/*
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 auth

import (
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"github.com/Sirupsen/logrus"
	"github.com/gravitational/roundtrip"

	"github.com/gravitational/teleport"
	"github.com/gravitational/teleport/lib/events"
	"github.com/gravitational/teleport/lib/httplib"
	"github.com/gravitational/teleport/lib/services"
	"github.com/gravitational/teleport/lib/session"
	"github.com/gravitational/trace"

	"github.com/tstranex/u2f"
)

// CurrentVersion is a current API version
const CurrentVersion = "v1"

type Dialer func(network, addr string) (net.Conn, error)

// Client is HTTP Auth API client. It works by connecting to auth servers
// via HTTP.
//
// When Teleport servers connect to auth API, they usually establish an SSH
// tunnel first, and then do HTTP-over-SSH. This client is wrapped by auth.TunClient
// in lib/auth/tun.go
type Client struct {
	roundtrip.Client
	transport *http.Transport
}

// NewAuthClient returns a new instance of the client which talks to
// an Auth server API (aka "site API") via HTTP-over-SSH
func NewClient(addr string, dialer Dialer, params ...roundtrip.ClientParam) (*Client, error) {
	if dialer == nil {
		dialer = net.Dial
	}
	transport := &http.Transport{Dial: dialer}
	params = append(params, roundtrip.HTTPClient(&http.Client{
		Transport: transport,
	}))

	c, err := roundtrip.NewClient(addr, CurrentVersion, params...)
	if err != nil {
		return nil, err
	}
	return &Client{
		Client:    *c,
		transport: transport,
	}, nil
}

func (c *Client) GetTransport() *http.Transport {
	return c.transport
}

// PostJSON is a generic method that issues http POST request to the server
func (c *Client) PostJSON(
	endpoint string, val interface{}) (*roundtrip.Response, error) {
	return httplib.ConvertResponse(c.Client.PostJSON(endpoint, val))
}

// PutJSON is a generic method that issues http PUT request to the server
func (c *Client) PutJSON(
	endpoint string, val interface{}) (*roundtrip.Response, error) {
	return httplib.ConvertResponse(c.Client.PutJSON(endpoint, val))
}

// PostForm is a generic method that issues http POST request to the server
func (c *Client) PostForm(
	endpoint string,
	vals url.Values,
	files ...roundtrip.File) (*roundtrip.Response, error) {

	return httplib.ConvertResponse(c.Client.PostForm(endpoint, vals, files...))
}

// Get issues http GET request to the server
func (c *Client) Get(u string, params url.Values) (*roundtrip.Response, error) {
	return httplib.ConvertResponse(c.Client.Get(u, params))
}

// Delete issues http Delete Request to the server
func (c *Client) Delete(u string) (*roundtrip.Response, error) {
	return httplib.ConvertResponse(c.Client.Delete(u))
}

// GetSessions returns a list of active sessions in the cluster
// as reported by auth server
func (c *Client) GetSessions(namespace string) ([]session.Session, error) {
	if namespace == "" {
		return nil, trace.BadParameter("missing namespace parameter")
	}
	out, err := c.Get(c.Endpoint("namespaces", namespace, "sessions"), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var sessions []session.Session
	if err := json.Unmarshal(out.Bytes(), &sessions); err != nil {
		return nil, err
	}
	return sessions, nil
}

// GetSession returns a session by ID
func (c *Client) GetSession(namespace string, id session.ID) (*session.Session, error) {
	if namespace == "" {
		return nil, trace.BadParameter("missing parameter namespace")
	}
	// saving extra round-trip
	if err := id.Check(); err != nil {
		return nil, trace.Wrap(err)
	}
	out, err := c.Get(c.Endpoint("namespaces", namespace, "sessions", string(id)), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var sess *session.Session
	if err := json.Unmarshal(out.Bytes(), &sess); err != nil {
		return nil, trace.Wrap(err)
	}
	return sess, nil
}

// DeleteSession deletes a session by ID
func (c *Client) DeleteSession(namespace, id string) error {
	if namespace == "" {
		return trace.BadParameter("missing namespace parameter")
	}
	_, err := c.Delete(c.Endpoint("namespaces", namespace, "sessions", id))
	return trace.Wrap(err)
}

// CreateSession creates new session
func (c *Client) CreateSession(sess session.Session) error {
	if sess.Namespace == "" {
		return trace.BadParameter("missing parameter namespace")
	}
	_, err := c.PostJSON(c.Endpoint("namespaces", sess.Namespace, "sessions"), createSessionReq{Session: sess})
	return trace.Wrap(err)
}

// UpdateSession updates existing session
func (c *Client) UpdateSession(req session.UpdateRequest) error {
	if err := req.Check(); err != nil {
		return trace.Wrap(err)
	}
	_, err := c.PutJSON(c.Endpoint("namespaces", req.Namespace, "sessions", string(req.ID)), updateSessionReq{Update: req})
	return trace.Wrap(err)
}

