package podsecuritypolicy

import (
	"fmt"

	v13 "github.com/rancher/types/apis/core/v1"
	"github.com/rancher/types/apis/extensions/v1beta1"
	"github.com/rancher/types/apis/management.cattle.io/v3"
	v12 "github.com/rancher/types/apis/rbac.authorization.k8s.io/v1"
	"github.com/rancher/types/config"
	"github.com/sirupsen/logrus"
	"k8s.io/api/core/v1"
	rbac "k8s.io/api/rbac/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/client-go/tools/cache"
)

const psptpbByTargetProjectNameAnnotationIndex = "podsecuritypolicy.rbac.user.cattle.io/psptpb-by-project-id"
const roleBindingByServiceAccountIndex = "podsecuritypolicy.rbac.user.cattle.io/role-binding-by-service-account"
const psptpbRoleBindingAnnotation = "podsecuritypolicy.rbac.user.cattle.io/psptpb-role-binding"

// RegisterServiceAccount ensures that:
// 	1. Each namespace has a pod security policy assigned to a role if:
//		a. its project has a PSPT assigned to it
//		OR
//		b. its cluster has a default PSPT assigned to it
//  2. PSPs are bound to their associated service accounts via a cluster role binding
func RegisterServiceAccount(context *config.UserContext) {
	logrus.Infof("registering podsecuritypolicy serviceaccount handler for cluster %v", context.ClusterName)

	psptpbInformer := context.Management.Management.PodSecurityPolicyTemplateProjectBindings("").Controller().Informer()
	psptpbIndexers := map[string]cache.IndexFunc{
		psptpbByTargetProjectNameAnnotationIndex: psptpbByTargetProjectName,
	}
	psptpbInformer.AddIndexers(psptpbIndexers)

	roleBindingInformer := context.RBAC.RoleBindings("").Controller().Informer()
	roleBindingIndexers := map[string]cache.IndexFunc{
		roleBindingByServiceAccountIndex: roleBindingByServiceAccount,
	}
	roleBindingInformer.AddIndexers(roleBindingIndexers)

	m := &serviceAccountManager{
		clusterName:        context.ClusterName,
		clusters:           context.Management.Management.Clusters(""),
		pspts:              context.Management.Management.PodSecurityPolicyTemplates(""),
		roleBindings:       context.RBAC.RoleBindings(""),
		roleBindingIndexer: roleBindingInformer.GetIndexer(),

		policies:      context.Extensions.PodSecurityPolicies(""),
		psptpbIndexer: psptpbInformer.GetIndexer(),

		clusterLister:     context.Management.Management.Clusters("").Controller().Lister(),
		psptLister:        context.Management.Management.PodSecurityPolicyTemplates("").Controller().Lister(),
		templateLister:    context.Management.Management.PodSecurityPolicyTemplates("").Controller().Lister(),
		policyLister:      context.Extensions.PodSecurityPolicies("").Controller().Lister(),
		roleBindingLister: context.RBAC.RoleBindings("").Controller().Lister(),
		roleLister:        context.RBAC.ClusterRoles("").Controller().Lister(),
		namespaceLister:   context.Core.Namespaces("").Controller().Lister(),
		projectLister:     context.Management.Management.Projects("").Controller().Lister(),
		psptpbLister: context.Management.Management.PodSecurityPolicyTemplateProjectBindings("").
			Controller().Lister(),
	}

	context.Core.ServiceAccounts("").AddHandler("ServiceAccountLifecycleHandler", m.sync)
}

func psptpbByTargetProjectName(obj interface{}) ([]string, error) {
	psptpb, ok := obj.(*v3.PodSecurityPolicyTemplateProjectBinding)
	if !ok || psptpb.TargetProjectName == "" {
		return []string{}, nil
	}

	return []string{psptpb.TargetProjectName}, nil
}

func roleBindingByServiceAccount(obj interface{}) ([]string, error) {
	roleBinding, ok := obj.(*rbac.RoleBinding)
	if !ok || len(roleBinding.Subjects) != 1 ||
		roleBinding.Subjects[0].Name == "" ||
		roleBinding.Subjects[0].Namespace == "" {
		return []string{}, nil
	}

	subject := roleBinding.Subjects[0]
	return []string{subject.Namespace + "-" + subject.Name}, nil
}

