First stab

plugin/build.gradle.kts

@@ -0,0 +1,34 @@
+plugins {
+    id("com.github.johnrengelman.shadow") version "4.0.0"
+    `java-gradle-plugin`
+    `kotlin-dsl`
+    `maven-publish`
+    kotlin("kapt") version embeddedKotlinVersion
+}
+
+group = "org.nixos"
+version = "1.0.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation(kotlin("stdlib-jdk8"))
+    implementation("org.apache.maven:maven-model:3.5.4")
+    implementation("org.apache.maven:maven-model-builder:3.5.4")
+    implementation("com.squareup.okio:okio:2.2.2")
+    implementation("com.squareup.moshi:moshi:1.8.0")
+    kapt("com.squareup.moshi:moshi-kotlin-codegen:1.8.0")
+}
+
+gradlePlugin {
+    plugins {
+        register("gradle2nix") {
+            id = "org.nixos.gradle2nix"
+            displayName = "gradle2nix"
+            description = "Create Nix configurations suitable for reproducible packaging"
+            implementationClass = "org.nixos.gradle2nix.Gradle2NixPlugin"
+        }
+    }
+}

plugin/src/main/kotlin/org/nixos/gradle2nix/Gradle2NixPlugin.kt

@@ -0,0 +1,137 @@
+package org.nixos.gradle2nix
+
+import com.squareup.moshi.Moshi
+import okio.buffer
+import okio.source
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.file.RegularFile
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.internal.DocumentationRegistry
+import org.gradle.api.internal.artifacts.ivyservice.ivyresolve.strategy.VersionSelectorScheme
+import org.gradle.api.internal.plugins.PluginRegistry
+import org.gradle.api.invocation.Gradle
+import org.gradle.api.provider.Provider
+import org.gradle.api.tasks.TaskProvider
+import org.gradle.api.tasks.wrapper.Wrapper
+import org.gradle.kotlin.dsl.create
+import org.gradle.kotlin.dsl.named
+import org.gradle.kotlin.dsl.property
+import org.gradle.kotlin.dsl.register
+import org.gradle.kotlin.dsl.withType
+import org.gradle.plugin.management.PluginRequest
+import org.gradle.plugin.use.internal.PluginDependencyResolutionServices
+import org.gradle.plugin.use.internal.PluginResolverFactory
+import java.io.File
+import java.net.URL
+import java.util.Locale
+import javax.inject.Inject
+
+open class Gradle2NixPlugin : Plugin<Gradle> {
+    override fun apply(gradle: Gradle) {
+        val configurationNames: List<String> =
+            System.getProperty("org.nixos.gradle2nix.configurations")?.split(",") ?: emptyList()
+
+        val pluginRequests = collectPlugins(gradle)
+
+        gradle.projectsLoaded {
+            val extension = rootProject.extensions.create<Gradle2NixExtension>(
+                "gradle2nix",
+                rootProject,
+                configurationNames
+            )
+
+            val gradleEnv = rootProject.tasks.register("nixGradleEnv", NixGradleEnv::class) {
+                outputDir.set(extension.outputDir)
+            }
+
+            val pluginEnv =
+                rootProject.tasks.register("nixPluginEnv", NixPluginEnv::class, pluginRequests)
+            gradleEnv.configure {
+                inputEnvs.from(pluginEnv)
+            }
+
+            allprojects {
+                val buildscriptEnv = tasks.register("nixBuildscriptEnv", NixBuildscriptEnv::class) {
+                    pluginEnvFile.set(pluginEnv.flatMap { it.outputFile })
+                }
+                val projectEnv = tasks.register("nixProjectEnv", NixProjectEnv::class) {
+                    configurations.addAll(extension.configurations)
+                }
+                gradleEnv.configure {
+                    inputEnvs.from(buildscriptEnv)
+                    inputEnvs.from(projectEnv)
+                }
+            }
+
+            resolveGradleDist(gradle, extension, gradleEnv)
+        }
+    }
+
+    private fun collectPlugins(gradle: Gradle): List<PluginRequest> {
+        val pluginRequests = mutableListOf<PluginRequest>()
+        gradle.settingsEvaluated {
+            pluginManagement.resolutionStrategy.eachPlugin {
+                if (requested.id.namespace != null && requested.id.namespace != "org.gradle") {
+                    pluginRequests.add(target)
+                }
+            }
+        }
+        return pluginRequests
+    }
+
+    private fun resolveGradleDist(
+        gradle: Gradle,
+        extension: Gradle2NixExtension,
+        gradleEnv: TaskProvider<NixGradleEnv>
+    ) {
+        gradle.projectsEvaluated {
+            val gradleDist = rootProject.tasks.named("wrapper", Wrapper::class).map {
+                GradleDist(
+                    version = it.gradleVersion,
+                    type = it.distributionType.name.toLowerCase(Locale.US),
+                    url = it.distributionUrl,
+                    sha256 = it.distributionSha256Sum ?: fetchDistSha256(it.distributionUrl),
+                    nativeVersion = gradle.gradleHomeDir?.resolve("lib")?.listFiles()
+                        ?.firstOrNull { f -> f.name.matches(nativePlatformJarRegex) }?.let { nf ->
+                            nativePlatformJarRegex.find(nf.name)?.groupValues?.get(1)
+                        }
+                        ?: throw IllegalStateException("""
+                            Failed to find native-platform jar in ${gradle.gradleHomeDir}.
+
+                            Ask Tad to fix this.
+                        """.trimIndent())
+                )
+            }
+            val gradleDistTask =
+                gradle.rootProject.tasks.register("nixGradleDist", NixGradleDist::class) {
+                    this.gradleDist.set(gradleDist)
+                    outputDir.set(extension.outputDir)
+                }
+            gradleEnv.configure {
+                dependsOn(gradleDistTask)
+            }
+        }
+    }
+}
+
+internal val moshi by lazy { Moshi.Builder().build() }
+
+open class Gradle2NixExtension(project: Project, defaultConfigurations: List<String>) {
+    var outputDir: File = project.projectDir.resolve("gradle/nix")
+    var configurations: MutableList<String> = mutableListOf<String>().apply {
+        addAll(defaultConfigurations)
+    }
+}
+
+private fun fetchDistSha256(url: String): String {
+    return URL("$url.sha256").openConnection().run {
+        connect()
+        getInputStream().source().buffer().use { source ->
+            source.readUtf8()
+        }
+    }
+}
+
+private val nativePlatformJarRegex = Regex("""native-platform-(\d\.\d+)\.jar""")
+

