Add the ability to use custom mapping files.

src/main/java/net/fabricmc/loom/LoomGradleExtension.java

@@ -34,6 +34,7 @@ public class LoomGradleExtension {
 	public String fabricVersion;
 	public String pomfVersion;
 	public String refmapName;
+	public boolean localMappings = false;
 
 	//Not to be set in the build.gradle
 	public Project project;
@@ -58,6 +59,9 @@ public class LoomGradleExtension {
 	}
 
 	public boolean hasPomf(){
+		if(localMappings){
+			return true;
+		}
 		return pomfVersion != null && !pomfVersion.isEmpty();
 	}
 }

src/main/java/net/fabricmc/loom/task/DownloadTask.java

@@ -76,9 +76,27 @@ public class DownloadTask extends DefaultTask {
 				this.getLogger().lifecycle(":downloading mappings");
 				FileUtils.copyURLToFile(new URL("http://modmuss50.me:8080/job/pomf/" + extension.version + "/" + extension.pomfVersion + "/artifact/build/libs/pomf-enigma-" + extension.version + "." + extension.pomfVersion + ".zip"), Constants.MAPPINGS_ZIP.get(extension));
 			}
+			if(!extension.hasPomf()){
+				if(Constants.MAPPINGS_DIR_LOCAL.get(extension).exists()){
+					if(Constants.MAPPINGS_TINY_GZ_LOCAL.get(extension).exists() && Constants.MAPPINGS_ZIP_LOCAL.get(extension).exists()){
+						this.getLogger().lifecycle("Found local mapping files");
+						extension.localMappings = true;
+						extension.pomfVersion = "local"; //TODO set this to include the hash or something to so the jar name is unique?
+
+						//We delete this to make sure they are always re extracted.
+						deleteIfExists(Constants.MAPPINGS_ZIP.get(extension));
+						deleteIfExists(Constants.MAPPINGS_TINY_GZ.get(extension));
+						deleteIfExists(Constants.MAPPINGS_TINY.get(extension));
+						deleteIfExists(Constants.MAPPINGS_DIR.get(extension));
+
+						Constants.MAPPINGS_TINY_GZ = Constants.MAPPINGS_TINY_GZ_LOCAL;
+						Constants.MAPPINGS_ZIP = Constants.MAPPINGS_ZIP_LOCAL;
+					}
+				}
+			}
 
 			if (!Constants.MAPPINGS_TINY.get(extension).exists() && extension.hasPomf()) {
-				if (!Constants.MAPPINGS_TINY_GZ.get(extension).exists()) {
+				if (!Constants.MAPPINGS_TINY_GZ.get(extension).exists() && !extension.localMappings) {
 					getLogger().lifecycle(":downloading tiny mappings");
 					FileUtils.copyURLToFile(new URL("http://modmuss50.me:8080/job/pomf/" + extension.version + "/" + extension.pomfVersion + "/artifact/build/libs/pomf-tiny-" + extension.version + "." + extension.pomfVersion + ".gz"), Constants.MAPPINGS_TINY_GZ.get(extension));
 				}
@@ -172,4 +190,19 @@ public class DownloadTask extends DefaultTask {
 			}
 		}
 	}
+
+	private static boolean deleteIfExists(File file){
+		if(file.exists()){
+			if(file.isDirectory()){
+				try {
+					FileUtils.deleteDirectory(file);
+					return file.mkdir();
+				} catch (IOException e) {
+					e.printStackTrace();
+				}
+			}
+			return file.delete();
+		}
+		return false;
+	}
 }

src/main/java/net/fabricmc/loom/util/Constants.java

@@ -44,12 +44,16 @@ public class Constants {
 	public static final IDelayed<File> MINECRAFT_FINAL_JAR = new DelayedFile(extension -> new File(CACHE_FILES, extension.getVersionString() + "-mixed-" + extension.pomfVersion + ".jar"));
 
 	public static final IDelayed<File> POMF_DIR = new DelayedFile(extension -> new File(extension.getFabricUserCache(), "pomf"));
-	public static final IDelayed<File> MAPPINGS_ZIP = new DelayedFile(extension -> new File(POMF_DIR.get(extension), "pomf-enigma-" + extension.version + "." + extension.pomfVersion + ".zip"));
+	public static       IDelayed<File> MAPPINGS_ZIP = new DelayedFile(extension -> new File(POMF_DIR.get(extension), "pomf-enigma-" + extension.version + "." + extension.pomfVersion + ".zip"));
 	public static final IDelayed<File> MAPPINGS_DIR = new DelayedFile(extension -> new File(POMF_DIR.get(extension), "pomf-enigma-" + extension.version + "." + extension.pomfVersion + ""));
-	public static final IDelayed<File> MAPPINGS_TINY_GZ = new DelayedFile(extension -> new File(POMF_DIR.get(extension), "pomf-tiny-" + extension.version + "." + extension.pomfVersion + ".gz"));
+	public static       IDelayed<File> MAPPINGS_TINY_GZ = new DelayedFile(extension -> new File(POMF_DIR.get(extension), "pomf-tiny-" + extension.version + "." + extension.pomfVersion + ".gz"));
 	public static final IDelayed<File> MAPPINGS_TINY = new DelayedFile(extension -> new File(POMF_DIR.get(extension), "pomf-tiny-" + extension.version + "." + extension.pomfVersion));
 	public static final IDelayed<File> MAPPINGS_MIXIN_EXPORT = new DelayedFile(extension -> new File(CACHE_FILES, "mixin-map-" + extension.version + "." + extension.pomfVersion + ".mappings"));
 
+	public static final IDelayed<File> MAPPINGS_DIR_LOCAL = new DelayedFile(extension -> new File(WORKING_DIRECTORY, "mappings"));
+	public static final IDelayed<File> MAPPINGS_ZIP_LOCAL = new DelayedFile(extension -> new File(MAPPINGS_DIR_LOCAL.get(extension), "pomf-enigma-" + extension.version + ".zip"));
+	public static final IDelayed<File> MAPPINGS_TINY_GZ_LOCAL = new DelayedFile(extension -> new File(MAPPINGS_DIR_LOCAL.get(extension), "pomf-tiny-" + extension.version + ".gz"));
+
 	public static final IDelayed<File> REF_MAP = new DelayedFile(extension -> new File(CACHE_FILES, "mixin-refmap.json"));
 
 	public static final IDelayed<File> MINECRAFT_LIBS = new DelayedFile(extension -> new File(extension.getFabricUserCache(), extension.version + "-libs"));