// Sampling/Roots/Logging are SEP-2577-deprecated; internal references are expected.
#![expect(deprecated)]
#[cfg(feature = "elicitation")]
use std::collections::HashSet;
use std::{borrow::Cow, sync::Arc};

use thiserror::Error;
#[cfg(feature = "elicitation")]
use url::Url;

use super::*;
#[cfg(feature = "elicitation")]
use crate::model::{ElicitRequest, ElicitRequestParams, ElicitResult, ElicitationAction};
use crate::{
    model::{
        CancelledNotification, CancelledNotificationParam, ClientInfo, ClientJsonRpcMessage,
        ClientNotification, ClientRequest, ClientResult, CreateMessageRequest,
        CreateMessageRequestParams, CreateMessageResult, EmptyResult, ErrorData, ListRootsRequest,
        ListRootsResult, LoggingMessageNotification, LoggingMessageNotificationParam,
        ProgressNotification, ProgressNotificationParam, PromptListChangedNotification,
        ProtocolVersion, ResourceListChangedNotification, ResourceUpdatedNotification,
        ResourceUpdatedNotificationParam, ServerInfo, ServerNotification, ServerRequest,
        ServerResult, SubscriptionFilter, SubscriptionsAcknowledgedNotification,
        SubscriptionsAcknowledgedNotificationParams, ToolListChangedNotification,
    },
    transport::DynamicTransportError,
};

#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
#[expect(clippy::exhaustive_structs, reason = "intentionally exhaustive")]
pub struct RoleServer;

impl ServiceRole for RoleServer {
    type Req = ServerRequest;
    type Resp = ServerResult;
    type Not = ServerNotification;
    type PeerReq = ClientRequest;
    type PeerResp = ClientResult;
    type PeerNot = ClientNotification;
    type Info = ServerInfo;
    type PeerInfo = ClientInfo;

    type InitializeError = ServerInitializeError;
    const IS_CLIENT: bool = false;

    fn peer_cancelled_params(notification: &Self::PeerNot) -> Option<&CancelledNotificationParam> {
        match notification {
            ClientNotification::CancelledNotification(notification) => Some(&notification.params),
            _ => None,
        }
    }

    fn enforce_request_association(
        request: &Self::Req,
        peer_info: Option<&Self::PeerInfo>,
        in_request_handler_scope: bool,
    ) -> Result<(), ServiceError> {
        let restricted = matches!(
            request,
            ServerRequest::CreateMessageRequest(_)
                | ServerRequest::ListRootsRequest(_)
                | ServerRequest::ElicitRequest(_)
        );
        if !restricted {
            return Ok(());
        }
        let strict =
            peer_info.is_some_and(|info| info.protocol_version >= ProtocolVersion::V_2026_07_28);
        if strict && !in_request_handler_scope {
            return Err(ServiceError::McpError(ErrorData::invalid_request(
                "SEP-2260: server-to-client requests must be associated with an originating client request",
                None,
            )));
        }
        Ok(())
    }
}

/// It represents the error that may occur when serving the server.
///
/// if you want to handle the error, you can use `serve_server_with_ct` or `serve_server` with `Result<RunningService<RoleServer, S>, ServerError>`
#[derive(Error, Debug)]
#[non_exhaustive]
pub enum ServerInitializeError {
    #[error("expect initialized request, but received: {0:?}")]
    ExpectedInitializeRequest(Option<ClientJsonRpcMessage>),

    #[deprecated(
        since = "1.4.0",
        note = "The server no longer gates on the initialized notification. This variant is never constructed and will be removed in a future major release."
    )]
    #[error("expect initialized notification, but received: {0:?}")]
    ExpectedInitializedNotification(Option<ClientJsonRpcMessage>),

    #[error("connection closed: {0}")]
    ConnectionClosed(String),

    #[error("unexpected initialize result: {0:?}")]
    UnexpectedInitializeResponse(ServerResult),

    #[error("initialize failed: {0}")]
    InitializeFailed(ErrorData),

    #[deprecated(
        since = "1.8.0",
        note = "Negotiation now falls back to the server-configured version. This variant is never constructed and will be removed in a future major release."
    )]
    #[error("unsupported protocol version: {0}")]
    UnsupportedProtocolVersion(ProtocolVersion),

    #[error("Send message error {error}, when {context}")]
    TransportError {
        error: DynamicTransportError,
        context: Cow<'static, str>,
    },

    #[error("Cancelled")]
    Cancelled,
}

impl ServerInitializeError {
    pub fn transport<T: Transport<RoleServer> + 'static>(
        error: T::Error,
        context: impl Into<Cow<'static, str>>,
    ) -> Self {
        Self::TransportError {
            error: DynamicTransportError::new::<T, _>(error),
            context: context.into(),
        }
    }
}
pub type ClientSink = Peer<RoleServer>;

/// Failure to send a notification through a [`SubscriptionSink`].
#[derive(Debug, Error)]
#[non_exhaustive]
pub enum SubscriptionSendError {
    #[error("subscription is no longer active")]
    SubscriptionClosed,
    #[error("notification is not allowed on a subscription stream: {0}")]
    UnsupportedNotification(&'static str),
    #[error("notification was not accepted for this subscription: {0}")]
    NotificationNotAccepted(&'static str),
    #[error(transparent)]
    Service(#[from] ServiceError),
}

