res_levis_backend/internal/pkg/apiclient/auth.go

package apiclient

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"strings"

	"github.com/AFASystems/presence/internal/pkg/config"
)

type response struct {
	Token string `json:"access_token"`
}

func GetToken(ctx context.Context, cfg *config.Config, client *http.Client) (string, error) {
	formData := url.Values{}
	formData.Set("grant_type", "password")
	formData.Set("client_id", cfg.HTTPClientID)
	formData.Set("client_secret", cfg.ClientSecret)
	formData.Set("username", cfg.HTTPUsername)
	formData.Set("password", cfg.HTTPPassword)
	formData.Set("audience", cfg.HTTPAudience)

	req, err := http.NewRequest("POST", fmt.Sprintf("%s/realms/API.Server.local/protocol/openid-connect/token", cfg.APIAuthURL), strings.NewReader(formData.Encode()))
	if err != nil {
		return "", err
	}
	req.Header.Add("Content-Type", "application/x-www-form-urlencoded")

	req = req.WithContext(ctx)
	res, err := client.Do(req)
	if err != nil {
		return "", err
	}

	var j response

	if err := json.NewDecoder(res.Body).Decode(&j); err != nil {
		return "", err
	}

	return j.Token, nil
}