/**
 * The session storage module provides apis for storing session data.
 *
 * "app.session.enable" must be set to true in order for these apis to work,
 * they fail silently otherwise.
 */
/** imports */
import * as express from 'express';
import { Future } from '@quenk/noni/lib/control/monad/future';
import { Object, Value } from '@quenk/noni/lib/data/jsonx';
import { Maybe } from '@quenk/noni/lib/data/maybe';
import { Storage } from './';
export declare const SESSION_DATA = "tendril.$data";
export declare const SESSION_DESCRIPTORS = "tendril.$descriptors";
/**
 * Descriptor is the internal configuration of a session property.
 *
 * The settings specified here have an impact no the treatment of the session
 * property.
 */
export interface Descriptor {
    /**
     * ttl if set is the number of requests a session value should be retained
     * for. When this reaches zero the propety will be automatically removed.
     */
    ttl?: number;
}
/**
 * SessionStorage acts as a bridge between the tendril applications and
 * the underlying express session store API.
 */
export interface SessionStorage extends Storage {
    /**
     * isEnabled returns true if session storage is enabled, false otherwise.
     */
    isEnabled(): boolean;
    /**
     * setWithDescriptor sets the value of a key in session storage along with
     * a descriptor.
     */
    setWithDescriptor(key: string, value: Value, desc: Descriptor): SessionStorage;
    /**
     * save the session data.
     *
     * Call this method to immediately persist any data written to the session.
     */
    save(): Future<void>;
    /**
     * regenerate the session.
     *
     * This hooks into the lower level API to invalidate the current session id
     * supplied by the client and issue a new one. All data stored in the
     * session will be lost, including data not set through this API.
     */
    regenerate(): Future<void>;
    /**
     * destroy the session.
     *
     * Everything comes to an end here.
     */
    destroy(): Future<void>;
}
/**
 * @private
 */
export declare class DisabledSessionStorage implements SessionStorage {
    warn(method: string): void;
    isEnabled(): boolean;
    get(_key: string): Maybe<Value>;
    getOrElse(_key: string, alt: Value): Value;
    getAll(): Object;
    exists(_key: string): boolean;
    set(_key: string, _value: Value): DisabledSessionStorage;
    setWithDescriptor(_key: string, _value: Value, _desc: Descriptor): DisabledSessionStorage;
    remove(_: string): DisabledSessionStorage;
    reset(): DisabledSessionStorage;
    save(): Future<void>;
    regenerate(): Future<void>;
    destroy(): Future<void>;
}
/**
 * EnabledSessionStorage class.
 */
export declare class EnabledSessionStorage implements SessionStorage {
    data: Object;
    /**
     * @private
     */
    constructor(data: Object);
    /**
     * fromExpress constructs a SessionStorage instance from an express
     * Request.
     *
     * If session support is not enabled, a DisabledSessionStorage will be
     * provided instead.
     */
    static fromExpress(r: express.Request): SessionStorage;
    /**
     * @private
     */
    target(): Object;
    /**
     * @private
     */
    descriptors(): Object;
    isEnabled(): boolean;
    get(key: string): Maybe<Value>;
    getOrElse(key: string, alt: Value): Value;
    getAll(): Object;
    exists(key: string): boolean;
    set(key: string, value: Value): EnabledSessionStorage;
    setWithDescriptor(key: string, value: Value, desc: Descriptor): EnabledSessionStorage;
    remove(key: string): EnabledSessionStorage;
    reset(): EnabledSessionStorage;
    save(): Future<void>;
    regenerate(): Future<void>;
    destroy(): Future<void>;
}
/**
 * @private
 */
export declare const getSessionValue: (session: Object, key: string) => Maybe<Value>;
/**
 * @private
 */
export declare const getSessionValueAsString: (session: Object, key: string) => string;
/**
 * @private
 */
export declare const getSessionValueOrElse: (session: Object, key: string, other: Value) => Value;
/**
 * @private
 */
export declare const setSessionValue: (session: Object, key: string, value: Value, desc: Descriptor) => void;
/**
 * @private
 */
export declare const deleteSessionKey: (session: Object, key: string) => void;