plugin/src/main/kotlin/org/nixos/gradle2nix/NixBuildscriptEnv.kt

@@ -0,0 +1,43 @@
+package org.nixos.gradle2nix
+
+import okio.buffer
+import okio.source
+import org.gradle.api.tasks.InputFile
+import java.lang.IllegalStateException
+import java.net.URI
+
+open class NixBuildscriptEnv : NixEnv() {
+    @InputFile
+    val pluginEnvFile = project.objects.fileProperty()
+
+    private val pluginEnv: BuildEnv by lazy {
+        pluginEnvFile.get().asFile.source().buffer().use { src ->
+            moshi.adapter(BuildEnv::class.java).fromJson(src)
+                ?: throw IllegalStateException(
+                    "Cannot load plugin env from ${pluginEnvFile.get().asFile.path}")
+        }
+    }
+
+    private val resolver by lazy {
+        Resolver(project.buildscript.configurations,
+            project.buildscript.dependencies,
+            logger
+        )
+    }
+
+    override fun environment(): String = "buildscript"
+
+    override fun repositories(): List<String> =
+        project.buildscript.repositories.flatMap { it.repositoryUrls() }.map(URI::toString)
+
+    override fun artifacts(): List<Artifact> {
+        return project.buildscript.configurations
+            .filter { it.isCanBeResolved }
+            .flatMap { resolver.resolveDependencies(it) + resolver.resolvePoms(it) }
+            .minus(pluginEnv.artifacts)
+            .sorted()
+            .distinct()
+    }
+
+    override fun filename(): String = "buildscript.json"
+}

