build.gradle.kts

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

plugins {
    kotlin("jvm") version "1.8.21"
    application
}

group = "org.example"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

dependencies {
    testImplementation(kotlin("test"))
}

tasks.test {
    useJUnitPlatform()
}

tasks.withType<KotlinCompile> {
    kotlinOptions.jvmTarget = "1.8"
}

tasks.withType<JavaCompile> {
    targetCompatibility = "1.8"
}

application {
    mainClass.set("MainKt")
}

tasks {
    val fatJar = register<Jar>("fatJar") {
        dependsOn.addAll(listOf("compileJava", "compileKotlin", "processResources")) // We need this for Gradle optimization to work
        archiveClassifier.set("standalone") // Naming the jar
        duplicatesStrategy = DuplicatesStrategy.EXCLUDE
        manifest { attributes(mapOf("Main-Class" to application.mainClass)) } // Provided we set it up in the application plugin configuration
        val sourcesMain = sourceSets.main.get()
        val contents = configurations.runtimeClasspath.get()
            .map { if (it.isDirectory) it else zipTree(it) } +
                sourcesMain.output
        from(contents)
    }
    build {
        dependsOn(fatJar) // Trigger fat jar creation during build
    }
}