three_legged.go

package oauth

import (
	"bytes"
	"encoding/json"
	"errors"
	"io/ioutil"
	"net/http"
	"net/url"
	"strconv"
)

// ThreeLeggedAuth struct holds data necessary for making requests in 3-legged context
type ThreeLeggedAuth struct {
	AuthData
	RedirectURI string `json:"redirect_uri,omitempty"`
}

// ThreeLeggedAuthenticator interface defines the method necessary to qualify as 3-legged authenticator
type ThreeLeggedAuthenticator interface {
	Authorize(scope string, state string) (string, error)
	GetToken(code string) (Bearer, error)
	RefreshToken(refreshToken string, scope string) (Bearer, error)
}

// NewThreeLeggedClient returns a 3-legged authenticator with default host and authPath
func NewThreeLeggedClient(clientID, clientSecret, redirectURI string) ThreeLeggedAuth {
	return ThreeLeggedAuth{
		AuthData{
			clientID,
			clientSecret,
			"https://developer.api.autodesk.com",
			"/authentication/v1",
		},
		redirectURI,
	}
}

// Authorize method returns an URL to redirect an end user, where it will be asked to give his consent for app to
//access the specified resources.
//
// The resources for which the permission is asked are specified as a space-separated list of required scopes.
// State can be used to specify, as URL-encoded payload, some arbitrary data that the authentication flow will pass back
// verbatim in a state query parameter to the callback URL.
//	Note: You do not call this URL directly in your server code.
//	See the Get a 3-Legged Token tutorial for more information on how to use this endpoint.
func (a ThreeLeggedAuth) Authorize(scope string, state string) (string, error) {

	request, err := http.NewRequest("GET",
		a.Host+a.AuthPath+"/authorize",
		nil,
	)

	if err != nil {
		return "", err
	}

	query := request.URL.Query()
	query.Add("client_id", a.ClientID)
	query.Add("response_type", "code")
	query.Add("redirect_uri", a.RedirectURI)
	query.Add("scope", scope)
	query.Add("state", state)

	request.URL.RawQuery = query.Encode()

	return request.URL.String(), nil
}

//GetToken is used to exchange the authorization code for a token and an exchange token
func (a ThreeLeggedAuth) GetToken(code string) (bearer Bearer, err error) {

	task := http.Client{}

	body := url.Values{}
	body.Add("client_id", a.ClientID)
	body.Add("client_secret", a.ClientSecret)
	body.Add("grant_type", "authorization_code")
	body.Add("code", code)
	body.Add("redirect_uri", a.RedirectURI)

	req, err := http.NewRequest("POST",
		a.Host+a.AuthPath+"/gettoken",
		bytes.NewBufferString(body.Encode()),
	)

	if err != nil {
		return
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	response, err := task.Do(req)

	if err != nil {
		return
	}

	defer response.Body.Close()

	if response.StatusCode != http.StatusOK {
		content, _ := ioutil.ReadAll(response.Body)
		err = errors.New("[" + strconv.Itoa(response.StatusCode) + "] " + string(content))
		return
	}

	decoder := json.NewDecoder(response.Body)
	err = decoder.Decode(&bearer)

	return
}

// RefreshToken is used to get a new access token by using the refresh token provided by GetToken
func (a ThreeLeggedAuth) RefreshToken(refreshToken string, scope string) (bearer Bearer, err error) {

	task := http.Client{}

	body := url.Values{}
	body.Add("client_id", a.ClientID)
	body.Add("client_secret", a.ClientSecret)
	body.Add("grant_type", "refresh_token")
	body.Add("refresh_token", refreshToken)
	body.Add("scope", scope)

	req, err := http.NewRequest("POST",
		a.Host+a.AuthPath+"/refreshtoken",
		bytes.NewBufferString(body.Encode()),
	)

	if err != nil {
		return
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	response, err := task.Do(req)

	if err != nil {
		return
	}

	defer response.Body.Close()

	if response.StatusCode != http.StatusOK {
		content, _ := ioutil.ReadAll(response.Body)
		err = errors.New("[" + strconv.Itoa(response.StatusCode) + "] " + string(content))
		return
	}
	decoder := json.NewDecoder(response.Body)
	err = decoder.Decode(&bearer)

	return
}