/// A server-side notification sink scoped to one `subscriptions/listen` request.
///
/// The sink applies the accepted filter and adds the subscription request ID to
/// every notification it sends.
#[derive(Debug, Clone)]
pub struct SubscriptionSink {
    peer: Peer<RoleServer>,
    id: RequestId,
    accepted: Arc<SubscriptionFilter>,
    active: CancellationToken,
}

impl SubscriptionSink {
    fn new(
        peer: Peer<RoleServer>,
        id: RequestId,
        accepted: Arc<SubscriptionFilter>,
        active: CancellationToken,
    ) -> Self {
        Self {
            peer,
            id,
            accepted,
            active,
        }
    }

    /// Return the JSON-RPC ID of the originating listen request.
    pub fn id(&self) -> &RequestId {
        &self.id
    }

    /// Return the filter accepted for this subscription.
    pub fn accepted(&self) -> &SubscriptionFilter {
        self.accepted.as_ref()
    }

    /// Send an allowed change notification with subscription metadata attached.
    ///
    /// # Errors
    ///
    /// Returns [`SubscriptionSendError::SubscriptionClosed`] after the request
    /// ends, a filter error for disallowed notifications, or a transport error.
    pub async fn send(
        &self,
        mut notification: ServerNotification,
    ) -> Result<(), SubscriptionSendError> {
        if self.active.is_cancelled() {
            return Err(SubscriptionSendError::SubscriptionClosed);
        }
        match &notification {
            ServerNotification::ToolListChangedNotification(_) => {
                if self.accepted.tools_list_changed != Some(true) {
                    return Err(SubscriptionSendError::NotificationNotAccepted(
                        "notifications/tools/list_changed",
                    ));
                }
            }
            ServerNotification::PromptListChangedNotification(_) => {
                if self.accepted.prompts_list_changed != Some(true) {
                    return Err(SubscriptionSendError::NotificationNotAccepted(
                        "notifications/prompts/list_changed",
                    ));
                }
            }
            ServerNotification::ResourceListChangedNotification(_) => {
                if self.accepted.resources_list_changed != Some(true) {
                    return Err(SubscriptionSendError::NotificationNotAccepted(
                        "notifications/resources/list_changed",
                    ));
                }
            }
            ServerNotification::ResourceUpdatedNotification(update) => {
                let accepted = self
                    .accepted
                    .resource_subscriptions
                    .as_ref()
                    .is_some_and(|uris| uris.contains(&update.params.uri));
                if !accepted {
                    return Err(SubscriptionSendError::NotificationNotAccepted(
                        "notifications/resources/updated",
                    ));
                }
            }
            ServerNotification::SubscriptionsAcknowledgedNotification(_) => {
                return Err(SubscriptionSendError::UnsupportedNotification(
                    "notifications/subscriptions/acknowledged",
                ));
            }
            ServerNotification::CancelledNotification(_) => {
                return Err(SubscriptionSendError::UnsupportedNotification(
                    "notifications/cancelled",
                ));
            }
            ServerNotification::ProgressNotification(_) => {
                return Err(SubscriptionSendError::UnsupportedNotification(
                    "notifications/progress",
                ));
            }
            ServerNotification::LoggingMessageNotification(_) => {
                return Err(SubscriptionSendError::UnsupportedNotification(
                    "notifications/message",
                ));
            }
            // SEP-2663 task status notifications are not yet routable through
            // `subscriptions/listen`: `SubscriptionFilter` has no `taskIds`
            // field yet (the upstream conformance check for this flow is also
            // still skipped, pending the subscriptions/listen rewrite).
            // Clients currently observe task state by polling `tasks/get`.
            ServerNotification::TaskStatusNotification(_) => {
                return Err(SubscriptionSendError::UnsupportedNotification(
                    "notifications/tasks",
                ));
            }
            ServerNotification::CustomNotification(_) => {
                return Err(SubscriptionSendError::UnsupportedNotification(
                    "custom notification",
                ));
            }
        }

        notification
            .get_meta_mut()
            .set_subscription_id(self.id.clone());
        self.peer.send_notification(notification).await?;
        Ok(())
    }

    /// Send `notifications/tools/list_changed`.
    ///
    /// # Errors
    ///
    /// See [`Self::send`].
    pub async fn notify_tool_list_changed(&self) -> Result<(), SubscriptionSendError> {
        self.send(ServerNotification::ToolListChangedNotification(
            ToolListChangedNotification {
                method: Default::default(),
                extensions: Default::default(),
            },
        ))
        .await
    }

    /// Send `notifications/prompts/list_changed`.
    ///
    /// # Errors
    ///
    /// See [`Self::send`].
    pub async fn notify_prompt_list_changed(&self) -> Result<(), SubscriptionSendError> {
        self.send(ServerNotification::PromptListChangedNotification(
            PromptListChangedNotification {
                method: Default::default(),
                extensions: Default::default(),
            },
        ))
        .await
    }

    /// Send `notifications/resources/list_changed`.
    ///
    /// # Errors
    ///
    /// See [`Self::send`].
    pub async fn notify_resource_list_changed(&self) -> Result<(), SubscriptionSendError> {
        self.send(ServerNotification::ResourceListChangedNotification(
            ResourceListChangedNotification {
                method: Default::default(),
                extensions: Default::default(),
            },
        ))
        .await
    }

    /// Send `notifications/resources/updated` for an accepted URI.
    ///
    /// # Errors
    ///
    /// See [`Self::send`].
    pub async fn notify_resource_updated(
        &self,
        uri: impl Into<String>,
    ) -> Result<(), SubscriptionSendError> {
        self.send(ServerNotification::ResourceUpdatedNotification(
            ResourceUpdatedNotification::new(ResourceUpdatedNotificationParam::new(uri)),
        ))
        .await
    }
}

