A Gradle plugin which creates tasks to download platform-specific JRE distributions from Adoptium

FetchPackagingDependencies.kt

package com.project.build

import org.gradle.api.Plugin
import org.gradle.api.Project
import java.io.File
import java.io.FileOutputStream
import java.net.URL
import java.nio.channels.Channels
import java.nio.file.Files
import java.nio.file.Path
import java.nio.file.Paths

enum class Platform(val friendlyName: String) {
    LINUX_X32("Linux32"),
    LINUX_X64("Linux64"),
    WINDOWS_X32("Windows32"),
    WINDOWS_X64("Windows64"),
    MAC("Mac")
}

class FetchPackagingDependencies: Plugin<Project> {
    private fun downloadFile(url: URL, outputFileName: String) {
        url.openStream().use {
            Channels.newChannel(it).use { rbc ->
                FileOutputStream(outputFileName).use { fos ->
                    fos.channel.transferFrom(rbc, 0, Long.MAX_VALUE)
                }
            }
        }
    }

    override fun apply(target: Project) {
        for (platform in Platform.values()) {
            target.tasks.create("fetchPackagingDependencies$platform") {
                doFirst {
                    val jreFileName = jreFileNameForPlatform(platform)

                    val dependenciesFolder = Paths.get(target.projectDir.path, "build", "dependencies", platform.name)
                    Files.createDirectories(dependenciesFolder)

                    val jrePath = dependenciesFolder.resolve(jreFileName)
                    if (!Files.exists(jrePath)) {
                        downloadFile(URL(jreBaseUrl + jreFileName), jrePath.toString())
                    }
                }
            }
        }
    }

    companion object {
        private const val jreBaseUrl = "https://github.com/adoptium/temurin17-binaries/releases/download/jdk-17.0.4%2B8/"
        private const val jrePrefix = "OpenJDK17U-jre_"
        private const val jrePostfix = "_hotspot_17.0.4_8"

        private fun jreFileNameForPlatform(platform: Platform) = when(platform) {
            Platform.LINUX_X32 -> "${jrePrefix}x32_linux${jrePostfix}.tar.gz"
            Platform.LINUX_X64 -> "${jrePrefix}x64_linux${jrePostfix}.tar.gz"
            Platform.WINDOWS_X32 -> "${jrePrefix}x32_windows${jrePostfix}.zip"
            Platform.WINDOWS_X64 -> "${jrePrefix}x64_windows${jrePostfix}.zip"
            Platform.MAC -> "${jrePrefix}x64_mac${jrePostfix}.tar.gz"
        }

        fun getJrePath(projectDir: File, platform: Platform): Path {
            val jreFileName = jreFileNameForPlatform(platform)
            return Paths.get(projectDir.path, "build", "dependencies", platform.name, jreFileName)
        }
    }
}