initial try to add a importmcdev task

paperweight-core/src/main/kotlin/taskcontainers/AllTasks.kt

@@ -126,4 +126,18 @@ open class AllTasks(
         description = "Rebuilds patches to api and server"
         dependsOn(rebuildApiPatches, rebuildServerPatches)
     }
+
+    @Suppress("unused")
+    val importMcDev by tasks.registering<ImportMcDev> {
+        group = "paper"
+        description = "Imports files from vanilla into the project"
+
+        patchDir.set(extension.paper.spigotServerPatchDir)
+        sourceMcDevJar.set(decompileJar.flatMap { it.outputJar })
+        mcLibrariesDir.set(downloadMcLibraries.flatMap { it.sourcesOutputDir })
+        libraryImports.set(extension.paper.libraryClassImports)
+        mcdevImports.set(extension.paper.mcdevClassImports.flatMap { project.provider { if (it.path.exists()) it else null } })
+
+        paperServerDir.set(extension.paper.paperServerDir)
+    }
 }

paperweight-lib/src/main/kotlin/tasks/ImportMcDev.kt

@@ -0,0 +1,62 @@
+/*
+ * paperweight is a Gradle plugin for the PaperMC project.
+ *
+ * Copyright (c) 2021 Kyle Wood (DemonWav)
+ *                    Contributors
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 only, no later versions.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
+ * USA
+ */
+
+package io.papermc.paperweight.tasks
+
+import io.papermc.paperweight.util.McDev
+import io.papermc.paperweight.util.path
+import io.papermc.paperweight.util.pathOrNull
+import kotlin.io.path.listDirectoryEntries
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.tasks.*
+
+abstract class ImportMcDev : DefaultTask() {
+
+    @get:InputDirectory
+    abstract val patchDir: DirectoryProperty
+
+    @get:InputFile
+    abstract val sourceMcDevJar: RegularFileProperty
+
+    @get:InputDirectory
+    abstract val mcLibrariesDir: DirectoryProperty
+
+    @get:Optional
+    @get:InputFile
+    abstract val libraryImports: RegularFileProperty
+
+    @get:Optional
+    @get:InputFile
+    abstract val mcdevImports: RegularFileProperty
+
+    @get:OutputDirectory
+    abstract val paperServerDir: DirectoryProperty
+
+    @TaskAction
+    fun run() {
+        val patches = patchDir.path.listDirectoryEntries("*.patch")
+        val sourceDir = paperServerDir.path.resolve("src/main/java")
+        McDev.importMcDev(patches, sourceMcDevJar.path, libraryImports.pathOrNull, mcLibrariesDir.path, mcdevImports.pathOrNull, sourceDir)
+    }
+}