/// Context for one established server-side notification subscription.
///
/// The acknowledgment has already been sent before this context is handed to
/// [`ServerHandler::listen`](crate::ServerHandler::listen).
#[derive(Debug)]
pub struct SubscriptionContext {
    request: RequestContext<RoleServer>,
    requested: SubscriptionFilter,
    accepted: Arc<SubscriptionFilter>,
    sink: SubscriptionSink,
    _active_guard: DropGuard,
}

impl SubscriptionContext {
    pub(crate) async fn establish(
        request: RequestContext<RoleServer>,
        requested: SubscriptionFilter,
        accepted: SubscriptionFilter,
    ) -> Result<Self, ErrorData> {
        let active = request.ct.child_token();
        let accepted = Arc::new(accepted);
        let sink = SubscriptionSink::new(
            request.peer.clone(),
            request.id.clone(),
            accepted.clone(),
            active.clone(),
        );
        let mut acknowledgment = SubscriptionsAcknowledgedNotification::new(
            SubscriptionsAcknowledgedNotificationParams::new(accepted.as_ref().clone()),
        );
        let mut meta = NotificationMetaObject::new();
        meta.set_subscription_id(request.id.clone());
        acknowledgment.extensions.insert(meta);
        request
            .peer
            .send_notification(ServerNotification::SubscriptionsAcknowledgedNotification(
                acknowledgment,
            ))
            .await
            .map_err(|error| {
                ErrorData::internal_error(
                    format!("failed to acknowledge subscription: {error}"),
                    None,
                )
            })?;
        Ok(Self {
            request,
            requested,
            accepted,
            sink,
            _active_guard: active.drop_guard(),
        })
    }

    /// Return the filter requested by the client.
    pub fn requested(&self) -> &SubscriptionFilter {
        &self.requested
    }

    /// Return the subset accepted by the server.
    pub fn accepted(&self) -> &SubscriptionFilter {
        self.accepted.as_ref()
    }

    /// Return a cloneable, filter-enforcing notification sink.
    pub fn sink(&self) -> &SubscriptionSink {
        &self.sink
    }

    /// Wait until the subscription request is cancelled.
    pub async fn cancelled(&self) {
        self.request.ct.cancelled().await;
    }

    /// Access the underlying request context.
    pub fn request_context(&self) -> &RequestContext<RoleServer> {
        &self.request
    }
}

impl<S: Service<RoleServer>> ServiceExt<RoleServer> for S {
    fn serve_with_ct<T, E, A>(
        self,
        transport: T,
        ct: CancellationToken,
    ) -> impl Future<Output = Result<RunningService<RoleServer, Self>, ServerInitializeError>>
    + MaybeSendFuture
    where
        T: IntoTransport<RoleServer, E, A>,
        E: std::error::Error + Send + Sync + 'static,
        Self: Sized,
    {
        serve_server_with_ct(self, transport, ct)
    }
}

pub async fn serve_server<S, T, E, A>(
    service: S,
    transport: T,
) -> Result<RunningService<RoleServer, S>, ServerInitializeError>
where
    S: Service<RoleServer>,
    T: IntoTransport<RoleServer, E, A>,
    E: std::error::Error + Send + Sync + 'static,
{
    serve_server_with_ct(service, transport, CancellationToken::new()).await
}

/// Helper function to get the next message from the stream
async fn expect_next_message<T>(
    transport: &mut T,
    context: &str,
) -> Result<ClientJsonRpcMessage, ServerInitializeError>
where
    T: Transport<RoleServer>,
{
    transport
        .receive()
        .await
        .ok_or_else(|| ServerInitializeError::ConnectionClosed(context.to_string()))
}

pub async fn serve_server_with_ct<S, T, E, A>(
    service: S,
    transport: T,
    ct: CancellationToken,
) -> Result<RunningService<RoleServer, S>, ServerInitializeError>
where
    S: Service<RoleServer>,
    T: IntoTransport<RoleServer, E, A>,
    E: std::error::Error + Send + Sync + 'static,
{
    tokio::select! {
        result = serve_server_with_ct_inner(service, transport.into_transport(), ct.clone()) => { result }
        _ = ct.cancelled() => {
            Err(ServerInitializeError::Cancelled)
        }
    }
}

/// Echoes the client-requested version if known; otherwise returns `server_fallback`.
pub(crate) fn negotiate_protocol_version(
    client_requested: &ProtocolVersion,
    server_fallback: ProtocolVersion,
) -> ProtocolVersion {
    if ProtocolVersion::KNOWN_VERSIONS.contains(client_requested) {
        client_requested.clone()
    } else {
        tracing::warn!(
            client_requested = %client_requested,
            server_fallback = %server_fallback,
            "client requested unsupported protocol version; falling back to server default"
        );
        server_fallback
    }
}

async fn serve_server_with_ct_inner<S, T>(
    service: S,
    transport: T,
    ct: CancellationToken,
) -> Result<RunningService<RoleServer, S>, ServerInitializeError>
where
    S: Service<RoleServer>,
    T: Transport<RoleServer> + 'static,
{
    let mut transport = transport.into_transport();
    let id_provider = <Arc<AtomicU32RequestIdProvider>>::default();

