1 files changed, 195 insertions, 0 deletions
diff --git a/mcp/bridge/index.js b/mcp/bridge/index.js
new file mode 100644
index 0000000..c978737
--- /dev/null
+++ b/mcp/bridge/index.js
@@ -0,0 +1,195 @@
+#!/usr/bin/env node
+
+import * as path from "node:path";
+import * as fs from "node:fs";
+import { Client } from "@modelcontextprotocol/sdk/client/index.js";
+import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";
+import express from "express";
+
+const app = express();
+const PORT = process.env.MCP_BRIDGE_PORT || 8808;
+
+let [rootDir] = process.argv.slice(2);
+
+if (!rootDir) {
+  console.error("Usage: mcp-bridge <llm-functions-dir>");
+  process.exit(1);
+}
+
+let mcpServers = {};
+const mcpJsonPath = path.join(rootDir, "mcp.json");
+try {
+  const data = await fs.promises.readFile(mcpJsonPath, "utf8");
+  mcpServers = JSON.parse(data)?.mcpServers;
+} catch {
+  console.error(`Failed to read json at '${mcpJsonPath}'`);
+  process.exit(1);
+}
+
+async function startMcpServer(id, serverConfig) {
+  console.log(`Starting ${id} server...`);
+  const capabilities = { tools: {} };
+  const transport = new StdioClientTransport({
+    ...serverConfig,
+  });
+  const client = new Client(
+    { name: id, version: "1.0.0" },
+    { capabilities }
+  );
+  await client.connect(transport);
+  const { tools: toolDefinitions } = await client.listTools()
+  const tools = toolDefinitions.map(
+    ({ name, description, inputSchema }) =>
+    ({
+      spec: {
+        name: `${normalizeToolName(`${id}_${name}`)}`,
+        description,
+        parameters: inputSchema,
+      },
+      impl: async args => {
+        const res = await client.callTool({
+          name: name,
+          arguments: args,
+        });
+        const content = res.content;
+        let text = arrayify(content)?.map(c => {
+          switch (c.type) {
+            case "text":
+              return c.text || ""
+            case "image":
+              return c.data
+            case "resource":
+              return c.resource?.uri || ""
+            default:
+              return c
+          }
+        }).join("\n");
+        if (res.isError) {
+          text = `Tool Error\n${text}`;
+        }
+        return text;
+      },
+    })
+  );
+  return {
+    tools,
+    [Symbol.asyncDispose]: async () => {
+      try {
+        console.log(`Closing ${id} server...`);
+        await client.close();
+        await transport.close();
+      } catch { }
+    },
+  }
+}
+
+async function runBridge() {
+  let hasError = false;
+  let runningMcpServers = await Promise.all(
+    Object.entries(mcpServers).map(
+      async ([name, serverConfig]) => {
+        try {
+          return await startMcpServer(name, serverConfig)
+        } catch (err) {
+          hasError = true;
+          console.error(`Failed to start ${name} server; ${err.message}`)
+        }
+      }
+    )
+  );
+  runningMcpServers = runningMcpServers.filter(s => !!s);
+  const stopMcpServers = () => Promise.all(runningMcpServers.map(s => s[Symbol.asyncDispose]()));
+  if (hasError) {
+    await stopMcpServers();
+    return;
+  }
+
+  const definitions = runningMcpServers.flatMap(s => s.tools.map(t => t.spec));
+  const runTool = async (name, args) => {
+    for (const server of runningMcpServers) {
+      const tool = server.tools.find(t => t.spec.name === name);
+      if (tool) {
+        return tool.impl(args);
+      }
+    }
+    return `Not found tool '${name}'`;
+  };
+
+  app.use((err, _req, res, _next) => {
+    res.status(500).send(err?.message || err);
+  });
+
+  app.use(express.json());
+
+  app.get("/", (_req, res) => {
+    res.send(`# MCP Bridge API
+  
+- POST /tools/:name 
+  \`\`\`
+  curl -X POST http://localhost:8808/tools/filesystem_write_file  \\
+    -H 'content-type: application/json' \\
+    -d '{"path": "/tmp/file1", "content": "hello world"}'
+  \`\`\`
+- GET /tools
+  \`\`\`
+  curl http://localhost:8808/tools
+  \`\`\`
+  `);
+  });
+
+  app.get("/tools", (_req, res) => {
+    res.json(definitions);
+  });
+
+  app.post("/tools/:name", async (req, res) => {
+    try {
+      const output = await runTool(req.params.name, req.body);
+      res.send(output);
+    } catch (err) {
+      res.status(500).send(err);
+    }
+  });
+
+  app.get("/pid", (_req, res) => {
+    res.send(process.pid.toString());
+  });
+
+  app.get("/health", (_req, res) => {
+    res.send("OK");
+  });
+
+  app.use((_req, res, _next) => {
+    res.status(404).send("Not found");
+  });
+
+  const server = app.listen(PORT, () => {
+    console.log(`Server is running on port ${PORT}`);
+  });
+
+  return async () => {
+    server.close(() => console.log("Http server closed"));
+    await stopMcpServers();
+  };
+}
+
+function arrayify(a) {
+  let r;
+  if (a === undefined) r = [];
+  else if (Array.isArray(a)) r = a.slice(0);
+  else r = [a];
+
+  return r
+}
+
+function normalizeToolName(name) {
+  return name.toLowerCase().replace(/-/g, "_");
+}
+
+runBridge()
+  .then(stop => {
+    if (stop) {
+      process.on('SIGINT', stop);
+      process.on('SIGTERM', stop);
+    }
+  })
+  .catch(console.error);
+\ No newline at end of file