package collector

import (
	"github.com/dcu/mongodb_exporter/shared"
	"github.com/golang/glog"
	"github.com/prometheus/client_golang/prometheus"
	"gopkg.in/mgo.v2"
)

var (
	// Namespace is the namespace of the metrics
	Namespace = "mongodb"
)

var (
	upGauge = prometheus.NewGaugeVec(prometheus.GaugeOpts{
		Namespace: Namespace,
		Name:      "up",
		Help:      "To show if we can connect to mongodb instance",
	}, []string{})
)

// MongodbCollectorOpts is the options of the mongodb collector.
type MongodbCollectorOpts struct {
	URI                      string
	TLSCertificateFile       string
	TLSPrivateKeyFile        string
	TLSCaFile                string
	TLSHostnameValidation    bool
	CollectReplSet           bool
	CollectOplog             bool
	CollectTopMetrics        bool
	CollectDatabaseMetrics   bool
	CollectCollectionMetrics bool
	CollectProfileMetrics    bool
	CollectConnPoolStats     bool
	UserName                 string
	AuthMechanism            string
}

func (in MongodbCollectorOpts) toSessionOps() shared.MongoSessionOpts {
	return shared.MongoSessionOpts{
		URI:                   in.URI,
		TLSCertificateFile:    in.TLSCertificateFile,
		TLSPrivateKeyFile:     in.TLSPrivateKeyFile,
		TLSCaFile:             in.TLSCaFile,
		TLSHostnameValidation: in.TLSHostnameValidation,
		UserName:              in.UserName,
		AuthMechanism:         in.AuthMechanism,
	}
}

// MongodbCollector is in charge of collecting mongodb's metrics.
type MongodbCollector struct {
	Opts MongodbCollectorOpts
}

// NewMongodbCollector returns a new instance of a MongodbCollector.
func NewMongodbCollector(opts MongodbCollectorOpts) *MongodbCollector {
	exporter := &MongodbCollector{
		Opts: opts,
	}

	return exporter
}

// Describe describes all mongodb's metrics.
func (exporter *MongodbCollector) Describe(ch chan<- *prometheus.Desc) {
	(&ServerStatus{}).Describe(ch)
	(&ReplSetStatus{}).Describe(ch)
	(&DatabaseStatus{}).Describe(ch)

	if exporter.Opts.CollectTopMetrics {
		(&TopStatus{}).Describe(ch)
	}
}

// Collect collects all mongodb's metrics.
func (exporter *MongodbCollector) Collect(ch chan<- prometheus.Metric) {
	mongoSess := shared.MongoSession(exporter.Opts.toSessionOps())
	if mongoSess != nil {
		upGauge.WithLabelValues().Set(float64(1))
		upGauge.Collect(ch)
		upGauge.Reset()
		defer mongoSess.Close()
		glog.Info("Collecting Server Status")
		exporter.collectServerStatus(mongoSess, ch)
		if exporter.Opts.CollectReplSet {
			glog.Info("Collecting ReplSet Status")
			exporter.collectReplSetStatus(mongoSess, ch)
		}
		if exporter.Opts.CollectOplog {
			glog.Info("Collecting Oplog Status")
			exporter.collectOplogStatus(mongoSess, ch)
		}

		if exporter.Opts.CollectTopMetrics {
			glog.Info("Collecting Top Metrics")
			exporter.collectTopStatus(mongoSess, ch)
		}

		if exporter.Opts.CollectDatabaseMetrics {
			glog.Info("Collecting Database Metrics")
			exporter.collectDatabaseStatus(mongoSess, ch)
		}

		if exporter.Opts.CollectCollectionMetrics {
			glog.Info("Collection Collection Metrics")
			exporter.collectCollectionStatus(mongoSess, ch)
		}

		if exporter.Opts.CollectProfileMetrics {
			glog.Info("Collection Profile Metrics")
			exporter.collectProfileStatus(mongoSess, ch)
		}

		if exporter.Opts.CollectConnPoolStats {
			glog.Info("Collecting Connection Pool Stats")
			exporter.collectConnPoolStats(mongoSess, ch)
		}
	} else {
		upGauge.WithLabelValues().Set(float64(0))
		upGauge.Collect(ch)
		upGauge.Reset()
	}
}

func (exporter *MongodbCollector) collectServerStatus(session *mgo.Session, ch chan<- prometheus.Metric) *ServerStatus {
	serverStatus := GetServerStatus(session)
	if serverStatus != nil {
		glog.Info("exporting ServerStatus Metrics")
		serverStatus.Export(ch)
	}
	return serverStatus
}

func (exporter *MongodbCollector) collectReplSetStatus(session *mgo.Session, ch chan<- prometheus.Metric) *ReplSetStatus {
	replSetStatus := GetReplSetStatus(session)

	if replSetStatus != nil {
		glog.Info("exporting ReplSetStatus Metrics")
		replSetStatus.Export(ch)
	}

	return replSetStatus
}

func (exporter *MongodbCollector) collectOplogStatus(session *mgo.Session, ch chan<- prometheus.Metric) *OplogStatus {
	oplogStatus := GetOplogStatus(session)

	if oplogStatus != nil {
		glog.Info("exporting OplogStatus Metrics")
		oplogStatus.Export(ch)
	}

	return oplogStatus
}

func (exporter *MongodbCollector) collectTopStatus(session *mgo.Session, ch chan<- prometheus.Metric) *TopStatus {
	topStatus := GetTopStatus(session)
	if topStatus != nil {
		glog.Info("exporting Top Metrics")
		topStatus.Export(ch)
	}
	return topStatus
}

func (exporter *MongodbCollector) collectDatabaseStatus(session *mgo.Session, ch chan<- prometheus.Metric) {
	all, err := session.DatabaseNames()
	if err != nil {
		glog.Error("Failed to get database names")
		return
	}
	for _, db := range all {
		if db == "admin" || db == "test" {
			continue
		}
		dbStatus := GetDatabaseStatus(session, db)
		if dbStatus != nil {
			glog.Infof("exporting Database Metrics for db=%q", dbStatus.Name)
			dbStatus.Export(ch)
		}
	}
}

func (exporter *MongodbCollector) collectCollectionStatus(session *mgo.Session, ch chan<- prometheus.Metric) {
	database_names, err := session.DatabaseNames()
	if err != nil {
		glog.Error("failed to get database names")
		return
	}
	for _, db := range database_names {
		if db == "admin" || db == "test" {
			continue
		}
		CollectCollectionStatus(session, db, ch)
	}
}

func (exporter *MongodbCollector) collectProfileStatus(session *mgo.Session, ch chan<- prometheus.Metric) {
	all, err := session.DatabaseNames()
	if err != nil {
		glog.Error("failed to get database names: %s", err)
		return
	}
	for _, db := range all {
		if db == "admin" || db == "test" {
			continue
		}
		CollectProfileStatus(session, db, ch)
	}
}

func (exporter *MongodbCollector) collectConnPoolStats(session *mgo.Session, ch chan<- prometheus.Metric) {
	connPoolStats := GetConnPoolStats(session)

	if connPoolStats != nil {
		glog.Info("exporting ConnPoolStats Metrics")
		connPoolStats.Export(ch)
	}
}