    // Get initialize request; the MCP spec permits ping before initialize.
    // See: https://modelcontextprotocol.io/specification/2025-11-25/basic/lifecycle#initialization
    let (request, id) = loop {
        let msg = expect_next_message(&mut transport, "initialize request").await?;
        match msg {
            ClientJsonRpcMessage::Request(req)
                if matches!(req.request, ClientRequest::PingRequest(_)) =>
            {
                transport
                    .send(ServerJsonRpcMessage::response(
                        ServerResult::EmptyResult(EmptyResult {}),
                        req.id,
                    ))
                    .await
                    .map_err(|error| {
                        ServerInitializeError::transport::<T>(
                            error,
                            "sending pre-init ping response",
                        )
                    })?;
            }
            ClientJsonRpcMessage::Request(req) => break (req.request, req.id),
            other => {
                return Err(ServerInitializeError::ExpectedInitializeRequest(Some(
                    other,
                )));
            }
        }
    };

    let initialize_request = match request {
        ClientRequest::InitializeRequest(request) => request,
        mut request => {
            if !request
                .get_meta()
                .missing_required_keys(&ProtocolVersion::V_2026_07_28)
                .is_empty()
            {
                return Err(ServerInitializeError::ExpectedInitializeRequest(Some(
                    ClientJsonRpcMessage::request(request, id),
                )));
            }
            let (peer, peer_rx) = Peer::new(id_provider, None);
            peer.require_request_metadata();
            let context = RequestContext {
                ct: ct.child_token(),
                id: id.clone(),
                meta: std::mem::take(request.get_meta_mut()),
                extensions: std::mem::take(request.extensions_mut()),
                peer: peer.clone(),
            };
            let response = match service.handle_request(request, context).await {
                Ok(result) => ServerJsonRpcMessage::response(result, id),
                Err(error) => ServerJsonRpcMessage::error(error, Some(id)),
            };
            transport.send(response).await.map_err(|error| {
                ServerInitializeError::transport::<T>(error, "sending negotiated request response")
            })?;
            return Ok(serve_inner(service, transport, peer, peer_rx, ct));
        }
    };
    let requested_protocol_version = initialize_request.params.protocol_version.clone();
    let mut negotiated_peer_info = initialize_request.params.clone();
    let (peer, peer_rx) = Peer::new(id_provider, Some(negotiated_peer_info.clone()));
    let request = ClientRequest::InitializeRequest(initialize_request);
    let context = RequestContext {
        ct: ct.child_token(),
        id: id.clone(),
        meta: request.get_meta().clone(),
        extensions: request.extensions().clone(),
        peer: peer.clone(),
    };
    // Send initialize response
    let init_response = service.handle_request(request, context).await;
    let mut init_response = match init_response {
        Ok(ServerResult::InitializeResult(init_response)) => init_response,
        Ok(result) => {
            return Err(ServerInitializeError::UnexpectedInitializeResponse(result));
        }
        Err(e) => {
            transport
                .send(ServerJsonRpcMessage::error(e.clone(), Some(id)))
                .await
                .map_err(|error| {
                    ServerInitializeError::transport::<T>(error, "sending error response")
                })?;
            return Err(ServerInitializeError::InitializeFailed(e));
        }
    };
    init_response.protocol_version =
        negotiate_protocol_version(&requested_protocol_version, init_response.protocol_version);
    // Update peer_info so context.protocol_version() reflects the negotiated
    // version in all subsequent request handlers.
    negotiated_peer_info.protocol_version = init_response.protocol_version.clone();
    peer.set_peer_info(negotiated_peer_info);
    transport
        .send(ServerJsonRpcMessage::response(
            ServerResult::InitializeResult(init_response),
            id,
        ))
        .await
        .map_err(|error| {
            ServerInitializeError::transport::<T>(error, "sending initialize response")
        })?;

    // Enter the main service loop immediately after sending InitializeResult.
    // The initialized notification will be handled as a regular notification by serve_inner.
    // This matches the TypeScript SDK behavior: no init gate, no waiting for initialized.
    // Streamable HTTP has no ordering guarantee between POSTs, and the MCP spec uses
    // SHOULD NOT (not MUST NOT) for pre-initialized messages, so any request arriving
    // before initialized is processed normally.
    Ok(serve_inner(service, transport, peer, peer_rx, ct))
}

macro_rules! method {
    ($(#[$meta:meta])* peer_req $method:ident $Req:ident() => $Resp: ident ) => {
        $(#[$meta])*
        pub async fn $method(&self) -> Result<$Resp, ServiceError> {
            let result = self
                .send_request(ServerRequest::$Req($Req {
                    method: Default::default(),
                    extensions: Default::default(),
                }))
                .await?;
            match result {
                ClientResult::$Resp(result) => Ok(result),
                _ => Err(ServiceError::UnexpectedResponse),
            }
        }
    };
    ($(#[$meta:meta])* peer_req $method:ident $Req:ident($Param: ident) => $Resp: ident ) => {
        $(#[$meta])*
        pub async fn $method(&self, params: $Param) -> Result<$Resp, ServiceError> {
            let result = self
                .send_request(ServerRequest::$Req($Req {
                    method: Default::default(),
                    params,
                    extensions: Default::default(),
                }))
                .await?;
            match result {
                ClientResult::$Resp(result) => Ok(result),
                _ => Err(ServiceError::UnexpectedResponse),
            }
        }
    };
    ($(#[$meta:meta])* peer_req $method:ident $Req:ident($Param: ident)) => {
        $(#[$meta])*
        pub fn $method(
            &self,
            params: $Param,
        ) -> impl Future<Output = Result<(), ServiceError>> + Send + '_ {
            async move {
                let result = self
                    .send_request(ServerRequest::$Req($Req {
                        method: Default::default(),
                        params,
                    }))
                    .await?;
                match result {
                    ClientResult::EmptyResult(_) => Ok(()),
                    _ => Err(ServiceError::UnexpectedResponse),
                }
            }
        }
    };