type serviceAccountManager struct {
	clusterName        string
	clusterLister      v3.ClusterLister
	clusters           v3.ClusterInterface
	pspts              v3.PodSecurityPolicyTemplateInterface
	psptLister         v3.PodSecurityPolicyTemplateLister
	psptpbIndexer      cache.Indexer
	templateLister     v3.PodSecurityPolicyTemplateLister
	policyLister       v1beta1.PodSecurityPolicyLister
	roleBindingLister  v12.RoleBindingLister
	roleBindings       v12.RoleBindingInterface
	roleBindingIndexer cache.Indexer
	policies           v1beta1.PodSecurityPolicyInterface
	roleLister         v12.ClusterRoleLister
	namespaceLister    v13.NamespaceLister
	projectLister      v3.ProjectLister
	psptpbLister       v3.PodSecurityPolicyTemplateProjectBindingLister
}

func (m *serviceAccountManager) sync(key string, obj *v1.ServiceAccount) error {
	if obj == nil {
		// do nothing
		return nil
	}

	namespace, err := m.namespaceLister.Get("", obj.Namespace)
	if err != nil {
		return fmt.Errorf("error getting projects: %v", err)
	}

	if namespace.Annotations[projectIDAnnotation] == "" {
		return nil
	}

	psptpbs, err := m.psptpbIndexer.ByIndex(psptpbByTargetProjectNameAnnotationIndex, namespace.Annotations[projectIDAnnotation])
	if err != nil {
		return fmt.Errorf("error getting psptpbs: %v", err)
	}

	onePSPTPBExists := false
	desiredBindings := map[string]*v3.PodSecurityPolicyTemplateProjectBinding{}

	for _, rawPSPTPB := range psptpbs {
		psptpb, ok := rawPSPTPB.(*v3.PodSecurityPolicyTemplateProjectBinding)
		if !ok {
			return fmt.Errorf("could not convert to *v3.PodSecurityPolicyTemplateProjectBinding: %v", rawPSPTPB)
		}

		if psptpb.DeletionTimestamp != nil {
			continue
		}

		onePSPTPBExists = true

		key := getClusterRoleName(psptpb.PodSecurityPolicyTemplateName)
		desiredBindings[key] = psptpb
	}

	originalDesiredBindingsLen := len(desiredBindings)

	roleBindings, err := m.roleBindingIndexer.ByIndex(roleBindingByServiceAccountIndex, obj.Namespace+"-"+obj.Name)
	if err != nil {
		return fmt.Errorf("error getting role bindings: %v", err)
	}

	cluster, err := m.clusterLister.Get("", m.clusterName)
	if err != nil {
		return fmt.Errorf("error getting cluster: %v", err)
	}

	for _, rawRoleBinding := range roleBindings {
		roleBinding, ok := rawRoleBinding.(*rbac.RoleBinding)
		if !ok {
			return fmt.Errorf("could not convert to *rbac2.RoleBinding: %v", rawRoleBinding)
		}

		key := roleBinding.RoleRef.Name

		if desiredBindings[key] == nil && okToDelete(obj, roleBinding, cluster, originalDesiredBindingsLen) {
			err = m.roleBindings.DeleteNamespaced(roleBinding.Namespace, roleBinding.Name, &metav1.DeleteOptions{})
			if err != nil {
				return fmt.Errorf("error deleting role binding: %v", err)
			}
		} else {
			delete(desiredBindings, key)
		}
	}

	for clusterRoleName, desiredBinding := range desiredBindings {
		roleBindingName := getRoleBindingName(obj, clusterRoleName)
		_, err = m.roleBindings.Create(&rbac.RoleBinding{
			ObjectMeta: metav1.ObjectMeta{
				Name:      roleBindingName,
				Namespace: obj.Namespace,
				Annotations: map[string]string{
					podSecurityPolicyTemplateParentAnnotation: desiredBinding.PodSecurityPolicyTemplateName,
					psptpbRoleBindingAnnotation:               "true",
				},
				OwnerReferences: []metav1.OwnerReference{
					{
						APIVersion: "v1",
						Name:       obj.Name,
						Kind:       "ServiceAccount",
						UID:        obj.UID,
					},
				},
			},
			TypeMeta: metav1.TypeMeta{
				Kind: "RoleBinding",
			},
			RoleRef: rbac.RoleRef{
				APIGroup: apiGroup,
				Name:     clusterRoleName,
				Kind:     "ClusterRole",
			},
			Subjects: []rbac.Subject{
				{
					Kind:      "ServiceAccount",
					Name:      obj.Name,
					Namespace: obj.Namespace,
				},
			},
		})
		if err != nil {
			return fmt.Errorf("error creating binding: %v", err)
		}
	}

