package rbac

import (
	"fmt"
	"reflect"
	"strings"

	"k8s.io/apimachinery/pkg/runtime"

	"github.com/pkg/errors"
	"github.com/rancher/norman/types/convert"
	"github.com/rancher/norman/types/slice"
	"github.com/rancher/types/apis/management.cattle.io/v3"
	"github.com/sirupsen/logrus"
	"k8s.io/api/core/v1"
	rbacv1 "k8s.io/api/rbac/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
)

const owner = "owner-user"

var globalResourcesNeededInProjects = []string{"persistentvolumes", "storageclasses"}

func newPRTBLifecycle(m *manager) *prtbLifecycle {
	return &prtbLifecycle{m: m}
}

type prtbLifecycle struct {
	m *manager
}

func (p *prtbLifecycle) Create(obj *v3.ProjectRoleTemplateBinding) (runtime.Object, error) {
	err := p.syncPRTB(obj)
	return obj, err
}

func (p *prtbLifecycle) Updated(obj *v3.ProjectRoleTemplateBinding) (runtime.Object, error) {
	err := p.syncPRTB(obj)
	return obj, err
}

func (p *prtbLifecycle) Remove(obj *v3.ProjectRoleTemplateBinding) (runtime.Object, error) {
	err := p.ensurePRTBDelete(obj)
	return obj, err
}

func (p *prtbLifecycle) syncPRTB(binding *v3.ProjectRoleTemplateBinding) error {
	if binding.RoleTemplateName == "" {
		logrus.Warnf("ProjectRoleTemplateBinding %v has no role template set. Skipping.", binding.Name)
		return nil
	}
	if binding.UserName == "" && binding.GroupPrincipalName == "" && binding.GroupName == "" {
		return nil
	}

	rt, err := p.m.rtLister.Get("", binding.RoleTemplateName)
	if err != nil {
		return errors.Wrapf(err, "couldn't get role template %v", binding.RoleTemplateName)
	}

	// Get namespaces belonging to project
	namespaces, err := p.m.nsIndexer.ByIndex(nsByProjectIndex, binding.ProjectName)
	if err != nil {
		return errors.Wrapf(err, "couldn't list namespaces with project ID %v", binding.ProjectName)
	}
	roles := map[string]*v3.RoleTemplate{}
	if err := p.m.gatherRoles(rt, roles); err != nil {
		return err
	}

	if err := p.m.ensureRoles(roles); err != nil {
		return errors.Wrap(err, "couldn't ensure roles")
	}

	for _, n := range namespaces {
		ns := n.(*v1.Namespace)
		if err := p.m.ensureProjectRoleBindings(ns.Name, roles, binding); err != nil {
			return errors.Wrapf(err, "couldn't ensure binding %v in %v", binding.Name, ns.Name)
		}
	}

	return p.reconcileProjectAccessToGlobalResources(binding, roles)
}

func (p *prtbLifecycle) ensurePRTBDelete(binding *v3.ProjectRoleTemplateBinding) error {
	// Get namespaces belonging to project
	namespaces, err := p.m.nsIndexer.ByIndex(nsByProjectIndex, binding.ProjectName)
	if err != nil {
		return errors.Wrapf(err, "couldn't list namespaces with project ID %v", binding.ProjectName)
	}

	set := labels.Set(map[string]string{rtbOwnerLabel: string(binding.UID)})
	for _, n := range namespaces {
		ns := n.(*v1.Namespace)
		bindingCli := p.m.workload.RBAC.RoleBindings(ns.Name)
		rbs, err := p.m.rbLister.List(ns.Name, set.AsSelector())
		if err != nil {
			return errors.Wrapf(err, "couldn't list rolebindings with selector %s", set.AsSelector())
		}

		for _, rb := range rbs {
			if err := bindingCli.Delete(rb.Name, &metav1.DeleteOptions{}); err != nil {
				if !apierrors.IsNotFound(err) {
					return errors.Wrapf(err, "error deleting rolebinding %v", rb.Name)
				}
			}
		}
	}