plugin/src/main/kotlin/org/nixos/gradle2nix/NixEnv.kt

@@ -0,0 +1,73 @@
+package org.nixos.gradle2nix
+
+import com.squareup.moshi.JsonClass
+import com.squareup.moshi.Moshi
+import okio.buffer
+import okio.sink
+import org.gradle.api.DefaultTask
+import org.gradle.api.artifacts.repositories.ArtifactRepository
+import org.gradle.api.artifacts.repositories.MavenArtifactRepository
+import org.gradle.api.tasks.Internal
+import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.tasks.OutputFile
+import org.gradle.api.tasks.TaskAction
+import java.net.URI
+
+abstract class NixEnv : DefaultTask() {
+    abstract fun environment(): String
+    abstract fun repositories(): List<String>
+    abstract fun artifacts(): List<Artifact>
+    abstract fun filename(): String
+
+    @Internal
+    val outputDir = project.objects.directoryProperty()
+        .convention(project.layout.buildDirectory.dir("nix"))
+
+    @OutputFile
+    val outputFile = project.objects.fileProperty()
+        .convention(outputDir.map { it.file(filename()) })
+
+    @TaskAction
+    open fun run() {
+        val outFile = outputFile.get().asFile
+        outFile.parentFile.mkdirs()
+
+        val buildEnv = BuildEnv(project.path, environment(), repositories(), artifacts())
+        outFile.sink().buffer().use { out ->
+            moshi.adapter(BuildEnv::class.java)
+                .indent("  ")
+                .toJson(out, buildEnv)
+        }
+    }
+}
+
+@JsonClass(generateAdapter = true)
+data class BuildEnv(
+    val path: String,
+    val env: String,
+    val repositories: List<String>,
+    val artifacts: List<Artifact>
+)
+
+@JsonClass(generateAdapter = true)
+data class Artifact(
+    val groupId: String,
+    val artifactId: String,
+    val version: String,
+    val classifier: String,
+    val extension: String,
+    val sha256: String
+) : Comparable<Artifact> {
+    override fun toString() = "$groupId:$artifactId:$version:$classifier:$extension"
+
+    override fun compareTo(other: Artifact): Int {
+        return toString().compareTo(other.toString())
+    }
+}
+
+internal fun ArtifactRepository.repositoryUrls(): Set<URI> {
+    return when (this) {
+        is MavenArtifactRepository -> setOf(url) + artifactUrls
+        else -> emptySet()
+    }.filterNotTo(mutableSetOf()) { it.scheme == "file" }
+}

plugin/src/main/kotlin/org/nixos/gradle2nix/NixGradleDist.kt

@@ -0,0 +1,44 @@
+package org.nixos.gradle2nix
+
+import com.squareup.moshi.JsonClass
+import okio.buffer
+import okio.sink
+import org.gradle.api.DefaultTask
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.tasks.OutputFile
+import org.gradle.api.tasks.TaskAction
+import org.gradle.kotlin.dsl.property
+import java.io.Serializable
+
+open class NixGradleDist : DefaultTask() {
+    @Input
+    internal val gradleDist = project.objects.property<GradleDist>()
+
+    @OutputDirectory
+    val outputDir = project.objects.directoryProperty()
+
+    @OutputFile
+    val outputFile = project.objects.fileProperty()
+        .convention(outputDir.file("gradle-dist.json"))
+
+    @TaskAction
+    fun run() {
+        if (gradleDist.isPresent) {
+            outputFile.asFile.get().also { it.parentFile.mkdirs() }.sink().buffer().use { out ->
+                moshi.adapter(GradleDist::class.java)
+                    .indent("  ")
+                    .toJson(out, gradleDist.get())
+            }
+        }
+    }
+}
+
+@JsonClass(generateAdapter = true)
+internal data class GradleDist(
+    val version: String,
+    val type: String,
+    val url: String,
+    val sha256: String,
+    val nativeVersion: String
+) : Serializable