	if !onePSPTPBExists {
		// create default pspt role binding if it is set
		clusterRoleName := getClusterRoleName(cluster.Spec.DefaultPodSecurityPolicyTemplateName)
		roleBindingName := getDefaultRoleBindingName(obj, clusterRoleName)

		if cluster.Spec.DefaultPodSecurityPolicyTemplateName != "" {
			_, err := m.roleBindingLister.Get(obj.Namespace, roleBindingName)
			if err != nil {
				if errors.IsNotFound(err) {
					_, err = m.roleBindings.Create(&rbac.RoleBinding{
						ObjectMeta: metav1.ObjectMeta{
							Name:      roleBindingName,
							Namespace: obj.Namespace,
							Annotations: map[string]string{
								podSecurityPolicyTemplateParentAnnotation: cluster.Spec.DefaultPodSecurityPolicyTemplateName,
								psptpbRoleBindingAnnotation:               "true",
							},
							OwnerReferences: []metav1.OwnerReference{
								{
									APIVersion: "v1",
									Name:       obj.Name,
									Kind:       "ServiceAccount",
									UID:        obj.UID,
								},
							},
						},
						TypeMeta: metav1.TypeMeta{
							Kind: "RoleBinding",
						},
						RoleRef: rbac.RoleRef{
							APIGroup: apiGroup,
							Name:     clusterRoleName,
							Kind:     "ClusterRole",
						},
						Subjects: []rbac.Subject{
							{
								Kind:      "ServiceAccount",
								Name:      obj.Name,
								Namespace: obj.Namespace,
							},
						},
					})
					if err != nil {
						return fmt.Errorf("error creating role binding: %v", err)
					}
				} else {
					return fmt.Errorf("error getting role binding %v: %v", roleBindingName, err)
				}
			}
		}
	}

	return nil
}

func okToDelete(svcAct *v1.ServiceAccount, rb *rbac.RoleBinding, cluster *v3.Cluster,
	originalDesiredBindingsLen int) bool {
	// This is not a role binding this logic should manage so exit immediately
	if rb.Annotations[psptpbRoleBindingAnnotation] == "" {
		return false
	}

	// No default PSPT is set so its ok to delete this if its a normal rolebinding or a leftover default PSPT binding
	if cluster.Spec.DefaultPodSecurityPolicyTemplateName == "" {
		return true
	}

	// at least one PSPTPB exists so we need to delete all default PSPT bindings
	if originalDesiredBindingsLen > 0 {
		return true
	}

	// the default PSPT has changed so we need to clean it up before creating the new one
	if getDefaultRoleBindingName(svcAct,
		getClusterRoleName(cluster.Spec.DefaultPodSecurityPolicyTemplateName)) != rb.Name {
		return true
	}

	return false
}

func getRoleBindingName(obj *v1.ServiceAccount, clusterRoleName string) string {
	return fmt.Sprintf("%v-%v-%v-binding", obj.Name, obj.Namespace, clusterRoleName)
}

func getDefaultRoleBindingName(obj *v1.ServiceAccount, clusterRoleName string) string {
	return fmt.Sprintf("default-%v-%v-%v-binding", obj.Name, obj.Namespace, clusterRoleName)
}

func getClusterRoleName(podSecurityPolicyTemplateName string) string {
	return fmt.Sprintf("%v-clusterrole", podSecurityPolicyTemplateName)
}

func resyncServiceAccounts(serviceAccountLister v13.ServiceAccountLister,
	serviceAccountController v13.ServiceAccountController, namespace string) error {
	serviceAccounts, err := serviceAccountLister.List(namespace, labels.Everything())
	if err != nil {
		return fmt.Errorf("error getting service accounts: %v", err)
	}

	for _, account := range serviceAccounts {
		serviceAccountController.Enqueue(account.Namespace, account.Name)
	}

	return nil
}