auth/auth.go

package kekskurseauth

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

type Auth struct {
	authConfig   AuthConfig
	clientConfig ClientConfig
}

type Token struct {
	AccessToken  string `json:"access_token"`
	TokenType    string `json:"token_type"`
	ExpiredIn    int    `json:"expires_in"`
	RefreshToken string `json:"refresh_token"`
	CreatedAt    time.Time
}

func NewAuthWithConfig(config ClientConfig, authConfig AuthConfig) (Auth, error) {
	a := Auth{}
	a.authConfig = authConfig
	a.clientConfig = config
	return a, nil
}

func NewAuthWithConfigurationURL(config ClientConfig, url string) (Auth, error) {
	a := Auth{}
	a.clientConfig = config
	authConfig := AuthConfig{}

	res, err := http.Get(url)
	if err != nil {
		return Auth{}, fmt.Errorf("%w: %q", ErrCantGetConfiguratorData, err)
	}
	defer res.Body.Close()

	bodyContent, err := io.ReadAll(res.Body)
	if err != nil {
		return Auth{}, fmt.Errorf("%w: %q", ErrCantGetConfiguratorData, err)
	}

	err = json.Unmarshal(bodyContent, &authConfig)
	if err != nil {
		return Auth{}, fmt.Errorf("%w: %q", ErrCantGetConfiguratorData, err)
	}

	a.authConfig = authConfig
	return a, nil
}

func (a Auth) GetAuthorizationURL(state string) (string, error) {
	if a.authConfig.AuthorizationEndpoint == "" {
		return "", fmt.Errorf("%w: %s", ErrCantGetAuthorizationURL, "AuthorizationEndpoint in config is empty")
	}

	if a.clientConfig.ClientID == "" {
		return "", fmt.Errorf("%w: %s", ErrCantGetAuthorizationURL, "clientid in config is empty")
	}

	url, err := url.Parse(a.authConfig.AuthorizationEndpoint)
	if err != nil {
		return "", fmt.Errorf("%w: %q", ErrCantGetAuthorizationURL, err)
	}

	values := url.Query()

	values.Set("client_id", a.clientConfig.ClientID)
	if a.clientConfig.RedirectURL != "" {
		values.Set("redirect_uri", a.clientConfig.RedirectURL)
	}

	if len(a.clientConfig.Scope) > 0 {
		values.Set("scope", strings.Join(a.clientConfig.Scope, "+"))
	}

	if state != "" {
		values.Set("state", state)
	}

	values.Set("response_type", "code")

	url.RawQuery = values.Encode()

	return url.String(), nil
}

func (a Auth) GetTokenFromCode(code string) (Token, error) {
	t := Token{}

	form := url.Values{}
	form.Add("grant_type", "authorization_code")
	form.Add("code", code)

	return t, nil
}