import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";
import { readFileSync, existsSync, statSync } from "node:fs";
import { join, extname } from "node:path";
import type { Config } from "../config.js";
import { validateProjectPath } from "../utils/safe-path.js";
/** Extensions that are safe to read as text */
const TEXT_EXTENSIONS = new Set([
".c", ".et", ".conf", ".gproj", ".ent", ".layer", ".st",
".layout", ".txt", ".json", ".xml", ".csv",
]);
function resolveGameDataPath(config: Config): string | null {
const dataPath = join(config.gamePath, "addons", "data");
if (existsSync(dataPath)) return dataPath;
const addonsPath = join(config.gamePath, "addons");
if (existsSync(addonsPath)) return addonsPath;
return null;
}
export function registerGameRead(server: McpServer, config: Config): void {
server.registerTool(
"game_read",
{
description:
"Read a file from the base Arma Reforger game installation. " +
"Use this to read vanilla .c script files to understand what to override, " +
"or inspect prefab .et files and config .conf files.",
inputSchema: {
path: z
.string()
.describe(
"Relative path within the game data (e.g., 'Scripts/Game/Character/SCR_CharacterControllerComponent.c')"
),
},
},
async ({ path: subPath }) => {
const basePath = resolveGameDataPath(config);
if (!basePath) {
return {
content: [
{
type: "text",
text: `Base game not found at ${config.gamePath}. Set ENFUSION_GAME_PATH or ensure Arma Reforger is installed.`,
},
],
};
}
try {
const filePath = validateProjectPath(basePath, subPath);
if (!existsSync(filePath)) {
return {
content: [
{ type: "text", text: `File not found: ${subPath}` },
],
};
}
const stats = statSync(filePath);
if (stats.isDirectory()) {
return {
content: [
{
type: "text",
text: `"${subPath}" is a directory. Use game_browse to list its contents.`,
},
],
};
}
const ext = extname(filePath).toLowerCase();
if (!TEXT_EXTENSIONS.has(ext)) {
return {
content: [
{
type: "text",
text: `Binary file: ${subPath} (${ext}, ${stats.size} bytes). Only text files (.c, .et, .conf, etc.) can be read.`,
},
],
};
}
// Cap file size at 500KB to avoid overwhelming context
if (stats.size > 512_000) {
return {
content: [
{
type: "text",
text: `File too large: ${subPath} (${(stats.size / 1024).toFixed(0)} KB). Maximum readable size is 500 KB.`,
},
],
};
}
const content = readFileSync(filePath, "utf-8");
return {
content: [
{
type: "text",
text: `// ${subPath}\n// ${stats.size} bytes\n\n${content}`,
},
],
};
} catch (e) {
const msg = e instanceof Error ? e.message : String(e);
return {
content: [{ type: "text", text: `Error reading game file: ${msg}` }],
};
}
}
);
}
