package common

import (
	"crypto/sha256"
	"encoding/base32"
	"encoding/json"
	"fmt"
	"reflect"
	"strings"
	"time"

	"github.com/pkg/errors"
	"github.com/rancher/norman/types"
	"github.com/rancher/norman/types/slice"
	"github.com/rancher/rancher/pkg/auth/tokens"
	"github.com/rancher/rancher/pkg/randomtoken"
	v3 "github.com/rancher/types/apis/management.cattle.io/v3"
	rbacv1 "github.com/rancher/types/apis/rbac.authorization.k8s.io/v1"
	"github.com/rancher/types/config"
	"github.com/rancher/types/user"
	"github.com/sirupsen/logrus"
	k8srbacv1 "k8s.io/api/rbac/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	apitypes "k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/tools/cache"
)

const (
	userAuthHeader               = "Impersonate-User"
	userByPrincipalIndex         = "auth.management.cattle.io/userByPrincipal"
	crtbsByPrincipalAndUserIndex = "auth.management.cattle.io/crtbByPrincipalAndUser"
	prtbsByPrincipalAndUserIndex = "auth.management.cattle.io/prtbByPrincipalAndUser"
	grbByUserIndex               = "auth.management.cattle.io/grbByUser"
	roleTemplatesRequired        = "authz.management.cattle.io/creator-role-bindings"
)

func NewUserManager(scaledContext *config.ScaledContext) (user.Manager, error) {
	userInformer := scaledContext.Management.Users("").Controller().Informer()
	userIndexers := map[string]cache.IndexFunc{
		userByPrincipalIndex: userByPrincipal,
	}
	if err := userInformer.AddIndexers(userIndexers); err != nil {
		return nil, err
	}

	crtbInformer := scaledContext.Management.ClusterRoleTemplateBindings("").Controller().Informer()
	crtbIndexers := map[string]cache.IndexFunc{
		crtbsByPrincipalAndUserIndex: crtbsByPrincipalAndUser,
	}
	if err := crtbInformer.AddIndexers(crtbIndexers); err != nil {
		return nil, err
	}

	prtbInformer := scaledContext.Management.ProjectRoleTemplateBindings("").Controller().Informer()
	prtbIndexers := map[string]cache.IndexFunc{
		prtbsByPrincipalAndUserIndex: prtbsByPrincipalAndUser,
	}
	if err := prtbInformer.AddIndexers(prtbIndexers); err != nil {
		return nil, err
	}

	grbInformer := scaledContext.Management.GlobalRoleBindings("").Controller().Informer()
	grbIndexers := map[string]cache.IndexFunc{
		grbByUserIndex: grbByUser,
	}
	if err := grbInformer.AddIndexers(grbIndexers); err != nil {
		return nil, err
	}

	return &userManager{
		users:                    scaledContext.Management.Users(""),
		userIndexer:              userInformer.GetIndexer(),
		crtbIndexer:              crtbInformer.GetIndexer(),
		prtbIndexer:              prtbInformer.GetIndexer(),
		tokens:                   scaledContext.Management.Tokens(""),
		tokenLister:              scaledContext.Management.Tokens("").Controller().Lister(),
		globalRoleBindings:       scaledContext.Management.GlobalRoleBindings(""),
		globalRoleLister:         scaledContext.Management.GlobalRoles("").Controller().Lister(),
		grbIndexer:               grbInformer.GetIndexer(),
		clusterRoleLister:        scaledContext.RBAC.ClusterRoles("").Controller().Lister(),
		clusterRoleBindingLister: scaledContext.RBAC.ClusterRoleBindings("").Controller().Lister(),
		rbacClient:               scaledContext.RBAC,
	}, nil
}

