import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";
import { execFile } from "node:child_process";
import { promisify } from "node:util";
import { mkdtemp, rm, mkdir } from "node:fs/promises";
import path from "node:path";

const execFileAsync = promisify(execFile);
const WORKSPACE_ROOT = "/workspace";

// Runs the real Claude Code CLI — billed against the Claude Pro/Max subscription
// (CLAUDE_CODE_OAUTH_TOKEN), not per-token API billing. This only works because it's
// the actual `claude` binary making the request: Anthropic rejects the same OAuth token
// used by any other HTTP client (proven earlier — direct curl replicating the same
// request shape gets rejected). Read-only: no git/file-write tools, since this is a
// quick-answer bridge, not a repo-editing agent (claude-agent's own webhook flow already
// owns that for PRs).
async function askClaudeSubscription(prompt) {
  await mkdir(WORKSPACE_ROOT, { recursive: true });
  const dir = await mkdtemp(path.join(WORKSPACE_ROOT, "mcp-"));
  try {
    const { stdout } = await execFileAsync(
      "claude",
      [
        "-p", prompt,
        "--output-format", "text",
        "--permission-mode", "bypassPermissions",
        "--disallowedTools", "Bash(git push:*),Bash(git commit:*),Edit,Write,NotebookEdit",
      ],
      { cwd: dir, maxBuffer: 1024 * 1024 * 32 }
    );
    return stdout;
  } finally {
    await rm(dir, { recursive: true, force: true });
  }
}

// A fresh McpServer per request (stateless transport) — cheap, and avoids any
// cross-request state for what's a single-tool, single-shot bridge.
export function createMcpServer() {
  const server = new McpServer({ name: "claude-code-bridge", version: "1.0.0" });

  server.registerTool(
    "ask_claude_code",
    {
      description:
        "Ask the real Claude Code CLI a question or reasoning task, billed against the " +
        "Claude Pro/Max subscription rather than per-token API credits. Use this when " +
        "you specifically want Claude's own model rather than whatever the default " +
        "routed model provides. Read-only — cannot edit files, push, or commit.",
      inputSchema: { prompt: z.string().describe("The question or task to ask Claude") },
    },
    async ({ prompt }) => {
      try {
        const text = await askClaudeSubscription(prompt);
        return { content: [{ type: "text", text }] };
      } catch (err) {
        return { content: [{ type: "text", text: `Error: ${err.message}` }], isError: true };
      }
    }
  );

  return server;
}

export function mcpAuthMiddleware(req, res, next) {
  const key = process.env.MCP_BRIDGE_KEY;
  if (!key) return res.status(500).send("MCP_BRIDGE_KEY not configured");
  if (req.get("Authorization") !== `Bearer ${key}`) return res.status(401).send("unauthorized");
  next();
}