plugin/src/main/kotlin/org/nixos/gradle2nix/NixGradleEnv.kt

@@ -0,0 +1,58 @@
+package org.nixos.gradle2nix
+
+import com.squareup.moshi.JsonWriter
+import okio.buffer
+import okio.sink
+import okio.source
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.RegularFile
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputFiles
+import org.gradle.api.tasks.Internal
+import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.tasks.OutputFile
+import org.gradle.api.tasks.TaskAction
+import org.gradle.kotlin.dsl.listProperty
+
+open class NixGradleEnv : DefaultTask() {
+
+    @InputFiles
+    val inputEnvs = project.objects.fileCollection()
+
+    @Internal
+    val outputDir = project.objects.directoryProperty()
+
+    @OutputFile
+    val outputFile = project.objects.fileProperty()
+        .convention(outputDir.file("gradle-env.json"))
+
+    @TaskAction
+    fun run() {
+        val envsByPath = inputEnvs.map { file ->
+            file.source().buffer().use {
+                moshi.adapter(BuildEnv::class.java).fromJson(it)
+                    ?: throw IllegalStateException(
+                        "Failed to load build env from ${file.path}."
+                    )
+            }
+        }.groupBy(BuildEnv::path)
+
+        val outFile = outputFile.get().asFile.also { it.parentFile.mkdirs() }
+
+        JsonWriter.of(outFile.sink().buffer()).use { writer ->
+            val adapter = moshi.adapter(BuildEnv::class.java).indent("  ")
+            writer.indent = "  "
+            writer.beginObject()
+            for ((path, envs) in envsByPath) {
+                writer.name(path)
+                writer.beginObject()
+                for (env in envs) {
+                    writer.name(env.env)
+                    adapter.toJson(writer, env)
+                }
+                writer.endObject()
+            }
+            writer.endObject()
+        }
+    }
+}

