use std::collections::BTreeMap;
#[cfg(any(feature = "server", feature = "macros"))]
use std::marker::PhantomData;

#[cfg(any(feature = "server", feature = "macros"))]
use pastey::paste;
use serde::{Deserialize, Serialize};

use super::JsonObject;
pub type ExperimentalCapabilities = BTreeMap<String, JsonObject>;

/// MCP extension capabilities map.
///
/// Keys are extension identifiers in the format `{vendor-prefix}/{extension-name}`
/// (e.g., `io.modelcontextprotocol/ui`, `io.modelcontextprotocol/oauth-client-credentials`).
/// Values are per-extension settings objects. An empty object indicates support with no settings.
///
/// # Example
///
/// ```rust
/// use rmcp::model::ExtensionCapabilities;
/// use serde_json::json;
///
/// let mut extensions = ExtensionCapabilities::new();
/// extensions.insert(
///     "io.modelcontextprotocol/ui".to_string(),
///     serde_json::from_value(json!({
///         "mimeTypes": ["text/html;profile=mcp-app"]
///     })).unwrap()
/// );
/// ```
pub type ExtensionCapabilities = BTreeMap<String, JsonObject>;

#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[serde(rename_all = "camelCase")]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct PromptsCapability {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub list_changed: Option<bool>,
}

#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[serde(rename_all = "camelCase")]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct ResourcesCapability {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub subscribe: Option<bool>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub list_changed: Option<bool>,
}

#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[serde(rename_all = "camelCase")]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct ToolsCapability {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub list_changed: Option<bool>,
}

/// Roots capability. Deprecated by SEP-2577; remains functional and will be
/// removed in a future release.
/// See <https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577>.
#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[serde(rename_all = "camelCase")]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct RootsCapabilities {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub list_changed: Option<bool>,
}

/// Capability for handling elicitation requests from servers.
/// Elicitation allows servers to request interactive input from users during tool execution.
/// This capability indicates that a client can handle elicitation requests and present
/// appropriate UI to users for collecting the requested information.
///
/// Capability for form mode elicitation.
#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[serde(rename_all = "camelCase")]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct FormElicitationCapability {
    /// Whether the client supports JSON Schema validation for elicitation responses.
    /// When true, the client will validate user input against the requested_schema
    /// before sending the response back to the server.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub schema_validation: Option<bool>,
}

impl FormElicitationCapability {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn with_schema_validation(mut self, enabled: bool) -> Self {
        self.schema_validation = Some(enabled);
        self
    }
}

/// Capability for URL mode elicitation.
#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct UrlElicitationCapability {}

impl UrlElicitationCapability {
    pub fn new() -> Self {
        Self::default()
    }
}

/// Elicitation allows servers to request interactive input from users during tool execution.
/// This capability indicates that a client can handle elicitation requests and present
/// appropriate UI to users for collecting the requested information.
#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[serde(rename_all = "camelCase")]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct ElicitationCapability {
    /// Whether client supports form-based elicitation.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub form: Option<FormElicitationCapability>,
    /// Whether client supports URL-based elicitation.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub url: Option<UrlElicitationCapability>,
}

impl ElicitationCapability {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn with_form(mut self, form: FormElicitationCapability) -> Self {
        self.form = Some(form);
        self
    }

    pub fn with_url(mut self, url: UrlElicitationCapability) -> Self {
        self.url = Some(url);
        self
    }
}

/// Sampling capability with optional sub-capabilities (SEP-1577).
///
/// Deprecated by SEP-2577; remains functional and will be removed in a future
/// release.
/// See <https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577>.
#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[serde(rename_all = "camelCase")]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct SamplingCapability {
    /// Support for `tools` and `toolChoice` parameters
    #[serde(skip_serializing_if = "Option::is_none")]
    pub tools: Option<JsonObject>,
    /// Support for `includeContext` (soft-deprecated)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub context: Option<JsonObject>,
}

