/**
 * MUA — Mikes Unraid Agent
 * index.ts — MCP over HTTP (Streamable HTTP) Server
 *
 * Portiert von mcp/server.php. Nutzt Bun.serve() statt php -S —
 * production-grade HTTP-Server, POST-Body wird korrekt gelesen.
 *
 * Transport: MCP Streamable HTTP (POST-only, JSON-RPC 2.0).
 * Endpunkte:
 *   POST   /mcp    — JSON-RPC Request
 *   GET    /mcp    — 405 (SSE nicht implementiert, spec-konform)
 *   DELETE /mcp    — Session-End
 *   GET    /health — Health-Check
 */

import {
  MUA_SERVER_NAME,
  MUA_VERSION,
  MUA_PROTOCOL_VERSION,
} from "./helpers";
import { TOOLS, toolByName } from "./tools";

const PORT = Number(process.env["MUA_PORT"] ?? 3002);
const HOST = process.env["MUA_HOST"] ?? "0.0.0.0";

// ── JSON-RPC Helpers ────────────────────────────────────────────────────
function rpcResult(id: number | string | null, result: unknown) {
  return { jsonrpc: "2.0", id, result };
}
function rpcError(id: number | string | null, code: number, message: string) {
  return { jsonrpc: "2.0", id, error: { code, message } };
}

// ── Session Management ──────────────────────────────────────────────────
const sessions = new Map<string, { createdAt: number; lastActivity: number }>();

function newSessionId(): string {
  return crypto.randomUUID();
}
function touchSession(id: string) {
  const now = Date.now();
  if (sessions.has(id)) {
    sessions.get(id)!.lastActivity = now;
  } else {
    sessions.set(id, { createdAt: now, lastActivity: now });
  }
}
function deleteSession(id: string | null) {
  if (id) sessions.delete(id);
}

// ── MCP Request Handler ─────────────────────────────────────────────────
async function handleMcpRequest(
  message: Record<string, unknown>,
  sessionId: string | null,
): Promise<{ response: unknown; sessionId: string } | null> {
  const method = (message["method"] as string) ?? "";
  const id = message["id"] as number | string | null;
  const params = (message["params"] as Record<string, unknown>) ?? {};

  // ── initialize ────────────────────────────────────────────────────────
  if (method === "initialize") {
    const sid = newSessionId();
    touchSession(sid);
    return {
      response: rpcResult(id, {
        protocolVersion: MUA_PROTOCOL_VERSION,
        capabilities: { tools: {} },
        serverInfo: { name: MUA_SERVER_NAME, version: MUA_VERSION },
      }),
      sessionId: sid,
    };
  }

  // ── notifications/initialized (kein Response) ─────────────────────────
  if (method === "notifications/initialized") {
    if (sessionId) touchSession(sessionId);
    return null;
  }

  // ── tools/list ────────────────────────────────────────────────────────
  if (method === "tools/list") {
    if (sessionId) touchSession(sessionId);
    return {
      response: rpcResult(id, {
        tools: TOOLS.map((t) => ({
          name: t.name,
          description: t.description,
          inputSchema: t.inputSchema,
        })),
      }),
      sessionId: sessionId ?? "",
    };
  }

  // ── tools/call ────────────────────────────────────────────────────────
  if (method === "tools/call") {
    if (sessionId) touchSession(sessionId);
    const toolName = (params["name"] as string) ?? "";
    const args = (params["arguments"] as Record<string, unknown>) ?? {};
    const tool = toolByName(toolName);
    if (!tool) {
      return {
        response: rpcResult(id, {
          content: [{ type: "text", text: `ERROR: Unknown tool: ${toolName}` }],
          isError: true,
        }),
        sessionId: sessionId ?? "",
      };
    }
    try {
      const text = await tool.handler(args);
      const result: Record<string, unknown> = {
        content: [{ type: "text", text }],
      };
      // structuredContent für Tools mit JSON-Output
      if (
        [
          "unraid_docker_list",
          "unraid_network_inventory",
          "unraid_docker_analyze_logs",
          "unraid_network_audit_tcp",
        ].includes(toolName)
      ) {
        try {
          result.structuredContent = JSON.parse(text);
        } catch {
          // ignore
        }
      }
      return { response: rpcResult(id, result), sessionId: sessionId ?? "" };
    } catch (e) {
      return {
        response: rpcResult(id, {
          content: [{ type: "text", text: `ERROR: ${String(e)}` }],
          isError: true,
        }),
        sessionId: sessionId ?? "",
      };
    }
  }

