",
			"value": evalContext.Error.Error(),
			"short": false,
		})
	}

	message := this.Mention
	if evalContext.Rule.State != m.AlertStateOK { //dont add message when going back to alert state ok.
		message += " " + evalContext.Rule.Message
	}

	body := map[string]interface{}{
		"attachments": []map[string]interface{}{
			{
				"fallback":    evalContext.GetNotificationTitle(),
				"color":       evalContext.GetStateModel().Color,
				"title":       evalContext.GetNotificationTitle(),
				"title_link":  ruleUrl,
				"text":        message,
				"fields":      fields,
				"image_url":   evalContext.ImagePublicUrl,
				"footer":      "Grafana v" + setting.BuildVersion,
				"footer_icon": "https://grafana.com/assets/img/fav32.png",
				"ts":          time.Now().Unix(),
			},
		},
		"parse": "full", // to linkify urls, users and channels in alert message.
	}

	//recipient override
	if this.Recipient != "" {
		body["channel"] = this.Recipient
	}

	data, _ := json.Marshal(&body)
	cmd := &m.SendWebhookSync{Url: this.Url, Body: string(data)}

	if err := bus.DispatchCtx(evalContext.Ctx, cmd); err != nil {
		this.log.Error("Failed to send slack notification", "error", err, "webhook", this.Name)
		return err
	}

	return nil
}