// GetDomainName returns local auth domain of the current auth server
func (c *Client) GetDomainName() (string, error) {
	out, err := c.Get(c.Endpoint("domain"), url.Values{})
	if err != nil {
		return "", trace.Wrap(err)
	}
	var domain string
	if err := json.Unmarshal(out.Bytes(), &domain); err != nil {
		return "", trace.Wrap(err)
	}
	return domain, nil
}

func (c *Client) Close() error {
	return nil
}

// UpsertCertAuthority updates or inserts new cert authority
func (c *Client) UpsertCertAuthority(ca services.CertAuthority, ttl time.Duration) error {
	if err := ca.Check(); err != nil {
		return trace.Wrap(err)
	}
	_, err := c.PostJSON(c.Endpoint("authorities", string(ca.Type)),
		upsertCertAuthorityReq{CA: ca, TTL: ttl})
	return trace.Wrap(err)
}

// GetCertAuthorities returns a list of certificate authorities
func (c *Client) GetCertAuthorities(caType services.CertAuthType, loadKeys bool) ([]*services.CertAuthority, error) {
	if err := caType.Check(); err != nil {
		return nil, trace.Wrap(err)
	}
	out, err := c.Get(c.Endpoint("authorities", string(caType)), url.Values{
		"load_keys": []string{fmt.Sprintf("%t", loadKeys)},
	})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var re []*services.CertAuthority
	if err := json.Unmarshal(out.Bytes(), &re); err != nil {
		return nil, err
	}
	return re, nil
}

// GetCertAuthority returns certificate authority by given id. Parameter loadSigningKeys
// controls if signing keys are loaded
func (c *Client) GetCertAuthority(id services.CertAuthID, loadSigningKeys bool) (*services.CertAuthority, error) {
	if err := id.Check(); err != nil {
		return nil, trace.Wrap(err)
	}
	out, err := c.Get(c.Endpoint("authorities", string(id.Type), id.DomainName), url.Values{
		"load_keys": []string{fmt.Sprintf("%t", loadSigningKeys)},
	})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var re services.CertAuthority
	if err := json.Unmarshal(out.Bytes(), &re); err != nil {
		return nil, err
	}
	return &re, nil
}

// DeleteCertAuthority deletes cert authority by ID
func (c *Client) DeleteCertAuthority(id services.CertAuthID) error {
	if err := id.Check(); err != nil {
		return trace.Wrap(err)
	}
	_, err := c.Delete(c.Endpoint("authorities", string(id.Type), id.DomainName))
	return trace.Wrap(err)
}

// GenerateToken creates a special provisioning token for a new SSH server
// that is valid for ttl period seconds.
//
// This token is used by SSH server to authenticate with Auth server
// and get signed certificate and private key from the auth server.
//
// The token can be used only once.
func (c *Client) GenerateToken(roles teleport.Roles, ttl time.Duration) (string, error) {
	out, err := c.PostJSON(c.Endpoint("tokens"), generateTokenReq{
		Roles: roles,
		TTL:   ttl,
	})
	if err != nil {
		return "", trace.Wrap(err)
	}
	var token string
	if err := json.Unmarshal(out.Bytes(), &token); err != nil {
		return "", trace.Wrap(err)
	}
	return token, nil
}

// RegisterUsingToken calls the auth service API to register a new node via registration token
// which has been previously issued via GenerateToken
func (c *Client) RegisterUsingToken(token, hostID string, role teleport.Role) (*PackedKeys, error) {
	out, err := c.PostJSON(c.Endpoint("tokens", "register"),
		registerUsingTokenReq{
			HostID: hostID,
			Token:  token,
			Role:   role,
		})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var keys PackedKeys
	if err := json.Unmarshal(out.Bytes(), &keys); err != nil {
		return nil, trace.Wrap(err)
	}
	return &keys, nil
}

// GetTokens returns a list of active invitation tokens for nodes and users
func (c *Client) GetTokens() (tokens []services.ProvisionToken, err error) {
	out, err := c.Get(c.Endpoint("tokens"), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	if err := json.Unmarshal(out.Bytes(), &tokens); err != nil {
		return nil, trace.Wrap(err)
	}
	return tokens, nil
}

// GetToken returns provisioning token
func (c *Client) GetToken(token string) (*services.ProvisionToken, error) {
	out, err := c.Get(c.Endpoint("tokens", token), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var tok services.ProvisionToken
	if err := json.Unmarshal(out.Bytes(), &tok); err != nil {
		return nil, trace.Wrap(err)
	}
	return &tok, nil
}

// DeleteToken deletes a given provisioning token on the auth server (CA). It
// could be a user token or a machine token
func (c *Client) DeleteToken(token string) error {
	_, err := c.Delete(c.Endpoint("tokens", token))
	return trace.Wrap(err)
}

// RegisterNewAuthServer is used to register new auth server with token
func (c *Client) RegisterNewAuthServer(token string) error {
	_, err := c.PostJSON(c.Endpoint("tokens", "register", "auth"), registerNewAuthServerReq{
		Token: token,
	})
	return trace.Wrap(err)
}

