// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Thibault Ducray
//
// This file is part of MyPwdTool's open-source sync/encryption core — see
// LICENSE-SYNC-CRYPTO.md at the repo root and https://tducray.fr/mypwdtool/open-source/.
// The rest of this application is proprietary and NOT covered by this license.

package fr.tducray.mypwdtool.relay

import kotlin.io.encoding.Base64
import kotlin.io.encoding.ExperimentalEncodingApi

/**
 * Port of the `base64urlEncode`/`base64urlDecode` free functions in
 * `Sync/RelayAPIClient.swift` — standard base64url without padding, same as the relay server
 * expects (see the E2EE Relay API spec).
 */
@OptIn(ExperimentalEncodingApi::class)
object Base64Url {
    fun encode(data: ByteArray): String = Base64.UrlSafe.encode(data).trimEnd('=')

    fun decode(s: String): ByteArray? {
        val padded = s + "=".repeat((4 - s.length % 4) % 4)
        return try {
            Base64.UrlSafe.decode(padded)
        } catch (e: IllegalArgumentException) {
            null
        }
    }
}