Convert Velocity buildscripts to Kotlin DSL (#918)

Spiritually indebted to #518 and @alexstaeding.

There's a minor break - we're going up to 3.2.0-SNAPSHOT as the API now compiles against Java 11. But this is more academic in practice.

buildSrc/build.gradle.kts

@@ -0,0 +1,27 @@
+plugins {
+    `kotlin-dsl`
+    checkstyle
+    id("net.kyori.indra.publishing") version "2.0.6"
+}
+
+repositories {
+    mavenCentral()
+    maven("https://plugins.gradle.org/m2")
+}
+
+gradlePlugin {
+    plugins {
+        register("set-manifest-impl-version") {
+            id = "set-manifest-impl-version"
+            implementationClass = "com.velocitypowered.script.SetManifestImplVersionPlugin"
+        }
+        register("velocity-checkstyle") {
+            id = "velocity-checkstyle"
+            implementationClass = "com.velocitypowered.script.VelocityCheckstylePlugin"
+        }
+        register("velocity-publish") {
+            id = "velocity-publish"
+            implementationClass = "com.velocitypowered.script.VelocityPublishPlugin"
+        }
+    }
+}

buildSrc/src/main/kotlin/com/velocitypowered/script/SetManifestImplVersionPlugin.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.script
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.jvm.tasks.Jar
+import org.gradle.kotlin.dsl.withType
+import java.io.ByteArrayOutputStream
+
+class SetManifestImplVersionPlugin : Plugin<Project> {
+    override fun apply(target: Project) = target.afterEvaluate { configure() }
+    private fun Project.configure() {
+        val currentShortRevision = ByteArrayOutputStream().use {
+            exec {
+                executable = "git"
+                args = listOf("rev-parse", "HEAD")
+                standardOutput = it
+            }
+            it.toString().trim().substring(0, 8)
+        }
+        tasks.withType<Jar> {
+            manifest {
+                val buildNumber = System.getenv("BUILD_NUMBER")
+                var velocityHumanVersion: String
+                if (project.version.toString().endsWith("-SNAPSHOT")) {
+                    if (buildNumber != null) {
+                        velocityHumanVersion = "${project.version} (git-$currentShortRevision-b$buildNumber)"
+                    } else {
+                        velocityHumanVersion = "${project.version} (git-$currentShortRevision)"
+                    }
+                } else {
+                    velocityHumanVersion = archiveVersion.get()
+                }
+                attributes["Implementation-Version"] = velocityHumanVersion
+            }
+        }
+    }
+}

buildSrc/src/main/kotlin/com/velocitypowered/script/VelocityCheckstylePlugin.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.script
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.plugins.quality.CheckstyleExtension
+import org.gradle.api.plugins.quality.CheckstylePlugin
+import org.gradle.kotlin.dsl.apply
+import org.gradle.kotlin.dsl.configure
+
+class VelocityCheckstylePlugin : Plugin<Project> {
+    override fun apply(target: Project) = target.configure()
+    private fun Project.configure() {
+        apply<CheckstylePlugin>()
+        extensions.configure<CheckstyleExtension> {
+            configFile = project.rootProject.file("config/checkstyle/checkstyle.xml")
+            maxErrors = 0
+            maxWarnings = 0
+            toolVersion = "10.6.0"
+        }
+    }
+}

buildSrc/src/main/kotlin/com/velocitypowered/script/VelocityPublishPlugin.kt

@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.script
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.artifacts.repositories.PasswordCredentials
+import org.gradle.api.plugins.JavaBasePlugin
+import org.gradle.api.plugins.JavaPluginExtension
+import org.gradle.api.publish.PublishingExtension
+import org.gradle.api.publish.maven.MavenPublication
+import org.gradle.api.publish.maven.plugins.MavenPublishPlugin
+import org.gradle.kotlin.dsl.apply
+import org.gradle.kotlin.dsl.configure
+import org.gradle.kotlin.dsl.create
+import org.gradle.kotlin.dsl.get
+import org.gradle.kotlin.dsl.getByType
+
+class VelocityPublishPlugin : Plugin<Project> {
+    override fun apply(target: Project) = target.afterEvaluate {
+        if (target.name != "velocity-proxy") {
+            configure()
+        }
+    }
+    private fun Project.configure() {
+        apply<JavaBasePlugin>()
+        apply<MavenPublishPlugin>()
+        extensions.configure<PublishingExtension> {
+            repositories {
+                maven {
+                    credentials(PasswordCredentials::class.java)
+
+                    name = "paper"
+                    val base = "https://papermc.io/repo/repository/maven-"
+                    val releasesRepoUrl = "$base-releases/"
+                    val snapshotsRepoUrl = "$base-snapshots/"
+                    setUrl(if (version.toString().endsWith("SNAPSHOT")) snapshotsRepoUrl else releasesRepoUrl)
+                }
+            }
+            publications {
+                create<MavenPublication>("maven") {
+                    from(components["java"])
+                    pom {
+                        name.set("Velocity")
+                        description.set("The modern, next-generation Minecraft server proxy")
+                        url.set("https://www.velocitypowered.com")
+                        scm {
+                            url.set("https://github.com/PaperMC/Velocity")
+                            connection.set("scm:git:https://github.com/PaperMC/Velocity.git")
+                            developerConnection.set("scm:git:https://github.com/PaperMC/Velocity.git")
+                        }
+                    }
+                }
+            }
+        }
+    }
+}