///
/// # Builder
/// ```rust
/// # use rmcp::model::ClientCapabilities;
/// let cap = ClientCapabilities::builder()
///     .enable_experimental()
///     .build();
/// ```
#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct ClientCapabilities {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub experimental: Option<ExperimentalCapabilities>,
    /// Optional MCP extensions that the client supports (SEP-1724).
    /// Keys are extension identifiers (e.g., `"io.modelcontextprotocol/ui"`),
    /// values are per-extension settings objects. An empty object indicates
    /// support with no settings.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub extensions: Option<ExtensionCapabilities>,
    /// Capability for filesystem roots (deprecated by SEP-2577).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub roots: Option<RootsCapabilities>,
    /// Capability for LLM sampling requests (SEP-1577, deprecated by SEP-2577).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub sampling: Option<SamplingCapability>,
    /// Capability to handle elicitation requests from servers for interactive user input
    #[serde(skip_serializing_if = "Option::is_none")]
    pub elicitation: Option<ElicitationCapability>,
}

impl ClientCapabilities {
    /// Returns `true` if the `io.modelcontextprotocol/tasks` extension
    /// (SEP-2663) is declared in [`Self::extensions`].
    pub fn supports_tasks(&self) -> bool {
        self.extensions
            .as_ref()
            .is_some_and(|e| e.contains_key(super::TASKS_EXTENSION_ID))
    }
}

///
/// ## Builder
/// ```rust
/// # use rmcp::model::ServerCapabilities;
/// let cap = ServerCapabilities::builder()
///     .enable_experimental()
///     .enable_prompts()
///     .enable_resources()
///     .enable_tools()
///     .enable_tool_list_changed()
///     .build();
/// ```
#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
#[serde(rename_all = "camelCase")]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct ServerCapabilities {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub experimental: Option<ExperimentalCapabilities>,
    /// Optional MCP extensions that the server supports (SEP-1724).
    /// Keys are extension identifiers (e.g., `"io.modelcontextprotocol/apps"`),
    /// values are per-extension settings objects. An empty object indicates
    /// support with no settings.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub extensions: Option<ExtensionCapabilities>,
    /// Capability for server log message notifications (deprecated by SEP-2577).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub logging: Option<JsonObject>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub completions: Option<JsonObject>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub prompts: Option<PromptsCapability>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub resources: Option<ResourcesCapability>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub tools: Option<ToolsCapability>,
}

impl ServerCapabilities {
    /// Returns `true` if the `io.modelcontextprotocol/tasks` extension
    /// (SEP-2663) is declared in [`Self::extensions`].
    pub fn supports_tasks(&self) -> bool {
        self.extensions
            .as_ref()
            .is_some_and(|e| e.contains_key(super::TASKS_EXTENSION_ID))
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
macro_rules! builder {
    ($Target: ident {$($(#[$fa:meta])* $f: ident: $T: ty),* $(,)?}) => {
        paste! {
            #[derive(Default, Clone, Copy, Debug)]
            #[expect(clippy::exhaustive_structs, reason = "intentionally exhaustive")]
            pub struct [<$Target BuilderState>]<
                $(const [<$f:upper>]: bool = false,)*
            >;
            #[derive(Debug, Default)]
            #[expect(clippy::exhaustive_structs, reason = "intentionally exhaustive")]
            pub struct [<$Target Builder>]<S = [<$Target BuilderState>]> {
                $(pub $f: Option<$T>,)*
                pub state: PhantomData<S>
            }
            impl $Target {
                #[doc = "Create a new [`" $Target "`] builder."]
                pub fn builder() -> [<$Target Builder>] {
                    <[<$Target Builder>]>::default()
                }
            }
            impl<S> [<$Target Builder>]<S> {
                pub fn build(self) -> $Target {
                    $Target {
                        $( $f: self.$f, )*
                    }
                }
            }
            impl<S> From<[<$Target Builder>]<S>> for $Target {
                fn from(builder: [<$Target Builder>]<S>) -> Self {
                    builder.build()
                }
            }
        }
        builder!($Target @toggle $($(#[$fa])* $f: $T,)*);