// UpsertNode is used by SSH servers to reprt their presense
// to the auth servers in form of hearbeat expiring after ttl period.
func (c *Client) UpsertNode(s services.Server, ttl time.Duration) error {
	if s.Namespace == "" {
		return trace.BadParameter("missing node namespace")
	}
	args := upsertServerReq{
		Server: s,
		TTL:    ttl,
	}
	_, err := c.PostJSON(c.Endpoint("namespaces", s.Namespace, "nodes"), args)
	return trace.Wrap(err)
}

// GetNodes returns the list of servers registered in the cluster.
func (c *Client) GetNodes(namespace string) ([]services.Server, error) {
	if namespace == "" {
		return nil, trace.BadParameter("missing parameter namespace")
	}
	out, err := c.Get(c.Endpoint("namespaces", namespace, "nodes"), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var re []services.Server
	if err := json.Unmarshal(out.Bytes(), &re); err != nil {
		return nil, trace.Wrap(err)
	}
	return re, nil
}

// UpsertReverseTunnel is used by admins to create a new reverse tunnel
// to the remote proxy to bypass firewall restrictions
func (c *Client) UpsertReverseTunnel(tunnel services.ReverseTunnel, ttl time.Duration) error {
	args := upsertReverseTunnelReq{
		ReverseTunnel: tunnel,
		TTL:           ttl,
	}
	_, err := c.PostJSON(c.Endpoint("reversetunnels"), args)
	return trace.Wrap(err)
}

// GetReverseTunnels returns the list of created reverse tunnels
func (c *Client) GetReverseTunnels() ([]services.ReverseTunnel, error) {
	out, err := c.Get(c.Endpoint("reversetunnels"), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var tunnels []services.ReverseTunnel
	if err := json.Unmarshal(out.Bytes(), &tunnels); err != nil {
		return nil, trace.Wrap(err)
	}
	return tunnels, nil
}

// DeleteReverseTunnel deletes reverse tunnel by domain name
func (c *Client) DeleteReverseTunnel(domainName string) error {
	// this is to avoid confusing error in case if domain emtpy for example
	// HTTP route will fail producing generic not found error
	// instead we catch the error here
	if strings.TrimSpace(domainName) == "" {
		return trace.BadParameter("empty domain name")
	}
	_, err := c.Delete(c.Endpoint("reversetunnels", domainName))
	return trace.Wrap(err)
}

// UpsertAuthServer is used by auth servers to report their presense
// to other auth servers in form of hearbeat expiring after ttl period.
func (c *Client) UpsertAuthServer(s services.Server, ttl time.Duration) error {
	args := upsertServerReq{
		Server: s,
		TTL:    ttl,
	}
	_, err := c.PostJSON(c.Endpoint("authservers"), args)
	return trace.Wrap(err)
}

// GetAuthServers returns the list of auth servers registered in the cluster.
func (c *Client) GetAuthServers() ([]services.Server, error) {
	out, err := c.Get(c.Endpoint("authservers"), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var re []services.Server
	if err := json.Unmarshal(out.Bytes(), &re); err != nil {
		return nil, trace.Wrap(err)
	}
	return re, nil
}

// UpsertProxy is used by proxies to report their presense
// to other auth servers in form of hearbeat expiring after ttl period.
func (c *Client) UpsertProxy(s services.Server, ttl time.Duration) error {
	args := upsertServerReq{
		Server: s,
		TTL:    ttl,
	}
	_, err := c.PostJSON(c.Endpoint("proxies"), args)
	return trace.Wrap(err)
}

// GetProxies returns the list of auth servers registered in the cluster.
func (c *Client) GetProxies() ([]services.Server, error) {
	out, err := c.Get(c.Endpoint("proxies"), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var re []services.Server
	if err := json.Unmarshal(out.Bytes(), &re); err != nil {
		return nil, trace.Wrap(err)
	}
	return re, nil
}

// GetU2FAppID returns U2F settings, like App ID and Facets
func (c *Client) GetU2FAppID() (string, error) {
	out, err := c.Get(c.Endpoint("u2f", "appID"), url.Values{})
	if err != nil {
		return "", trace.Wrap(err)
	}
	var appid string
	if err := json.Unmarshal(out.Bytes(), &appid); err != nil {
		return "", trace.Wrap(err)
	}
	return appid, nil
}

// UpsertPassword updates web access password for the user
func (c *Client) UpsertPassword(user string,
	password []byte) (hotpURL string, hotpQR []byte, err error) {
	out, err := c.PostJSON(
		c.Endpoint("users", user, "web", "password"),
		upsertPasswordReq{
			Password: string(password),
		})
	if err != nil {
		return "", nil, trace.Wrap(err)
	}
	var re *upsertPasswordResponse
	if err := json.Unmarshal(out.Bytes(), &re); err != nil {
		return "", nil, err
	}
	return re.HotpURL, re.HotpQR, err
}

// UpsertUser user updates or inserts user entry
func (c *Client) UpsertUser(user services.User) error {
	_, err := c.PostJSON(c.Endpoint("users"), upsertUserReq{User: user})
	return trace.Wrap(err)
}

