/*
Copyright 2020 The Flux 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 controller

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	flaggerv1 "github.com/fluxcd/flagger/pkg/apis/flagger/v1beta1"
	"github.com/fluxcd/flagger/pkg/metrics/observers"
	"github.com/fluxcd/flagger/pkg/metrics/providers"
	serving "knative.dev/serving/pkg/apis/serving/v1"
)

const (
	MetricsProviderServiceSuffix = ":service"
)

// to be called during canary initialization
func (c *Controller) checkMetricProviderAvailability(canary *flaggerv1.Canary) error {
	for _, metric := range canary.GetAnalysis().Metrics {
		if metric.Name == "request-success-rate" || metric.Name == "request-duration" {
			observerFactory := c.observerFactory
			if canary.Spec.MetricsServer != "" {
				var err error
				observerFactory, err = observers.NewFactory(canary.Spec.MetricsServer)
				if err != nil {
					return fmt.Errorf("error building Prometheus client for %s %v", canary.Spec.MetricsServer, err)
				}
			}
			if ok, err := observerFactory.Client.IsOnline(); !ok || err != nil {
				return fmt.Errorf("prometheus not avaiable: %v", err)
			}
			continue
		}

		if metric.TemplateRef != nil {
			namespace := canary.Namespace
			if metric.TemplateRef.Namespace != canary.Namespace && metric.TemplateRef.Namespace != "" {
				namespace = metric.TemplateRef.Namespace
			}

			template, err := c.flaggerInformers.MetricInformer.Lister().MetricTemplates(namespace).Get(metric.TemplateRef.Name)
			if err != nil {
				return fmt.Errorf("metric template %s.%s error: %v", metric.TemplateRef.Name, namespace, err)
			}

			var credentials map[string][]byte
			if template.Spec.Provider.SecretRef != nil {
				secret, err := c.kubeClient.CoreV1().Secrets(namespace).Get(context.TODO(), template.Spec.Provider.SecretRef.Name, metav1.GetOptions{})
				if err != nil {
					return fmt.Errorf("metric template %s.%s secret %s error: %v",
						metric.TemplateRef.Name, namespace, template.Spec.Provider.SecretRef.Name, err)
				}
				credentials = secret.Data
			}

			factory := providers.Factory{}
			provider, err := factory.Provider(metric.Interval, template.Spec.Provider, credentials, c.kubeConfig)
			if err != nil {
				return fmt.Errorf("metric template %s.%s provider %s error: %v",
					metric.TemplateRef.Name, namespace, template.Spec.Provider.Type, err)
			}

			if ok, err := provider.IsOnline(); !ok || err != nil {
				return fmt.Errorf("%v in metric template %s.%s not avaiable: %v", template.Spec.Provider.Type,
					template.Name, template.Namespace, err)
			}
		}
	}
	c.recordEventInfof(canary, "all the metrics providers are available!")
	return nil
}

func (c *Controller) runBuiltinMetricChecks(canary *flaggerv1.Canary) bool {
	// override the global provider if one is specified in the canary spec
	var metricsProvider string
	// set the metrics provider to Crossover Prometheus when Crossover is the mesh provider
	// For example, `crossover` metrics provider should be used for `smi:crossover` mesh provider
	if strings.Contains(c.meshProvider, "crossover") {
		metricsProvider = "crossover"
	} else {
		metricsProvider = c.meshProvider
	}

	if canary.Spec.Provider != "" {
		metricsProvider = canary.Spec.Provider

		// set the metrics provider to Linkerd Prometheus when Linkerd is the default mesh provider
		if strings.Contains(c.meshProvider, "linkerd") {
			metricsProvider = "linkerd"
		}
	}
	// set the metrics provider to query Prometheus for the canary Kubernetes service if the canary target is Service
	if canary.Spec.TargetRef.Kind == "Service" && !canary.Spec.TargetRef.IsKnativeService() {
		metricsProvider = metricsProvider + MetricsProviderServiceSuffix
	}

	var knativeService *serving.Service
	if canary.Spec.Provider == flaggerv1.KnativeProvider || c.meshProvider == flaggerv1.KnativeProvider {
		var err error
		knativeService, err = c.knativeClient.ServingV1().Services(canary.Namespace).Get(context.TODO(), canary.Spec.TargetRef.Name, metav1.GetOptions{})
		if err != nil {
			c.recordEventErrorf(canary, "Error fetching Knative service %s/%s %v", canary.Namespace, canary.Spec.TargetRef.Name, err)
			return false
		}
	}

	// create observer based on the mesh provider
	observerFactory := c.observerFactory

	// override the global metrics server if one is specified in the canary spec
	if canary.Spec.MetricsServer != "" {
		var err error
		observerFactory, err = observers.NewFactory(canary.Spec.MetricsServer)
		if err != nil {
			c.recordEventErrorf(canary, "Error building Prometheus client for %s %v", canary.Spec.MetricsServer, err)
			return false
		}
	}
	observer := observerFactory.Observer(metricsProvider)