    };
    ($Target: ident @toggle $(#[$fa0:meta])* $f0: ident: $T0: ty, $($(#[$fa:meta])* $f: ident: $T: ty,)*) => {
        builder!($Target @toggle [][$(#[$fa0])* $f0: $T0][$($(#[$fa])* $f: $T,)*]);
    };
    ($Target: ident @toggle [$($ff: ident: $Tf: ty,)*][$(#[$fna:meta])* $fn: ident: $TN: ty][$(#[$fn1a:meta])* $fn_1: ident: $Tn_1: ty, $($(#[$fta:meta])* $ft: ident: $Tt: ty,)*]) => {
        builder!($Target @impl_toggle [$($ff: $Tf,)*][$(#[$fna])* $fn: $TN][$fn_1: $Tn_1, $($ft:$Tt,)*]);
        builder!($Target @toggle [$($ff: $Tf,)* $fn: $TN,][$(#[$fn1a])* $fn_1: $Tn_1][$($(#[$fta])* $ft: $Tt,)*]);
    };
    ($Target: ident @toggle [$($ff: ident: $Tf: ty,)*][$(#[$fna:meta])* $fn: ident: $TN: ty][]) => {
        builder!($Target @impl_toggle [$($ff: $Tf,)*][$(#[$fna])* $fn: $TN][]);
    };
    ($Target: ident @impl_toggle [$($ff: ident: $Tf: ty,)*][$(#[$fna:meta])* $fn: ident: $TN: ty][$($ft: ident: $Tt: ty,)*]) => {
        paste! {
            impl<
                $(const [<$ff:upper>]: bool,)*
                $(const [<$ft:upper>]: bool,)*
            > [<$Target Builder>]<[<$Target BuilderState>]<
                $([<$ff:upper>],)*
                false,
                $([<$ft:upper>],)*
            >> {
                $(#[$fna])*
                pub fn [<enable_ $fn>](self) -> [<$Target Builder>]<[<$Target BuilderState>]<
                    $([<$ff:upper>],)*
                    true,
                    $([<$ft:upper>],)*
                >> {
                    [<$Target Builder>] {
                        $( $ff: self.$ff, )*
                        $fn: Some($TN::default()),
                        $( $ft: self.$ft, )*
                        state: PhantomData
                    }
                }
                $(#[$fna])*
                pub fn [<enable_ $fn _with>](self, $fn: $TN) -> [<$Target Builder>]<[<$Target BuilderState>]<
                    $([<$ff:upper>],)*
                    true,
                    $([<$ft:upper>],)*
                >> {
                    [<$Target Builder>] {
                        $( $ff: self.$ff, )*
                        $fn: Some($fn),
                        $( $ft: self.$ft, )*
                        state: PhantomData
                    }
                }
            }
            // do we really need to disable some thing in builder?
            // impl<
            //     $(const [<$ff:upper>]: bool,)*
            //     $(const [<$ft:upper>]: bool,)*
            // > [<$Target Builder>]<[<$Target BuilderState>]<
            //     $([<$ff:upper>],)*
            //     true,
            //     $([<$ft:upper>],)*
            // >> {
            //     pub fn [<disable_ $fn>](self) -> [<$Target Builder>]<[<$Target BuilderState>]<
            //         $([<$ff:upper>],)*
            //         false,
            //         $([<$ft:upper>],)*
            //     >> {
            //         [<$Target Builder>] {
            //             $( $ff: self.$ff, )*
            //             $fn: None,
            //             $( $ft: self.$ft, )*
            //             state: PhantomData
            //         }
            //     }
            // }
        }
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
builder! {
    ServerCapabilities {
        experimental: ExperimentalCapabilities,
        extensions: ExtensionCapabilities,
        #[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"
        )]
        logging: JsonObject,
        completions: JsonObject,
        prompts: PromptsCapability,
        resources: ResourcesCapability,
        tools: ToolsCapability,
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
impl<const E: bool, const EXT: bool, const L: bool, const C: bool, const P: bool, const R: bool>
    ServerCapabilitiesBuilder<ServerCapabilitiesBuilderState<E, EXT, L, C, P, R, true>>
{
    pub fn enable_tool_list_changed(mut self) -> Self {
        if let Some(c) = self.tools.as_mut() {
            c.list_changed = Some(true);
        }
        self
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
impl<const E: bool, const EXT: bool, const L: bool, const C: bool, const R: bool, const T: bool>
    ServerCapabilitiesBuilder<ServerCapabilitiesBuilderState<E, EXT, L, C, true, R, T>>
{
    pub fn enable_prompts_list_changed(mut self) -> Self {
        if let Some(c) = self.prompts.as_mut() {
            c.list_changed = Some(true);
        }
        self
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
impl<const E: bool, const EXT: bool, const L: bool, const C: bool, const P: bool, const T: bool>
    ServerCapabilitiesBuilder<ServerCapabilitiesBuilderState<E, EXT, L, C, P, true, T>>
{
    pub fn enable_resources_list_changed(mut self) -> Self {
        if let Some(c) = self.resources.as_mut() {
            c.list_changed = Some(true);
        }
        self
    }