// CheckPassword checks if the suplied web access password is valid.
func (c *Client) CheckPassword(user string, password []byte, hotpToken string) error {
	_, err := c.PostJSON(
		c.Endpoint("users", user, "web", "password", "check"),
		checkPasswordReq{
			Password:  string(password),
			HOTPToken: hotpToken,
		})
	return trace.Wrap(err)
}

// SignIn checks if the web access password is valid, and if it is valid
// returns a secure web session id.
func (c *Client) SignIn(user string, password []byte) (*Session, error) {
	out, err := c.PostJSON(
		c.Endpoint("users", user, "web", "signin"),
		signInReq{
			Password: string(password),
		},
	)
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var sess *Session
	if err := json.Unmarshal(out.Bytes(), &sess); err != nil {
		return nil, err
	}
	return sess, nil
}

// PreAuthenticatedSignIn is for 2-way authentication methods like U2F where the password is
// already checked before issueing the second factor challenge
func (c *Client) PreAuthenticatedSignIn(user string) (*Session, error) {
	out, err := c.Get(
		c.Endpoint("users", user, "web", "signin", "preauth"),
		url.Values{},
	)
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var sess *Session
	if err := json.Unmarshal(out.Bytes(), &sess); err != nil {
		return nil, err
	}
	return sess, nil
}

// GetU2FSignRequest generates request for user trying to authenticate with U2F token
func (c *Client) GetU2FSignRequest(user string, password []byte) (*u2f.SignRequest, error) {
	out, err := c.PostJSON(
		c.Endpoint("u2f", "users", user, "sign"),
		signInReq{
			Password: string(password),
		},
	)
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var signRequest *u2f.SignRequest
	if err := json.Unmarshal(out.Bytes(), &signRequest); err != nil {
		return nil, err
	}
	return signRequest, nil
}

// ExtendWebSession creates a new web session for a user based on another
// valid web session
func (c *Client) ExtendWebSession(user string, prevSessionID string) (*Session, error) {
	out, err := c.PostJSON(
		c.Endpoint("users", user, "web", "sessions"),
		createWebSessionReq{
			PrevSessionID: prevSessionID,
		},
	)
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var sess *Session
	if err := json.Unmarshal(out.Bytes(), &sess); err != nil {
		return nil, err
	}
	return sess, nil
}

// CreateWebSession creates a new web session for a user
func (c *Client) CreateWebSession(user string) (*Session, error) {
	out, err := c.PostJSON(
		c.Endpoint("users", user, "web", "sessions"),
		createWebSessionReq{},
	)
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var sess *Session
	if err := json.Unmarshal(out.Bytes(), &sess); err != nil {
		return nil, err
	}
	return sess, nil
}

// GetWebSessionInfo checks if a web sesion is valid, returns session id in case if
// it is valid, or error otherwise.
func (c *Client) GetWebSessionInfo(user string, sid string) (*Session, error) {
	out, err := c.Get(
		c.Endpoint("users", user, "web", "sessions", sid), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var sess *Session
	if err := json.Unmarshal(out.Bytes(), &sess); err != nil {
		return nil, trace.Wrap(err)
	}
	return sess, nil
}

// DeleteWebSession deletes a web session for this user by id
func (c *Client) DeleteWebSession(user string, sid string) error {
	_, err := c.Delete(c.Endpoint("users", user, "web", "sessions", sid))
	return trace.Wrap(err)
}

// GetUser returns a list of usernames registered in the system
func (c *Client) GetUser(name string) (services.User, error) {
	if name == "" {
		return nil, trace.BadParameter("missing username")
	}
	out, err := c.Get(c.Endpoint("users", name), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	user, err := services.GetUserMarshaler().UnmarshalUser(out.Bytes())
	if err != nil {
		return nil, trace.Wrap(err)
	}
	return user, nil
}

// GetUsers returns a list of usernames registered in the system
func (c *Client) GetUsers() ([]services.User, error) {
	out, err := c.Get(c.Endpoint("users"), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var items []json.RawMessage
	if err := json.Unmarshal(out.Bytes(), &items); err != nil {
		return nil, trace.Wrap(err)
	}
	users := make([]services.User, len(items))
	for i, userBytes := range items {
		user, err := services.GetUserMarshaler().UnmarshalUser(userBytes)
		if err != nil {
			return nil, trace.Wrap(err)
		}
		users[i] = user
	}
	return users, nil
}

// DeleteUser deletes a user by username
func (c *Client) DeleteUser(user string) error {
	_, err := c.Delete(c.Endpoint("users", user))
	return trace.Wrap(err)
}

// GenerateKeyPair generates SSH private/public key pair optionally protected
// by password. If the pass parameter is an empty string, the key pair
// is not password-protected.
func (c *Client) GenerateKeyPair(pass string) ([]byte, []byte, error) {
	out, err := c.PostJSON(c.Endpoint("keypair"), generateKeyPairReq{Password: pass})
	if err != nil {
		return nil, nil, trace.Wrap(err)
	}
	var kp *generateKeyPairResponse
	if err := json.Unmarshal(out.Bytes(), &kp); err != nil {
		return nil, nil, err
	}
	return kp.PrivKey, []byte(kp.PubKey), err
}

