import { Entry, CommandMessage, ActionMessage } from './messages';
import DataSource from './data-source';
export declare type DispatchDelegate<TMessage> = (message: TMessage) => Promise<TMessage>;
export declare enum MiddlewareHooks {
    Connect = "connect",
    Disconnect = "disconnect",
    Command = "command",
    Respond = "respond",
    Write = "write",
    Process = "process"
}
/**
 * Context for an execution chain shared between middlewares.
 */
export declare type DispatchContext = {
    /**
     * Stack of middlewares to be executed when delegating to `next()`.
     * Middlewares can be removed from the stack to prevent them from executing.
     */
    stack: Middleware[];
    /**
     * A bag of properties shared between middlewares. Use this to pass messages to subsequent
     * middlewares in the execution chain.
     */
    properties: {
        [key: string]: any;
    };
};
export default interface Middleware {
    name?: string;
    /**
     * Hook executed when the `DataSource` is connected.
     */
    connect?: (next: DispatchDelegate<any>, dataSource: DataSource, context: DispatchContext) => (data?: any) => void | Promise<void>;
    /**
     * Hook executed when the `DataSource` is disconnected.
     */
    disconnect?: (next: DispatchDelegate<any>, dataSource: DataSource, context: DispatchContext) => (data?: any) => void | Promise<void>;
    /**
     * Hook executed when the `DataSource` dispatched a command.
     */
    command?: (next: DispatchDelegate<CommandMessage>, dataSource: DataSource, context: DispatchContext) => (message: CommandMessage) => void | Promise<void>;
    /**
     * Hook executed when the `DataSource` responds with an action.
     */
    respond?: (next: DispatchDelegate<ActionMessage>, dataSource: DataSource, context: DispatchContext) => (message: ActionMessage) => void | Promise<void>;
    /**
     * Hook executed when the `DataSource` is written to.
     */
    write?: (next: DispatchDelegate<Entry[]>, dataSource: DataSource, context: DispatchContext) => (entries: Entry[]) => Entry[] | Promise<Entry[]>;
    /**
     * Hook executed when the `DataSource` processes its stream of entries.
     */
    process?: (next: DispatchDelegate<Entry[]>, dataSource: DataSource, context: DispatchContext) => (entries: Entry[]) => Entry[] | Promise<Entry[]>;
}
export declare function callMiddleware(dataSource: DataSource, method: string, data: any): Promise<any>;
export interface AddMiddlewareOptions {
    before?: string;
    after?: string;
}
export declare function addMiddleware(dataSource: DataSource, middleware: Middleware, options: AddMiddlewareOptions): void;
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