plugin/src/main/kotlin/org/nixos/gradle2nix/NixPluginEnv.kt

@@ -0,0 +1,110 @@
+package org.nixos.gradle2nix
+
+import org.gradle.api.artifacts.ExternalModuleDependency
+import org.gradle.api.internal.artifacts.ivyservice.ivyresolve.strategy.VersionSelectorScheme
+import org.gradle.api.internal.plugins.PluginImplementation
+import org.gradle.plugin.management.PluginRequest
+import org.gradle.plugin.management.internal.PluginRequestInternal
+import org.gradle.plugin.use.PluginId
+import org.gradle.plugin.use.internal.PluginDependencyResolutionServices
+import org.gradle.plugin.use.resolve.internal.ArtifactRepositoriesPluginResolver
+import org.gradle.plugin.use.resolve.internal.PluginResolution
+import org.gradle.plugin.use.resolve.internal.PluginResolutionResult
+import org.gradle.plugin.use.resolve.internal.PluginResolveContext
+import java.net.URI
+import javax.inject.Inject
+
+open class NixPluginEnv @Inject constructor(
+    private val pluginDependencyResolutionServices: PluginDependencyResolutionServices,
+    versionSelectorScheme: VersionSelectorScheme,
+    private val pluginRequests: Collection<PluginRequest>
+) : NixEnv() {
+    private val repositories by lazy {
+        pluginDependencyResolutionServices.resolveRepositoryHandler
+    }
+
+    private val artifactRepositoriesPluginResolver = ArtifactRepositoriesPluginResolver(
+        pluginDependencyResolutionServices,
+        versionSelectorScheme
+    )
+
+    private val resolver by lazy {
+        Resolver(
+            pluginDependencyResolutionServices.configurationContainer,
+            pluginDependencyResolutionServices.dependencyHandler,
+            logger
+        )
+    }
+
+    private val pluginResult by lazy {
+        PluginResult().apply {
+            for (request in pluginRequests.filterIsInstance<PluginRequestInternal>()) {
+                artifactRepositoriesPluginResolver.resolve(request, this)
+            }
+        }
+    }
+
+    private val pluginContext by lazy {
+        PluginContext().apply {
+            for (result in pluginResult.found) result.execute(this)
+        }
+    }
+
+    override fun environment(): String = "plugins"
+
+    override fun repositories(): List<String> {
+        return repositories.flatMap { it.repositoryUrls() }.map(URI::toString) +
+            pluginContext.repositories.toList()
+    }
+
+    override fun artifacts(): List<Artifact> {
+        return (resolver.resolveDependencies(pluginContext.dependencies, true) +
+            resolver.resolvePoms(pluginContext.dependencies, true))
+            .sorted()
+            .distinct()
+    }
+
+    override fun filename(): String = "plugins.json"
+}
+
+private class PluginResult : PluginResolutionResult {
+    val found = mutableSetOf<PluginResolution>()
+
+    override fun notFound(sourceDescription: String?, notFoundMessage: String?) {}
+
+    override fun notFound(
+        sourceDescription: String?,
+        notFoundMessage: String?,
+        notFoundDetail: String?
+    ) {
+    }
+
+    override fun isFound(): Boolean = true
+
+    override fun found(sourceDescription: String, pluginResolution: PluginResolution) {
+        found.add(pluginResolution)
+    }
+}
+
+private class PluginContext : PluginResolveContext {
+    val dependencies = mutableSetOf<ExternalModuleDependency>()
+    val repositories = mutableSetOf<String>()
+
+    override fun add(plugin: PluginImplementation<*>) {
+        println("add: $plugin")
+    }
+
+    override fun addFromDifferentLoader(plugin: PluginImplementation<*>) {
+        println("addFromDifferentLoader: $plugin")
+    }
+
+    override fun addLegacy(pluginId: PluginId, m2RepoUrl: String, dependencyNotation: Any) {
+        repositories.add(m2RepoUrl)
+    }
+
+    override fun addLegacy(pluginId: PluginId, dependencyNotation: Any) {
+        if (dependencyNotation is ExternalModuleDependency) {
+            dependencies.add(dependencyNotation)
+        }
+    }
+}

plugin/src/main/kotlin/org/nixos/gradle2nix/NixProjectEnv.kt

@@ -0,0 +1,41 @@
+package org.nixos.gradle2nix
+
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.Optional
+import org.gradle.kotlin.dsl.setProperty
+import java.net.URI
+
+open class NixProjectEnv : NixEnv() {
+    @Input @Optional
+    val configurations = project.objects.setProperty<String>()
+
+    private val resolveConfigurations by lazy {
+        val configs = configurations.get()
+        if (configs.isEmpty()) {
+            project.configurations.filter { it.isCanBeResolved }
+        } else {
+            project.configurations.filter { it.name in configs }
+        }
+    }
+
+    private val resolver by lazy {
+        Resolver(project.configurations,
+            project.dependencies,
+            logger
+        )
+    }
+
+    override fun environment(): String = "project"
+
+    override fun repositories(): List<String> =
+        project.repositories.flatMap { it.repositoryUrls() }.map(URI::toString)
+
+    override fun artifacts(): List<Artifact> {
+        return resolveConfigurations
+            .flatMap { resolver.resolveDependencies(it) + resolver.resolvePoms(it) }
+            .sorted()
+            .distinct()
+    }
+
+    override fun filename(): String = "project.json"
+}

