Build using Toothpick scripts (#122)

Co-authored-by: BillyGalbreath <blake.galbreath@gmail.com>

buildSrc/src/main/kotlin/ToothpickExtension.kt

@@ -0,0 +1,52 @@
+import org.gradle.api.Project
+import org.gradle.api.model.ObjectFactory
+import java.io.File
+import java.util.Locale
+
+@Suppress("UNUSED_PARAMETER")
+open class ToothpickExtension(objects: ObjectFactory) {
+    lateinit var project: Project
+    lateinit var forkName: String
+    val forkNameLowercase
+        get() = forkName.toLowerCase(Locale.ENGLISH)
+    lateinit var forkVersion: String
+    lateinit var groupId: String
+    lateinit var minecraftVersion: String
+    lateinit var nmsRevision: String
+
+    lateinit var upstream: String
+    val upstreamLowercase
+        get() = upstream.toLowerCase(Locale.ENGLISH)
+
+    lateinit var serverProject: ToothpickSubproject
+    fun server(receiver: ToothpickSubproject.() -> Unit) {
+        serverProject = ToothpickSubproject()
+        receiver(serverProject)
+    }
+
+    lateinit var apiProject: ToothpickSubproject
+    fun api(receiver: ToothpickSubproject.() -> Unit) {
+        apiProject = ToothpickSubproject()
+        receiver(apiProject)
+    }
+
+    val subprojects: Map<String, ToothpickSubproject>
+        get() = if (::forkName.isInitialized) mapOf(
+            "$forkName-API" to apiProject,
+            "$forkName-Server" to serverProject
+        ) else emptyMap()
+
+    val paperDir: File by lazy {
+        if (upstream == "Paper") {
+            project.upstreamDir
+        } else {
+            project.upstreamDir.walk().find {
+                it.name == "Paper" && it.isDirectory
+                        && it.resolve("work/Minecraft/${minecraftVersion}").exists()
+            } ?: error("Failed to find Paper directory!")
+        }
+    }
+
+    val paperWorkDir: File
+        get() = paperDir.resolve("work/Minecraft/${minecraftVersion}")
+}