cpp-mcp/include/mcp_client.h

/**
 * @file mcp_client.h
 * @brief MCP Client implementation using cpp-httplib
 * 
 * This file implements the client-side functionality for the Model Context Protocol.
 */

#ifndef MCP_CLIENT_H
#define MCP_CLIENT_H

#include "mcp_protocol.h"

// Include the HTTP library
#include "httplib.h"

#include <string>
#include <map>
#include <vector>
#include <memory>
#include <mutex>
#include <functional>

namespace mcp {

/**
 * @class client
 * @brief Client for connecting to MCP servers
 * 
 * The client class provides functionality to connect to MCP servers,
 * discover available resources and tools, and make requests to them.
 */
class client {
public:
    /**
     * @brief Constructor
     * @param host The server host (e.g., "localhost", "example.com")
     * @param port The server port
     */
    client(const std::string& host, int port = 8080);
    
    /**
     * @brief Destructor
     */
    ~client();
    
    /**
     * @brief Set authentication credentials
     * @param username The username
     * @param password The password
     */
    void set_auth(const std::string& username, const std::string& password);
    
    /**
     * @brief Set a request header that will be sent with all requests
     * @param key Header name
     * @param value Header value
     */
    void set_header(const std::string& key, const std::string& value);
    
    /**
     * @brief Set timeout for requests
     * @param timeout_seconds Timeout in seconds
     */
    void set_timeout(int timeout_seconds);
    
    /**
     * @brief Get server information
     * @return Server information as a JSON object
     * @throws mcp_exception on error
     */
    json get_server_info();
    
    /**
     * @brief Get available tools
     * @return List of available tools as a JSON array
     * @throws mcp_exception on error
     */
    json get_tools();
    
    /**
     * @brief Call a tool
     * @param tool_name The name of the tool to call
     * @param parameters The parameters to pass to the tool
     * @return The result of the tool call as a JSON object
     * @throws mcp_exception on error
     */
    json call_tool(const std::string& tool_name, const json& parameters = json::object());
    
    /**
     * @brief Make a GET request
     * @param path The path to request
     * @param query_params Query parameters
     * @return The response
     * @throws mcp_exception on error
     */
    response get(const std::string& path, 
                 const std::map<std::string, std::string>& query_params = {});
    
    /**
     * @brief Make a POST request
     * @param path The path to request
     * @param body The request body
     * @param content_type The content type
     * @return The response
     * @throws mcp_exception on error
     */
    response post(const std::string& path, 
                  const std::string& body = "", 
                  const std::string& content_type = content_type::json);
    
    /**
     * @brief Make a POST request with JSON body
     * @param path The path to request
     * @param json_body The JSON body
     * @return The response
     * @throws mcp_exception on error
     */
    response post_json(const std::string& path, const json& json_body);
    
    /**
     * @brief Make a PUT request
     * @param path The path to request
     * @param body The request body
     * @param content_type The content type
     * @return The response
     * @throws mcp_exception on error
     */
    response put(const std::string& path, 
                 const std::string& body = "", 
                 const std::string& content_type = content_type::json);
    
    /**
     * @brief Make a DELETE request
     * @param path The path to request
     * @return The response
     * @throws mcp_exception on error
     */
    response delete_request(const std::string& path);
    
    /**
     * @brief Make a generic request
     * @param method The HTTP method
     * @param path The path
     * @param body The request body (for POST, PUT, etc.)
     * @param headers Additional headers
     * @param query_params Query parameters
     * @return The response
     * @throws mcp_exception on error
     */
    response make_request(http_method method, 
                          const std::string& path, 
                          const std::string& body = "", 
                          const std::map<std::string, std::string>& headers = {}, 
                          const std::map<std::string, std::string>& query_params = {});

private:
    std::string host_;
    int port_;
    std::string auth_header_;
    int timeout_seconds_ = 30;
    
    std::map<std::string, std::string> default_headers_;
    
    // HTTP client
    std::unique_ptr<httplib::Client> http_client_;
    
    // Mutex for thread safety
    mutable std::mutex mutex_;
    
    // Initialize the client
    void init_client();
    
    // Process response
    response process_response(const httplib::Result& result);
};

} // namespace mcp

#endif // MCP_CLIENT_H