package jwt

import (
	"encoding/base64"
	"fmt"
	"strings"
)

// Base64Encode encodes a payload of data as a string, like specified
// in RFC 7515 (no trailing '='
func Base64Encode(b []byte) string {
	return strings.TrimRight(base64.URLEncoding.EncodeToString(b), "=")
}

// Base64Decode decodes a payload of data as a []byte, like specified
// in RFC 7515 (no trailing '=')
func Base64Decode(s string) ([]byte, error) {
	switch len(s) % 4 {
	case 2:
		s += "=="
	case 3:
		s += "="
	case 1:
		return nil, fmt.Errorf("jwt: Invalid base64 string (length:%d %% 4 == 1): '%s'", len(s), s)
	}
	d, err := base64.URLEncoding.DecodeString(s)
	if err != nil {
		return nil, fmt.Errorf("jwt: %s", err)
	}
	return d, nil

}