	// run metrics checks
	for _, metric := range canary.GetAnalysis().Metrics {
		if metric.Interval == "" {
			metric.Interval = canary.GetMetricInterval()
		}

		if metric.Name == "request-success-rate" {
			model := toMetricModel(canary, metric.Interval, metric.TemplateVariables)
			if knativeService != nil {
				model.Route = knativeService.Status.LatestCreatedRevisionName
			}
			val, err := observer.GetRequestSuccessRate(model)
			if err != nil {
				if errors.Is(err, providers.ErrNoValuesFound) {
					c.recordEventWarningf(canary,
						"Halt advancement no values found for %s metric %s probably %s.%s is not receiving traffic: %v",
						metricsProvider, metric.Name, canary.Spec.TargetRef.Name, canary.Namespace, err)
				} else {
					c.recordEventErrorf(canary, "Prometheus query failed: %v", err)
				}
				return false
			}
			c.recorder.SetAnalysis(canary, metric.Name, val)
			if metric.ThresholdRange != nil {
				tr := *metric.ThresholdRange
				if tr.Min != nil && val < *tr.Min {
					c.recordEventWarningf(canary, "Halt %s.%s advancement success rate %.2f%% < %v%%",
						canary.Name, canary.Namespace, val, *tr.Min)
					return false
				}
				if tr.Max != nil && val > *tr.Max {
					c.recordEventWarningf(canary, "Halt %s.%s advancement success rate %.2f%% > %v%%",
						canary.Name, canary.Namespace, val, *tr.Max)
					return false
				}
			} else if metric.Threshold > val {
				c.recordEventWarningf(canary, "Halt %s.%s advancement success rate %.2f%% < %v%%",
					canary.Name, canary.Namespace, val, metric.Threshold)
				return false
			}
		}

		if metric.Name == "request-duration" {
			model := toMetricModel(canary, metric.Interval, metric.TemplateVariables)
			if knativeService != nil {
				model.Route = knativeService.Status.LatestCreatedRevisionName
			}
			val, err := observer.GetRequestDuration(model)
			if err != nil {
				if errors.Is(err, providers.ErrNoValuesFound) {
					c.recordEventWarningf(canary, "Halt advancement no values found for %s metric %s probably %s.%s is not receiving traffic",
						metricsProvider, metric.Name, canary.Spec.TargetRef.Name, canary.Namespace)
				} else {
					c.recordEventErrorf(canary, "Prometheus query failed: %v", err)
				}
				return false
			}
			c.recorder.SetAnalysis(canary, metric.Name, val.Seconds())
			if metric.ThresholdRange != nil {
				tr := *metric.ThresholdRange
				if tr.Min != nil && val < time.Duration(*tr.Min)*time.Millisecond {
					c.recordEventWarningf(canary, "Halt %s.%s advancement request duration %v < %v",
						canary.Name, canary.Namespace, val, time.Duration(*tr.Min)*time.Millisecond)
					return false
				}
				if tr.Max != nil && val > time.Duration(*tr.Max)*time.Millisecond {
					c.recordEventWarningf(canary, "Halt %s.%s advancement request duration %v > %v",
						canary.Name, canary.Namespace, val, time.Duration(*tr.Max)*time.Millisecond)
					return false
				}
			} else if val > time.Duration(metric.Threshold)*time.Millisecond {
				c.recordEventWarningf(canary, "Halt %s.%s advancement request duration %v > %v",
					canary.Name, canary.Namespace, val, time.Duration(metric.Threshold)*time.Millisecond)
				return false
			}
		}

		// in-line PromQL
		if metric.Query != "" {
			model := toMetricModel(canary, metric.Interval, metric.TemplateVariables)
			if knativeService != nil {
				model.Route = knativeService.Status.LatestCreatedRevisionName
			}
			query, err := observers.RenderQuery(metric.Query, model)
			val, err := observerFactory.Client.RunQuery(query)
			if err != nil {
				if errors.Is(err, providers.ErrNoValuesFound) {
					c.recordEventWarningf(canary, "Halt advancement no values found for metric: %s",
						metric.Name)
				} else {
					c.recordEventErrorf(canary, "Prometheus query failed for %s: %v", metric.Name, err)
				}
				return false
			}
			c.recorder.SetAnalysis(canary, metric.Name, val)
			if metric.ThresholdRange != nil {
				tr := *metric.ThresholdRange
				if tr.Min != nil && val < *tr.Min {
					c.recordEventWarningf(canary, "Halt %s.%s advancement %s %.2f < %v",
						canary.Name, canary.Namespace, metric.Name, val, *tr.Min)
					return false
				}
				if tr.Max != nil && val > *tr.Max {
					c.recordEventWarningf(canary, "Halt %s.%s advancement %s %.2f > %v",
						canary.Name, canary.Namespace, metric.Name, val, *tr.Max)
					return false
				}
			} else if val > metric.Threshold {
				c.recordEventWarningf(canary, "Halt %s.%s advancement %s %.2f > %v",
					canary.Name, canary.Namespace, metric.Name, val, metric.Threshold)
				return false
			}
		}
	}