// GenerateHostCert takes the public key in the Open SSH ``authorized_keys``
// plain text format, signs it using Host Certificate Authority private key and returns the
// resulting certificate.
func (c *Client) GenerateHostCert(
	key []byte, hostname, authDomain string, roles teleport.Roles, ttl time.Duration) ([]byte, error) {

	out, err := c.PostJSON(c.Endpoint("ca", "host", "certs"),
		generateHostCertReq{
			Key:        key,
			Hostname:   hostname,
			AuthDomain: authDomain,
			Roles:      roles,
			TTL:        ttl,
		})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var cert string
	if err := json.Unmarshal(out.Bytes(), &cert); err != nil {
		return nil, err
	}
	return []byte(cert), nil
}

// GenerateUserCert takes the public key in the Open SSH ``authorized_keys``
// plain text format, signs it using User Certificate Authority signing key and returns the
// resulting certificate.
func (c *Client) GenerateUserCert(
	key []byte, user string, ttl time.Duration) ([]byte, error) {

	out, err := c.PostJSON(c.Endpoint("ca", "user", "certs"),
		generateUserCertReq{
			Key:  key,
			User: user,
			TTL:  ttl,
		})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var cert string
	if err := json.Unmarshal(out.Bytes(), &cert); err != nil {
		return nil, trace.Wrap(err)
	}
	return []byte(cert), nil
}

// CreateSignupToken creates one time token for creating account for the user
// For each token it creates username and hotp generator
func (c *Client) CreateSignupToken(user services.User) (string, error) {
	if err := user.Check(); err != nil {
		return "", trace.Wrap(err)
	}
	out, err := c.PostJSON(c.Endpoint("signuptokens"), createSignupTokenReq{
		User: user,
	})
	if err != nil {
		return "", trace.Wrap(err)
	}
	var token string
	if err := json.Unmarshal(out.Bytes(), &token); err != nil {
		return "", trace.Wrap(err)
	}
	return token, nil
}

// GetSignupTokenData returns token data for a valid token
func (c *Client) GetSignupTokenData(token string) (user string,
	QRImg []byte, hotpFirstValues []string, e error) {

	out, err := c.Get(c.Endpoint("signuptokens", token), url.Values{})
	if err != nil {
		return "", nil, nil, err
	}
	var tokenData getSignupTokenDataResponse
	if err := json.Unmarshal(out.Bytes(), &tokenData); err != nil {
		return "", nil, nil, err
	}
	return tokenData.User, tokenData.QRImg, tokenData.HotpFirstValues, nil
}

// GetSignupU2FRegisterRequest generates sign request for user trying to sign up with invite tokenx
func (c *Client) GetSignupU2FRegisterRequest(token string) (u2fRegisterRequest *u2f.RegisterRequest, e error) {
	out, err := c.Get(c.Endpoint("u2f", "signuptokens", token), url.Values{})
	if err != nil {
		return nil, err
	}
	var u2fRegReq u2f.RegisterRequest
	if err := json.Unmarshal(out.Bytes(), &u2fRegReq); err != nil {
		return nil, err
	}
	return &u2fRegReq, nil
}

// CreateUserWithToken creates account with provided token and password.
// Account username and hotp generator are taken from token data.
// Deletes token after account creation.
func (c *Client) CreateUserWithToken(token, password, hotpToken string) (*Session, error) {
	out, err := c.PostJSON(c.Endpoint("signuptokens", "users"), createUserWithTokenReq{
		Token:     token,
		Password:  password,
		HOTPToken: hotpToken,
	})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var sess *Session
	if err := json.Unmarshal(out.Bytes(), &sess); err != nil {
		return nil, trace.Wrap(err)
	}
	return sess, nil
}

// CreateUserWithU2FToken creates user account with provided token and U2F sign response
func (c *Client) CreateUserWithU2FToken(token string, password string, u2fRegisterResponse u2f.RegisterResponse) (*Session, error) {
	out, err := c.PostJSON(c.Endpoint("u2f", "users"), createUserWithU2FTokenReq{
		Token:               token,
		Password:            password,
		U2FRegisterResponse: u2fRegisterResponse,
	})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var sess *Session
	if err := json.Unmarshal(out.Bytes(), &sess); err != nil {
		return nil, trace.Wrap(err)
	}
	return sess, nil
}

// UpsertOIDCConnector updates or creates OIDC connector
func (c *Client) UpsertOIDCConnector(connector services.OIDCConnector, ttl time.Duration) error {
	_, err := c.PostJSON(c.Endpoint("oidc", "connectors"), upsertOIDCConnectorReq{
		Connector: connector,
		TTL:       ttl,
	})
	if err != nil {
		return trace.Wrap(err)
	}
	return nil
}

