#
# Copyright (C) 2026 GNS3 Technologies Inc.
# Author: Yue Guobin
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
MCP (Model Context Protocol) service for GNS3 server.

Implements the standard MCP protocol over SSE transport using FastMCP:

  /v3/mcp/sse     — SSE stream
  /v3/mcp/messages/ — JSON-RPC messages

Tools are registered via @mcp.tool() decorators.
"""

import contextvars
import json
import asyncio
import logging
from typing import Any
from urllib.parse import parse_qs

from fastapi import APIRouter
from fastapi.responses import Response

from mcp.server.fastmcp import FastMCP

from gns3server.config import Config
from gns3server.services import auth_service
from .projects import (
    list_projects_handler, get_project_handler, create_project_handler,
    delete_project_handler, open_project_handler, close_project_handler,
    get_project_stats_handler,
)
from .nodes import (
    get_nodes_handler, get_node_handler, start_node_handler,
    stop_node_handler, reload_node_handler, suspend_node_handler,
    create_node_handler, delete_node_handler, update_node_handler,
    get_node_console_info_handler,
)
from .links import (
    get_links_handler, get_link_handler, create_link_handler,
    delete_link_handler, update_link_handler,
)
from .templates import (
    list_templates_handler, get_template_handler, create_template_handler,
    update_template_handler, delete_template_handler,
)
from .computes import (
    list_computes_handler, get_compute_handler, get_compute_images_handler,
)

log = logging.getLogger(__name__)


# ── Per‑connection JWT token  ─────────────────────────────────────────
# Set during SSE authentication, read by tool handlers running in the
# same asyncio task (contextvars propagate through asyncio.to_thread).

_jwt_token_var: contextvars.ContextVar[str | None] = contextvars.ContextVar(
    "mcp_jwt_token", default=None
)


# ── Token validation ──────────────────────────────────────────────────

async def _validate_token(token: str) -> bool:
    """Return True if token is a valid GNS3 JWT."""
    try:
        auth_service.get_username_from_token(token)
        return True
    except Exception:
        return False


# ── Server URL helper ─────────────────────────────────────────────────

def _server_url() -> str:
    cfg = Config.instance().settings
    host = cfg.Server.host
    if host == "0.0.0.0":
        host = "127.0.0.1"
    scheme = "https" if cfg.Server.enable_ssl else "http"
    return f"{scheme}://{host}:{cfg.Server.port}"


# ── FastMCP Server ────────────────────────────────────────────────────

mcp = FastMCP("GNS3 MCP Server")


# ── Tool handlers ─────────────────────────────────────────────────────

def _run_handler_sync(handler, params: dict[str, Any]) -> list[dict[str, Any]]:
    """Run a synchronous Gns3Connector handler in a thread."""
    ctx = {
        "server_url": _server_url(),
        "jwt_token": _jwt_token_var.get(),
    }
    result = handler(params, ctx)
    return [{"type": "text", "text": json.dumps(result, ensure_ascii=False, default=str)}]


@mcp.tool()
async def list_projects() -> list[dict[str, Any]]:
    """List all GNS3 projects accessible to the current user."""
    return await asyncio.to_thread(_run_handler_sync, list_projects_handler, {})


@mcp.tool()
async def get_project(project_id: str) -> list[dict[str, Any]]:
    """Get detailed information about a specific project.

    Args:
        project_id: Project UUID
    """
    return await asyncio.to_thread(_run_handler_sync, get_project_handler, {"project_id": project_id})


@mcp.tool()
async def create_project(name: str, description: str = "") -> list[dict[str, Any]]:
    """Create a new GNS3 project.

    Args:
        name: Project name
        description: Optional project description
    """
    params = {"name": name}
    if description:
        params["description"] = description
    return await asyncio.to_thread(_run_handler_sync, create_project_handler, params)


@mcp.tool()
async def delete_project(project_id: str) -> list[dict[str, Any]]:
    """Delete a GNS3 project permanently.