    ($(#[$meta:meta])* peer_not $method:ident $Not:ident($Param: ident)) => {
        $(#[$meta])*
        pub async fn $method(&self, params: $Param) -> Result<(), ServiceError> {
            self.send_notification(ServerNotification::$Not($Not {
                method: Default::default(),
                params,
                extensions: Default::default(),
            }))
            .await?;
            Ok(())
        }
    };
    ($(#[$meta:meta])* peer_not $method:ident $Not:ident) => {
        $(#[$meta])*
        pub async fn $method(&self) -> Result<(), ServiceError> {
            self.send_notification(ServerNotification::$Not($Not {
                method: Default::default(),
                extensions: Default::default(),
            }))
            .await?;
            Ok(())
        }
    };

    // Timeout-only variants (base method should be created separately with peer_req)
    ($(#[$meta:meta])* peer_req_with_timeout $method_with_timeout:ident $Req:ident() => $Resp: ident) => {
        $(#[$meta])*
        pub async fn $method_with_timeout(
            &self,
            timeout: Option<std::time::Duration>,
        ) -> Result<$Resp, ServiceError> {
            let request = ServerRequest::$Req($Req {
                method: Default::default(),
                extensions: Default::default(),
            });
            let options = crate::service::PeerRequestOptions {
                timeout,
                meta: None,
                reset_timeout_on_progress: false,
                max_total_timeout: None,
            };
            let result = self
                .send_request_with_option(request, options)
                .await?
                .await_response()
                .await?;
            match result {
                ClientResult::$Resp(result) => Ok(result),
                _ => Err(ServiceError::UnexpectedResponse),
            }
        }
    };

    ($(#[$meta:meta])* peer_req_with_timeout $method_with_timeout:ident $Req:ident($Param: ident) => $Resp: ident) => {
        $(#[$meta])*
        pub async fn $method_with_timeout(
            &self,
            params: $Param,
            timeout: Option<std::time::Duration>,
        ) -> Result<$Resp, ServiceError> {
            let request = ServerRequest::$Req($Req {
                method: Default::default(),
                params,
                extensions: Default::default(),
            });
            let options = crate::service::PeerRequestOptions {
                timeout,
                meta: None,
                reset_timeout_on_progress: false,
                max_total_timeout: None,
            };
            let result = self
                .send_request_with_option(request, options)
                .await?
                .await_response()
                .await?;
            match result {
                ClientResult::$Resp(result) => Ok(result),
                _ => Err(ServiceError::UnexpectedResponse),
            }
        }
    };
}

impl Peer<RoleServer> {
    /// Check if the client supports sampling tools capability.
    pub fn supports_sampling_tools(&self) -> bool {
        if let Some(client_info) = self.peer_info() {
            client_info
                .capabilities
                .sampling
                .as_ref()
                .and_then(|s| s.tools.as_ref())
                .is_some()
        } else {
            false
        }
    }

    /// # SEP-2260: request association
    ///
    /// From protocol version `2026-07-28` this must be issued while handling a
    /// client request; see [`OriginatingRequestId`].
    #[deprecated(
        since = "1.8.0",
        note = "Sampling is deprecated by SEP-2577 and will be removed in a future release. See https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577"
    )]
    pub async fn create_message(
        &self,
        params: CreateMessageRequestParams,
    ) -> Result<CreateMessageResult, ServiceError> {
        // MUST throw error when tools/toolChoice provided without capability
        if (params.tools.is_some() || params.tool_choice.is_some())
            && !self.supports_sampling_tools()
        {
            return Err(ServiceError::McpError(ErrorData::invalid_params(
                "tools or toolChoice provided but client does not support sampling tools capability",
                None,
            )));
        }
        // Validate message structure
        params
            .validate()
            .map_err(|e| ServiceError::McpError(ErrorData::invalid_params(e, None)))?;
        let result = self
            .send_request(ServerRequest::CreateMessageRequest(CreateMessageRequest {
                method: Default::default(),
                params,
                extensions: Default::default(),
            }))
            .await?;
        match result {
            ClientResult::CreateMessageResult(result) => Ok(*result),
            _ => Err(ServiceError::UnexpectedResponse),
        }
    }
    method!(
        /// # SEP-2260: request association
        ///
        /// From protocol version `2026-07-28` this must be issued while handling a
        /// client request; see [`OriginatingRequestId`].
        #[deprecated(
            since = "1.8.0",
            note = "Roots is deprecated by SEP-2577 and will be removed in a future release. See https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577"
        )]
        peer_req list_roots ListRootsRequest() => ListRootsResult
    );
    #[cfg(feature = "elicitation")]
    method!(
        /// # SEP-2260: request association
        ///
        /// From protocol version `2026-07-28` this must be issued while handling a
        /// client request; see [`OriginatingRequestId`].
        peer_req create_elicitation ElicitRequest(ElicitRequestParams) => ElicitResult
    );
    #[cfg(feature = "elicitation")]
    method!(
        /// # SEP-2260: request association
        ///
        /// From protocol version `2026-07-28` this must be issued while handling a
        /// client request; see [`OriginatingRequestId`].
        peer_req_with_timeout create_elicitation_with_timeout ElicitRequest(ElicitRequestParams) => ElicitResult
    );

    method!(peer_not notify_cancelled CancelledNotification(CancelledNotificationParam));
    method!(peer_not notify_progress ProgressNotification(ProgressNotificationParam));
    method!(
        #[deprecated(
            since = "1.8.0",
            note = "Logging is deprecated by SEP-2577 and will be removed in a future release. See https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577"
        )]
        peer_not notify_logging_message LoggingMessageNotification(LoggingMessageNotificationParam)
    );
    method!(peer_not notify_resource_updated ResourceUpdatedNotification(ResourceUpdatedNotificationParam));
    method!(peer_not notify_resource_list_changed ResourceListChangedNotification);
    method!(peer_not notify_tool_list_changed ToolListChangedNotification);
    method!(peer_not notify_prompt_list_changed PromptListChangedNotification);
}

