1 files changed, 70 insertions, 0 deletions
diff --git a/buildSrc/src/InnerJarsUnpacker.kt b/buildSrc/src/InnerJarsUnpacker.kt
new file mode 100644
index 0000000..de06467
--- /dev/null
+++ b/buildSrc/src/InnerJarsUnpacker.kt
@@ -0,0 +1,70 @@
+import com.google.gson.Gson
+import com.google.gson.JsonArray
+import com.google.gson.JsonObject
+import com.google.gson.JsonPrimitive
+import java.io.File
+import java.util.zip.ZipInputStream
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.InputFiles
+import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.tasks.OutputFiles
+import org.gradle.api.tasks.TaskAction
+import kotlin.io.path.createDirectories
+import kotlin.io.path.outputStream
+
+abstract class InnerJarsUnpacker : DefaultTask() {
+    @get:InputFiles
+    abstract val inputJars: ConfigurableFileCollection
+
+    @get:OutputDirectory
+    abstract val outputDir: DirectoryProperty
+
+    private fun getFabricModJson(inputFile: File): JsonObject {
+        inputFile.inputStream().use {
+            val zis = ZipInputStream(it)
+            while (true) {
+                val entry = zis.nextEntry ?: error("Failed to find fabric.mod.json")
+                if (entry.name == "fabric.mod.json") {
+                    return Gson().fromJson(zis.reader(), JsonObject::class.java)
+                }
+            }
+        }
+    }
+
+    @TaskAction
+    fun unpack() {
+        inputJars.forEach { inputFile ->
+            val fabricModObject = getFabricModJson(inputFile)
+            val jars = fabricModObject["jars"] as? JsonArray ?: error("No jars to unpack in $inputFile")
+            val jarPaths = jars.map {
+                ((it as? JsonObject)?.get("file") as? JsonPrimitive)?.asString
+                    ?: error("Invalid Jar $it in $inputFile")
+            }
+            extractJars(inputFile, jarPaths)
+        }
+    }
+
+    private fun extractJars(inputFile: File, jarPaths: List<String>) {
+        val outputFile = outputDir.get().asFile.toPath()
+        val jarPathSet = jarPaths.toMutableSet()
+        inputFile.inputStream().use {
+            val zis = ZipInputStream(it)
+            while (true) {
+                val entry = zis.nextEntry ?: break
+                if (jarPathSet.remove(entry.name)) {
+                    val resolvedPath = outputFile.resolve(entry.name)
+                    resolvedPath.parent.createDirectories()
+                    resolvedPath.outputStream().use { os ->
+                        zis.copyTo(os)
+                    }
+                }
+            }
+        }
+        if (jarPathSet.isNotEmpty()) {
+            error("Could not extract all jars: $jarPathSet")
+        }
+    }
+}