    Args:
        project_id: UUID of the project to delete
    """
    return await asyncio.to_thread(_run_handler_sync, delete_project_handler, {"project_id": project_id})


@mcp.tool()
async def open_project(project_id: str) -> list[dict[str, Any]]:
    """Open a closed GNS3 project.

    Args:
        project_id: Project UUID
    """
    return await asyncio.to_thread(_run_handler_sync, open_project_handler, {"project_id": project_id})


@mcp.tool()
async def close_project(project_id: str) -> list[dict[str, Any]]:
    """Close an open GNS3 project.

    Args:
        project_id: Project UUID
    """
    return await asyncio.to_thread(_run_handler_sync, close_project_handler, {"project_id": project_id})


@mcp.tool()
async def get_project_stats(project_id: str) -> list[dict[str, Any]]:
    """Get statistics (nodes, links, snapshots, drawings) for a project.

    Args:
        project_id: Project UUID
    """
    return await asyncio.to_thread(_run_handler_sync, get_project_stats_handler, {"project_id": project_id})


# ── Node tools ────────────────────────────────────────────────────────

@mcp.tool()
async def get_nodes(project_id: str) -> list[dict[str, Any]]:
    """List all nodes in a project."""
    return await asyncio.to_thread(_run_handler_sync, get_nodes_handler, {"project_id": project_id})


@mcp.tool()
async def get_node(project_id: str, node_id: str) -> list[dict[str, Any]]:
    """Get detailed information about a specific node.

    Args:
        project_id: Project UUID
        node_id: Node UUID
    """
    return await asyncio.to_thread(_run_handler_sync, get_node_handler, {"project_id": project_id, "node_id": node_id})


@mcp.tool()
async def start_node(project_id: str, node_id: str) -> list[dict[str, Any]]:
    """Start a node in a project.

    Args:
        project_id: Project UUID
        node_id: Node UUID
    """
    return await asyncio.to_thread(_run_handler_sync, start_node_handler, {"project_id": project_id, "node_id": node_id})


@mcp.tool()
async def stop_node(project_id: str, node_id: str) -> list[dict[str, Any]]:
    """Stop a node in a project.

    Args:
        project_id: Project UUID
        node_id: Node UUID
    """
    return await asyncio.to_thread(_run_handler_sync, stop_node_handler, {"project_id": project_id, "node_id": node_id})


@mcp.tool()
async def reload_node(project_id: str, node_id: str) -> list[dict[str, Any]]:
    """Reload (restart) a node in a project.

    Args:
        project_id: Project UUID
        node_id: Node UUID
    """
    return await asyncio.to_thread(_run_handler_sync, reload_node_handler, {"project_id": project_id, "node_id": node_id})


@mcp.tool()
async def suspend_node(project_id: str, node_id: str) -> list[dict[str, Any]]:
    """Suspend a node in a project.

    Args:
        project_id: Project UUID
        node_id: Node UUID
    """
    return await asyncio.to_thread(_run_handler_sync, suspend_node_handler, {"project_id": project_id, "node_id": node_id})


@mcp.tool()
async def create_node(project_id: str, template_id: str, x: int = 0, y: int = 0, compute_id: str = "local") -> list[dict[str, Any]]:
    """Create a new node from a template in a project.

    Args:
        project_id: Project UUID
        template_id: Template UUID
        x: X coordinate (optional)
        y: Y coordinate (optional)
        compute_id: Compute ID (optional, default: local)
    """
    return await asyncio.to_thread(_run_handler_sync, create_node_handler, {
        "project_id": project_id, "template_id": template_id,
        "x": x, "y": y, "compute_id": compute_id,
    })


@mcp.tool()
async def delete_node(project_id: str, node_id: str) -> list[dict[str, Any]]:
    """Delete a node from a project.