type userManager struct {
	users                    v3.UserInterface
	globalRoleBindings       v3.GlobalRoleBindingInterface
	globalRoleLister         v3.GlobalRoleLister
	grbIndexer               cache.Indexer
	userIndexer              cache.Indexer
	crtbIndexer              cache.Indexer
	prtbIndexer              cache.Indexer
	tokenLister              v3.TokenLister
	tokens                   v3.TokenInterface
	clusterRoleLister        rbacv1.ClusterRoleLister
	clusterRoleBindingLister rbacv1.ClusterRoleBindingLister
	rbacClient               rbacv1.Interface
}

func (m *userManager) SetPrincipalOnCurrentUser(apiContext *types.APIContext, principal v3.Principal) (*v3.User, error) {
	userID := m.GetUser(apiContext)
	if userID == "" {
		return nil, errors.New("user not provided")
	}

	return m.SetPrincipalOnCurrentUserByUserID(userID, principal)
}

func (m *userManager) SetPrincipalOnCurrentUserByUserID(userID string, principal v3.Principal) (*v3.User, error) {
	user, err := m.users.Get(userID, v1.GetOptions{})
	if err != nil {
		return nil, err
	}

	if providerExists(user.PrincipalIDs, principal.Provider) {
		var principalIDs []string
		for _, id := range user.PrincipalIDs {
			if !strings.Contains(id, principal.Provider) {
				principalIDs = append(principalIDs, id)
			}
		}
		user.PrincipalIDs = principalIDs
	}

	if !slice.ContainsString(user.PrincipalIDs, principal.Name) {
		user.PrincipalIDs = append(user.PrincipalIDs, principal.Name)
		logrus.Infof("Updating user %v. Adding principal", user.Name)
		return m.users.Update(user)
	}
	return user, nil
}

func (m *userManager) GetUser(apiContext *types.APIContext) string {
	return apiContext.Request.Header.Get(userAuthHeader)
}

// checkis if the supplied principal can login based on the accessMode and allowed principals
func (m *userManager) CheckAccess(accessMode string, allowedPrincipalIDs []string, userPrincipalID string, groups []v3.Principal) (bool, error) {
	if accessMode == "unrestricted" || accessMode == "" {
		return true, nil
	}

	if accessMode == "required" || accessMode == "restricted" {
		user, err := m.checkCache(userPrincipalID)
		if err != nil {
			return false, err
		}

		userPrincipals := []string{userPrincipalID}
		if user != nil {
			for _, p := range user.PrincipalIDs {
				if userPrincipalID != p {
					userPrincipals = append(userPrincipals, p)
				}
			}
		}

		for _, p := range userPrincipals {
			if slice.ContainsString(allowedPrincipalIDs, p) {
				return true, nil
			}
		}

		for _, g := range groups {
			if slice.ContainsString(allowedPrincipalIDs, g.Name) {
				return true, nil
			}
		}

		if accessMode == "restricted" {
			// check if any of the user's principals are in a project or cluster
			var userNameAndPrincipals []string
			for _, g := range groups {
				userNameAndPrincipals = append(userNameAndPrincipals, g.Name)
			}
			if user != nil {
				userNameAndPrincipals = append(userNameAndPrincipals, user.Name)
				userNameAndPrincipals = append(userNameAndPrincipals, userPrincipals...)
			}

			return m.userExistsInClusterOrProject(userNameAndPrincipals)
		}
		return false, nil
	}
	return false, errors.Errorf("Unsupported accessMode: %v", accessMode)
}

func (m *userManager) EnsureToken(tokenName, description, userName string) (string, error) {
	return m.EnsureClusterToken("", tokenName, description, userName)
}

func (m *userManager) EnsureClusterToken(clusterName, tokenName, description, userName string) (string, error) {
	if strings.HasPrefix(tokenName, "token-") {
		return "", errors.New("token names can't start with token-")
	}

	token, err := m.tokenLister.Get("", tokenName)
	if err != nil && !apierrors.IsNotFound(err) {
		return "", err
	}

	if token == nil {
		key, err := randomtoken.Generate()
		if err != nil {
			return "", fmt.Errorf("failed to generate token key")
		}

