import type { Agile } from '../agile';
import { StateIngestConfigInterface, StateObserver } from './state.observer';
import { Observer } from '../runtime';
export declare class State<ValueType = any> {
    agileInstance: () => Agile;
    _key?: StateKey;
    isSet: boolean;
    isPlaceholder: boolean;
    initialStateValue: ValueType;
    _value: ValueType;
    previousStateValue: ValueType;
    nextStateValue: ValueType;
    observers: StateObserversInterface<ValueType>;
    sideEffects: {
        [key: string]: SideEffectInterface<State<ValueType>>;
    };
    /**
     * A State manages a piece of Information
     * that we need to remember globally at a later point in time.
     * While providing a toolkit to use and mutate this piece of Information.
     *
     * You can create as many global States as you need.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/)
     *
     * @public
     * @param agileInstance - Instance of Agile the State belongs to.
     * @param initialValue - Initial value of the State.
     * @param config - Configuration object
     */
    constructor(agileInstance: Agile, initialValue: ValueType, config?: StateConfigInterface);
    /**
     * Assigns a new value to the State
     * and re-renders all subscribed Components.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/properties#value)
     *
     * @public
     * @param value - New State value.
     */
    set value(value: ValueType);
    /**
     * Returns a reference-free version of the current State value.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/properties#value)
     *
     * @public
     */
    get value(): ValueType;
    /**
     * Updates the key/name identifier of the State.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/properties#key)
     *
     * @public
     * @param value - New key/name identifier.
     */
    set key(value: StateKey | undefined);
    /**
     * Returns the key/name identifier of the State.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/properties#key)
     *
     * @public
     */
    get key(): StateKey | undefined;
    /**
     * Updates the key/name identifier of the State.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/methods/#setkey)
     *
     * @public
     * @param value - New key/name identifier.
     */
    setKey(value: StateKey | undefined): this;
    /**
     * Assigns a new value to the State
     * and re-renders all subscribed UI-Components.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/methods/#set)
     *
     * @public
     * @param value - New State value
     * @param config - Configuration object
     */
    set(value: ValueType | ((value: ValueType) => ValueType), config?: StateIngestConfigInterface): this;
    /**
     * Ingests the State without any specified new value into the runtime.
     *
     * Since no new value was defined either the new State value is computed
     * based on a compute method (Computed Class)
     * or the `nextStateValue` is taken as the next State value.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/methods/#ingest)
     *
     * @internal
     * @param config - Configuration object
     */
    ingest(config?: StateIngestConfigInterface): this;
    /**
     *
     * Registers a `callback` function that is executed in the `runtime`
     * as a side effect of State changes.
     *
     * For example, it is called when the State value changes from 'jeff' to 'hans'.
     *
     * A typical side effect of a State change
     * could be the updating of the external Storage value.
     *
     * @internal
     * @param key - Key/Name identifier of the to register side effect.
     * @param callback - Callback function to be fired on each State value change.
     * @param config - Configuration object
     */
    addSideEffect<Instance extends State<ValueType>>(key: string, callback: SideEffectFunctionType<Instance>, config?: AddSideEffectConfigInterface): this;
    /**
     * Removes a side effect callback with the specified key/name identifier from the State.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/methods/#removesideeffect)
     *
     * @internal
     * @param key - Key/Name identifier of the side effect callback to be removed.
     */
    removeSideEffect(key: string): this;
    /**
     * Returns a boolean indicating whether a side effect callback with the specified `key`
     * exists in the State or not.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/methods/#hassideeffect)
     *
     * @internal
     * @param key - Key/Name identifier of the side effect callback to be checked for existence.
     */
    hasSideEffect(key: string): boolean;
}
export declare type StateKey = string | number;
export interface StateObserversInterface<ValueType = any> {
    /**
     * Observer responsible for the value of the State.
     */
    value: StateObserver<ValueType>;
}
export interface StateConfigInterface {
    /**
     * Key/Name identifier of the State.
     * @default undefined
     */
    key?: StateKey;
    /**
     * Observers that depend on the State.
     * @default []
     */
    dependents?: Array<Observer>;
    /**
     * Whether the State should be a placeholder
     * and therefore should only exist in the background.
     * @default false
     */
    isPlaceholder?: boolean;
}
export declare type SideEffectFunctionType<Instance extends State> = (instance: Instance, properties?: {
    [key: string]: any;
}) => void;
export interface SideEffectInterface<Instance extends State> {
    /**
     * Callback function to be called on every State value change.
     * @return () => {}
     */
    callback: SideEffectFunctionType<Instance>;
    /**
     * Weight of the side effect.
     * The weight determines the order of execution of the registered side effects.
     * The higher the weight, the earlier it is executed.
     */
    weight: number;
}
export interface AddSideEffectConfigInterface {
    /**
     * Weight of the side effect.
     * The weight determines the order of execution of the registered side effects.
     * The higher the weight, the earlier it is executed.
     */
    weight?: number;
}