// =============================================================================
// ELICITATION CONVENIENCE METHODS
// These methods are specific to server role and provide typed elicitation functionality
// =============================================================================

/// Errors that can occur during typed elicitation operations
#[cfg(feature = "elicitation")]
#[derive(Error, Debug)]
#[non_exhaustive]
pub enum ElicitationError {
    /// The elicitation request failed at the service level
    #[error("Service error: {0}")]
    Service(#[from] ServiceError),

    /// User explicitly declined to provide the requested information
    /// This indicates a conscious decision by the user to reject the request
    /// (e.g., clicked "Reject", "Decline", "No", etc.)
    #[error("User explicitly declined the request")]
    UserDeclined,

    /// User dismissed the request without making an explicit choice
    /// This indicates the user cancelled without explicitly declining
    /// (e.g., closed dialog, clicked outside, pressed Escape, etc.)
    #[error("User cancelled/dismissed the request")]
    UserCancelled,

    /// The response data could not be parsed into the requested type
    #[error("Failed to parse response data: {error}\nReceived data: {data}")]
    ParseError {
        error: serde_json::Error,
        data: serde_json::Value,
    },

    /// No response content was provided by the user
    #[error("No response content provided")]
    NoContent,

    /// Client does not support elicitation capability
    #[error("Client does not support elicitation - capability not declared during initialization")]
    CapabilityNotSupported,
}

/// Marker trait to ensure that elicitation types generate object-type JSON schemas.
///
/// This trait provides compile-time safety to ensure that types used with
/// `elicit<T>()` methods will generate JSON schemas of type "object", which
/// aligns with MCP client expectations for structured data input.
///
/// # Type Safety Rationale
///
/// MCP clients typically expect JSON objects for elicitation schemas to
/// provide structured forms and validation. This trait prevents common
/// mistakes like:
///
/// ```compile_fail
/// // These would not compile due to missing ElicitationSafe bound:
/// let name: String = server.elicit("Enter name").await?;        // Primitive
/// let items: Vec<i32> = server.elicit("Enter items").await?;    // Array
/// ```
#[cfg(feature = "elicitation")]
pub trait ElicitationSafe: schemars::JsonSchema {}

/// Macro to mark types as safe for elicitation by verifying they generate object schemas.
///
/// This macro automatically implements the `ElicitationSafe` trait for struct types
/// that should be used with `elicit<T>()` methods.
///
/// # Example
///
/// ```rust
/// use rmcp::elicit_safe;
/// use schemars::JsonSchema;
/// use serde::{Deserialize, Serialize};
///
/// #[derive(Serialize, Deserialize, JsonSchema)]
/// struct UserProfile {
///     name: String,
///     email: String,
/// }
///
/// elicit_safe!(UserProfile);
///
/// // Now safe to use in async context:
/// // let profile: UserProfile = server.elicit("Enter profile").await?;
/// ```
#[cfg(feature = "elicitation")]
#[macro_export]
macro_rules! elicit_safe {
    ($($t:ty),* $(,)?) => {
        $(
            impl $crate::service::ElicitationSafe for $t {}
        )*
    };
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
#[non_exhaustive]
pub enum ElicitationMode {
    Form,
    Url,
}

#[cfg(feature = "elicitation")]
impl Peer<RoleServer> {
    /// Check if the client supports elicitation capability
    ///
    /// Returns true if the client declared elicitation capability during initialization,
    /// false otherwise. According to MCP 2025-06-18 specification, clients that support
    /// elicitation MUST declare the capability during initialization.
    pub fn supported_elicitation_modes(&self) -> HashSet<ElicitationMode> {
        if let Some(client_info) = self.peer_info() {
            if let Some(elicit_capability) = &client_info.capabilities.elicitation {
                let mut modes = HashSet::new();
                // Backward compatibility: if neither form nor url is specified, assume form
                if elicit_capability.form.is_none() && elicit_capability.url.is_none() {
                    modes.insert(ElicitationMode::Form);
                } else {
                    if elicit_capability.form.is_some() {
                        modes.insert(ElicitationMode::Form);
                    }
                    if elicit_capability.url.is_some() {
                        modes.insert(ElicitationMode::Url);
                    }
                }
                modes
            } else {
                HashSet::new()
            }
        } else {
            HashSet::new()
        }
    }