		token = &v3.Token{
			ObjectMeta: v1.ObjectMeta{
				Name: tokenName,
				Labels: map[string]string{
					tokens.UserIDLabel: userName,
				},
			},
			TTLMillis:    0,
			Description:  description,
			UserID:       userName,
			AuthProvider: "local",
			IsDerived:    true,
			Token:        key,
			ClusterName:  clusterName,
		}

		logrus.Infof("Creating token for user %v", userName)
		createdToken, err := m.tokens.Create(token)
		if err != nil {
			if !apierrors.IsAlreadyExists(err) {
				return "", err
			}
			token, err = m.tokens.Get(tokenName, v1.GetOptions{})
			if err != nil {
				return "", err
			}
		} else {
			token = createdToken
		}
	}

	return token.Name + ":" + token.Token, nil
}

func (m *userManager) EnsureUser(principalName, displayName string) (*v3.User, error) {
	var user *v3.User
	var err error
	var labelSet labels.Set

	// First check the local cache
	user, err = m.checkCache(principalName)
	if err != nil {
		return nil, err
	}

	if user == nil {
		// Not in cache, query API by label
		user, labelSet, err = m.checkLabels(principalName)
		if err != nil {
			return nil, err
		}
	}

	if user != nil {
		// If the user does not have the annotation it indicates the user was created
		// through the UI or from a previous rancher version so don't add the
		// default bindings.
		if _, ok := user.Annotations[roleTemplatesRequired]; !ok {
			return user, nil
		}

		if v3.UserConditionInitialRolesPopulated.IsTrue(user) {
			// The users global role bindings were already created. They can differ
			// from what is in the annotation if they were updated manually.
			return user, nil
		}
	} else {
		// User doesn't exist, create user
		logrus.Infof("Creating user for principal %v", principalName)

		// Create a hash of the principalName to use as the name for the user,
		// this lets k8s tell us if there are duplicate users with the same name
		// thus avoiding a race.
		hasher := sha256.New()
		hasher.Write([]byte(principalName))
		sha := base32.StdEncoding.WithPadding(-1).EncodeToString(hasher.Sum(nil))[:10]

		annotations, err := m.createUsersRoleAnnotation()
		if err != nil {
			return nil, err
		}

		user = &v3.User{
			ObjectMeta: v1.ObjectMeta{
				Name:        "u-" + strings.ToLower(sha),
				Labels:      labelSet,
				Annotations: annotations,
			},
			DisplayName:  displayName,
			PrincipalIDs: []string{principalName},
		}

		user, err = m.users.Create(user)
		if err != nil {
			return nil, err
		}

		err = m.CreateNewUserClusterRoleBinding(user.Name, user.UID)
		if err != nil {
			return nil, err
		}
	}

	logrus.Infof("Creating globalRoleBindings for %v", user.Name)
	err = m.createUsersBindings(user)
	if err != nil {
		return nil, err
	}

	return user, nil
}

func (m *userManager) CreateNewUserClusterRoleBinding(userName string, userUID apitypes.UID) error {
	roleName := userName + "-view"
	bindingName := "grb-" + roleName

	ownerReference := v1.OwnerReference{
		APIVersion: "management.cattle.io/v3",
		Kind:       "User",
		Name:       userName,
		UID:        userUID,
	}

	cr, err := m.clusterRoleLister.Get("", roleName)
	if err != nil {
		if !apierrors.IsNotFound(err) {
			return err
		}
		// ClusterRole doesn't exist yet, create it.
		rule := k8srbacv1.PolicyRule{
			Verbs:         []string{"get"},
			APIGroups:     []string{"management.cattle.io"},
			Resources:     []string{"users"},
			ResourceNames: []string{userName},
		}
		role := &k8srbacv1.ClusterRole{
			ObjectMeta: v1.ObjectMeta{
				Name:            roleName,
				OwnerReferences: []v1.OwnerReference{ownerReference},
			},
			Rules: []k8srbacv1.PolicyRule{rule},
		}

		cr, err = m.rbacClient.ClusterRoles("").Create(role)
		if err != nil {
			if !apierrors.IsAlreadyExists(err) {
				return err
			}
		}
	}