	return p.reconcileProjectAccessToGlobalResourcesForDelete(binding)
}

func (p *prtbLifecycle) reconcileProjectAccessToGlobalResources(binding *v3.ProjectRoleTemplateBinding, rts map[string]*v3.RoleTemplate) error {
	var role string
	var createNSPerms bool
	var roles []string
	if parts := strings.SplitN(binding.ProjectName, ":", 2); len(parts) == 2 && len(parts[1]) > 0 {
		projectName := parts[1]
		var roleVerb, roleSuffix string
		for _, r := range rts {
			for _, rule := range r.Rules {
				if slice.ContainsString(rule.Resources, "namespaces") && len(rule.ResourceNames) == 0 {
					if slice.ContainsString(rule.Verbs, "*") || slice.ContainsString(rule.Verbs, "create") {
						roleVerb = "*"
						createNSPerms = true
						break
					}
				}

			}
		}
		if roleVerb == "" {
			roleVerb = "get"
		}
		roleSuffix = projectNSVerbToSuffix[roleVerb]
		role = fmt.Sprintf(projectNSGetClusterRoleNameFmt, projectName, roleSuffix)
		roles = append(roles, role)

		for _, rt := range rts {
			for _, resource := range globalResourcesNeededInProjects {
				verbs, err := p.m.checkForGlobalResourceRules(rt, resource)
				if err != nil {
					return err
				}
				if len(verbs) > 0 {
					roleName, err := p.m.reconcileRoleForProjectAccessToGlobalResource(resource, rt, verbs)
					if err != nil {
						return err
					}
					roles = append(roles, roleName)
				}
			}
		}
	}

	if len(roles) == 0 {
		return nil
	}

	bindingCli := p.m.workload.RBAC.ClusterRoleBindings("")

	if createNSPerms {
		roles = append(roles, "create-ns")
		if nsRole, _ := p.m.crLister.Get("", "create-ns"); nsRole == nil {
			createNSRT, err := p.m.rtLister.Get("", "create-ns")
			if err != nil {
				return err
			}
			if err := p.m.ensureRoles(map[string]*v3.RoleTemplate{"create-ns": createNSRT}); err != nil && !apierrors.IsAlreadyExists(err) {
				return err
			}
		}
	}

	rtbUID := string(binding.UID)
	subject, err := buildSubjectFromRTB(binding)
	if err != nil {
		return err
	}
	for _, role := range roles {
		crbKey := rbRoleSubjectKey(role, subject)
		crbs, _ := p.m.crbIndexer.ByIndex(crbByRoleAndSubjectIndex, crbKey)
		if len(crbs) == 0 {
			logrus.Infof("Creating clusterRoleBinding for project access to global resource for subject %v role %v.", subject.Name, role)
			_, err := bindingCli.Create(&rbacv1.ClusterRoleBinding{
				ObjectMeta: metav1.ObjectMeta{
					GenerateName: "clusterrolebinding-",
					Labels: map[string]string{
						rtbUID: owner,
					},
				},
				Subjects: []rbacv1.Subject{subject},
				RoleRef: rbacv1.RoleRef{
					Kind: "ClusterRole",
					Name: role,
				},
			})
			if err != nil {
				return err
			}
		} else {
		CRBs:
			for _, obj := range crbs {
				crb, ok := obj.(*rbacv1.ClusterRoleBinding)
				if !ok {
					continue
				}

				for owner := range crb.Labels {
					if rtbUID == owner {
						continue CRBs
					}
				}

				crb = crb.DeepCopy()
				if crb.Labels == nil {
					crb.Labels = map[string]string{}
				}
				crb.Labels[rtbUID] = owner
				logrus.Infof("Updating clusterRoleBinding %v for project access to global resource for subject %v role %v.", crb.Name, subject.Name, role)
				_, err := bindingCli.Update(crb)
				if err != nil {
					return err
				}
			}
		}

