"""
User-defined tool adapter (HTTP + MCP) for Agno Agent tools.
"""

from __future__ import annotations

import asyncio
import json
import os
import re
from datetime import timedelta
from typing import Any
from urllib.parse import quote, urlencode, urlparse

import httpx
from agno.tools import Toolkit
from agno.tools.function import Function

try:
    from agno.tools.mcp import MCPTools
    from agno.tools.mcp.params import SSEClientParams, StreamableHTTPClientParams
except Exception:  # pragma: no cover - optional dependency
    MCPTools = None
    StreamableHTTPClientParams = None
    SSEClientParams = None


_mcp_tools_cache: dict[str, Any] = {}
_mcp_tools_lock = asyncio.Lock()
_REMOTE_MCP_TIMEOUT_SECONDS = max(15, int(os.getenv("REMOTE_MCP_TIMEOUT_SECONDS", "45")))
_REMOTE_MCP_SSE_READ_TIMEOUT_SECONDS = max(
    _REMOTE_MCP_TIMEOUT_SECONDS,
    int(os.getenv("REMOTE_MCP_SSE_READ_TIMEOUT_SECONDS", "300")),
)


def _normalize_mcp_transport(transport: str | None) -> str:
    normalized = str(transport or "streamable-http").strip().lower()
    if normalized in {"streamable_http", "streamablehttp", "http"}:
        return "streamable-http"
    if normalized == "sse":
        return "sse"
    if normalized == "stdio":
        return "stdio"
    return "streamable-http"


def _replace_template(template: Any, args: dict[str, Any]) -> Any:
    if not isinstance(template, str):
        return template
    def _replace(match):
        key = match.group(1)
        if key in args:
            return quote(str(args[key]), safe="")
        return match.group(0)
    return _TEMPLATE_REGEX.sub(_replace, template)


def _replace_templates(params: dict[str, Any], args: dict[str, Any]) -> dict[str, Any]:
    result: dict[str, Any] = {}
    for key, value in (params or {}).items():
        if isinstance(value, str):
            result[key] = _replace_template(value, args)
        else:
            result[key] = value
    return result


def _build_url(base_url: str, params: dict[str, Any]) -> str:
    if not params:
        return base_url
    query = urlencode({k: v for k, v in params.items() if v not in (None, "", [])}, doseq=True)
    if not query:
        return base_url
    return f"{base_url}{'&' if '?' in base_url else '?'}{query}"


def _validate_domain(url: str, allowed_domains: list[str]) -> None:
    if not allowed_domains:
        raise ValueError("No allowed domains configured for this tool")
    hostname = urlparse(url).hostname or ""
    for domain in allowed_domains:
        if hostname == domain:
            return
        if domain.startswith("*."):
            base = domain[2:]
            if hostname == base or hostname.endswith(f".{base}"):
                return
    raise ValueError(f"Domain {hostname} is not in the allowed list: {', '.join(allowed_domains)}")


async def _execute_http_tool(tool: dict[str, Any], args: dict[str, Any]) -> dict[str, Any]:
    config = tool.get("config") or {}
    url = config.get("url")
    method = (config.get("method") or "GET").upper()
    params = config.get("params") or {}
    headers = config.get("headers") or {}
    security = config.get("security") or {}

    if not url:
        raise ValueError("HTTP tool missing url")

    allowed_domains = security.get("allowedDomains") or []
    max_response_size = int(security.get("maxResponseSize") or 1000000)
    timeout_ms = int(security.get("timeout") or 10000)

    final_params = _replace_templates(params, args or {})
    processed_url = _replace_template(url, args or {})
    final_url = _build_url(processed_url, final_params) if method == "GET" else processed_url

    _validate_domain(final_url, allowed_domains)

    request_headers = {"Content-Type": "application/json"}
    request_headers.update(headers or {})

    timeout = httpx.Timeout(timeout_ms / 1000.0)
    async with httpx.AsyncClient(timeout=timeout) as client:
        if method in ("GET", "HEAD"):
            response = await client.request(method, final_url, headers=request_headers)
        else:
            response = await client.request(
                method,
                final_url,
                headers=request_headers,
                json=final_params,
            )

    response.raise_for_status()
    text = response.text
    if len(text) > max_response_size:
        raise ValueError(
            f"Response size {len(text)} bytes exceeds limit of {max_response_size} bytes"
        )

    try:
        return json.loads(text)
    except Exception:
        return {"data": text}


async def _get_mcp_tools(server_url: str, transport: str, headers: dict[str, Any]) -> Any:
    if MCPTools is None:
        raise RuntimeError("`mcp` not installed. Please install using `pip install mcp`.")