    Args:
        project_id: Project UUID
        node_id: Node UUID
    """
    return await asyncio.to_thread(_run_handler_sync, delete_node_handler, {"project_id": project_id, "node_id": node_id})


@mcp.tool()
async def update_node(project_id: str, node_id: str, **kwargs: Any) -> list[dict[str, Any]]:
    """Update a node's properties (name, position, etc.).

    Args:
        project_id: Project UUID
        node_id: Node UUID
    """
    params = {"project_id": project_id, "node_id": node_id, **kwargs}
    return await asyncio.to_thread(_run_handler_sync, update_node_handler, params)


@mcp.tool()
async def get_node_console_info(project_id: str, node_id: str) -> list[dict[str, Any]]:
    """Get console WebSocket URL for a node (use websocat to connect).

    Args:
        project_id: Project UUID
        node_id: Node UUID
    """
    return await asyncio.to_thread(_run_handler_sync, get_node_console_info_handler, {
        "project_id": project_id, "node_id": node_id,
    })


# ── Link tools ────────────────────────────────────────────────────────

@mcp.tool()
async def get_links(project_id: str) -> list[dict[str, Any]]:
    """List all links in a project."""
    return await asyncio.to_thread(_run_handler_sync, get_links_handler, {"project_id": project_id})


@mcp.tool()
async def get_link(project_id: str, link_id: str) -> list[dict[str, Any]]:
    """Get detailed information about a specific link.

    Args:
        project_id: Project UUID
        link_id: Link UUID
    """
    return await asyncio.to_thread(_run_handler_sync, get_link_handler, {"project_id": project_id, "link_id": link_id})


@mcp.tool()
async def create_link(project_id: str, nodes: list, link_type: str = "ethernet", filters: dict = None) -> list[dict[str, Any]]:
    """Create a link between two nodes in a project.

    Args:
        project_id: Project UUID
        nodes: List of node connections, e.g. [{"node_id": "...", "adapter_number": 0, "port_number": 0}, ...]
        link_type: Link type - ethernet or serial (optional)
        filters: Packet filters (optional)
    """
    params = {"project_id": project_id, "nodes": nodes, "link_type": link_type}
    if filters:
        params["filters"] = filters
    return await asyncio.to_thread(_run_handler_sync, create_link_handler, params)


@mcp.tool()
async def delete_link(project_id: str, link_id: str) -> list[dict[str, Any]]:
    """Delete a link from a project.

    Args:
        project_id: Project UUID
        link_id: Link UUID
    """
    return await asyncio.to_thread(_run_handler_sync, delete_link_handler, {"project_id": project_id, "link_id": link_id})


@mcp.tool()
async def update_link(project_id: str, link_id: str, **kwargs: Any) -> list[dict[str, Any]]:
    """Update a link's properties (suspend, filters, etc.).

    Args:
        project_id: Project UUID
        link_id: Link UUID
    """
    params = {"project_id": project_id, "link_id": link_id, **kwargs}
    return await asyncio.to_thread(_run_handler_sync, update_link_handler, params)


# ── Template tools ────────────────────────────────────────────────────

@mcp.tool()
async def list_templates() -> list[dict[str, Any]]:
    """List all available templates on the server."""
    return await asyncio.to_thread(_run_handler_sync, list_templates_handler, {})


@mcp.tool()
async def get_template(template_id: str = None, name: str = None) -> list[dict[str, Any]]:
    """Get detailed information about a specific template.

    Args:
        template_id: Template UUID (optional if name is provided)
        name: Template name (optional if template_id is provided)
    """
    return await asyncio.to_thread(_run_handler_sync, get_template_handler, {
        "template_id": template_id, "name": name,
    })


@mcp.tool()
async def create_template(name: str, template_type: str, compute_id: str = "local") -> list[dict[str, Any]]:
    """Create a new template.

