cora-code 0.16.0

//! MCP protocol types — JSON-RPC 2.0 messages for Model Context Protocol.

use serde::{Deserialize, Serialize};

/// JSON-RPC 2.0 request.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct JsonRpcRequest {
    pub jsonrpc: String,
    pub id: Option<RequestId>,
    pub method: String,
    #[serde(default)]
    pub params: serde_json::Value,
}

/// JSON-RPC 2.0 response.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct JsonRpcResponse {
    pub jsonrpc: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub id: Option<RequestId>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub result: Option<serde_json::Value>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub error: Option<JsonRpcError>,
}

/// JSON-RPC error object.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct JsonRpcError {
    pub code: i64,
    pub message: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub data: Option<serde_json::Value>,
}

/// Request ID — can be a number or string.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(untagged)]
pub enum RequestId {
    Number(i64),
    String(String),
}

// ─── MCP-specific types ───

/// MCP tool definition.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Tool {
    pub name: String,
    pub description: String,
    #[serde(rename = "inputSchema")]
    pub input_schema: serde_json::Value,
}

/// MCP tool call result.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ToolResult {
    pub content: Vec<ContentBlock>,
    #[serde(default)]
    pub is_error: bool,
}

/// Content block in a tool result.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ContentBlock {
    #[serde(rename = "type")]
    pub content_type: String,
    pub text: String,
}

impl ToolResult {
    /// Create a text result.
    pub fn text(text: impl Into<String>) -> Self {
        Self {
            content: vec![ContentBlock {
                content_type: "text".to_string(),
                text: text.into(),
            }],
            is_error: false,
        }
    }

    /// Create an error result.
    pub fn error(text: impl Into<String>) -> Self {
        Self {
            content: vec![ContentBlock {
                content_type: "text".to_string(),
                text: text.into(),
            }],
            is_error: true,
        }
    }
}

/// Server info for initialization.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ServerInfo {
    pub name: String,
    pub version: String,
}

/// Server capabilities.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ServerCapabilities {
    pub tools: serde_json::Value,
}

/// Initialize result.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct InitializeResult {
    #[serde(rename = "protocolVersion")]
    pub protocol_version: String,
    pub capabilities: ServerCapabilities,
    #[serde(rename = "serverInfo")]
    pub server_info: ServerInfo,
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn parse_request() {
        let req: JsonRpcRequest =
            serde_json::from_str(r#"{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}"#)
                .unwrap();
        assert_eq!(req.method, "tools/list");
    }

    #[test]
    fn serialize_response() {
        let resp = JsonRpcResponse {
            jsonrpc: "2.0".to_string(),
            id: Some(RequestId::Number(1)),
            result: Some(serde_json::json!({"ok": true})),
            error: None,
        };
        let json = serde_json::to_string(&resp).unwrap();
        assert!(json.contains("\"result\""));
    }

    #[test]
    fn tool_result_text() {
        let result = ToolResult::text("hello");
        assert!(!result.is_error);
        assert_eq!(result.content[0].text, "hello");
    }

    #[test]
    fn tool_result_error() {
        let result = ToolResult::error("fail");
        assert!(result.is_error);
    }
}