Kotlin zip utils

zip.kt

/*
 * Copyright 2020 Michael Rittmeister
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

package com.github.devcordde.devcordbot.util

import java.io.FileInputStream
import java.nio.ByteBuffer
import java.nio.channels.FileChannel
import java.nio.file.Files
import java.nio.file.Path
import java.nio.file.StandardOpenOption
import java.util.zip.ZipEntry
import java.util.zip.ZipInputStream

fun unzipFile(path: Path, into: Path, strip: Int = 0, delete: Boolean = true) {
    val stream = ZipInputStream(FileInputStream(path.toFile()))
    val buffer = ByteArray(1024)
    stream.use {
        it.asIterable().forEach { entry ->
            val destination = Path.of(entry.name)
            val sanitizedDestination = if (destination.nameCount > strip) {
                destination.subpath(strip, destination.nameCount)
            } else destination

            val finalDestination = into.resolve(sanitizedDestination)
            if (finalDestination.parent?.let { parent -> !Files.exists(parent) } == true) {
                Files.createDirectories(finalDestination.parent)
            }
            if (entry.isDirectory) {
                if (sanitizedDestination.nameCount > strip) {
                    if (!Files.exists(finalDestination)) {
                        Files.createDirectories(finalDestination)
                    }
                }
            } else {
                Files.createFile(finalDestination)
                FileChannel.open(finalDestination, StandardOpenOption.WRITE).use { writer ->
                    while (it.read(buffer) > 0) {
                        writer.write(ByteBuffer.wrap(buffer))
                    }
                }
            }
        }
    }

    if (delete) {
        Files.deleteIfExists(path)
    }
}

private fun ZipInputStream.asIterable(): Iterable<ZipEntry> = object : Iterable<ZipEntry> {
    override fun iterator(): Iterator<ZipEntry> = ZipIterator(this@asIterable)
}

private class ZipIterator(private val stream: ZipInputStream) : Iterator<ZipEntry> {
  private var next: ZipEntry? = null
  override fun hasNext(): Boolean {
    next = stream.nextEntry
    return next != null
  }

  override fun next(): ZipEntry = next ?: throw NoSuchElementException()
}

ZipIterator class doesn't work correctly because the scope function also in next method move the pointer inside ZipInputStream.

You should use this version:

private class ZipIterator(private val stream: ZipInputStream) : Iterator<ZipEntry> {
  private var next: ZipEntry? = null
  override fun hasNext(): Boolean {
    next = stream.nextEntry
    return next != null
  }

  override fun next(): ZipEntry = next ?: throw NoSuchElementException()
}

Thx