import logging
from datetime import timedelta
from typing import Any, Protocol

import anyio.lowlevel
from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
from jsonschema import SchemaError, ValidationError, validate
from pydantic import AnyUrl, TypeAdapter

import mcp.types as types
from mcp.shared.context import RequestContext
from mcp.shared.message import SessionMessage
from mcp.shared.session import BaseSession, ProgressFnT, RequestResponder
from mcp.shared.version import SUPPORTED_PROTOCOL_VERSIONS

DEFAULT_CLIENT_INFO = types.Implementation(name="mcp", version="0.1.0")

logger = logging.getLogger("client")


class SamplingFnT(Protocol):
    async def __call__(
        self,
        context: RequestContext["ClientSession", Any],
        params: types.CreateMessageRequestParams,
    ) -> types.CreateMessageResult | types.ErrorData: ...


class ElicitationFnT(Protocol):
    async def __call__(
        self,
        context: RequestContext["ClientSession", Any],
        params: types.ElicitRequestParams,
    ) -> types.ElicitResult | types.ErrorData: ...


class ListRootsFnT(Protocol):
    async def __call__(
        self, context: RequestContext["ClientSession", Any]
    ) -> types.ListRootsResult | types.ErrorData: ...


class LoggingFnT(Protocol):
    async def __call__(
        self,
        params: types.LoggingMessageNotificationParams,
    ) -> None: ...


class MessageHandlerFnT(Protocol):
    async def __call__(
        self,
        message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
    ) -> None: ...


async def _default_message_handler(
    message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
) -> None:
    await anyio.lowlevel.checkpoint()


async def _default_sampling_callback(
    context: RequestContext["ClientSession", Any],
    params: types.CreateMessageRequestParams,
) -> types.CreateMessageResult | types.ErrorData:
    return types.ErrorData(
        code=types.INVALID_REQUEST,
        message="Sampling not supported",
    )


async def _default_elicitation_callback(
    context: RequestContext["ClientSession", Any],
    params: types.ElicitRequestParams,
) -> types.ElicitResult | types.ErrorData:
    return types.ErrorData(
        code=types.INVALID_REQUEST,
        message="Elicitation not supported",
    )


async def _default_list_roots_callback(
    context: RequestContext["ClientSession", Any],
) -> types.ListRootsResult | types.ErrorData:
    return types.ErrorData(
        code=types.INVALID_REQUEST,
        message="List roots not supported",
    )


async def _default_logging_callback(
    params: types.LoggingMessageNotificationParams,
) -> None:
    pass


ClientResponse: TypeAdapter[types.ClientResult | types.ErrorData] = TypeAdapter(types.ClientResult | types.ErrorData)


class ClientSession(
    BaseSession[
        types.ClientRequest,
        types.ClientNotification,
        types.ClientResult,
        types.ServerRequest,
        types.ServerNotification,
    ]
):
    def __init__(
        self,
        read_stream: MemoryObjectReceiveStream[SessionMessage | Exception],
        write_stream: MemoryObjectSendStream[SessionMessage],
        read_timeout_seconds: timedelta | None = None,
        sampling_callback: SamplingFnT | None = None,
        elicitation_callback: ElicitationFnT | None = None,
        list_roots_callback: ListRootsFnT | None = None,
        logging_callback: LoggingFnT | None = None,
        message_handler: MessageHandlerFnT | None = None,
        client_info: types.Implementation | None = None,
    ) -> None:
        super().__init__(
            read_stream,
            write_stream,
            types.ServerRequest,
            types.ServerNotification,
            read_timeout_seconds=read_timeout_seconds,
        )
        self._client_info = client_info or DEFAULT_CLIENT_INFO
        self._sampling_callback = sampling_callback or _default_sampling_callback
        self._elicitation_callback = elicitation_callback or _default_elicitation_callback
        self._list_roots_callback = list_roots_callback or _default_list_roots_callback
        self._logging_callback = logging_callback or _default_logging_callback
        self._message_handler = message_handler or _default_message_handler
        self._tool_output_schemas: dict[str, dict[str, Any] | None] = {}

    async def initialize(self) -> types.InitializeResult:
        sampling = types.SamplingCapability() if self._sampling_callback is not _default_sampling_callback else None
        elicitation = (
            types.ElicitationCapability() if self._elicitation_callback is not _default_elicitation_callback else None
        )
        roots = (
            # TODO: Should this be based on whether we
            # _will_ send notifications, or only whether
            # they're supported?
            types.RootsCapability(listChanged=True)
            if self._list_roots_callback is not _default_list_roots_callback
            else None
        )