    pub fn enable_resources_subscribe(mut self) -> Self {
        if let Some(c) = self.resources.as_mut() {
            c.subscribe = Some(true);
        }
        self
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
impl<S> ServerCapabilitiesBuilder<S> {
    /// Declare support for the `io.modelcontextprotocol/tasks` extension
    /// (SEP-2663) in the `extensions` capability map.
    pub fn enable_tasks(mut self) -> Self {
        self.extensions
            .get_or_insert_with(ExtensionCapabilities::new)
            .insert(super::TASKS_EXTENSION_ID.to_string(), JsonObject::new());
        self
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
builder! {
    ClientCapabilities{
        experimental: ExperimentalCapabilities,
        extensions: ExtensionCapabilities,
        #[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"
        )]
        roots: RootsCapabilities,
        #[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"
        )]
        sampling: SamplingCapability,
        elicitation: ElicitationCapability,
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
impl<S> ClientCapabilitiesBuilder<S> {
    /// Declare support for the `io.modelcontextprotocol/tasks` extension
    /// (SEP-2663) in the `extensions` capability map.
    pub fn enable_tasks(mut self) -> Self {
        self.extensions
            .get_or_insert_with(ExtensionCapabilities::new)
            .insert(super::TASKS_EXTENSION_ID.to_string(), JsonObject::new());
        self
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
impl<const E: bool, const EXT: bool, const S: bool, const EL: bool>
    ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, EXT, true, S, EL>>
{
    #[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"
    )]
    pub fn enable_roots_list_changed(mut self) -> Self {
        if let Some(c) = self.roots.as_mut() {
            c.list_changed = Some(true);
        }
        self
    }
}

#[cfg(any(feature = "server", feature = "macros"))]
impl<const E: bool, const EXT: bool, const R: bool, const EL: bool>
    ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, EXT, R, true, EL>>
{
    /// Enable tool calling in sampling requests
    #[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 fn enable_sampling_tools(mut self) -> Self {
        if let Some(c) = self.sampling.as_mut() {
            c.tools = Some(JsonObject::default());
        }
        self
    }

    /// Enable context inclusion in sampling (soft-deprecated)
    #[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 fn enable_sampling_context(mut self) -> Self {
        if let Some(c) = self.sampling.as_mut() {
            c.context = Some(JsonObject::default());
        }
        self
    }
}

#[cfg(all(feature = "elicitation", any(feature = "server", feature = "macros")))]
impl<const E: bool, const EXT: bool, const R: bool, const S: bool>
    ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, EXT, R, S, true>>
{
    /// Enable JSON Schema validation for elicitation responses in form mode.
    /// When enabled, the client will validate user input against the requested_schema
    /// before sending responses back to the server.
    pub fn enable_elicitation_schema_validation(mut self) -> Self {
        if let Some(c) = self.elicitation.as_mut() {
            c.form = Some(FormElicitationCapability {
                schema_validation: Some(true),
            });
        }
        self
    }
}

#[cfg(test)]
#[cfg(any(feature = "server", feature = "macros"))]
mod test {
    use super::*;
    #[test]
    #[allow(deprecated)]
    fn test_builder() {
        let builder = <ServerCapabilitiesBuilder>::default()
            .enable_logging()
            .enable_experimental()
            .enable_prompts()
            .enable_resources()
            .enable_tools()
            .enable_tool_list_changed();
        assert_eq!(builder.logging, Some(JsonObject::default()));
        assert_eq!(builder.prompts, Some(PromptsCapability::default()));
        assert_eq!(builder.resources, Some(ResourcesCapability::default()));
        assert_eq!(
            builder.tools,
            Some(ToolsCapability {
                list_changed: Some(true),
            })
        );
        assert_eq!(
            builder.experimental,
            Some(ExperimentalCapabilities::default())
        );
        let client_builder = <ClientCapabilitiesBuilder>::default()
            .enable_experimental()
            .enable_roots()
            .enable_roots_list_changed()
            .enable_sampling();
        assert_eq!(
            client_builder.experimental,
            Some(ExperimentalCapabilities::default())
        );
        assert_eq!(
            client_builder.roots,
            Some(RootsCapabilities {
                list_changed: Some(true),
            })
        );
    }