    /// Request typed data from the user with automatic schema generation.
    ///
    /// This method automatically generates the JSON schema from the Rust type using `schemars`,
    /// eliminating the need to manually create schemas. The response is automatically parsed
    /// into the requested type.
    ///
    /// **Requires the `elicitation` feature to be enabled.**
    ///
    /// # Type Requirements
    /// The type `T` must implement:
    /// - `schemars::JsonSchema` - for automatic schema generation
    /// - `serde::Deserialize` - for parsing the response
    ///
    /// # Arguments
    /// * `message` - The prompt message for the user
    ///
    /// # Returns
    /// * `Ok(Some(data))` if user provided valid data that matches type T
    /// * `Err(ElicitationError::UserDeclined)` if user explicitly declined the request
    /// * `Err(ElicitationError::UserCancelled)` if user cancelled/dismissed the request
    /// * `Err(ElicitationError::ParseError { .. })` if response data couldn't be parsed into type T
    /// * `Err(ElicitationError::NoContent)` if no response content was provided
    /// * `Err(ElicitationError::Service(_))` if the underlying service call failed
    ///
    /// # Example
    ///
    /// Add to your `Cargo.toml`:
    /// ```toml
    /// [dependencies]
    /// rmcp = { version = "0.3", features = ["elicitation"] }
    /// serde = { version = "1.0", features = ["derive"] }
    /// schemars = "1.0"
    /// ```
    ///
    /// ```rust,no_run
    /// # use rmcp::*;
    /// # use rmcp::service::ElicitationError;
    /// # use serde::{Deserialize, Serialize};
    /// # use schemars::JsonSchema;
    /// #
    /// #[derive(Debug, Serialize, Deserialize, JsonSchema)]
    /// struct UserProfile {
    ///     #[schemars(description = "Full name")]
    ///     name: String,
    ///     #[schemars(description = "Email address")]
    ///     email: String,
    ///     #[schemars(description = "Age")]
    ///     age: u8,
    /// }
    ///
    /// // Mark as safe for elicitation (generates object schema)
    /// rmcp::elicit_safe!(UserProfile);
    ///
    /// # async fn example(peer: Peer<RoleServer>) -> Result<(), Box<dyn std::error::Error>> {
    /// match peer.elicit::<UserProfile>("Please enter your profile information").await {
    ///     Ok(Some(profile)) => {
    ///         println!("Name: {}, Email: {}, Age: {}", profile.name, profile.email, profile.age);
    ///     }
    ///     Ok(None) => {
    ///         println!("User provided no content");
    ///     }
    ///     Err(ElicitationError::UserDeclined) => {
    ///         println!("User explicitly declined to provide information");
    ///         // Handle explicit decline - perhaps offer alternatives
    ///     }
    ///     Err(ElicitationError::UserCancelled) => {
    ///         println!("User cancelled the request");
    ///         // Handle cancellation - perhaps prompt again later
    ///     }
    ///     Err(ElicitationError::ParseError { error, data }) => {
    ///         println!("Failed to parse response: {}\nData: {}", error, data);
    ///     }
    ///     Err(e) => return Err(e.into()),
    /// }
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// # SEP-2260: request association
    ///
    /// From protocol version `2026-07-28` this must be issued while handling a
    /// client request; see [`OriginatingRequestId`].
    #[cfg(all(feature = "schemars", feature = "elicitation"))]
    pub async fn elicit<T>(&self, message: impl Into<String>) -> Result<Option<T>, ElicitationError>
    where
        T: ElicitationSafe + for<'de> serde::Deserialize<'de>,
    {
        self.elicit_with_timeout(message, None).await
    }

    /// Request typed data from the user with custom timeout.
    ///
    /// Same as `elicit()` but allows specifying a custom timeout for the request.
    /// If the user doesn't respond within the timeout, the request will be cancelled.
    ///
    /// # Arguments
    /// * `message` - The prompt message for the user
    /// * `timeout` - Optional timeout duration. If None, uses default timeout behavior
    ///
    /// # Returns
    /// Same as `elicit()` but may also return `ServiceError::Timeout` if timeout expires
    ///
    /// # Example
    /// ```rust,no_run
    /// # use rmcp::*;
    /// # use rmcp::service::ElicitationError;
    /// # use serde::{Deserialize, Serialize};
    /// # use schemars::JsonSchema;
    /// # use std::time::Duration;
    /// #
    /// #[derive(Debug, Serialize, Deserialize, JsonSchema)]
    /// struct QuickResponse {
    ///     answer: String,
    /// }
    ///
    /// // Mark as safe for elicitation
    /// rmcp::elicit_safe!(QuickResponse);
    ///
    /// # async fn example(peer: Peer<RoleServer>) -> Result<(), Box<dyn std::error::Error>> {
    /// // Give user 30 seconds to respond
    /// let timeout = Some(Duration::from_secs(30));
    /// match peer.elicit_with_timeout::<QuickResponse>(
    ///     "Quick question - what's your answer?",
    ///     timeout
    /// ).await {
    ///     Ok(Some(response)) => println!("Got answer: {}", response.answer),
    ///     Ok(None) => println!("User provided no content"),
    ///     Err(ElicitationError::UserDeclined) => {
    ///         println!("User explicitly declined");
    ///         // Handle explicit decline
    ///     }
    ///     Err(ElicitationError::UserCancelled) => {
    ///         println!("User cancelled/dismissed");
    ///         // Handle cancellation
    ///     }
    ///     Err(ElicitationError::Service(ServiceError::Timeout { .. })) => {
    ///         println!("User didn't respond in time");
    ///     }
    ///     Err(e) => return Err(e.into()),
    /// }
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// # SEP-2260: request association
    ///
    /// From protocol version `2026-07-28` this must be issued while handling a
    /// client request; see [`OriginatingRequestId`].
    #[cfg(all(feature = "schemars", feature = "elicitation"))]
    pub async fn elicit_with_timeout<T>(
        &self,
        message: impl Into<String>,
        timeout: Option<std::time::Duration>,
    ) -> Result<Option<T>, ElicitationError>
    where
        T: ElicitationSafe + for<'de> serde::Deserialize<'de>,
    {
        // Check if client supports form elicitation capability
        if !self
            .supported_elicitation_modes()
            .contains(&ElicitationMode::Form)
        {
            return Err(ElicitationError::CapabilityNotSupported);
        }