	return true
}

func (c *Controller) runMetricChecks(canary *flaggerv1.Canary) bool {
	var knativeService *serving.Service
	if canary.Spec.Provider == flaggerv1.KnativeProvider || c.meshProvider == flaggerv1.KnativeProvider {
		var err error
		knativeService, err = c.knativeClient.ServingV1().Services(canary.Namespace).Get(context.TODO(), canary.Spec.TargetRef.Name, metav1.GetOptions{})
		if err != nil {
			c.recordEventErrorf(canary, "Error fetching Knative service %s/%s %v", canary.Namespace, canary.Spec.TargetRef.Name, err)
			return false
		}
	}

	for _, metric := range canary.GetAnalysis().Metrics {
		if metric.TemplateRef != nil {
			namespace := canary.Namespace
			if metric.TemplateRef.Namespace != canary.Namespace && metric.TemplateRef.Namespace != "" {
				namespace = metric.TemplateRef.Namespace
			}

			template, err := c.flaggerInformers.MetricInformer.Lister().MetricTemplates(namespace).Get(metric.TemplateRef.Name)
			if err != nil {
				c.recordEventErrorf(canary, "Metric template %s.%s error: %v", metric.TemplateRef.Name, namespace, err)
				return false
			}

			var credentials map[string][]byte
			if template.Spec.Provider.SecretRef != nil {
				secret, err := c.kubeClient.CoreV1().Secrets(namespace).Get(context.TODO(), template.Spec.Provider.SecretRef.Name, metav1.GetOptions{})
				if err != nil {
					c.recordEventErrorf(canary, "Metric template %s.%s secret %s error: %v",
						metric.TemplateRef.Name, namespace, template.Spec.Provider.SecretRef.Name, err)
					return false
				}
				credentials = secret.Data
			}

			factory := providers.Factory{}
			provider, err := factory.Provider(metric.Interval, template.Spec.Provider, credentials, c.kubeConfig)
			if err != nil {
				c.recordEventErrorf(canary, "Metric template %s.%s provider %s error: %v",
					metric.TemplateRef.Name, namespace, template.Spec.Provider.Type, err)
				return false
			}

			model := toMetricModel(canary, metric.Interval, metric.TemplateVariables)
			if knativeService != nil {
				model.Route = knativeService.Status.LatestCreatedRevisionName
			}
			query, err := observers.RenderQuery(template.Spec.Query, model)
			c.logger.With("canary", fmt.Sprintf("%s.%s", canary.Name, namespace)).
				Debugf("Metric template %s.%s query: %s", metric.TemplateRef.Name, namespace, query)
			if err != nil {
				c.recordEventErrorf(canary, "Metric template %s.%s query render error: %v",
					metric.TemplateRef.Name, namespace, err)
				return false
			}

			val, err := provider.RunQuery(query)
			if err != nil {
				if errors.Is(err, providers.ErrNoValuesFound) {
					c.recordEventWarningf(canary, "Halt advancement no values found for custom metric: %s: %v",
						metric.Name, err)
				} else {
					c.recordEventErrorf(canary, "Metric query failed for %s: %v", metric.Name, err)
				}
				return false
			}

			c.recorder.SetAnalysis(canary, metric.Name, val)

			if metric.ThresholdRange != nil {
				tr := *metric.ThresholdRange
				if tr.Min != nil && val < *tr.Min {
					c.recordEventWarningf(canary, "Halt %s.%s advancement %s %.2f < %v",
						canary.Name, canary.Namespace, metric.Name, val, *tr.Min)
					return false
				}
				if tr.Max != nil && val > *tr.Max {
					c.recordEventWarningf(canary, "Halt %s.%s advancement %s %.2f > %v",
						canary.Name, canary.Namespace, metric.Name, val, *tr.Max)
					return false
				}
			} else if val > metric.Threshold {
				c.recordEventWarningf(canary, "Halt %s.%s advancement %s %.2f > %v",
					canary.Name, canary.Namespace, metric.Name, val, metric.Threshold)
				return false
			}
		} else if metric.Name != "request-success-rate" && metric.Name != "request-duration" && metric.Query == "" {
			c.recordEventErrorf(canary, "Metric query failed for no usable metrics template and query were configured")
			return false
		}
	}

	return true
}

func toMetricModel(r *flaggerv1.Canary, interval string, variables map[string]string) flaggerv1.MetricTemplateModel {
	service := r.Spec.TargetRef.Name
	if r.Spec.Service.Name != "" {
		service = r.Spec.Service.Name
	}
	ingress := r.Spec.TargetRef.Name
	if r.Spec.IngressRef != nil {
		ingress = r.Spec.IngressRef.Name
	}
	route := r.Spec.TargetRef.Name
	if r.Spec.RouteRef != nil {
		route = r.Spec.RouteRef.Name
	}
	return flaggerv1.MetricTemplateModel{
		Name:      r.Name,
		Namespace: r.Namespace,
		Target:    r.Spec.TargetRef.Name,
		Service:   service,
		Ingress:   ingress,
		Route:     route,
		Interval:  interval,
		Variables: variables,
	}
}