plugin/src/main/kotlin/org/nixos/gradle2nix/Resolver.kt

@@ -0,0 +1,166 @@
+package org.nixos.gradle2nix
+
+import okio.ByteString
+import okio.HashingSource
+import okio.blackholeSink
+import okio.buffer
+import okio.source
+import org.apache.maven.model.Parent
+import org.apache.maven.model.Repository
+import org.apache.maven.model.building.DefaultModelBuilderFactory
+import org.apache.maven.model.building.DefaultModelBuildingRequest
+import org.apache.maven.model.building.ModelBuildingRequest
+import org.apache.maven.model.building.ModelSource2
+import org.apache.maven.model.resolution.ModelResolver
+import org.gradle.api.artifacts.Configuration
+import org.gradle.api.artifacts.ConfigurationContainer
+import org.gradle.api.artifacts.Dependency
+import org.gradle.api.artifacts.component.ModuleComponentIdentifier
+import org.gradle.api.artifacts.dsl.DependencyHandler
+import org.gradle.api.artifacts.result.ResolvedArtifactResult
+import org.gradle.api.logging.Logger
+import org.gradle.maven.MavenModule
+import org.gradle.maven.MavenPomArtifact
+import java.io.File
+import java.io.InputStream
+import java.net.URI
+
+internal class Resolver(
+    private val configurations: ConfigurationContainer,
+    private val dependencies: DependencyHandler,
+    private val logger: Logger
+) {
+    private val mavenPomResolver = MavenPomResolver(configurations, dependencies)
+
+    fun resolveDependencies(configuration: Configuration): Set<Artifact> {
+        if (!configuration.isCanBeResolved) {
+            logger.warn("Cannot resolve configuration ${configuration.name}; ignoring.")
+            return emptySet()
+        }
+        return configuration.resolvedConfiguration.resolvedArtifacts.mapTo(sortedSetOf()) {
+            with (it) {
+                Artifact(
+                    groupId = moduleVersion.id.group,
+                    artifactId = moduleVersion.id.name,
+                    version = moduleVersion.id.version,
+                    classifier = classifier ?: "",
+                    extension = extension,
+                    sha256 = sha256(file)
+                )
+            }
+        }
+    }
+
+    fun resolveDependencies(
+        dependencies: Collection<Dependency>,
+        includeTransitive: Boolean = false
+    ): Set<Artifact> {
+        val configuration = configurations.detachedConfiguration(*(dependencies.toTypedArray()))
+        configuration.isTransitive = includeTransitive
+        return resolveDependencies(configuration)
+    }
+
+    fun resolvePoms(configuration: Configuration): Set<Artifact> {
+        return dependencies.createArtifactResolutionQuery()
+            .forComponents(configuration.incoming.resolutionResult.allComponents.map { it.id })
+            .withArtifacts(MavenModule::class.java, MavenPomArtifact::class.java)
+            .execute()
+            .resolvedComponents.asSequence()
+            .flatMap { component ->
+                val id = component.id
+                if (id !is ModuleComponentIdentifier) {
+                    emptySequence()
+                } else {
+                    component.getArtifacts(MavenPomArtifact::class.java).asSequence()
+                        .filterIsInstance<ResolvedArtifactResult>()
+                        .map { id to it }
+                }
+            }
+            .flatMapTo(sortedSetOf()) { (id, artifact) ->
+                sequenceOf(Artifact(
+                    groupId = id.group,
+                    artifactId = id.module,
+                    version = id.version,
+                    classifier = "",
+                    extension = artifact.file.extension,
+                    sha256 = sha256(artifact.file)
+                )) + mavenPomResolver.resolve(artifact.file).asSequence()
+            }
+    }
+
+    fun resolvePoms(
+        dependencies: Collection<Dependency>,
+        includeTransitive: Boolean = false
+    ): Set<Artifact> {
+        val configuration = configurations.detachedConfiguration(*(dependencies.toTypedArray()))
+        configuration.isTransitive = includeTransitive
+        return resolvePoms(configuration)
+    }
+}
+
+private class MavenPomResolver(
+    private val configurations: ConfigurationContainer,
+    private val dependencies: DependencyHandler
+) : ModelResolver {
+    private val modelBuilder = DefaultModelBuilderFactory().newInstance()
+    private val resolvedDependencies = mutableSetOf<Artifact>()
+
+    @Synchronized
+    fun resolve(pom: File): Set<Artifact> {
+        resolvedDependencies.clear()
+        modelBuilder.build(
+            DefaultModelBuildingRequest()
+                .setModelResolver(this)
+                .setPomFile(pom)
+                .setSystemProperties(System.getProperties())
+                .setValidationLevel(ModelBuildingRequest.VALIDATION_LEVEL_MINIMAL)
+        ).effectiveModel
+        return resolvedDependencies.toSet()
+    }
+
+    override fun newCopy() = this
+
+    override fun resolveModel(
+        groupId: String,
+        artifactId: String,
+        version: String
+    ): ModelSource2 {
+        val file = configurations
+            .detachedConfiguration(dependencies.create("$groupId:$artifactId:$version@pom"))
+            .singleFile
+        resolvedDependencies.add(Artifact(
+            groupId = groupId,
+            artifactId = artifactId,
+            version = version,
+            classifier = "",
+            extension = file.extension,
+            sha256 = sha256(file)
+        ))
+
+        return object : ModelSource2 {
+            override fun getLocation(): String = file.absolutePath
+            override fun getLocationURI(): URI = file.absoluteFile.toURI()
+            override fun getRelatedSource(relPath: String?): ModelSource2? = null
+            override fun getInputStream(): InputStream = file.inputStream()
+        }
+    }
+
+    override fun resolveModel(parent: Parent): ModelSource2 =
+        resolveModel(parent.groupId, parent.artifactId, parent.version)
+
+    override fun resolveModel(dependency: org.apache.maven.model.Dependency): ModelSource2 =
+        resolveModel(dependency.groupId, dependency.artifactId, dependency.version)
+
+    override fun addRepository(repository: Repository) {}
+
+    override fun addRepository(repository: Repository, replace: Boolean) {}
+}
+
+fun sha256(file: File): String {
+    val hashSource = HashingSource.sha256(file.source())
+    val hash: ByteString = hashSource.buffer().use { source ->
+        source.readAll(blackholeSink())
+        hashSource.hash
+    }
+    return hash.base64()
+}