        result = await self.send_request(
            types.ClientRequest(
                types.InitializeRequest(
                    params=types.InitializeRequestParams(
                        protocolVersion=types.LATEST_PROTOCOL_VERSION,
                        capabilities=types.ClientCapabilities(
                            sampling=sampling,
                            elicitation=elicitation,
                            experimental=None,
                            roots=roots,
                        ),
                        clientInfo=self._client_info,
                    ),
                )
            ),
            types.InitializeResult,
        )

        if result.protocolVersion not in SUPPORTED_PROTOCOL_VERSIONS:
            raise RuntimeError(f"Unsupported protocol version from the server: {result.protocolVersion}")

        await self.send_notification(types.ClientNotification(types.InitializedNotification()))

        return result

    async def send_ping(self) -> types.EmptyResult:
        """Send a ping request."""
        return await self.send_request(
            types.ClientRequest(types.PingRequest()),
            types.EmptyResult,
        )

    async def send_progress_notification(
        self,
        progress_token: str | int,
        progress: float,
        total: float | None = None,
        message: str | None = None,
    ) -> None:
        """Send a progress notification."""
        await self.send_notification(
            types.ClientNotification(
                types.ProgressNotification(
                    params=types.ProgressNotificationParams(
                        progressToken=progress_token,
                        progress=progress,
                        total=total,
                        message=message,
                    ),
                ),
            )
        )

    async def set_logging_level(self, level: types.LoggingLevel) -> types.EmptyResult:
        """Send a logging/setLevel request."""
        return await self.send_request(
            types.ClientRequest(
                types.SetLevelRequest(
                    params=types.SetLevelRequestParams(level=level),
                )
            ),
            types.EmptyResult,
        )

    async def list_resources(self, cursor: str | None = None) -> types.ListResourcesResult:
        """Send a resources/list request."""
        return await self.send_request(
            types.ClientRequest(
                types.ListResourcesRequest(
                    params=types.PaginatedRequestParams(cursor=cursor) if cursor is not None else None,
                )
            ),
            types.ListResourcesResult,
        )

    async def list_resource_templates(self, cursor: str | None = None) -> types.ListResourceTemplatesResult:
        """Send a resources/templates/list request."""
        return await self.send_request(
            types.ClientRequest(
                types.ListResourceTemplatesRequest(
                    params=types.PaginatedRequestParams(cursor=cursor) if cursor is not None else None,
                )
            ),
            types.ListResourceTemplatesResult,
        )

    async def read_resource(self, uri: AnyUrl) -> types.ReadResourceResult:
        """Send a resources/read request."""
        return await self.send_request(
            types.ClientRequest(
                types.ReadResourceRequest(
                    params=types.ReadResourceRequestParams(uri=uri),
                )
            ),
            types.ReadResourceResult,
        )

    async def subscribe_resource(self, uri: AnyUrl) -> types.EmptyResult:
        """Send a resources/subscribe request."""
        return await self.send_request(
            types.ClientRequest(
                types.SubscribeRequest(
                    params=types.SubscribeRequestParams(uri=uri),
                )
            ),
            types.EmptyResult,
        )

    async def unsubscribe_resource(self, uri: AnyUrl) -> types.EmptyResult:
        """Send a resources/unsubscribe request."""
        return await self.send_request(
            types.ClientRequest(
                types.UnsubscribeRequest(
                    params=types.UnsubscribeRequestParams(uri=uri),
                )
            ),
            types.EmptyResult,
        )

    async def call_tool(
        self,
        name: str,
        arguments: dict[str, Any] | None = None,
        read_timeout_seconds: timedelta | None = None,
        progress_callback: ProgressFnT | None = None,
    ) -> types.CallToolResult:
        """Send a tools/call request with optional progress callback support."""