  // ── ping ──────────────────────────────────────────────────────────────
  if (method === "ping") {
    if (sessionId) touchSession(sessionId);
    return { response: rpcResult(id, {}), sessionId: sessionId ?? "" };
  }

  // ── Unknown method ────────────────────────────────────────────────────
  if (id !== null && id !== undefined) {
    return {
      response: rpcError(id, -32601, `Method not found: ${method}`),
      sessionId: sessionId ?? "",
    };
  }
  return null;
}

// ── HTTP Server (Bun.serve — production-grade) ──────────────────────────
const server = Bun.serve({
  port: PORT,
  hostname: HOST,
  idleTimeout: 120, // Sekunden (für lange docker stats / audit)
  async fetch(req) {
    const url = new URL(req.url);
    const path = url.pathname;
    const method = req.method;
    const sessionHeader = req.headers.get("mcp-session-id");

    // CORS für lokale Nutzung
    const corsHeaders: Record<string, string> = {
      "Access-Control-Allow-Origin": "*",
      "Access-Control-Allow-Methods": "GET, POST, DELETE, OPTIONS",
      "Access-Control-Allow-Headers": "Content-Type, Mcp-Session-Id",
    };

    // ── OPTIONS (CORS Preflight) ────────────────────────────────────────
    if (method === "OPTIONS") {
      return new Response(null, { status: 204, headers: corsHeaders });
    }

    // ── Health-Check ────────────────────────────────────────────────────
    if (path === "/health") {
      return Response.json(
        {
          status: "ok",
          server: MUA_SERVER_NAME,
          version: MUA_VERSION,
          port: PORT,
          time: new Date().toISOString(),
        },
        { headers: corsHeaders },
      );
    }

    // ── MCP-Endpunkt ────────────────────────────────────────────────────
    if (path === "/mcp" || path === "/") {
      // POST: JSON-RPC Request
      if (method === "POST") {
        let body: string;
        try {
          body = await req.text();
        } catch (e) {
          return Response.json(
            rpcError(null, -32700, "Parse error"),
            { status: 400, headers: corsHeaders },
          );
        }

        let message: Record<string, unknown>;
        try {
          message = JSON.parse(body);
        } catch {
          return Response.json(
            rpcError(null, -32700, "Parse error"),
            { status: 400, headers: corsHeaders },
          );
        }

        const result = await handleMcpRequest(message, sessionHeader);

        // Notification (kein Response nötig)
        if (result === null) {
          return new Response(null, {
            status: 202,
            headers: {
              ...corsHeaders,
              "Mcp-Session-Id": sessionHeader ?? "",
            },
          });
        }

        return Response.json(result.response, {
          headers: {
            ...corsHeaders,
            "Mcp-Session-Id": result.sessionId,
          },
        });
      }

      // GET: SSE-Stream (nicht implementiert, spec-konform 405)
      if (method === "GET") {
        return Response.json(
          { error: "SSE not supported. Use POST /mcp for JSON-RPC requests." },
          { status: 405, headers: corsHeaders },
        );
      }

      // DELETE: Session-End
      if (method === "DELETE") {
        deleteSession(sessionHeader);
        return new Response(null, { status: 200, headers: corsHeaders });
      }
    }

    // ── 404 ─────────────────────────────────────────────────────────────
    return Response.json(
      { error: "Not found. Use /mcp or /health" },
      { status: 404, headers: corsHeaders },
    );
  },
});

console.log(
  `[MUA] ${MUA_SERVER_NAME} v${MUA_VERSION} listening on ${HOST}:${PORT} (MCP Streamable HTTP)`,
);

// Graceful shutdown
process.on("SIGTERM", () => {
  console.log("[MUA] SIGTERM received, shutting down");
  server.stop(true);
  process.exit(0);
});
process.on("SIGINT", () => {
  console.log("[MUA] SIGINT received, shutting down");
  server.stop(true);
  process.exit(0);
});