/*
 * Copyright (c) 2022 Florian Schrofner
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

package fi.schro.util

import kotlinx.cinterop.ByteVar
import kotlinx.cinterop.allocArray
import kotlinx.cinterop.memScoped
import kotlinx.cinterop.toKString
import platform.posix.fclose
import platform.posix.fgets
import platform.posix.fopen

class FileUtilImpl: FileUtil {
    override fun readAllText(filePath: String): String {
        val returnBuffer = StringBuilder()
        val file = fopen(filePath, "r") ?:
        throw IllegalArgumentException("Cannot open input file $filePath")

        try {
            memScoped {
                val readBufferLength = 64 * 1024
                val buffer = allocArray<ByteVar>(readBufferLength)
                var line = fgets(buffer, readBufferLength, file)?.toKString()
                while (line != null) {
                    returnBuffer.append(line)
                    line = fgets(buffer, readBufferLength, file)?.toKString()
                }
            }
        } finally {
            fclose(file)
        }

        return returnBuffer.toString()
    }

}