plugin/src/main/resources/gradle-env.nix

@@ -0,0 +1,51 @@
+# This file is generated by gradle2nix.
+
+{ stdenvNoCC, lib, buildEnv, fetchurl }:
+
+{ name, repositories, dependencies }:
+
+let
+  mkPath = artifact: with artifact; lib.concatStringsSep "/" [
+    (lib.replaceChars ["."] ["/"] artifact.groupId)
+    artifact.artifactId
+    artifact.version
+  ];
+
+  mkFilename = artifact: with artifact;
+    "${artifactId}-${version}${lib.optionalString (classifier != "") "-${classifier}"}.${extension}";
+
+  mkArtifactUrl = base: artifact:
+    "${lib.removeSuffix "/" base}/${mkPath artifact}/${mkFilename artifact}";
+
+  fetchArtifact = artifact:
+  let
+    artifactPath = mkPath artifact;
+    artifactName = mkFilename artifact;
+  in stdenvNoCC.mkDerivation rec {
+    name = with artifact; lib.concatStrings [
+      (lib.replaceChars ["."] ["_"] groupId) "-"
+      (lib.replaceChars ["."] ["_"] artifactId) "-"
+      version
+      (lib.optionalString (classifier != "") "-${classifier}")
+      "-" type
+    ];
+
+    src = fetchurl {
+      name = mkFilename artifact;
+      urls = map (url: mkArtifactUrl url artifact) repositories;
+      inherit (artifact) sha256;
+    };
+
+    phases = "installPhase fixupPhase";
+
+    installPhase = ''
+      mkdir -p $out/${artifactPath}
+      ln -s ${src} $out/${artifactPath}/${artifactName}
+    '';
+  };
+
+in
+buildEnv {
+  inherit name;
+  paths = map fetchArtifact dependencies;
+}