Move shared generated resources to common project

In 1.20.1, Forge and Fabric have different "common" tag conventions (for
instance, Forge uses forge:dusts/redstone, while Fabric uses
c:redstone_dusts). This means the generated recipes (and advancements)
will be different for the two loader projects. As such, we run data
generators for each loader, and store the results separately.

However, aside from some recipes and advancements, most resources /are/
the same between the two. This means we end up with a lot of duplicate
files, which make the diff even harder to read. This gets worse in
1.20.5, when NeoForge and Fabric have (largely) unified their tag names.

This commit now merges the generated resources of the two loaders,
moving shared files to the common project.

 - Add a new MergeTrees command, to handle the de-duplication of files.
 - Change the existing runData tasks to write to
   build/generatedResources.
 - Add a new :common:runData task, that reads from the
   build/generatedResources folder and writes to the per-project
   src/generated/resources.

.reuse/dep5

@@ -8,8 +8,7 @@ Files:
   projects/common/src/main/resources/assets/computercraft/sounds/empty.ogg
   projects/common/src/testMod/resources/data/cctest/computercraft/turtle_upgrades/*
   projects/common/src/testMod/resources/data/cctest/structures/*
-  projects/fabric/src/generated/*
-  projects/forge/src/generated/*
+  projects/*/src/generated/*
   projects/web/src/htmlTransform/export/index.json
   projects/web/src/htmlTransform/export/items/minecraft/*
 Comment: Generated/data files are CC0.

buildSrc/src/main/kotlin/cc/tweaked/gradle/MergeTrees.kt

@@ -0,0 +1,121 @@
+// SPDX-FileCopyrightText: 2024 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package cc.tweaked.gradle
+
+import cc.tweaked.vanillaextract.core.util.MoreFiles
+import org.gradle.api.Action
+import org.gradle.api.DefaultTask
+import org.gradle.api.GradleException
+import org.gradle.api.file.*
+import org.gradle.api.model.ObjectFactory
+import org.gradle.api.provider.ListProperty
+import org.gradle.api.tasks.*
+import javax.inject.Inject
+
+/**
+ * Merge common files across multiple directories into one destination directory.
+ *
+ * This is intended for merging the generated resources from the Forge and Fabric projects. Files common between the two
+ * are written to the global [output] directory, while distinct files are written to the per-source
+ * [MergeTrees.Source.output] directory.
+ */
+abstract class MergeTrees : DefaultTask() {
+    /**
+     * A source directory to read from.
+     */
+    interface Source {
+        /**
+         * The folder contianing all input files.
+         */
+        @get:InputFiles
+        @get:PathSensitive(PathSensitivity.RELATIVE)
+        val input: ConfigurableFileTree
+
+        fun input(configure: Action<ConfigurableFileTree>) {
+            configure.execute(input)
+        }
+
+        /**
+         * The folder to write files unique to this folder to.
+         */
+        @get:OutputDirectory
+        val output: DirectoryProperty
+    }
+
+    /**
+     * The list of sources.
+     */
+    @get:Nested
+    abstract val sources: ListProperty<Source>
+
+    /**
+     * Add and configure a new source.
+     */
+    fun source(configure: Action<Source>) {
+        val instance = objectFactory.newInstance(Source::class.java)
+        configure.execute(instance)
+        instance.output.disallowChanges()
+        sources.add(instance)
+    }
+
+    /**
+     * The directory to write common files to.
+     */
+    @get:OutputDirectory
+    abstract val output: DirectoryProperty
+
+    @get:Inject
+    protected abstract val objectFactory: ObjectFactory
+
+    @get:Inject
+    protected abstract val fsOperations: FileSystemOperations
+
+    @TaskAction
+    fun run() {
+        val sources = this.sources.get()
+        if (sources.isEmpty()) throw GradleException("Cannot have an empty list of sources")
+
+        val files = mutableMapOf<String, SharedFile>()
+        for (source in sources) {
+            source.input.visit(
+                object : FileVisitor {
+                    override fun visitDir(dirDetails: FileVisitDetails) = Unit
+                    override fun visitFile(fileDetails: FileVisitDetails) {
+                        val path = fileDetails.file.toRelativeString(source.input.dir)
+                        val hash = MoreFiles.computeSha1(fileDetails.file.toPath())
+
+                        val existing = files[path]
+                        if (existing == null) {
+                            files[path] = SharedFile(hash, 1)
+                        } else if (existing.hash == hash) {
+                            existing.found++
+                        }
+                    }
+                },
+            )
+        }
+
+        val sharedFiles = files.entries.asSequence().filter { (_, v) -> v.found == sources.size }.map { (k, _) -> k }.toList()
+        println(sharedFiles)
+
+        // Copy shared files to the common directory
+        fsOperations.sync {
+            from(sources[0].input)
+            into(output)
+            include(sharedFiles)
+        }
+
+        // And all other files to their per-source directory
+        for (source in sources) {
+            fsOperations.sync {
+                from(source.input)
+                into(source.output)
+                exclude(sharedFiles)
+            }
+        }
+    }
+
+    class SharedFile(val hash: String, var found: Int)
+}

projects/common/build.gradle.kts

@@ -11,6 +11,12 @@ plugins {
     id("cc-tweaked.publishing")
 }
 
+sourceSets {
+    main {
+        resources.srcDir("src/generated/resources")
+    }
+}
+
 minecraft {
     accessWideners(
         "src/main/resources/computercraft.accesswidener",
@@ -105,3 +111,19 @@ val lintLua by tasks.registering(IlluaminateExec::class) {
     doFirst { if (System.getenv("GITHUB_ACTIONS") != null) println("::add-matcher::.github/matchers/illuaminate.json") }
     doLast { if (System.getenv("GITHUB_ACTIONS") != null) println("::remove-matcher owner=illuaminate::") }
 }
+
+val runData by tasks.registering(MergeTrees::class) {
+    output = layout.projectDirectory.dir("src/generated/resources")
+
+    for (loader in listOf("forge", "fabric")) {
+        mustRunAfter(":$loader:runData")
+        source {
+            input {
+                from(project(":$loader").layout.buildDirectory.dir("generatedResources"))
+                exclude(".cache")
+            }
+
+            output = project(":$loader").layout.projectDirectory.dir("src/generated/resources")
+        }
+    }
+}