import type { AgentArtifactParams, AgentStreamQueue, AgentTaskParams } from "./types.ts";
import { AgentExecutionContext } from "./context.ts";
import type { AgentStreamEvent } from "./types.ts";
import { Task, TaskState } from "../../types/types.ts";
/**
 * Checks if a task state is final (terminal)
 *
 * Final states indicate that the task has completed processing and will not
 * transition to any other state. These include successful completion, failures,
 * cancellation, and rejection.
 *
 * @param state - The task state to check
 * @returns true if the state is final, false otherwise
 */
declare const isFinalTaskState: (state: TaskState) => boolean;
/**
 * Checks if a task state is pending (requires external input)
 *
 * Pending states indicate that the task is waiting for external input
 * or authorization before it can continue processing.
 *
 * @param state - The task state to check
 * @returns true if the state is pending, false otherwise
 */
declare const isPendingTaskState: (state: TaskState) => boolean;
/**
 * Checks if a stream event indicates the end of the stream
 *
 * @param event - The agent stream event to check
 * @returns true if this is an end-of-stream event, false otherwise
 */
declare function isEndOfStream(event: AgentStreamEvent): boolean;
/**
 * Manages streaming updates for an agent task
 *
 * AgentTaskStream provides a way to send incremental updates about a task's progress
 * to clients through a queue-based system. It supports artifact streaming, status updates,
 * and automatic stream termination when tasks reach final or pending states.
 */
declare class AgentTaskStream {
    /** Whether the stream has been closed */
    closed: boolean;
    /** The execution context associated with this stream */
    cx: AgentExecutionContext;
    /** The queue for streaming events */
    streamQueue: AgentStreamQueue;
    /**
     * Creates a new AgentTaskStream
     * @param cx - The execution context that must have a current task
     * @throws Error if the execution context has no current task
     */
    constructor(cx: AgentExecutionContext);
    /**
     * Terminates the stream if the task is in a pending or final state
     * Sends an end-of-stream event when terminating
     * @private
     */
    private _terminateIfPendingOrFinalState;
    /**
     * Ensures the stream is still open for writing
     * @throws Error if the stream has been closed
     * @private
     */
    private _ensureOpen;
    /**
     * Sends a task status update event to the stream
     * @private
     */
    _sendTaskStatusUpdate(): Promise<void>;
    /**
     * Gets the current task associated with this stream
     * @returns The current task
     * @throws Error if no task is found
     */
    getTask(): Task;
    /**
     * Writes an artifact update to the stream
     *
     * This method sends artifact data to connected clients and automatically
     * sets the task state to 'working' if not already set. It supports both
     * complete artifacts and chunked streaming.
     *
     * @param params - Artifact parameters
     * @param params.artifact - The artifact to stream
     * @param params.append - Whether to append to existing artifact (default: false)
     * @param params.lastChunk - Whether this is the final chunk (default: false)
     * @param sendTaskStatusUpdate - Whether to send status update (default: true)
     */
    writeArtifact({ artifact, append, lastChunk }: AgentArtifactParams, sendTaskStatusUpdate?: boolean): Promise<void>;
    /**
     * Sets the task state and sends status update if changed
     * @param state - The new task state
     * @throws Error if no task is found
     * @private
     * @todo Use this method to set the task state consistently
     */
    private _setTaskState;
    /**
     * Starts the task with the provided parameters
     * Sets the task state to 'working' and sends status update
     * @param taskParams - Task parameters to update
     */
    start(taskParams: AgentTaskParams): Promise<void>;
    /**
     * Rejects the task with the provided parameters
     * Sets the task state to 'rejected' and terminates the stream
     * @param taskParams - Task parameters including rejection reason
     */
    reject(taskParams: AgentTaskParams): Promise<void>;
    /**
     * Marks the task as requiring authentication
     * Sets the task state to 'auth-required' and terminates the stream
     * @param taskParams - Task parameters including auth requirements
     */
    authRequired(taskParams: AgentTaskParams): Promise<void>;
    /**
     * Marks the task as requiring additional input
     * Sets the task state to 'input-required' and terminates the stream
     * @param taskParams - Task parameters including input requirements
     */
    inputRequired(taskParams: AgentTaskParams): Promise<void>;
    /**
     * Completes the task with the provided parameters
     * Sets the task state to 'completed' and terminates the stream
     * @param taskParams - Task parameters including completion details
     */
    complete(taskParams: AgentTaskParams): Promise<void>;
}
export { isFinalTaskState, isPendingTaskState, isEndOfStream, AgentTaskStream };