import type { JSONRPCMessage } from "../jsonrpc2/types.js";
import type { Logger } from "../logger/types.js";
/**
 * MessageHandler is a JSON RPC handler for processing messages on the transport
 *
 * @param message - The received JSON-RPC message
 * @returns - A promise that resolves to a response JSON RPC message or void (for notifications)
 */
export type MessageHandler = (message: JSONRPCMessage) => Promise<JSONRPCMessage | null>;
export interface TransportOptions {
    timeout?: number;
    headers?: Record<string, string>;
    enableSessions?: boolean;
    fetch?: typeof fetch;
    logger?: Logger;
}
/**
 * Describes the minimal contract for a MCP transport that a client or server can communicate over.
 */
export interface Transport {
    /**
     * Connects and starts receiving messages.
     */
    connect(): Promise<void>;
    /**
     * Send a JSON RPC Message on the connected transport
     */
    send(message: JSONRPCMessage): Promise<void>;
    /**
     * Handler for received messages
     */
    onMessage(handler: MessageHandler): void;
    /**
     * Closes the connection.
     */
    close(): Promise<void>;
    /**
     * Sets a callback for when the transport is closed
     */
    onClose?: (callback: () => void) => void;
    /**
     * Sets a callback for transport errors
     */
    onError(callback: (error: Error) => void): void;
    /**
     * Get the current session ID if one exists
     */
    getSessionId(): string | undefined;
    /**
     * Set a session ID for subsequent requests
     */
    setSessionId(sessionId: string | undefined): void;
    /**
     * Set custom headers for requests
     */
    setHeaders(headers: Record<string, string>): void;
}