package handler

import (
	"sort"
	"strings"
	"crypto/sha1"
	"strconv"
	"bytes"

	"github.com/sirupsen/logrus"
	"github.com/stakater/Reloader/pkg/kube"
	"k8s.io/api/core/v1"
	"k8s.io/client-go/kubernetes"
	meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

const (
	updateOnChangeAnnotation = "reloader.stakater.com/update-on-change"
)

// ResourceUpdatedHandler contains updated objects
type ResourceUpdatedHandler struct {
	Resource    interface{}
	OldResource interface{}
}

// Handle processes the updated resource
func (r ResourceUpdatedHandler) Handle() error {
	if r.Resource == nil || r.OldResource == nil {
		logrus.Errorf("Error in Handler")
	} else {
		logrus.Infof("Detected changes in object %s", r.Resource)
		// process resource based on its type
		if _, ok := r.Resource.(*v1.ConfigMap); ok {
			logrus.Infof("Performing 'Updated' action for resource of type 'configmap'")
			rollingUpgrade(r, "configmaps", "deployments")
			rollingUpgrade(r, "configmaps", "daemonsets")
			rollingUpgrade(r, "configmaps", "statefulSets")
		} else if _, ok := r.Resource.(*v1.Secret); ok {
			logrus.Infof("Performing 'Updated' action for resource of type 'secret'")
			rollingUpgrade(r, "secrets", "deployments")
			rollingUpgrade(r, "secrets", "daemonsets")
			rollingUpgrade(r, "secrets", "statefulSets")
		} else {
			logrus.Warnf("Invalid resource: Resource should be 'Secret' or 'Configmap' but found %v", r.Resource)
		}
	}
	return nil
}

func rollingUpgrade(r ResourceUpdatedHandler, resourceType string, rollingUpgradeType string){
	client, err := kube.GetClient()
	if err != nil {
		logrus.Fatalf("Unable to create Kubernetes client error = %v", err)
	}
	var namespace, name, sshData, envName string
	if resourceType == "configmaps" {
		namespace = r.Resource.(*v1.ConfigMap).Namespace
		name = r.Resource.(*v1.ConfigMap).Name
		sshData = convertConfigmapToSHA(r.Resource.(*v1.ConfigMap))
		envName = "_CONFIGMAP"
	} else if resourceType == "secrets" {
		namespace = r.Resource.(*v1.Secret).Namespace
		name = r.Resource.(*v1.Secret).Name
		sshData = convertSecretToSHA(r.Resource.(*v1.Secret))
		envName = "_SECRET"
	}

	if rollingUpgradeType == "deployments" {
		rollingUpgradeForDeployment(client, r, namespace, name, sshData, envName)
	} else if rollingUpgradeType == "daemonsets" {
		rollingUpgradeForDaemonSets(client, r, namespace, name, sshData, envName)
	} else if rollingUpgradeType == "statefulSets" {
		rollingUpgradeForStatefulSets(client, r, namespace, name, sshData, envName)
	}
}

func rollingUpgradeForDeployment(client kubernetes.Interface, r ResourceUpdatedHandler, namespace string, name string, sshData string, envName string) error {
	deployments, err := client.ExtensionsV1beta1().Deployments(namespace).List(meta_v1.ListOptions{})
	if err != nil {
		logrus.Fatalf("Failed to list deployments %v", err)
	}
	for _, d := range deployments.Items {
		containers := d.Spec.Template.Spec.Containers
		// match deployments with the correct annotation
		annotationValue := d.ObjectMeta.Annotations[updateOnChangeAnnotation]
		if annotationValue != "" {
			values := strings.Split(annotationValue, ",")
			matches := false
			for _, value := range values {
				if value == name {
					matches = true
					break
				}
			}
			if matches {
				updated := updateContainers(containers, annotationValue, sshData, envName)

				if !updated {
					logrus.Warnf("Rolling upgrade did not happen")
				} else {
					// update the deployment
					_, err := client.ExtensionsV1beta1().Deployments(namespace).Update(&d)
					if err != nil {
						logrus.Fatalf("Update deployment failed %v", err)
					}
					logrus.Infof("Updated Deployment %s", d.Name)
				}
			}
		}
	}
	return nil
}