// GetOIDCConnector returns OIDC connector information by id
func (c *Client) GetOIDCConnector(id string, withSecrets bool) (*services.OIDCConnector, error) {
	if id == "" {
		return nil, trace.BadParameter("missing connector id")
	}
	out, err := c.Get(c.Endpoint("oidc", "connectors", id),
		url.Values{"with_secrets": []string{fmt.Sprintf("%t", withSecrets)}})
	if err != nil {
		return nil, err
	}
	var conn *services.OIDCConnector
	if err := json.Unmarshal(out.Bytes(), &conn); err != nil {
		return nil, trace.Wrap(err)
	}
	return conn, nil
}

// GetOIDCConnector gets OIDC connectors list
func (c *Client) GetOIDCConnectors(withSecrets bool) ([]services.OIDCConnector, error) {
	out, err := c.Get(c.Endpoint("oidc", "connectors"),
		url.Values{"with_secrets": []string{fmt.Sprintf("%t", withSecrets)}})
	if err != nil {
		return nil, err
	}
	var connectors []services.OIDCConnector
	if err := json.Unmarshal(out.Bytes(), &connectors); err != nil {
		return nil, trace.Wrap(err)
	}
	return connectors, nil
}

// DeleteOIDCConnector deletes OIDC connector by ID
func (c *Client) DeleteOIDCConnector(connectorID string) error {
	if connectorID == "" {
		return trace.BadParameter("missing connector id")
	}
	_, err := c.Delete(c.Endpoint("oidc", "connectors", connectorID))
	return trace.Wrap(err)
}

// CreateOIDCAuthRequest creates OIDCAuthRequest
func (c *Client) CreateOIDCAuthRequest(req services.OIDCAuthRequest) (*services.OIDCAuthRequest, error) {
	out, err := c.PostJSON(c.Endpoint("oidc", "requests", "create"), createOIDCAuthRequestReq{
		Req: req,
	})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var response *services.OIDCAuthRequest
	if err := json.Unmarshal(out.Bytes(), &response); err != nil {
		return nil, trace.Wrap(err)
	}
	return response, nil
}

// ValidateOIDCAuthCallback validates OIDC auth callback returned from redirect
func (c *Client) ValidateOIDCAuthCallback(q url.Values) (*OIDCAuthResponse, error) {
	out, err := c.PostJSON(c.Endpoint("oidc", "requests", "validate"), validateOIDCAuthCallbackReq{
		Query: q,
	})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var response *OIDCAuthResponse
	if err := json.Unmarshal(out.Bytes(), &response); err != nil {
		return nil, trace.Wrap(err)
	}
	return response, nil
}

// EmitAuditEvent sends an auditable event to the auth server (part of evets.IAuditLog interface)
func (c *Client) EmitAuditEvent(eventType string, fields events.EventFields) error {
	_, err := c.PostJSON(c.Endpoint("events"), &auditEventReq{
		Type:   eventType,
		Fields: fields,
	})
	if err != nil {
		return trace.Wrap(err)
	}
	return nil
}

// PostSessionChunk allows clients to submit session stream chunks to the audit log
// (part of evets.IAuditLog interface)
//
// The data is POSTed to HTTP server as a simple binary body (no encodings of any
// kind are needed)
func (c *Client) PostSessionChunk(namespace string, sid session.ID, reader io.Reader) error {
	if namespace == "" {
		return trace.BadParameter("missing parameter namespace")
	}
	r, err := http.NewRequest("POST", c.Endpoint("namespaces", namespace, "sessions", string(sid), "stream"), reader)
	if err != nil {
		return trace.Wrap(err)
	}
	r.Header.Set("Content-Type", "application/octet-stream")
	c.Client.SetAuthHeader(r.Header)
	re, err := c.Client.HTTPClient().Do(r)
	if err != nil {
		return trace.Wrap(err)
	}
	// we **must** consume response by reading all of its body, otherwise the http
	// client will allocate a new connection for subsequent requests
	defer re.Body.Close()
	responseBytes, _ := ioutil.ReadAll(re.Body)
	return trace.ReadError(re.StatusCode, responseBytes)
}

// GetSessionChunk allows clients to receive a byte array (chunk) from a recorded
// session stream, starting from 'offset', up to 'max' in length. The upper bound
// of 'max' is set to events.MaxChunkBytes
func (c *Client) GetSessionChunk(namespace string, sid session.ID, offsetBytes, maxBytes int) ([]byte, error) {
	if namespace == "" {
		return nil, trace.BadParameter("missing parameter namespace")
	}
	response, err := c.Get(c.Endpoint("namespaces", namespace, "sessions", string(sid), "stream"), url.Values{
		"offset": []string{strconv.Itoa(offsetBytes)},
		"bytes":  []string{strconv.Itoa(maxBytes)},
	})
	if err != nil {
		logrus.Error(err)
		return nil, trace.Wrap(err)
	}
	return response.Bytes(), nil
}