        // Generate schema automatically from type
        let schema = crate::model::ElicitationSchema::from_type::<T>().map_err(|e| {
            ElicitationError::Service(ServiceError::McpError(crate::ErrorData::invalid_params(
                format!(
                    "Invalid schema for type {}: {}",
                    std::any::type_name::<T>(),
                    e
                ),
                None,
            )))
        })?;

        let response = self
            .create_elicitation_with_timeout(
                ElicitRequestParams::FormElicitationParams {
                    meta: None,
                    message: message.into(),
                    requested_schema: schema,
                },
                timeout,
            )
            .await?;

        match response.action {
            crate::model::ElicitationAction::Accept => {
                if let Some(value) = response.content {
                    match serde_json::from_value::<T>(value.clone()) {
                        Ok(parsed) => Ok(Some(parsed)),
                        Err(error) => Err(ElicitationError::ParseError { error, data: value }),
                    }
                } else {
                    Err(ElicitationError::NoContent)
                }
            }
            crate::model::ElicitationAction::Decline => Err(ElicitationError::UserDeclined),
            crate::model::ElicitationAction::Cancel => Err(ElicitationError::UserCancelled),
        }
    }

    /// Request the user to visit a URL and confirm completion.
    ///
    /// This method sends a URL elicitation request to the client, prompting the user
    /// to visit the specified URL and confirm completion. It returns the user's action
    /// (accept/decline/cancel) without any additional data.
    /// **Requires the `elicitation` feature to be enabled.**
    ///
    /// # Arguments
    /// * `message` - The prompt message for the user
    /// * `url` - The URL the user is requested to visit
    /// * `elicitation_id` - A unique identifier for this elicitation request
    /// # Returns
    /// * `Ok(action)` indicating the user's response action
    /// * `Err(ElicitationError::CapabilityNotSupported)` if client does not support elicitation via URL
    /// * `Err(ElicitationError::Service(_))` if the underlying service call failed
    /// # Example
    /// ```rust,no_run
    /// # use rmcp::*;
    /// # use rmcp::model::ElicitationAction;
    /// # use url::Url;
    ///
    /// async fn example(peer: Peer<RoleServer>) -> Result<(), Box<dyn std::error::Error>> {
    /// let elicit_result = peer.elicit_url("Please visit the following URL to complete the action",
    ///      Url::parse("https://example.com/complete_action")?, "elicit_123").await?;
    ///  match elicit_result {
    ///        ElicitationAction::Accept => {
    ///        println!("User accepted and confirmed completion");
    ///     }
    ///     ElicitationAction::Decline => {
    ///          println!("User declined the request");
    ///     }
    ///     ElicitationAction::Cancel => {
    ///         println!("User cancelled/dismissed the request");
    ///     }
    ///     _ => {}
    ///  }
    ///  Ok(())
    /// }
    /// ```
    ///
    /// # SEP-2260: request association
    ///
    /// From protocol version `2026-07-28` this must be issued while handling a
    /// client request; see [`OriginatingRequestId`].
    #[cfg(feature = "elicitation")]
    pub async fn elicit_url(
        &self,
        message: impl Into<String>,
        url: impl Into<Url>,
        elicitation_id: impl Into<String>,
    ) -> Result<ElicitationAction, ElicitationError> {
        self.elicit_url_with_timeout(message, url, elicitation_id, None)
            .await
    }

    /// Request the user to visit a URL and confirm completion.
    ///
    /// Same as `elicit_url()` but allows specifying a custom timeout for the request.
    ///
    /// # Arguments
    /// * `message` - The prompt message for the user
    /// * `url` - The URL the user is requested to visit
    /// * `elicitation_id` - A unique identifier for this elicitation request
    /// * `timeout` - Optional timeout duration. If None, uses default timeout behavior
    /// # Returns
    /// * `Ok(action)` indicating the user's response action
    /// * `Err(ElicitationError::CapabilityNotSupported)` if client does not support elicitation via URL
    /// * `Err(ElicitationError::Service(_))` if the underlying service call failed
    /// # Example
    /// ```rust,no_run
    /// # use std::time::Duration;
    /// use rmcp::*;
    /// # use rmcp::model::ElicitationAction;
    /// # use url::Url;
    ///
    /// async fn example(peer: Peer<RoleServer>) -> Result<(), Box<dyn std::error::Error>> {
    /// let elicit_result = peer.elicit_url_with_timeout("Please visit the following URL to complete the action",
    ///      Url::parse("https://example.com/complete_action")?,
    ///     "elicit_123",
    ///     Some(Duration::from_secs(30))).await?;
    ///  match elicit_result {
    ///        ElicitationAction::Accept => {
    ///        println!("User accepted and confirmed completion");
    ///     }
    ///     ElicitationAction::Decline => {
    ///          println!("User declined the request");
    ///     }
    ///     ElicitationAction::Cancel => {
    ///         println!("User cancelled/dismissed the request");
    ///     }
    ///     _ => {}
    ///  }
    ///  Ok(())
    /// }
    /// ```
    ///
    /// # SEP-2260: request association
    ///
    /// From protocol version `2026-07-28` this must be issued while handling a
    /// client request; see [`OriginatingRequestId`].
    #[cfg(feature = "elicitation")]
    pub async fn elicit_url_with_timeout(
        &self,
        message: impl Into<String>,
        url: impl Into<Url>,
        elicitation_id: impl Into<String>,
        timeout: Option<std::time::Duration>,
    ) -> Result<ElicitationAction, ElicitationError> {
        // Check if client supports url elicitation
        if !self
            .supported_elicitation_modes()
            .contains(&ElicitationMode::Url)
        {
            return Err(ElicitationError::CapabilityNotSupported);
        }

        let action = self
            .create_elicitation_with_timeout(
                ElicitRequestParams::UrlElicitationParams {
                    meta: None,
                    message: message.into(),
                    url: url.into().to_string(),
                    elicitation_id: elicitation_id.into(),
                },
                timeout,
            )
            .await?
            .action;
        Ok(action)
    }
}