        result = await self.send_request(
            types.ClientRequest(
                types.CallToolRequest(
                    params=types.CallToolRequestParams(
                        name=name,
                        arguments=arguments,
                    ),
                )
            ),
            types.CallToolResult,
            request_read_timeout_seconds=read_timeout_seconds,
            progress_callback=progress_callback,
        )

        if not result.isError:
            await self._validate_tool_result(name, result)

        return result

    async def _validate_tool_result(self, name: str, result: types.CallToolResult) -> None:
        """Validate the structured content of a tool result against its output schema."""
        if name not in self._tool_output_schemas:
            # refresh output schema cache
            await self.list_tools()

        output_schema = None
        if name in self._tool_output_schemas:
            output_schema = self._tool_output_schemas.get(name)
        else:
            logger.warning(f"Tool {name} not listed by server, cannot validate any structured content")

        if output_schema is not None:
            if result.structuredContent is None:
                raise RuntimeError(f"Tool {name} has an output schema but did not return structured content")
            try:
                validate(result.structuredContent, output_schema)
            except ValidationError as e:
                raise RuntimeError(f"Invalid structured content returned by tool {name}: {e}")
            except SchemaError as e:
                raise RuntimeError(f"Invalid schema for tool {name}: {e}")

    async def list_prompts(self, cursor: str | None = None) -> types.ListPromptsResult:
        """Send a prompts/list request."""
        return await self.send_request(
            types.ClientRequest(
                types.ListPromptsRequest(
                    params=types.PaginatedRequestParams(cursor=cursor) if cursor is not None else None,
                )
            ),
            types.ListPromptsResult,
        )

    async def get_prompt(self, name: str, arguments: dict[str, str] | None = None) -> types.GetPromptResult:
        """Send a prompts/get request."""
        return await self.send_request(
            types.ClientRequest(
                types.GetPromptRequest(
                    params=types.GetPromptRequestParams(name=name, arguments=arguments),
                )
            ),
            types.GetPromptResult,
        )

    async def complete(
        self,
        ref: types.ResourceTemplateReference | types.PromptReference,
        argument: dict[str, str],
        context_arguments: dict[str, str] | None = None,
    ) -> types.CompleteResult:
        """Send a completion/complete request."""
        context = None
        if context_arguments is not None:
            context = types.CompletionContext(arguments=context_arguments)

        return await self.send_request(
            types.ClientRequest(
                types.CompleteRequest(
                    params=types.CompleteRequestParams(
                        ref=ref,
                        argument=types.CompletionArgument(**argument),
                        context=context,
                    ),
                )
            ),
            types.CompleteResult,
        )

    async def list_tools(self, cursor: str | None = None) -> types.ListToolsResult:
        """Send a tools/list request."""
        result = await self.send_request(
            types.ClientRequest(
                types.ListToolsRequest(
                    params=types.PaginatedRequestParams(cursor=cursor) if cursor is not None else None,
                )
            ),
            types.ListToolsResult,
        )

        # Cache tool output schemas for future validation
        # Note: don't clear the cache, as we may be using a cursor
        for tool in result.tools:
            self._tool_output_schemas[tool.name] = tool.outputSchema

        return result

    async def send_roots_list_changed(self) -> None:
        """Send a roots/list_changed notification."""
        await self.send_notification(types.ClientNotification(types.RootsListChangedNotification()))

    async def _received_request(self, responder: RequestResponder[types.ServerRequest, types.ClientResult]) -> None:
        ctx = RequestContext[ClientSession, Any](
            request_id=responder.request_id,
            meta=responder.request_meta,
            session=self,
            lifespan_context=None,
        )

        match responder.request.root:
            case types.CreateMessageRequest(params=params):
                with responder:
                    response = await self._sampling_callback(ctx, params)
                    client_response = ClientResponse.validate_python(response)
                    await responder.respond(client_response)

            case types.ElicitRequest(params=params):
                with responder:
                    response = await self._elicitation_callback(ctx, params)
                    client_response = ClientResponse.validate_python(response)
                    await responder.respond(client_response)

            case types.ListRootsRequest():
                with responder:
                    response = await self._list_roots_callback(ctx)
                    client_response = ClientResponse.validate_python(response)
                    await responder.respond(client_response)

            case types.PingRequest():
                with responder:
                    return await responder.respond(types.ClientResult(root=types.EmptyResult()))

    async def _handle_incoming(
        self,
        req: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
    ) -> None:
        """Handle incoming messages by forwarding to the message handler."""
        await self._message_handler(req)

    async def _received_notification(self, notification: types.ServerNotification) -> None:
        """Handle notifications from the server."""
        # Process specific notification types
        match notification.root:
            case types.LoggingMessageNotification(params=params):
                await self._logging_callback(params)
            case _:
                pass
