"""
REST endpoint for serving MCP App resources.

Maps ui:// URIs to static HTML App files under the bot's skill directory.

GET /api/v1/mcp/resources?uri=ui://data-dashboard/chart&bot_id=xxx
  -> projects/robot/{bot_id}/skills/data-dashboard/apps/chart.html
"""

import logging
from pathlib import Path

from fastapi import APIRouter, Query, HTTPException
from fastapi.responses import HTMLResponse

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/api/v1/mcp", tags=["mcp-resources"])

PROJECT_ROOT = Path(__file__).parent.parent

# In-memory cache: (bot_id, uri) -> html string
_resource_cache: dict[tuple[str, str], str] = {}


def _resolve_uri_to_path(uri: str, bot_id: str) -> Path:
    """Resolve a ui:// URI to a local file path.

    URI format: ui://{server-name}/{resource-name}
    File path:  projects/robot/{bot_id}/skills/{server-name}/apps/{resource-name}.html
    """
    if not uri.startswith("ui://"):
        raise ValueError(f"Invalid URI scheme: {uri}")

    rest = uri[5:]  # Remove "ui://"
    parts = rest.split("/", 1)
    if len(parts) != 2 or not parts[0] or not parts[1]:
        raise ValueError(f"Invalid URI format: {uri}")

    server_name, resource_name = parts

    # Prevent path traversal
    if ".." in server_name or "/" in server_name:
        raise ValueError(f"Invalid server name: {server_name}")
    safe_name = Path(resource_name).name
    if safe_name != resource_name:
        raise ValueError(f"Invalid resource name: {resource_name}")

    return PROJECT_ROOT / "projects" / "robot" / bot_id / "skills" / server_name / "apps" / f"{resource_name}.html"


@router.get("/resources")
async def get_resource(
    uri: str = Query(..., description="Resource URI (e.g. ui://data-dashboard/chart)"),
    bot_id: str = Query(..., description="Bot ID"),
):
    """Fetch an MCP App HTML resource by URI and bot_id.

    Returns the static HTML App that should be loaded into an iframe.
    The host sends tool result data to the iframe via postMessage.
    """
    cache_key = (bot_id, uri)
    if cache_key in _resource_cache:
        return HTMLResponse(content=_resource_cache[cache_key], media_type="text/html")

    try:
        file_path = _resolve_uri_to_path(uri, bot_id)
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))

    if not file_path.is_file():
        raise HTTPException(status_code=404, detail=f"Resource not found: {uri} (bot_id={bot_id})")

    html = file_path.read_text(encoding="utf-8")
    _resource_cache[cache_key] = html

    return HTMLResponse(content=html, media_type="text/html")