auth.go

// Package login2 provides sign in and sign up by oauth2 and email and password.
// Inspired in omniauth and devise gem
//
package login2

import (
	"encoding/base64"
	"encoding/json"
	"log"
	"math/rand"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"

	"code.google.com/p/go.crypto/bcrypt"
	"code.google.com/p/goauth2/oauth"
	"github.com/gorilla/sessions"
)

var store = sessions.NewCookieStore([]byte(os.Getenv("SESSION_SECRET")))

// Provider is a oauth2 provider, like facebook or google
// Name is provider name, it's like a key, will can be use it after,
// the package only use it as a index.
// Key is oauth2 key
// Secret is oauth2 secret key
// RedirectURL is a url will config on provider
// TokenURL is a URL to get the token on provider
// AuthURL is a URL to auth user on provider
// UserInfoURL is a URL to get User Information on provider
// Scope is whats the scope your app wants
type Provider struct {
	Name        string
	Key         string
	Secret      string
	RedirectURL string
	TokenURL    string
	AuthURL     string
	UserInfoURL string
	Scope       string
}

// Internal auth config
type builderConfig struct {
	Auth        *oauth.Config
	UserInfoURL string
}

// URLS

type URLS struct {
	Redirect             string
	SignIn               string
	SignUp               string
	ResetPasswordSuccess string
}

// Builder is the app configuration, store providers and callbacks
//
// Follow the callbacks documentation:
//
//	UserSetupFn         func(provider string, user *login2.User, rawResponse *http.Response) (int64, error)
//
// Called when user return from oauth provider, this method will send a provider
// origin as string, some user information as ```login2.User``` and the raw
// response from origin(login2 will make a request to ``` UserInfoURL```
// configured on provider config). To sign in user the method expect the user
// id as int64
//
//
//	UserCreateFn        func(email string, password string, token string, request *http.Request) (int64, error)
//
// Called when user sign up by email/password, the method will send email and password as string, password // is encrypted hash, and expect the user id as int64
//
//	UserIdByEmail       func(email string) (int64, error)
//
// Called when user sign in by email/password to get the user id by email after check the password with ```UserPasswordByEmail```, the method will send the user email as string and expect the user id as int64
//
//	UserPasswordByEmail func(email string) (string, bool)
//
// Called when user sign in by email/password to get user password and check with inputed password, the method will send user email as string and expect the user password as string
//
//	UserResetPasswordFn func(token string, email string)
// TODO
type Builder struct {
	Providers           map[string]*builderConfig
	UserSetupFn         func(provider string, user *User, rawResponde *http.Response) (int64, error)
	UserCreateFn        func(email string, password string, token string, request *http.Request) (int64, error)
	UserResetPasswordFn func(token string, email string)
	UserIdByEmail       func(email string) (int64, error) // TODO: use bool as second params
	UserIdByToken       func(token string) (int64, bool)
	UserPasswordByEmail func(email string) (string, bool)
	LoginFn             func(userId string)
	URLS                URLS
}

type User struct {
	Id      string
	Email   string
	Link    string
	Name    string
	Gender  string
	Locale  string
	Picture string
	Token   string
}

func NewBuilder() *Builder { // TODO: changes to NewAuth
	builder := new(Builder)
	builder.Providers = make(map[string]*builderConfig, 0)
	return builder
}

func (b *Builder) NewProviders(providers []*Provider) {
	for _, p := range providers {
		b.NewProvider(p)
	}
}

func (b *Builder) NewProvider(p *Provider) {
	config := &oauth.Config{
		ClientId:     p.Key,
		ClientSecret: p.Secret,
		RedirectURL:  p.RedirectURL,
		Scope:        p.Scope,
		AuthURL:      p.AuthURL,
		TokenURL:     p.TokenURL,
	}

	provider := new(builderConfig)
	provider.Auth = config
	provider.UserInfoURL = p.UserInfoURL

	b.Providers[p.Name] = provider
}

// HTTP server

// OAuthAuthorize To authorize user on defined provider. Send provider name as params and method will return http handle
//
//	```
//	GET   /auth/google     loginBuilder.OAuthAuthorize("google")
//	GET   /auth/facebook   loginBuilder.OAuthAuthorize("facebook")
//	```
func (b *Builder) OAuthAuthorize(provider string) func(http.ResponseWriter, *http.Request) {
	config := b.Providers[provider]

	return func(w http.ResponseWriter, r *http.Request) {
		url := config.Auth.AuthCodeURL("")
		log.Println("Send user to", provider)
		http.Redirect(w, r, url, http.StatusFound)
	}
}

// OAuthLogin	The oauth endpoint callback, configured on provider, Send provider name as params and method will return http handle
//
//	```
//	GET   /auth/callback/google     loginBuilder.OAuthLogin("google")
//	GET   /auth/callback/facebook   loginBuilder.OAuthLogin("facebook")
//	```
func (b *Builder) OAuthLogin(provider string) func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, request *http.Request) {
		userId, err := b.OAuthCallback(provider, request)

		if err != nil {
			http.Redirect(w, request, b.URLS.SignIn, http.StatusTemporaryRedirect)
		} else {
			b.login(request, w, strconv.FormatInt(userId, 10))
		}
	}
}

