/*
Copyright 2015 Gravitational, Inc.

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 ui

import (
	"github.com/gravitational/teleport/api/client/proto"
	apidefaults "github.com/gravitational/teleport/api/defaults"
	"github.com/gravitational/teleport/api/types"
	"github.com/gravitational/teleport/lib/services"
)

type access struct {
	List   bool `json:"list"`
	Read   bool `json:"read"`
	Edit   bool `json:"edit"`
	Create bool `json:"create"`
	Delete bool `json:"remove"`
}

type accessStrategy struct {
	// Type determines how a user should access teleport resources.
	// ie: does the user require a request to access resources?
	Type types.RequestStrategy `json:"type"`
	// Prompt is the optional dialog shown to user,
	// when the access strategy type requires a reason.
	Prompt string `json:"prompt"`
}

// AccessCapabilities defines allowable access request rules defined in a user's roles.
type AccessCapabilities struct {
	// RequestableRoles is a list of roles that the user can select when requesting access.
	RequestableRoles []string `json:"requestableRoles"`
	// SuggestedReviewers is a list of reviewers that the user can select when creating a request.
	SuggestedReviewers []string `json:"suggestedReviewers"`
}

type userACL struct {
	// RecordedSessions defines access to recorded sessions.
	RecordedSessions access `json:"recordedSessions"`
	// ActiveSessions defines access to active sessions.
	ActiveSessions access `json:"activeSessions"`
	// AuthConnectors defines access to auth.connectors.
	AuthConnectors access `json:"authConnectors"`
	// Roles defines access to roles.
	Roles access `json:"roles"`
	// Users defines access to users.
	Users access `json:"users"`
	// TrustedClusters defines access to trusted clusters.
	TrustedClusters access `json:"trustedClusters"`
	// Events defines access to audit logs.
	Events access `json:"events"`
	// Tokens defines access to tokens.
	Tokens access `json:"tokens"`
	// Nodes defines access to nodes.
	Nodes access `json:"nodes"`
	// AppServers defines access to application servers
	AppServers access `json:"appServers"`
	// DBServers defines access to database servers.
	DBServers access `json:"dbServers"`
	// DB defines access to database resource.
	DB access `json:"db"`
	// KubeServers defines access to kubernetes servers.
	KubeServers access `json:"kubeServers"`
	// Desktops defines access to desktops.
	Desktops access `json:"desktops"`
	// AccessRequests defines access to access requests.
	AccessRequests access `json:"accessRequests"`
	// Billing defines access to billing information.
	Billing access `json:"billing"`
	// ConnectionDiagnostic defines access to connection diagnostics.
	ConnectionDiagnostic access `json:"connectionDiagnostic"`
	// Clipboard defines whether the user can use a shared clipboard during windows desktop sessions.
	Clipboard bool `json:"clipboard"`
	// DesktopSessionRecording defines whether the user's desktop sessions are being recorded.
	DesktopSessionRecording bool `json:"desktopSessionRecording"`
	// DirectorySharing defines whether a user is permitted to share a directory during windows desktop sessions.
	DirectorySharing bool `json:"directorySharing"`
	// Download defines whether the user has access to download Teleport Enterprise Binaries
	Download access `json:"download"`
	// Download defines whether the user has access to download the license
	License access `json:"license"`
	// Plugins defines whether the user has access to manage hosted plugin instances
	Plugins access `json:"plugins"`
}

type authType string

const (
	authLocal authType = "local"
	authSSO   authType = "sso"
)

// UserContext describes user settings and access to various resources.
type UserContext struct {
	// AuthType is auth method of this user.
	AuthType authType `json:"authType"`
	// Name is this user name.
	Name string `json:"userName"`
	// ACL contains user access control list.
	ACL userACL `json:"userAcl"`
	// Cluster contains cluster detail for this user's context.
	Cluster *Cluster `json:"cluster"`
	// AccessStrategy describes how a user should access teleport resources.
	AccessStrategy accessStrategy `json:"accessStrategy"`
	// AccessCapabilities defines allowable access request rules defined in a user's roles.
	AccessCapabilities AccessCapabilities `json:"accessCapabilities"`
	// ConsumedAccessRequestID is the request ID of the access request from which the assumed role was
	// obtained
	ConsumedAccessRequestID string `json:"accessRequestId,omitempty"`
}

func hasAccess(roleSet services.RoleSet, ctx *services.Context, kind string, verbs ...string) bool {
	for _, verb := range verbs {
		// Since this check occurs often and does not imply the caller is trying to
		// access any resource, silence any logging done on the proxy.
		if err := roleSet.GuessIfAccessIsPossible(ctx, apidefaults.Namespace, kind, verb, true); err != nil {
			return false
		}
	}
	return true
}

