fix(install): add ModLoader for legacy Forge versions

src/main/api/install.ts

@@ -2,6 +2,7 @@ import { containers } from "@/main/container/manage";
 import { games } from "@/main/game/manage";
 import { fabricInstaller } from "@/main/install/fabric";
 import { forgeInstaller } from "@/main/install/forge";
+import { forgeCompat } from "@/main/install/forge-compat";
 import { neoforgedInstaller } from "@/main/install/neoforged";
 import { quiltInstaller } from "@/main/install/quilt";
 import { smelt, type SmeltInstallInit } from "@/main/install/smelt";
@@ -54,6 +55,7 @@ ipcMain.on("installGame", async (e, gameId) => {
         let p = vanillaProfile;
 
         let forgeInstallerPath: string | null = null;
+        let forgeModLoaderPath: string | null = null;
         let forgeInstallerInit: SmeltInstallInit | null = null;
         let forgeInstallAction: ForgeInstallActionType = "none";
 
@@ -103,6 +105,9 @@ ipcMain.on("installGame", async (e, gameId) => {
             const installerType = forgeInstaller.getInstallType(gameVersion);
             forgeInstallerPath = await forgeInstaller.downloadInstaller(loaderVersion, installerType, { onProgress });
 
+            const modLoaderUrl = await forgeCompat.getModLoaderUrl(gameVersion);
+            forgeModLoaderPath = modLoaderUrl && await forgeCompat.downloadModLoader(modLoaderUrl);
+
             if (installerType === "installer") {
                 const legacyProfileId = await smeltLegacy.dumpContent(forgeInstallerPath, c);
                 if (legacyProfileId) {
@@ -116,7 +121,16 @@ ipcMain.on("installGame", async (e, gameId) => {
                 }
             } else {
                 forgeInstallAction = "merge";
-                p = vanillaProfile;
+                if (modLoaderUrl) {
+                    // There exists a bug with ModLoader which makes it incompatible with the directory structure
+                    // This cannot be fixed even with VENV
+                    // We're using a patch named DAMT: https://www.minecraftforum.net/forums/mapping-and-modding-java-edition/minecraft-mods/mods-discussion/1291855-a-custom-tweaker-for-using-older-modloaders-in-the
+                    await forgeCompat.patchProfile(c, gameVersion);
+                    p = await profileLoader.fromContainer(gameVersion, c);
+                } else {
+                    p = vanillaProfile;
+                }
+
             }
         }
 
@@ -136,10 +150,16 @@ ipcMain.on("installGame", async (e, gameId) => {
                     c
                 );
 
-                await smeltLegacy.mergeClient(forgeInstallerPath!, c.client(p.version || p.id));
-                game.launchHint.venv = true;
+                const clientPath = c.client(p.version || p.id);
+
+                if (forgeModLoaderPath) {
+                    await smeltLegacy.mergeClient(forgeModLoaderPath, clientPath);
+                }
+
+                await smeltLegacy.mergeClient(forgeInstallerPath!, clientPath);
             }
 
+            game.launchHint.venv = await forgeCompat.shouldUseVenv(gameVersion);
             await fs.remove(forgeInstallerPath!);
         }
 