func rollingUpgradeForDaemonSets(client kubernetes.Interface, r ResourceUpdatedHandler, namespace string, name string, sshData string, envName string) error {
	daemonSets, err := client.ExtensionsV1beta1().DaemonSets(namespace).List(meta_v1.ListOptions{})
	if err != nil {
		logrus.Fatalf("Failed to list daemonSets %v", err)
	}
	for _, d := range daemonSets.Items {
		containers := d.Spec.Template.Spec.Containers
		// match daemonSets with the correct annotation
		annotationValue := d.ObjectMeta.Annotations[updateOnChangeAnnotation]
		if annotationValue != "" {
			values := strings.Split(annotationValue, ",")
			matches := false
			for _, value := range values {
				if value == name {
					matches = true
					break
				}
			}
			if matches {
				updated := updateContainers(containers, annotationValue, sshData, envName)

				if !updated {
					logrus.Warnf("Rolling upgrade did not happen")
				} else {
					// update the daemonSet
					_, err := client.ExtensionsV1beta1().DaemonSets(namespace).Update(&d)
					if err != nil {
						logrus.Fatalf("Update daemonSet failed %v", err)
					}
					logrus.Infof("Updated daemonSet %s", d.Name)
				}
			}
		}
	}
	return nil
}

func rollingUpgradeForStatefulSets(client kubernetes.Interface, r ResourceUpdatedHandler, namespace string, name string, sshData string, envName string) error {
	statefulSets, err := client.AppsV1beta1().StatefulSets(namespace).List(meta_v1.ListOptions{})
	if err != nil {
		logrus.Fatalf("Failed to list statefulSets %v", err)
	}
	for _, d := range statefulSets.Items {
		containers := d.Spec.Template.Spec.Containers
		// match statefulSets with the correct annotation
		annotationValue := d.ObjectMeta.Annotations[updateOnChangeAnnotation]
		if annotationValue != "" {
			values := strings.Split(annotationValue, ",")
			matches := false
			for _, value := range values {
				if value == name {
					matches = true
					break
				}
			}
			if matches {
				updated := updateContainers(containers, annotationValue, sshData, envName)

				if !updated {
					logrus.Warnf("Rolling upgrade did not happen")
				} else {
					// update the statefulSet
					_, err := client.AppsV1beta1().StatefulSets(namespace).Update(&d)
					if err != nil {
						logrus.Fatalf("Update statefulSet failed %v", err)
					}
					logrus.Infof("Updated statefulSet %s", d.Name)
				}
			}
		}
	}
	return nil
}

func updateContainers(containers []v1.Container, annotationValue, sshData string, resourceType string) bool {
	// we can have multiple resourceTypes to update
	updated := false
	resourceTypes := strings.Split(annotationValue, ",")
	for _, nameToUpdate := range resourceTypes {
		envar := "STAKATER_" + convertToEnvVarName(nameToUpdate) + resourceType

		for i := range containers {
			envs := containers[i].Env
			matched := false
			for j := range envs {
				if envs[j].Name == envar {
					matched = true
					if envs[j].Value != sshData {
						logrus.Infof("Updating %s to %s", envar, sshData)
						envs[j].Value = sshData
						updated = true
					}
				}
			}
			// if no existing env var exists lets create one
			if !matched {
				e := v1.EnvVar{
					Name:  envar,
					Value: sshData,
				}
				containers[i].Env = append(containers[i].Env, e)
				updated = true
			}
		}
	}
	return updated
}

// convertToEnvVarName converts the given text into a usable env var
// removing any special chars with '_'
func convertToEnvVarName(text string) string {
	var buffer bytes.Buffer
	upper := strings.ToUpper(text)
	lastCharValid := false
	for i := 0; i < len(upper); i++ {
		ch := upper[i]
		if (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9') {
			buffer.WriteString(string(ch))
			lastCharValid = true
		} else {
			if lastCharValid {
				buffer.WriteString("_")
			}
			lastCharValid = false
		}
	}
	return buffer.String()
}

func convertConfigmapToSHA(cm *v1.ConfigMap) string {
	values := []string{}
	for k, v := range cm.Data {
		values = append(values, k+"="+v)
	}
	sort.Strings(values)
	bytes := []byte(strings.Join(values, ";"))
	sha := generateSHA(bytes)
	return sha
}

func convertSecretToSHA(se *v1.Secret) string {
	values := []string{}
	for k, v := range se.Data {
		values = append(values, k+"="+string(v[:]))
	}
	sort.Strings(values)
	bytes := []byte(strings.Join(values, ";"))
	sha := generateSHA(bytes)
	return sha
}

func generateSHA(bytes []byte) string {
	hasher := sha1.New()
	sha, err := hasher.Write(bytes)
	if err != nil {
		logrus.Fatalf("Error while generating SHA hash of data %v", err)
	}
	return strconv.Itoa(sha)
}