Remap less (#77)

* Avoid remapping jars every time Loom starts

* Attempt to find installer JSON if it isn't found

Remapping Fabric-Loader used to find it every time, now we might skip that we have to go looking for it

* Log a little more when skipping things

Makes it more clear cut when it is avoiding doing things compared to failing after trying

src/main/java/net/fabricmc/loom/providers/ModRemapperProvider.java

@@ -50,17 +50,21 @@ public class ModRemapperProvider extends DependencyProvider {
 		//Output name should match whatever it's under as a dependency so Gradle finds it
 		String outputNamePrefix = rds.substring(rds.indexOf(':') + 1).replace(':', '-') + verSuffix; //group:name:version -> name-version.mapped.yarn.5
 		File modStore = extension.getRemappedModCache();
-		File output = new File(modStore, outputNamePrefix + ".jar");
-		if(output.exists()){
-			output.delete();
-		}
 
+		File output = new File(modStore, outputNamePrefix + ".jar");
+		if (!output.exists() || input.lastModified() <= 0 || input.lastModified() > output.lastModified()) {
+			//If the output doesn't exist, or appears to be outdated compared to the input we'll remap it
 			ModProcessor.handleMod(input, output, project);
 
 			if (!output.exists()){
 				throw new RuntimeException("Failed to remap mod");
 			}
 
+			output.setLastModified(input.lastModified());
+		} else {
+			project.getLogger().info(output.getName() + " is up to date with " + input.getName());
+		}
+
 		project.getDependencies().add(Constants.COMPILE_MODS_MAPPED, project.getDependencies().module(
 				rds + verSuffix
 		));
@@ -71,11 +75,23 @@ public class ModRemapperProvider extends DependencyProvider {
 			if (sourcesFile.isPresent()) {
 				project.getLogger().lifecycle(":providing " + rds + " sources");
 
+				File sources = sourcesFile.get();
+				File remappedSources = new File(modStore, outputNamePrefix + "-sources.jar");
+
+				if (!remappedSources.exists() || sources.lastModified() <= 0 || sources.lastModified() > remappedSources.lastModified()) {
 					try {
-					SourceRemapper.remapSources(project, sourcesFile.get(), new File(modStore, outputNamePrefix + "-sources.jar"), true);
+						SourceRemapper.remapSources(project, sources, remappedSources, true);
+
+						//Set the remapped sources creation date to match the sources if we're likely succeeded in making it
+						remappedSources.setLastModified(sources.lastModified());
 					} catch (Exception e) {
 						e.printStackTrace();
 					}
+				} else {
+					project.getLogger().info(remappedSources.getName() + " is up to date with " + sources.getName());
+				}
+			} else {
+				project.getLogger().info(":skipping " + rds + " sources, not found");
 			}
 		});
 	}

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

@@ -30,9 +30,11 @@ import net.fabricmc.loom.util.DependencyProvider.DependencyInfo;
 
 import org.gradle.api.Project;
 import org.gradle.api.artifacts.Configuration;
+import org.gradle.api.artifacts.Dependency;
 import org.gradle.api.artifacts.ExternalModuleDependency;
 import org.gradle.api.artifacts.repositories.MavenArtifactRepository;
 
+import java.io.File;
 import java.util.ArrayList;
 import java.util.LinkedHashSet;
 import java.util.List;
@@ -87,6 +89,23 @@ public class LoomDependencyManager {
 			});
 		}
 
+		if (extension.getInstallerJson() == null) {
+			//If we've not found the installer JSON we've probably skipped remapping Fabric loader, let's go looking
+			project.getLogger().info("Didn't find installer JSON, searching through compileMods");
+			Configuration configuration = project.getConfigurations().getByName(Constants.COMPILE_MODS);
+
+			for (Dependency dependency : configuration.getDependencies()) {
+				DependencyInfo info = DependencyInfo.create(project, dependency, configuration);
+				File input = info.resolveFile().orElseThrow(() -> new RuntimeException("Could not find dependency " + info));
+
+				ModProcessor.readInstallerJson(input, project);
+				if (extension.getInstallerJson() != null) {
+					project.getLogger().info("Found installer JSON in " + info);
+					break; //Found it, probably don't need to look any further
+				}
+			}
+		}
+
 		if (extension.getInstallerJson() != null) {
 			handleInstallerJson(extension.getInstallerJson(), project);
 		} else {

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

@@ -190,7 +190,7 @@ public class ModProcessor {
 		}
 	}
 
-	private static void readInstallerJson(File file, Project project){
+	static void readInstallerJson(File file, Project project){
 		try {
 			JarFile jarFile = new JarFile(file);