/*
Copyright 2015 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package collectors

import (
	"fmt"
	"time"

	"github.com/golang/glog"
	"github.com/prometheus/client_golang/prometheus"

	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/ingress-nginx/internal/ingress"
)

var (
	operation    = []string{"controller_namespace", "controller_class", "controller_pod"}
	sslLabelHost = []string{"namespace", "class", "host"}
)

// Controller defines base metrics about the ingress controller
type Controller struct {
	prometheus.Collector

	configHash        prometheus.Gauge
	configSuccess     prometheus.Gauge
	configSuccessTime prometheus.Gauge

	reloadOperation       *prometheus.CounterVec
	reloadOperationErrors *prometheus.CounterVec
	sslExpireTime         *prometheus.GaugeVec

	constLabels prometheus.Labels
	labels      prometheus.Labels
}

// NewController creates a new prometheus collector for the
// Ingress controller operations
func NewController(pod, namespace, class string) *Controller {
	constLabels := prometheus.Labels{
		"controller_namespace": namespace,
		"controller_class":     class,
		"controller_pod":       pod,
	}

	cm := &Controller{
		constLabels: constLabels,

		labels: prometheus.Labels{
			"namespace": namespace,
			"class":     class,
		},

		configHash: prometheus.NewGauge(
			prometheus.GaugeOpts{
				Namespace:   PrometheusNamespace,
				Name:        "config_hash",
				Help:        "Running configuration hash actually running",
				ConstLabels: constLabels,
			},
		),
		configSuccess: prometheus.NewGauge(
			prometheus.GaugeOpts{
				Namespace:   PrometheusNamespace,
				Name:        "config_last_reload_successful",
				Help:        "Whether the last configuration reload attempt was successful",
				ConstLabels: constLabels,
			}),
		configSuccessTime: prometheus.NewGauge(
			prometheus.GaugeOpts{
				Namespace:   PrometheusNamespace,
				Name:        "config_last_reload_successful_timestamp_seconds",
				Help:        "Timestamp of the last successful configuration reload.",
				ConstLabels: constLabels,
			}),
		reloadOperation: prometheus.NewCounterVec(
			prometheus.CounterOpts{
				Namespace: PrometheusNamespace,
				Name:      "success",
				Help:      `Cumulative number of Ingress controller reload operations`,
			},
			operation,
		),
		reloadOperationErrors: prometheus.NewCounterVec(
			prometheus.CounterOpts{
				Namespace: PrometheusNamespace,
				Name:      "errors",
				Help:      `Cumulative number of Ingress controller errors during reload operations`,
			},
			operation,
		),
		sslExpireTime: prometheus.NewGaugeVec(
			prometheus.GaugeOpts{
				Namespace: PrometheusNamespace,
				Name:      "ssl_expire_time_seconds",
				Help: `Number of seconds since 1970 to the SSL Certificate expire.
			An example to check if this certificate will expire in 10 days is: "nginx_ingress_controller_ssl_expire_time_seconds < (time() + (10 * 24 * 3600))"`,
			},
			sslLabelHost,
		),
	}

	return cm
}

// IncReloadCount increment the reload counter
func (cm *Controller) IncReloadCount() {
	cm.reloadOperation.With(cm.constLabels).Inc()
}

// IncReloadErrorCount increment the reload error counter
func (cm *Controller) IncReloadErrorCount() {
	cm.reloadOperationErrors.With(cm.constLabels).Inc()
}

// ConfigSuccess set a boolean flag according to the output of the controller configuration reload
func (cm *Controller) ConfigSuccess(hash uint64, success bool) {
	if success {
		cm.configSuccessTime.Set(float64(time.Now().Unix()))
		cm.configSuccess.Set(1)

		cm.configHash.Set(float64(hash))

		return
	}

	cm.configSuccess.Set(0)
	cm.configHash.Set(0)
}

// Describe implements prometheus.Collector
func (cm Controller) Describe(ch chan<- *prometheus.Desc) {
	cm.configHash.Describe(ch)
	cm.configSuccess.Describe(ch)
	cm.configSuccessTime.Describe(ch)
	cm.reloadOperation.Describe(ch)
	cm.reloadOperationErrors.Describe(ch)
	cm.sslExpireTime.Describe(ch)
}

// Collect implements the prometheus.Collector interface.
func (cm Controller) Collect(ch chan<- prometheus.Metric) {
	cm.configHash.Collect(ch)
	cm.configSuccess.Collect(ch)
	cm.configSuccessTime.Collect(ch)
	cm.reloadOperation.Collect(ch)
	cm.reloadOperationErrors.Collect(ch)
	cm.sslExpireTime.Collect(ch)
}

// SetSSLExpireTime sets the expiration time of SSL Certificates
func (cm *Controller) SetSSLExpireTime(servers []*ingress.Server) {
	for _, s := range servers {
		if s.Hostname != "" && s.SSLCert.ExpireTime.Unix() > 0 {
			labels := make(prometheus.Labels, len(cm.labels)+1)
			for k, v := range cm.labels {
				labels[k] = v
			}
			labels["host"] = s.Hostname

			cm.sslExpireTime.With(labels).Set(float64(s.SSLCert.ExpireTime.Unix()))
		}
	}
}

// RemoveMetrics removes metrics for hostnames not available anymore
func (cm *Controller) RemoveMetrics(hosts []string, registry prometheus.Gatherer) {
	mfs, err := registry.Gather()
	if err != nil {
		glog.Errorf("Error gathering metrics: %v", err)
		return
	}

	glog.V(2).Infof("removing SSL certificate metrics for %v hosts", hosts)
	toRemove := sets.NewString(hosts...)

	for _, mf := range mfs {
		metricName := mf.GetName()
		if fmt.Sprintf("%v_ssl_expire_time_seconds", PrometheusNamespace) != metricName {
			continue
		}

		for _, m := range mf.GetMetric() {
			labels := make(map[string]string, len(m.GetLabel()))
			for _, labelPair := range m.GetLabel() {
				labels[*labelPair.Name] = *labelPair.Value
			}

			// remove labels that are constant
			deleteConstants(labels)

			host, ok := labels["host"]
			if !ok {
				continue
			}

			if !toRemove.Has(host) {
				continue
			}

			glog.V(2).Infof("Removing prometheus metric from gauge %v for host %v", metricName, host)
			removed := cm.sslExpireTime.Delete(labels)
			if !removed {
				glog.V(2).Infof("metric %v for host %v with labels not removed: %v", metricName, host, labels)
			}
		}
	}
}