src/main/install/forge-compat.ts

@@ -0,0 +1,49 @@
+import type { Container } from "@/main/container/spec";
+import { paths } from "@/main/fs/paths";
+import { dlx } from "@/main/net/dlx";
+import type { Library } from "@/main/profile/version-profile";
+import { unwrapESM } from "@/main/util/module";
+import fs from "fs-extra";
+import { nanoid } from "nanoid";
+
+async function loadCompat() {
+    return await unwrapESM(import("@/refs/legacy-forge-compat.json"));
+}
+
+async function shouldUseVenv(v: string): Promise<boolean> {
+    return (await loadCompat()).venv.includes(v);
+}
+
+async function getModLoaderUrl(v: string): Promise<string> {
+    return (await loadCompat() as any)["mod-loader"][v] ?? "";
+}
+
+async function downloadModLoader(url: string): Promise<string> {
+    console.debug(`Fetching ModLoader from ${url}`);
+    const fp = paths.temp.to(`mod-loader-${nanoid()}.jar`);
+    await dlx.getAll([{ url, path: fp }]);
+    return fp;
+}
+
+async function getModLoaderDamtLibrary(): Promise<Library> {
+    return (await loadCompat())["damt"];
+}
+
+async function getModLoaderDamtArg(): Promise<string> {
+    return (await loadCompat())["damt-arg"];
+}
+
+async function patchProfile(container: Container, id: string) {
+    console.debug(`Patching ${id} with DAMT...`);
+    const prof = await fs.readJSON(container.profile(id));
+    prof.libraries.push(await getModLoaderDamtLibrary());
+    prof.minecraftArguments += (" " + await getModLoaderDamtArg());
+    await fs.writeJSON(container.profile(id), prof);
+}
+
+export const forgeCompat = {
+    shouldUseVenv,
+    getModLoaderUrl,
+    downloadModLoader,
+    patchProfile
+};

src/main/install/forge.ts

@@ -30,6 +30,11 @@ async function syncVersions(): Promise<string[]> {
 async function queryLoaderVersions(gameVersion: string, control?: ProgressController): Promise<string[]> {
     control?.onProgress?.(progress.indefinite("forge.download"));
 
+    // This is the only except in versioning
+    if (gameVersion === "1.4") {
+        gameVersion = "1.4.0";
+    }
+
     const versions = await syncVersions();
 
     // Versions of Forge are named in the format `<gameVersion>-<suffix>`

src/main/install/smelt-legacy.ts

@@ -10,7 +10,7 @@ import StreamZip from "node-stream-zip";
 import child_process from "node:child_process";
 import path from "node:path";
 import { pEvent } from "p-event";
-import { COMPRESSION_LEVEL, zip } from "zip-a-folder";
+import { zip } from "zip-a-folder";
 
 async function dumpContent(installer: string, container: Container): Promise<string> {
     let zip: StreamZip.StreamZipAsync | null = null;
@@ -143,7 +143,7 @@ async function mergeClient(src: string, fp: string): Promise<void> {
 
     await fs.remove(path.join(workDir, "META-INF")); // Drop signatures
     await fs.remove(fp);
-    await zip(workDir, fp, { compression: COMPRESSION_LEVEL.uncompressed });
+    await zip(workDir, fp);
     await fs.remove(workDir);
 }
 

src/refs/legacy-forge-compat.json

@@ -0,0 +1,33 @@
+{
+    "mod-loader": {
+        "1.2.4": "https://github.com/skjsjhb/ModLoader-Binaries/releases/download/1.0/ModLoader.1.2.4.zip",
+        "1.2.3": "https://github.com/skjsjhb/ModLoader-Binaries/releases/download/1.0/ModLoader.1.2.3.zip",
+        "1.1": "https://github.com/skjsjhb/ModLoader-Binaries/releases/download/1.0/ModLoader.1.1.zip"
+    },
+    "damt": {
+        "name": "damt:damt:0.1",
+        "downloads": {
+            "artifact": {
+                "url": "https://github.com/skjsjhb/ModLoader-Binaries/releases/download/1.0/damt-0.1.jar"
+            }
+        }
+    },
+    "damt-arg": "--tweakClass damt.ModLoaderTweaker",
+    "venv": [
+        "1.5.1",
+        "1.5",
+        "1.4.7",
+        "1.4.6",
+        "1.4.5",
+        "1.4.4",
+        "1.4.3",
+        "1.4.2",
+        "1.4.1",
+        "1.4",
+        "1.3.2",
+        "1.2.5",
+        "1.2.4",
+        "1.2.3",
+        "1.1"
+    ]
+}