    normalized_transport = _normalize_mcp_transport(transport)

    key = json.dumps(
        {
            "url": server_url,
            "transport": normalized_transport,
            "headers": headers,
        },
        sort_keys=True,
    )

    async with _mcp_tools_lock:
        if key in _mcp_tools_cache:
            return _mcp_tools_cache[key]

        server_params = None
        if normalized_transport == "sse":
            server_params = (
                SSEClientParams(
                    url=server_url,
                    headers=headers,
                    timeout=_REMOTE_MCP_TIMEOUT_SECONDS,
                    sse_read_timeout=_REMOTE_MCP_SSE_READ_TIMEOUT_SECONDS,
                )
                if SSEClientParams
                else None
            )
        else:
            server_params = (
                StreamableHTTPClientParams(
                    url=server_url,
                    headers=headers,
                    timeout=timedelta(seconds=_REMOTE_MCP_TIMEOUT_SECONDS),
                    sse_read_timeout=timedelta(seconds=_REMOTE_MCP_SSE_READ_TIMEOUT_SECONDS),
                )
                if StreamableHTTPClientParams
                else None
            )

        tools = MCPTools(
            url=server_url,
            transport=normalized_transport,
            server_params=server_params,
            timeout_seconds=_REMOTE_MCP_TIMEOUT_SECONDS,
        )
        await tools.connect()
        _mcp_tools_cache[key] = tools
        return tools


async def _execute_mcp_tool(tool: dict[str, Any], args: dict[str, Any]) -> Any:
    if MCPTools is None:
        raise RuntimeError("`mcp` not installed. Please install using `pip install mcp`.")

    config = tool.get("config") or {}
    server_url = config.get("serverUrl") or config.get("server_url") or config.get("url")
    if not server_url:
        raise ValueError("MCP tool missing serverUrl")
    transport = _normalize_mcp_transport(
        config.get("transport") or config.get("serverTransport") or "streamable-http"
    )
    headers = dict(config.get("headers") or {})
    bearer = config.get("bearerToken") or config.get("authToken")
    if bearer and "Authorization" not in headers:
        headers["Authorization"] = f"Bearer {bearer}"

    tool_name = config.get("toolName") or tool.get("name")
    if not tool_name:
        raise ValueError("MCP tool missing toolName")

    tools = await _get_mcp_tools(server_url, transport, headers)
    functions = tools.get_async_functions()
    fn = functions.get(tool_name) or tools.get_functions().get(tool_name)
    if not fn or not fn.entrypoint:
        raise RuntimeError(f"MCP tool '{tool_name}' not found in server")

    return await fn.entrypoint(**(args or {}))


def build_user_tools_toolkit(user_tools: list[dict[str, Any]] | None) -> Toolkit | None:
    if not user_tools:
        return None

    functions: list[Function] = []
    for tool in user_tools:
        name = tool.get("name")
        if not name:
            continue
        description = tool.get("description") or ""
        parameters = (
            tool.get("input_schema")
            or tool.get("inputSchema")
            or tool.get("parameters")
            or {
            "type": "object",
            "properties": {},
        }
        )

        if tool.get("type") == "mcp":
            async def _mcp_entrypoint(*, _tool=tool, **kwargs):
                return await _execute_mcp_tool(_tool, kwargs)

            entrypoint = _mcp_entrypoint
        else:
            async def _http_entrypoint(*, _tool=tool, **kwargs):
                return await _execute_http_tool(_tool, kwargs)

            entrypoint = _http_entrypoint

        functions.append(
            Function(
                name=name,
                description=description,
                parameters=parameters,
                entrypoint=entrypoint,
                skip_entrypoint_processing=True,
            )
        )

    if not functions:
        return None
    return Toolkit(name="user_tools", tools=functions)


_TEMPLATE_REGEX = re.compile(r"\{\{(\w+)\}\}")