// Returns events that happen during a session sorted by time
// (oldest first).
//
// afterN allows to filter by "newer than N" value where N is the cursor ID
// of previously returned bunch (good for polling for latest)
//
// This function is usually used in conjunction with GetSessionReader to
// replay recorded session streams.
func (c *Client) GetSessionEvents(namespace string, sid session.ID, afterN int) (retval []events.EventFields, err error) {
	if namespace == "" {
		return nil, trace.BadParameter("missing parameter namespace")
	}
	query := make(url.Values)
	if afterN > 0 {
		query.Set("after", strconv.Itoa(afterN))
	}
	response, err := c.Get(c.Endpoint("namespaces", namespace, "sessions", string(sid), "events"), query)
	if err != nil {
		return nil, trace.Wrap(err)
	}
	retval = make([]events.EventFields, 0)
	if err := json.Unmarshal(response.Bytes(), &retval); err != nil {
		return nil, trace.Wrap(err)
	}
	return retval, nil
}

// SearchEvents returns events that fit the criteria
func (c *Client) SearchEvents(from, to time.Time, query string) ([]events.EventFields, error) {
	q, err := url.ParseQuery(query)
	if err != nil {
		return nil, trace.BadParameter("query")
	}
	q.Set("from", from.Format(time.RFC3339))
	q.Set("to", to.Format(time.RFC3339))
	response, err := c.Get(c.Endpoint("events"), q)
	if err != nil {
		return nil, trace.Wrap(err)
	}
	retval := make([]events.EventFields, 0)
	if err := json.Unmarshal(response.Bytes(), &retval); err != nil {
		return nil, trace.Wrap(err)
	}
	return retval, nil
}

// GetNamespaces returns a list of namespaces
func (c *Client) GetNamespaces() ([]services.Namespace, error) {
	out, err := c.Get(c.Endpoint("namespaces"), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var re []services.Namespace
	if err := json.Unmarshal(out.Bytes(), &re); err != nil {
		return nil, trace.Wrap(err)
	}
	return re, nil
}

// GetNamespace returns namespace by name
func (c *Client) GetNamespace(name string) (*services.Namespace, error) {
	if name == "" {
		return nil, trace.BadParameter("missing namespace name")
	}
	out, err := c.Get(c.Endpoint("namespaces", name), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var ns services.Namespace
	if err := json.Unmarshal(out.Bytes(), &ns); err != nil {
		return nil, trace.Wrap(err)
	}
	return &ns, nil
}

// UpsertNamespace upserts namespace
func (c *Client) UpsertNamespace(ns services.Namespace) error {
	_, err := c.PostJSON(c.Endpoint("namespaces"), upsertNamespaceReq{Namespace: ns})
	return trace.Wrap(err)
}

// DeleteNamespace deletes namespace by name
func (c *Client) DeleteNamespace(name string) error {
	_, err := c.Delete(c.Endpoint("namespaces", name))
	return trace.Wrap(err)
}

// GetRoles returns a list of roles
func (c *Client) GetRoles() ([]services.Role, error) {
	out, err := c.Get(c.Endpoint("roles"), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	var items []json.RawMessage
	if err := json.Unmarshal(out.Bytes(), &items); err != nil {
		return nil, trace.Wrap(err)
	}
	roles := make([]services.Role, len(items))
	for i, roleBytes := range items {
		role, err := services.GetRoleMarshaler().UnmarshalRole(roleBytes)
		if err != nil {
			return nil, trace.Wrap(err)
		}
		roles[i] = role
	}
	return roles, nil
}

// UpsertRole creates or updates role
func (c *Client) UpsertRole(role services.Role) error {
	_, err := c.PostJSON(c.Endpoint("roles"), upsertRoleReq{Role: role})
	return trace.Wrap(err)
}

// GetRole returns role by name
func (c *Client) GetRole(name string) (services.Role, error) {
	if name == "" {
		return nil, trace.BadParameter("missing name")
	}
	out, err := c.Get(c.Endpoint("roles", name), url.Values{})
	if err != nil {
		return nil, trace.Wrap(err)
	}
	role, err := services.GetRoleMarshaler().UnmarshalRole(out.Bytes())
	if err != nil {
		return nil, trace.Wrap(err)
	}
	return role, nil
}

// DeleteRole deletes role by name
func (c *Client) DeleteRole(name string) error {
	_, err := c.Delete(c.Endpoint("roles", name))
	return trace.Wrap(err)
}

// WebService implements features used by Web UI clients
type WebService interface {
	// GetWebSessionInfo checks if a web sesion is valid, returns session id in case if
	// it is valid, or error otherwise.
	GetWebSessionInfo(user string, sid string) (*Session, error)
	// ExtendWebSession creates a new web session for a user based on another
	// valid web session
	ExtendWebSession(user string, prevSessionID string) (*Session, error)
	// CreateWebSession creates a new web session for a user
	CreateWebSession(user string) (*Session, error)
	// DeleteWebSession deletes a web session for this user by id
	DeleteWebSession(user string, sid string) error
}

// IdentityService manages identities and userse
type IdentityService interface {
	// UpsertPassword updates web access password for the user
	UpsertPassword(user string, password []byte) (hotpURL string, hotpQR []byte, err error)