    #[test]
    fn test_tasks_extension_capability() {
        // SEP-2663: tasks are declared via the extensions map.
        let capabilities = ClientCapabilities::builder().enable_tasks().build();
        assert!(capabilities.supports_tasks());
        let json = serde_json::to_value(&capabilities).unwrap();
        assert_eq!(
            json["extensions"][crate::model::TASKS_EXTENSION_ID],
            serde_json::json!({})
        );

        let server = ServerCapabilities::builder().enable_tasks().build();
        assert!(server.supports_tasks());
        let json = serde_json::to_value(&server).unwrap();
        assert_eq!(
            json["extensions"][crate::model::TASKS_EXTENSION_ID],
            serde_json::json!({})
        );
    }

    #[test]
    #[allow(deprecated)]
    fn test_client_extensions_capability() {
        // Test building ClientCapabilities with extensions (MCP Apps support)
        let mut extensions = ExtensionCapabilities::new();
        extensions.insert(
            "io.modelcontextprotocol/ui".to_string(),
            serde_json::from_value(serde_json::json!({
                "mimeTypes": ["text/html;profile=mcp-app"]
            }))
            .unwrap(),
        );

        let capabilities = ClientCapabilities::builder()
            .enable_extensions_with(extensions)
            .enable_sampling()
            .build();

        // Verify serialization matches MCP Apps spec format
        let json = serde_json::to_value(&capabilities).unwrap();
        assert_eq!(
            json["extensions"]["io.modelcontextprotocol/ui"]["mimeTypes"],
            serde_json::json!(["text/html;profile=mcp-app"])
        );
        assert!(json["sampling"].is_object());
    }

    #[test]
    fn test_server_extensions_capability() {
        // Test building ServerCapabilities with extensions
        let mut extensions = ExtensionCapabilities::new();
        extensions.insert(
            "io.modelcontextprotocol/apps".to_string(),
            serde_json::from_value(serde_json::json!({})).unwrap(),
        );

        let capabilities = ServerCapabilities::builder()
            .enable_extensions_with(extensions)
            .enable_tools()
            .build();

        // Verify serialization
        let json = serde_json::to_value(&capabilities).unwrap();
        assert!(json["extensions"]["io.modelcontextprotocol/apps"].is_object());
        assert!(json["tools"].is_object());
    }

    #[test]
    fn test_extensions_deserialization() {
        // Test deserializing capabilities with extensions from JSON
        let json = serde_json::json!({
            "extensions": {
                "io.modelcontextprotocol/ui": {
                    "mimeTypes": ["text/html;profile=mcp-app"]
                }
            },
            "sampling": {}
        });

        let capabilities: ClientCapabilities = serde_json::from_value(json).unwrap();
        assert!(capabilities.extensions.is_some());
        let extensions = capabilities.extensions.unwrap();
        assert!(extensions.contains_key("io.modelcontextprotocol/ui"));
        let ui_ext = extensions.get("io.modelcontextprotocol/ui").unwrap();
        assert!(ui_ext.contains_key("mimeTypes"));
    }

    #[test]
    fn test_extensions_empty_settings() {
        // Test that empty extension settings work (indicates support with no settings)
        let mut extensions = ExtensionCapabilities::new();
        extensions.insert(
            "io.modelcontextprotocol/oauth-client-credentials".to_string(),
            JsonObject::new(),
        );

        let capabilities = ClientCapabilities::builder()
            .enable_extensions_with(extensions)
            .build();

        let json = serde_json::to_value(&capabilities).unwrap();
        assert_eq!(
            json["extensions"]["io.modelcontextprotocol/oauth-client-credentials"],
            serde_json::json!({})
        );
    }
}