	_, err = m.clusterRoleBindingLister.Get("", bindingName)
	if err != nil {
		if !apierrors.IsNotFound(err) {
			return err
		}
		// ClusterRoleBinding doesn't exit yet, create it.
		crb := &k8srbacv1.ClusterRoleBinding{
			ObjectMeta: v1.ObjectMeta{
				Name:            bindingName,
				OwnerReferences: []v1.OwnerReference{ownerReference},
			},
			Subjects: []k8srbacv1.Subject{
				k8srbacv1.Subject{
					Kind: "User",
					Name: userName,
				},
			},
			RoleRef: k8srbacv1.RoleRef{
				Kind: "ClusterRole",
				Name: cr.Name,
			},
		}
		_, err = m.rbacClient.ClusterRoleBindings("").Create(crb)
		if err != nil {
			if !apierrors.IsAlreadyExists(err) {
				return err
			}
		}
	}

	return nil
}

func (m *userManager) createUsersBindings(user *v3.User) error {
	roleMap := make(map[string][]string)
	err := json.Unmarshal([]byte(user.Annotations[roleTemplatesRequired]), &roleMap)
	if err != nil {
		return err
	}

	// Collect the users existing globalRoleBindings
	var existingGRB []string
	grbs, err := m.grbIndexer.ByIndex(grbByUserIndex, user.Name)
	if err != nil {
		return err
	}

	for _, grb := range grbs {
		binding, ok := grb.(*v3.GlobalRoleBinding)
		if !ok {
			continue
		}
		existingGRB = append(existingGRB, binding.GlobalRoleName)
	}

	var createdRoles []string
	for _, role := range roleMap["required"] {
		if !slice.ContainsString(existingGRB, role) {
			_, err := m.globalRoleBindings.Create(&v3.GlobalRoleBinding{
				ObjectMeta: v1.ObjectMeta{
					GenerateName: "grb-",
				},
				UserName:       user.Name,
				GlobalRoleName: role,
			})

			if err != nil {
				return err
			}
		}
		createdRoles = append(createdRoles, role)
	}

	roleMap["created"] = createdRoles
	d, err := json.Marshal(roleMap)
	if err != nil {
		return err
	}

	rtr := string(d)

	sleepTime := 100
	// The user needs updated so keep trying if there is a conflict
	for i := 0; i <= 3; i++ {
		user, err = m.users.Get(user.Name, v1.GetOptions{})
		if err != nil {
			return err
		}

		user.Annotations[roleTemplatesRequired] = rtr

		if reflect.DeepEqual(roleMap["required"], createdRoles) {
			v3.UserConditionInitialRolesPopulated.True(user)
		}

		_, err = m.users.Update(user)
		if err != nil {
			if apierrors.IsConflict(err) {
				// Conflict on the user, sleep and try again
				time.Sleep(time.Duration(sleepTime) * time.Millisecond)
				sleepTime *= 2
				continue
			}
			return err
		}
		break
	}

	return nil
}

func (m *userManager) createUsersRoleAnnotation() (map[string]string, error) {
	roleMap := make(map[string][]string)

	roles, err := m.globalRoleLister.List("", labels.NewSelector())
	if err != nil {
		return nil, err
	}

	for _, gr := range roles {
		if gr.NewUserDefault {
			roleMap["required"] = append(roleMap["required"], gr.Name)
		}
	}

	d, err := json.Marshal(roleMap)
	if err != nil {
		return nil, err
	}

	annotations := make(map[string]string)
	annotations[roleTemplatesRequired] = string(d)

	return annotations, nil
}

func (m *userManager) GetUserByPrincipalID(principalName string) (*v3.User, error) {
	user, err := m.checkCache(principalName)
	if err != nil {
		return nil, err
	}
	if user == nil {
		// Not in cache, query API by label
		user, _, err = m.checkLabels(principalName)
		if err != nil {
			return nil, err
		}
	}
	return user, nil
}