	}
	return nil
}

func (p *prtbLifecycle) reconcileProjectAccessToGlobalResourcesForDelete(binding *v3.ProjectRoleTemplateBinding) error {
	bindingCli := p.m.workload.RBAC.ClusterRoleBindings("")
	rtbUID := string(binding.UID)
	set := labels.Set(map[string]string{rtbUID: owner})
	crbs, err := p.m.crbLister.List("", set.AsSelector())
	if err != nil {
		return err
	}

	for _, crb := range crbs {
		crb = crb.DeepCopy()
		for k, v := range crb.Labels {
			if k == rtbUID && v == owner {
				delete(crb.Labels, k)
			}
		}

		delete, err := p.m.noRemainingOwnerLabels(crb)
		if err != nil {
			return err
		}

		if delete {
			if err := bindingCli.Delete(crb.Name, &metav1.DeleteOptions{}); err != nil {
				if apierrors.IsNotFound(err) {
					continue
				}
				return err
			}
		} else {
			if _, err := bindingCli.Update(crb); err != nil {
				return err
			}
		}
	}

	return nil
}

func (m *manager) noRemainingOwnerLabels(crb *rbacv1.ClusterRoleBinding) (bool, error) {
	for k, v := range crb.Labels {
		if v == owner {
			if exists, err := m.ownerExists(k); exists || err != nil {
				return false, err
			}
		}

		if k == rtbOwnerLabel {
			if exists, err := m.ownerExists(v); exists || err != nil {
				return false, err
			}
		}
	}

	return true, nil
}

func (m *manager) ownerExists(uid interface{}) (bool, error) {
	prtbs, err := m.prtbIndexer.ByIndex(prtbByUIDIndex, convert.ToString(uid))
	return len(prtbs) > 0, err
}

// If the roleTemplate has rules granting access to non-namespaced (global) resource, return the verbs for those rules
func (m *manager) checkForGlobalResourceRules(role *v3.RoleTemplate, resource string) (map[string]bool, error) {
	var rules []rbacv1.PolicyRule
	if role.External {
		externalRole, err := m.crLister.Get("", role.Name)
		if err != nil && !apierrors.IsNotFound(err) {
			// dont error if it doesnt exist
			return nil, err
		}
		if externalRole != nil {
			rules = externalRole.Rules
		}
	} else {
		rules = role.Rules
	}

	verbs := map[string]bool{}
	for _, rule := range rules {
		if (slice.ContainsString(rule.Resources, resource) || slice.ContainsString(rule.Resources, "*")) && len(rule.ResourceNames) == 0 {
			for _, v := range rule.Verbs {
				verbs[v] = true
			}
		}
	}

	return verbs, nil
}

// Ensure the clusterRole used to grant access of global resources to users/groups in projects has appropriate rulesfor the give resource and verbs
func (m *manager) reconcileRoleForProjectAccessToGlobalResource(resource string, rt *v3.RoleTemplate, newVerbs map[string]bool) (string, error) {
	clusterRoles := m.workload.RBAC.ClusterRoles("")
	roleName := rt.Name + "-promoted"
	if role, err := m.crLister.Get("", roleName); err == nil && role != nil {
		currentVerbs := map[string]bool{}
		for _, rule := range role.Rules {
			if slice.ContainsString(rule.Resources, resource) {
				for _, v := range rule.Verbs {
					currentVerbs[v] = true
				}
			}
		}

		if !reflect.DeepEqual(currentVerbs, newVerbs) {
			role = role.DeepCopy()
			added := false
			for i, rule := range role.Rules {
				if slice.ContainsString(rule.Resources, resource) {
					role.Rules[i] = buildRule(resource, newVerbs)
					added = true
				}
			}
			if !added {
				role.Rules = append(role.Rules, buildRule(resource, newVerbs))
			}
			logrus.Infof("Updating clusterRole %v for project access to global resource.", role.Name)
			_, err := clusterRoles.Update(role)
			return roleName, err
		}
		return roleName, nil
	}

	logrus.Infof("Creating clusterRole %v for project access to global resource.", roleName)
	rules := []rbacv1.PolicyRule{buildRule(resource, newVerbs)}
	_, err := clusterRoles.Create(&rbacv1.ClusterRole{
		ObjectMeta: metav1.ObjectMeta{
			Name: roleName,
		},
		Rules: rules,
	})
	if err != nil {
		return roleName, errors.Wrapf(err, "couldn't create role %v", roleName)
	}

	return roleName, nil
}

func buildRule(resource string, verbs map[string]bool) rbacv1.PolicyRule {
	var vs []string
	for v := range verbs {
		vs = append(vs, v)
	}
	return rbacv1.PolicyRule{
		Resources: []string{resource},
		Verbs:     vs,
		APIGroups: []string{"*"},
	}
}