package alerting

import (
	"errors"

	"fmt"

	"github.com/grafana/grafana/pkg/bus"
	"github.com/grafana/grafana/pkg/components/simplejson"
	"github.com/grafana/grafana/pkg/log"
	m "github.com/grafana/grafana/pkg/models"
)

type DashAlertExtractor struct {
	Dash  *m.Dashboard
	OrgId int64
	log   log.Logger
}

func NewDashAlertExtractor(dash *m.Dashboard, orgId int64) *DashAlertExtractor {
	return &DashAlertExtractor{
		Dash:  dash,
		OrgId: orgId,
		log:   log.New("alerting.extractor"),
	}
}

func (e *DashAlertExtractor) lookupDatasourceId(dsName string) (*m.DataSource, error) {
	if dsName == "" {
		query := &m.GetDataSourcesQuery{OrgId: e.OrgId}
		if err := bus.Dispatch(query); err != nil {
			return nil, err
		} else {
			for _, ds := range query.Result {
				if ds.IsDefault {
					return ds, nil
				}
			}
		}
	} else {
		query := &m.GetDataSourceByNameQuery{Name: dsName, OrgId: e.OrgId}
		if err := bus.Dispatch(query); err != nil {
			return nil, err
		} else {
			return query.Result, nil
		}
	}

	return nil, errors.New("Could not find datasource id for " + dsName)
}

func findPanelQueryByRefId(panel *simplejson.Json, refId string) *simplejson.Json {
	for _, targetsObj := range panel.Get("targets").MustArray() {
		target := simplejson.NewFromAny(targetsObj)

		if target.Get("refId").MustString() == refId {
			return target
		}
	}
	return nil
}

func copyJson(in *simplejson.Json) (*simplejson.Json, error) {
	rawJson, err := in.MarshalJSON()
	if err != nil {
		return nil, err
	}

	return simplejson.NewJson(rawJson)
}

func (e *DashAlertExtractor) GetAlerts() ([]*m.Alert, error) {
	e.log.Debug("GetAlerts")

	dashboardJson, err := copyJson(e.Dash.Data)
	if err != nil {
		return nil, err
	}

	alerts := make([]*m.Alert, 0)
	for _, rowObj := range dashboardJson.Get("rows").MustArray() {
		row := simplejson.NewFromAny(rowObj)

		for _, panelObj := range row.Get("panels").MustArray() {
			panel := simplejson.NewFromAny(panelObj)
			jsonAlert, hasAlert := panel.CheckGet("alert")

			if !hasAlert {
				continue
			}

			panelId, err := panel.Get("id").Int64()
			if err != nil {
				return nil, fmt.Errorf("panel id is required. err %v", err)
			}

			// backward compatibility check, can be removed later
			enabled, hasEnabled := jsonAlert.CheckGet("enabled")
			if hasEnabled && enabled.MustBool() == false {
				continue
			}

			frequency, err := getTimeDurationStringToSeconds(jsonAlert.Get("frequency").MustString())
			if err != nil {
				return nil, ValidationError{Reason: "Could not parse frequency"}
			}

			alert := &m.Alert{
				DashboardId: e.Dash.Id,
				OrgId:       e.OrgId,
				PanelId:     panelId,
				Id:          jsonAlert.Get("id").MustInt64(),
				Name:        jsonAlert.Get("name").MustString(),
				Handler:     jsonAlert.Get("handler").MustInt64(),
				Message:     jsonAlert.Get("message").MustString(),
				Frequency:   frequency,
			}

			for _, condition := range jsonAlert.Get("conditions").MustArray() {
				jsonCondition := simplejson.NewFromAny(condition)

				jsonQuery := jsonCondition.Get("query")
				queryRefId := jsonQuery.Get("params").MustArray()[0].(string)
				panelQuery := findPanelQueryByRefId(panel, queryRefId)

				if panelQuery == nil {
					reason := fmt.Sprintf("Alert on PanelId: %v refers to query(%s) that cannot be found", alert.PanelId, queryRefId)
					return nil, ValidationError{Reason: reason}
				}

				dsName := ""
				if panelQuery.Get("datasource").MustString() != "" {
					dsName = panelQuery.Get("datasource").MustString()
				} else if panel.Get("datasource").MustString() != "" {
					dsName = panel.Get("datasource").MustString()
				}

				if datasource, err := e.lookupDatasourceId(dsName); err != nil {
					return nil, err
				} else {
					jsonQuery.SetPath([]string{"datasourceId"}, datasource.Id)
				}

				if interval, err := panel.Get("interval").String(); err == nil {
					panelQuery.Set("interval", interval)
				}

				jsonQuery.Set("model", panelQuery.Interface())
			}

			alert.Settings = jsonAlert

			// validate
			_, err = NewRuleFromDBAlert(alert)
			if err == nil && alert.ValidToSave() {
				alerts = append(alerts, alert)
			} else {
				return nil, err
			}
		}
	}

	e.log.Debug("Extracted alerts from dashboard", "alertCount", len(alerts))
	return alerts, nil
}