	// UpsertOIDCConnector updates or creates OIDC connector
	UpsertOIDCConnector(connector services.OIDCConnector, ttl time.Duration) error

	// GetOIDCConnector returns OIDC connector information by id
	GetOIDCConnector(id string, withSecrets bool) (*services.OIDCConnector, error)

	// GetOIDCConnector gets OIDC connectors list
	GetOIDCConnectors(withSecrets bool) ([]services.OIDCConnector, error)

	// DeleteOIDCConnector deletes OIDC connector by ID
	DeleteOIDCConnector(connectorID string) error

	// CreateOIDCAuthRequest creates OIDCAuthRequest
	CreateOIDCAuthRequest(req services.OIDCAuthRequest) (*services.OIDCAuthRequest, error)

	// ValidateOIDCAuthCallback validates OIDC auth callback returned from redirect
	ValidateOIDCAuthCallback(q url.Values) (*OIDCAuthResponse, error)

	// GetU2FSignRequest generates request for user trying to authenticate with U2F token
	GetU2FSignRequest(user string, password []byte) (*u2f.SignRequest, error)

	// GetSignupU2FRegisterRequest generates sign request for user trying to sign up with invite token
	GetSignupU2FRegisterRequest(token string) (*u2f.RegisterRequest, error)

	// CreateUserWithU2FToken creates user account with provided token and U2F sign response
	CreateUserWithU2FToken(token string, password string, u2fRegisterResponse u2f.RegisterResponse) (*Session, error)

	// PreAuthenticatedSignIn is used get web session for a user that is already authenticated
	PreAuthenticatedSignIn(user string) (*Session, error)

	// GetU2FAppID returns U2F settings, like App ID and Facets
	GetU2FAppID() (string, error)

	// GetUser returns a list of usernames registered in the system
	GetUser(name string) (services.User, error)

	// UpsertUser user updates or inserts user entry
	UpsertUser(user services.User) error

	// DeleteUser deletes a user by username
	DeleteUser(user string) error

	// GetUsers returns a list of usernames registered in the system
	GetUsers() ([]services.User, error)

	// CheckPassword checks if the suplied web access password is valid.
	CheckPassword(user string, password []byte, hotpToken string) error

	// SignIn checks if the web access password is valid, and if it is valid
	// returns a secure web session id.
	SignIn(user string, password []byte) (*Session, error)

	// CreateUserWithToken creates account with provided token and password.
	// Account username and hotp generator are taken from token data.
	// Deletes token after account creation.
	CreateUserWithToken(token, password, hotpToken string) (*Session, error)

	// GenerateToken creates a special provisioning token for a new SSH server
	// that is valid for ttl period seconds.
	//
	// This token is used by SSH server to authenticate with Auth server
	// and get signed certificate and private key from the auth server.
	//
	// The token can be used only once.
	GenerateToken(roles teleport.Roles, ttl time.Duration) (string, error)

	// GenerateKeyPair generates SSH private/public key pair optionally protected
	// by password. If the pass parameter is an empty string, the key pair
	// is not password-protected.
	GenerateKeyPair(pass string) ([]byte, []byte, error)

	// GenerateHostCert takes the public key in the Open SSH ``authorized_keys``
	// plain text format, signs it using Host Certificate Authority private key and returns the
	// resulting certificate.
	GenerateHostCert(key []byte, hostname, authDomain string, roles teleport.Roles, ttl time.Duration) ([]byte, error)

	// GenerateUserCert takes the public key in the Open SSH ``authorized_keys``
	// plain text format, signs it using User Certificate Authority signing key and returns the
	// resulting certificate.
	GenerateUserCert(key []byte, user string, ttl time.Duration) ([]byte, error)

	// GetSignupTokenData returns token data for a valid token
	GetSignupTokenData(token string) (user string, QRImg []byte, hotpFirstValues []string, e error)

	// CreateSignupToken creates one time token for creating account for the user
	// For each token it creates username and hotp generator
	CreateSignupToken(user services.User) (string, error)
}

// ProvisioningService is a service in control
// of adding new nodes, auth servers and proxies to the cluster
type ProvisioningService interface {
	// GetTokens returns a list of active invitation tokens for nodes and users
	GetTokens() (tokens []services.ProvisionToken, err error)

	// GetToken returns provisioning token
	GetToken(token string) (*services.ProvisionToken, error)

	// DeleteToken deletes a given provisioning token on the auth server (CA). It
	// could be a user token or a machine token
	DeleteToken(token string) error
	// RegisterUsingToken calls the auth service API to register a new node via registration token
	// which has been previously issued via GenerateToken
	RegisterUsingToken(token, hostID string, role teleport.Role) (*PackedKeys, error)

	// RegisterNewAuthServer is used to register new auth server with token
	RegisterNewAuthServer(token string) error
}

// ClientI is a client to Auth service
type ClientI interface {
	IdentityService
	ProvisioningService
	services.Trust
	events.IAuditLog
	services.Presence
	services.Access
	WebService
	session.Service

	GetDomainName() (string, error)
}