func newAccess(roleSet services.RoleSet, ctx *services.Context, kind string) access {
	return access{
		List:   hasAccess(roleSet, ctx, kind, types.VerbList),
		Read:   hasAccess(roleSet, ctx, kind, types.VerbRead),
		Edit:   hasAccess(roleSet, ctx, kind, types.VerbUpdate),
		Create: hasAccess(roleSet, ctx, kind, types.VerbCreate),
		Delete: hasAccess(roleSet, ctx, kind, types.VerbDelete),
	}
}

func getAccessStrategy(roleset services.RoleSet) accessStrategy {
	strategy := types.RequestStrategyOptional
	prompt := ""

	for _, role := range roleset {
		options := role.GetOptions()

		if options.RequestAccess == types.RequestStrategyReason {
			strategy = types.RequestStrategyReason
			prompt = options.RequestPrompt
			break
		}

		if options.RequestAccess == types.RequestStrategyAlways {
			strategy = types.RequestStrategyAlways
		}
	}

	return accessStrategy{
		Type:   strategy,
		Prompt: prompt,
	}
}

// NewUserContext returns user context
func NewUserContext(user types.User, userRoles services.RoleSet, features proto.Features, desktopRecordingEnabled bool) (*UserContext, error) {
	ctx := &services.Context{User: user}
	recordedSessionAccess := newAccess(userRoles, ctx, types.KindSession)
	activeSessionAccess := newAccess(userRoles, ctx, types.KindSSHSession)
	roleAccess := newAccess(userRoles, ctx, types.KindRole)
	authConnectors := newAccess(userRoles, ctx, types.KindAuthConnector)
	trustedClusterAccess := newAccess(userRoles, ctx, types.KindTrustedCluster)
	eventAccess := newAccess(userRoles, ctx, types.KindEvent)
	userAccess := newAccess(userRoles, ctx, types.KindUser)
	tokenAccess := newAccess(userRoles, ctx, types.KindToken)
	nodeAccess := newAccess(userRoles, ctx, types.KindNode)
	appServerAccess := newAccess(userRoles, ctx, types.KindAppServer)
	dbServerAccess := newAccess(userRoles, ctx, types.KindDatabaseServer)
	dbAccess := newAccess(userRoles, ctx, types.KindDatabase)
	kubeServerAccess := newAccess(userRoles, ctx, types.KindKubeServer)
	requestAccess := newAccess(userRoles, ctx, types.KindAccessRequest)
	desktopAccess := newAccess(userRoles, ctx, types.KindWindowsDesktop)
	cnDiagnosticAccess := newAccess(userRoles, ctx, types.KindConnectionDiagnostic)

	var billingAccess access
	if features.Cloud {
		billingAccess = newAccess(userRoles, ctx, types.KindBilling)
	}

	var pluginsAccess access
	if features.Plugins {
		pluginsAccess = newAccess(userRoles, ctx, types.KindPlugin)
	}

	accessStrategy := getAccessStrategy(userRoles)
	clipboard := userRoles.DesktopClipboard()
	desktopSessionRecording := desktopRecordingEnabled && userRoles.RecordDesktopSession()
	directorySharing := userRoles.DesktopDirectorySharing()
	download := newAccess(userRoles, ctx, types.KindDownload)
	license := newAccess(userRoles, ctx, types.KindLicense)

	acl := userACL{
		AccessRequests:          requestAccess,
		AppServers:              appServerAccess,
		DBServers:               dbServerAccess,
		DB:                      dbAccess,
		KubeServers:             kubeServerAccess,
		Desktops:                desktopAccess,
		AuthConnectors:          authConnectors,
		TrustedClusters:         trustedClusterAccess,
		RecordedSessions:        recordedSessionAccess,
		ActiveSessions:          activeSessionAccess,
		Roles:                   roleAccess,
		Events:                  eventAccess,
		Users:                   userAccess,
		Tokens:                  tokenAccess,
		Nodes:                   nodeAccess,
		Billing:                 billingAccess,
		ConnectionDiagnostic:    cnDiagnosticAccess,
		Clipboard:               clipboard,
		DesktopSessionRecording: desktopSessionRecording,
		DirectorySharing:        directorySharing,
		Download:                download,
		License:                 license,
		Plugins:                 pluginsAccess,
	}

	// local user
	authType := authLocal

	// check for any SSO identities
	isSSO := len(user.GetOIDCIdentities()) > 0 ||
		len(user.GetGithubIdentities()) > 0 ||
		len(user.GetSAMLIdentities()) > 0

	if isSSO {
		// SSO user
		authType = authSSO
	}

	return &UserContext{
		Name:           user.GetName(),
		ACL:            acl,
		AuthType:       authType,
		AccessStrategy: accessStrategy,
	}, nil
}