package login

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"math/rand"
	"net/http"
	"net/url"
	"strings"

	"github.com/pkg/errors"
)

type apiHelper interface {
	queryToken(data url.Values, tenantID string) (azureToken, error)
	openAzureLoginPage(redirectURL string)
	queryAuthorizationAPI(authorizationURL string, authorizationHeader string) ([]byte, int, error)
}

type azureAPIHelper struct{}

func (helper azureAPIHelper) openAzureLoginPage(redirectURL string) {
	state := randomString("", 10)
	authURL := fmt.Sprintf(authorizeFormat, clientID, redirectURL, state, scopes)
	openbrowser(authURL)
}

func (helper azureAPIHelper) queryAuthorizationAPI(authorizationURL string, authorizationHeader string) ([]byte, int, error) {
	req, err := http.NewRequest(http.MethodGet, authorizationURL, nil)
	if err != nil {
		return nil, 0, err
	}
	req.Header.Add("Authorization", authorizationHeader)
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, 0, err
	}
	bits, err := ioutil.ReadAll(res.Body)
	if err != nil {
		return nil, 0, err
	}
	return bits, res.StatusCode, nil
}

func (helper azureAPIHelper) queryToken(data url.Values, tenantID string) (azureToken, error) {
	res, err := http.Post(fmt.Sprintf(tokenEndpoint, tenantID), "application/x-www-form-urlencoded", strings.NewReader(data.Encode()))
	if err != nil {
		return azureToken{}, err
	}
	if res.StatusCode != 200 {
		return azureToken{}, errors.Errorf("error while renewing access token, status : %s", res.Status)
	}
	bits, err := ioutil.ReadAll(res.Body)
	if err != nil {
		return azureToken{}, err
	}
	token := azureToken{}
	if err := json.Unmarshal(bits, &token); err != nil {
		return azureToken{}, err
	}
	return token, nil
}

var (
	letterRunes = []rune("abcdefghijklmnopqrstuvwxyz123456789")
)

func randomString(prefix string, length int) string {
	b := make([]rune, length)
	for i := range b {
		b[i] = letterRunes[rand.Intn(len(letterRunes))]
	}
	return prefix + string(b)
}