// OAuthCallback receive code params from provider and get user information
func (b *Builder) OAuthCallback(provider string, r *http.Request) (int64, error) {
	config := b.Providers[provider]
	code := r.FormValue("code")
	t := &oauth.Transport{Config: config.Auth}
	t.Exchange(code)
	responseAuth, _ := t.Client().Get(config.UserInfoURL)
	defer responseAuth.Body.Close()

	var user User
	decoder := json.NewDecoder(responseAuth.Body)
	user.Token = NewUserToken()
	err := decoder.Decode(&user)
	if err != nil {
		panic(err)
	}

	return b.UserSetupFn(provider, &user, responseAuth)
}

// SignUp Hanlder to sign up user, send a http POST with email and password params on body
//
//	```
//	POST   /users/sign_up   SignUp
//	```
func (b *Builder) SignUp() func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, request *http.Request) {
		email := request.FormValue("email")
		password := request.FormValue("password")
		hpassword, err := generateHash(password)
		if err != nil {
			http.Redirect(w, request, b.URLS.SignUp+"?password=error", http.StatusTemporaryRedirect)
			return
		}

		userID, err := b.UserCreateFn(email, hpassword, NewUserToken(), request)
		if err != nil {
			http.Redirect(w, request, b.URLS.SignIn+"?user=exists", http.StatusTemporaryRedirect)
		} else {
			b.login(request, w, strconv.FormatInt(userID, 10))
		}
	}
}

// SignIn Handler to sign in user, send a http POST with email and password params on body
//
//	```
//	POST   /users/sign_in   SignIn
//	```
func (b *Builder) SignIn() func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		email := r.FormValue("email")
		password := r.FormValue("password")
		userPassword, ok := b.UserPasswordByEmail(email)

		if !ok {
			http.Redirect(w, r, b.URLS.SignIn+"?user=not_found", http.StatusTemporaryRedirect)
		}

		err := checkHash(userPassword, password)
		if err != nil {
			http.Redirect(w, r, b.URLS.SignIn+"?user=no_match", http.StatusTemporaryRedirect)
		} else {
			userId, _ := b.UserIdByEmail(email)
			b.login(r, w, strconv.FormatInt(userId, 10))
		}
	}
}

// SignOut Handler Method to sign out user, send a http GET
//
//	```
//	GET   /users/sign_out   SignOut
//	```
func (b *Builder) SignOut() func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		session := b.Logout(r)
		session.Save(r, w)

		http.Redirect(w, r, b.URLS.SignIn, http.StatusTemporaryRedirect)
	}
}

// Protected to be used on protected path, send the original http handle as params and if user is logged Protected will pass user to original handler else Protected will save URL and send user to Sign In. Protected send as first params the user id.
//
//	```
//	GET   /dashboard   Protected(DashboardHandle)
//	```
func (b *Builder) Protected(fn func(string, http.ResponseWriter, *http.Request)) func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		userID, ok := b.CurrentUser(r)
		if ok {
			fn(userID, w, r)
		} else {
			b.SetReturnTo(w, r, r.URL.String())
			http.Redirect(w, r, b.URLS.SignIn, http.StatusTemporaryRedirect)
		}
	}
}

func (b *Builder) SetReturnTo(w http.ResponseWriter, r *http.Request, url string) {
	session, _ := store.Get(r, "_session")
	session.Values["return_to"] = url
	session.Save(r, w)
}

func (b *Builder) ResetPassword() func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		email := r.FormValue("email")
		token := NewUserToken()
		go b.UserResetPasswordFn(token, email)
		http.Redirect(w, r, b.URLS.ResetPasswordSuccess, http.StatusTemporaryRedirect)
	}
}

func (b *Builder) Login(r *http.Request, userId string) *sessions.Session {
	session, _ := store.Get(r, "_session")
	session.Values["user_id"] = userId
	return session
}

func (b *Builder) Logout(r *http.Request) *sessions.Session {
	session, _ := store.Get(r, "_session")
	session.Values["user_id"] = nil
	return session
}

// helper

func (b *Builder) login(r *http.Request, w http.ResponseWriter, userId string) {
	session := b.Login(r, userId)

	var returnTo string
	returnToSession := session.Values["return_to"]
	returnTo, ok := returnToSession.(string)
	if !ok {
		returnTo = b.URLS.Redirect
	}

	go b.LoginFn(userId)

	session.Values["return_to"] = nil
	session.Save(r, w)
	http.Redirect(w, r, returnTo, 302)
}

// CurrentUser func expect you send the request(```http.Request```) and return the user id as string and bool true if is OK
func (b *Builder) CurrentUser(r *http.Request) (id string, ok bool) {
	session, _ := store.Get(r, "_session")
	userId := session.Values["user_id"]
	id, ok = userId.(string)
	if !ok {
		id, ok = b.getUserIdByAuthorizationToken(r)
	}
	return
}

func (b *Builder) getUserIdByAuthorizationToken(r *http.Request) (id string, ok bool) {
	tokenAuthorization := strings.Split(r.Header.Get("Authorization"), " ")
	if len(tokenAuthorization) == 2 {
		var _id int64
		_id, ok = b.UserIdByToken(tokenAuthorization[1])
		id = strconv.Itoa(int(_id))
		return
	}
	return
}

// GenerateHash wrapper to bcrypt.GenerateFromPassword
func generateHash(data string) (string, error) {
	h, err := bcrypt.GenerateFromPassword([]byte(data), 0)
	return string(h[:]), err
}

func checkHash(hashed, plain string) error {
	return bcrypt.CompareHashAndPassword([]byte(hashed), []byte(plain))
}

func generateRandomToken() int64 {
	rand.Seed(time.Now().Unix())
	return rand.Int63()
}

func NewUserToken() string {
	hash, _ := generateHash(strconv.Itoa(int(generateRandomToken())))
	return base64.URLEncoding.EncodeToString([]byte(hash))
}