func (m *userManager) checkCache(principalName string) (*v3.User, error) {
	users, err := m.userIndexer.ByIndex(userByPrincipalIndex, principalName)
	if err != nil {
		return nil, err
	}
	if len(users) > 1 {
		return nil, errors.Errorf("can't find unique user for principal %v", principalName)
	}
	if len(users) == 1 {
		u := users[0].(*v3.User)
		return u.DeepCopy(), nil
	}
	return nil, nil
}

func (m *userManager) userExistsInClusterOrProject(userNameAndPrincipals []string) (bool, error) {
	for _, principal := range userNameAndPrincipals {
		crtbs, err := m.crtbIndexer.ByIndex(crtbsByPrincipalAndUserIndex, principal)
		if err != nil {
			return false, err
		}
		if len(crtbs) > 0 {
			return true, nil
		}
		prtbs, err := m.prtbIndexer.ByIndex(prtbsByPrincipalAndUserIndex, principal)
		if err != nil {
			return false, err
		}
		if len(prtbs) > 0 {
			return true, nil
		}
	}

	return false, nil
}

func (m *userManager) checkLabels(principalName string) (*v3.User, labels.Set, error) {
	encodedPrincipalID := base32.HexEncoding.WithPadding(base32.NoPadding).EncodeToString([]byte(principalName))
	if len(encodedPrincipalID) > 63 {
		encodedPrincipalID = encodedPrincipalID[:63]
	}
	set := labels.Set(map[string]string{encodedPrincipalID: "hashed-principal-name"})
	users, err := m.users.List(v1.ListOptions{LabelSelector: set.String()})
	if err != nil {
		return nil, nil, err
	}

	if len(users.Items) == 0 {
		return nil, set, nil
	}

	var match *v3.User
	for _, u := range users.Items {
		if slice.ContainsString(u.PrincipalIDs, principalName) {
			if match != nil {
				// error out on duplicates
				return nil, nil, errors.Errorf("can't find unique user for principal %v", principalName)
			}
			match = &u
		}
	}

	return match, set, nil
}

func userByPrincipal(obj interface{}) ([]string, error) {
	u, ok := obj.(*v3.User)
	if !ok {
		return []string{}, nil
	}

	return u.PrincipalIDs, nil
}

func crtbsByPrincipalAndUser(obj interface{}) ([]string, error) {
	var principals []string
	b, ok := obj.(*v3.ClusterRoleTemplateBinding)
	if !ok {
		return []string{}, nil
	}
	if b.GroupPrincipalName != "" {
		principals = append(principals, b.GroupPrincipalName)
	}
	if b.UserPrincipalName != "" {
		principals = append(principals, b.UserPrincipalName)
	}
	if b.UserName != "" {
		principals = append(principals, b.UserName)
	}
	return principals, nil
}

func prtbsByPrincipalAndUser(obj interface{}) ([]string, error) {
	var principals []string
	b, ok := obj.(*v3.ProjectRoleTemplateBinding)
	if !ok {
		return []string{}, nil
	}
	if b.GroupPrincipalName != "" {
		principals = append(principals, b.GroupPrincipalName)
	}
	if b.UserPrincipalName != "" {
		principals = append(principals, b.UserPrincipalName)
	}
	if b.UserName != "" {
		principals = append(principals, b.UserName)
	}
	return principals, nil
}

func grbByUser(obj interface{}) ([]string, error) {
	grb, ok := obj.(*v3.GlobalRoleBinding)
	if !ok {
		return []string{}, nil
	}

	return []string{grb.UserName}, nil
}

func providerExists(principalIDs []string, provider string) bool {
	for _, id := range principalIDs {
		splitID := strings.Split(id, ":")[0]
		if strings.Contains(splitID, provider) {
			return true
		}
	}
	return false
}