Pull Changelog into its own plugin, if you want to use it without the…

… rest of the utils.

Use recommended method of sharing task outputs between sub-projects.
https://docs.gradle.org/current/samples/sample_cross_project_output_sharing.html

build.gradle

@@ -41,11 +41,15 @@ gradlePlugin {
             id = 'net.minecraftforge.gradleutils'
             implementationClass = 'net.minecraftforge.gradleutils.GradleUtilsPlugin'
         }
+        changelog {
+            id = 'net.minecraftforge.changelog'
+            implementationClass = 'net.minecraftforge.gradleutils.changelog.ChangelogPlugin'
+        }
     }
 }
 
 changelog {
-    fromTag '1.0'
+    fromBase()
     publishAll = false
 }
 

buildSrc/build.gradle

@@ -27,5 +27,9 @@ gradlePlugin {
             id = 'net.minecraftforge.gradleutils'
             implementationClass = 'net.minecraftforge.gradleutils.GradleUtilsPlugin'
         }
+        changelog {
+            id = 'net.minecraftforge.changelog'
+            implementationClass = 'net.minecraftforge.gradleutils.changelog.ChangelogPlugin'
+        }
     }
 }

src/main/groovy/net/minecraftforge/gradleutils/GradleUtils.groovy

@@ -326,12 +326,10 @@ class GradleUtils {
      * @param projectDir THe project directory.
      * @return
      */
-    static String buildProjectUrl(final File projectDir) {
-        Git git = Git.open(projectDir) //Create a git workspace.
-
+    static String buildProjectUrl(Git git) {
         List<RemoteConfig> remotes = git.remoteList().call() //Get all remotes.
         if (remotes.isEmpty())
-            throw new IllegalStateException("No remotes found in " + projectDir)
+            throw new IllegalStateException("No remotes found in " + git.repository.directory)
 
         //Get the origin remote.
         final originRemote = remotes.find { remote -> remote.name == 'origin' }

src/main/groovy/net/minecraftforge/gradleutils/GradleUtilsPlugin.groovy

@@ -5,16 +5,16 @@
 package net.minecraftforge.gradleutils
 
 import groovy.transform.CompileStatic
+import net.minecraftforge.gradleutils.changelog.ChangelogPlugin
 import org.gradle.api.Plugin
 import org.gradle.api.Project
 
 @CompileStatic
 class GradleUtilsPlugin implements Plugin<Project> {
     @Override
     void apply(Project project) {
-        GradleUtilsExtension extension = project.extensions.create("gradleutils", GradleUtilsExtension, project)
-        ChangelogGenerationExtension changelogGenerationExtension = project.extensions.create("changelog", ChangelogGenerationExtension, project)
-
+        project.plugins.apply(ChangelogPlugin)
+        project.extensions.create("gradleutils", GradleUtilsExtension, project)
         //Setup the teamcity project task.
         GradleUtils.setupCITasks(project)
     }

src/main/groovy/net/minecraftforge/gradleutils/changelog/ChangelogExtension.groovy

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+package net.minecraftforge.gradleutils.changelog
+
+import groovy.transform.PackageScope
+import org.gradle.api.Project
+import org.gradle.api.file.Directory
+import org.gradle.api.publish.maven.MavenPublication
+import org.gradle.api.tasks.TaskProvider
+
+import javax.inject.Inject
+
+class ChangelogExtension {
+    public static final String NAME = "changelog"
+
+    @PackageScope final Project project
+    @PackageScope TaskProvider<GenerateChangelog> task
+
+    boolean publishAll = true
+    Directory gitRoot
+
+    @Inject
+    ChangelogExtension(Project project) {
+        this.project = project
+    }
+
+    void fromBase() {
+        from(null)
+    }
+
+    void from(String marker) {
+        task = ChangelogUtils.setupChangelogTask(this.project)
+        task.configure {
+            start = marker
+        }
+
+        project.afterEvaluate {
+            if (gitRoot != null) {
+                task.configure {
+                    gitDirectory = gitRoot
+                }
+            }
+
+            if (publishAll)
+                ChangelogUtils.setupChangelogGenerationOnAllPublishTasks(project)
+        }
+    }
+
+    void publish(MavenPublication publication) {
+        ChangelogUtils.setupChangelogGenerationForPublishing(project, publication)
+    }
+}

src/main/groovy/net/minecraftforge/gradleutils/changelog/ChangelogPlugin.groovy

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+package net.minecraftforge.gradleutils.changelog
+
+import groovy.transform.CompileStatic
+import net.minecraftforge.gradleutils.GradleUtils
+import net.minecraftforge.gradleutils.GradleUtilsExtension
+import net.minecraftforge.gradleutils.changelog.ChangelogExtension
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+
+@CompileStatic
+class ChangelogPlugin implements Plugin<Project> {
+    @Override
+    void apply(Project project) {
+        project.extensions.create(ChangelogExtension.NAME, ChangelogExtension, project)
+    }
+}