// This is Free Software under GNU Affero General Public License v >= 3.0
// without warranty, see README.md and license for details.
//
// SPDX-License-Identifier: AGPL-3.0-or-later
// License-Filename: LICENSES/AGPL-3.0.txt
//
// Copyright (C) 2022 by via donau
//   – Österreichische Wasserstraßen-Gesellschaft mbH
// Software engineering by Intevation GmbH
//
// Author(s):
//  * Sascha L. Teichmann <sascha.teichmann@intevation.de>

package soap

import (
	"encoding/base64"
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
)

type Token struct {
	AccessToken string `json:"access_token"`
	Scope       string `json:"scope"`
	TokenType   string `json:"token_type"`
	ExpiresIn   int    `json:"expires_in"`
}

func (token *Token) AddAuth(request *http.Request) {
	request.Header.Add("Authorization", "Bearer "+token.AccessToken)
}

func FetchToken(tokenURL, key, secret string) (*Token, error) {

	keyPair := key + ":" + secret

	encodedKeyPair := base64.URLEncoding.EncodeToString([]byte(keyPair))

	req, err := http.NewRequest(
		http.MethodPost,
		tokenURL,
		strings.NewReader("grant_type=client_credentials"))

	if err != nil {
		return nil, err
	}

	req.Header.Set("Authorization", "Basic "+encodedKeyPair)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf(
			"POST failed: %s (%d)",
			http.StatusText(resp.StatusCode),
			resp.StatusCode)
	}

	var token Token
	defer resp.Body.Close()

	if err = json.NewDecoder(resp.Body).Decode(&token); err != nil {
		return nil, err
	}
	return &token, err
}