    Args:
        name: Template name
        template_type: Template type (e.g. qemu, docker, dynamips)
        compute_id: Compute ID (optional, default: local)
    """
    return await asyncio.to_thread(_run_handler_sync, create_template_handler, {
        "name": name, "template_type": template_type, "compute_id": compute_id,
    })


@mcp.tool()
async def update_template(template_id: str = None, name: str = None, **kwargs: Any) -> list[dict[str, Any]]:
    """Update an existing template's properties.

    Args:
        template_id: Template UUID (optional if name is provided)
        name: Template name (optional if template_id is provided)
    """
    params = {"template_id": template_id, "name": name, **kwargs}
    return await asyncio.to_thread(_run_handler_sync, update_template_handler, params)


@mcp.tool()
async def delete_template(template_id: str = None, name: str = None) -> list[dict[str, Any]]:
    """Delete a template.

    Args:
        template_id: Template UUID (optional if name is provided)
        name: Template name (optional if template_id is provided)
    """
    return await asyncio.to_thread(_run_handler_sync, delete_template_handler, {
        "template_id": template_id, "name": name,
    })


# ── Compute tools ─────────────────────────────────────────────────────

@mcp.tool()
async def list_computes() -> list[dict[str, Any]]:
    """List all compute nodes available to the server."""
    return await asyncio.to_thread(_run_handler_sync, list_computes_handler, {})


@mcp.tool()
async def get_compute(compute_id: str = "local") -> list[dict[str, Any]]:
    """Get detailed information about a compute node.

    Args:
        compute_id: Compute ID (default: local)
    """
    return await asyncio.to_thread(_run_handler_sync, get_compute_handler, {"compute_id": compute_id})


@mcp.tool()
async def get_compute_images(emulator: str, compute_id: str = "local") -> list[dict[str, Any]]:
    """List available images for an emulator on a compute node.

    Args:
        emulator: Emulator type (e.g. qemu, iou, docker)
        compute_id: Compute ID (default: local)
    """
    return await asyncio.to_thread(_run_handler_sync, get_compute_images_handler, {
        "emulator": emulator, "compute_id": compute_id,
    })


# ── Auth‑wrapped SSE app ──────────────────────────────────────────────

def _make_auth_wrapper(inner_app):
    """Wrap the SSE app with JWT validation.

    Supports two ways to pass the token (checked in order):
      1. Authorization: Bearer <jwt> header
      2. ?token=<jwt> query parameter

    POST messages are passed through (authenticated by their session).
    """

    async def auth_wrapper(scope, receive, send):
        if scope["type"] == "http" and scope["method"] == "GET":
            token = None
            headers = dict(scope.get("headers", []))
            auth = headers.get(b"authorization", b"").decode()
            if auth.startswith("Bearer "):
                token = auth[7:]
            if not token:
                params = parse_qs(scope.get("query_string", b"").decode())
                tokens = params.get("token", [])
                if tokens:
                    token = tokens[0]
            if not token or not await _validate_token(token):
                response = Response("Missing or invalid token", status_code=401)
                await response(scope, receive, send)
                return
            _jwt_token_var.set(token)
        await inner_app(scope, receive, send)

    return auth_wrapper


# ── FastAPI router ────────────────────────────────────────────────────

router = APIRouter(prefix="/mcp", tags=["MCP"])


@router.get("/")
async def mcp_root():
    """MCP service metadata."""
    return {
        "name": "GNS3 MCP Server",
        "version": "1.0.0",
        "authentication": ["Authorization: Bearer <jwt>", "?token=<jwt>"],
        "transports": {
            "sse": "/v3/mcp/transport/sse",
        },
    }


def register_starlette_routes(app):
    """Mount MCP transports on the FastAPI app."""
    sse_app = _make_auth_wrapper(mcp.sse_app(mount_path=""))
    app.mount("/v3/mcp/transport", sse_app, name="mcp-sse")
    log.info("MCP SSE server mounted at /v3/mcp/transport")