package oauth

import (
	"bytes"
	"crypto/rand"
	"encoding/base64"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"strings"
)

func randomToken(size int) (string, error) {
	buf := make([]byte, size)
	if _, err := rand.Read(buf); err != nil {
		return "", err
	}
	return base64.RawURLEncoding.EncodeToString(buf), nil
}

func encodeSegment(value any) (string, error) {
	raw, err := json.Marshal(value)
	if err != nil {
		return "", err
	}
	return base64.RawURLEncoding.EncodeToString(raw), nil
}

func decodeSegment(segment string, value any) error {
	raw, err := base64.RawURLEncoding.DecodeString(segment)
	if err != nil {
		return err
	}
	decoder := json.NewDecoder(bytes.NewReader(raw))
	decoder.UseNumber()
	if err := decoder.Decode(value); err != nil {
		return err
	}
	if _, err := decoder.Token(); !errors.Is(err, io.EOF) {
		return fmt.Errorf("oauth: trailing JSON data")
	}
	return nil
}

func splitJWT(token string) (string, string, string, bool) {
	parts := strings.Split(token, ".")
	if len(parts) != 3 {
		return "", "", "", false
	}
	return parts[0], parts[1], parts[2], true
}