src/main/kotlin/io/bazel/kotlin/builder/utils/jars/JarExtractor.kt

/*
 * Copyright 2018 The Bazel Authors. All rights reserved.
 *
 * 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 io.bazel.kotlin.builder.utils.jars

import java.nio.file.Files
import java.nio.file.Path
import java.util.jar.JarFile


open class JarExtractor protected constructor(
    protected var destDir: Path
) {

    /**
     * @param isDirectory is the target a directory.
     * @param target path the operation will apply to.
     * @return weather the operation should be applied or not.
     */
    internal open fun preWrite(isDirectory: Boolean, target: Path): Boolean = true

    protected fun extract(jarFile: Path) {
        JarFile(jarFile.toFile()).use { jar ->
            jar.entries().also { entries ->
                while (entries.hasMoreElements()) {
                    (entries.nextElement() as java.util.jar.JarEntry).also { entry ->
                        destDir.resolve(entry.name).also { target ->
                            if (preWrite(entry.isDirectory, target)) {
                                when {
                                    entry.isDirectory ->
                                        Files.createDirectories(target)
                                    else -> jar.getInputStream(entry).use {
                                        Files.createDirectories(target.parent)
                                        Files.copy(it, target)
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}