export interface Metadata {
    key: string;
}
export type Getter<TValue> = () => TValue;
export type Setter<TValue, TContext = unknown> = (newValue: TValue | ((value: TValue) => TValue), context?: TContext) => void;
export type Unsubscriber = () => void;
export type StateListener<TValue> = (nextValue: TValue, prevValue: TValue) => void;
export type StateSubscriber<TValue> = (listener: StateListener<TValue>) => Unsubscriber;
export interface State<TValue, TMeta = unknown, TContext = unknown> {
    get: Getter<TValue>;
    set: Setter<TValue, TContext>;
    subscribe: StateSubscriber<TValue>;
    meta: () => TMeta;
}
export type StateWithAction<TValue, TAction, TMeta = unknown, TContext = unknown> = Omit<TAction, keyof State<TValue, TMeta, TContext>> & State<TValue, TMeta, TContext>;
export type ActionBuilder<TValue, TAction, TContext = unknown> = (set: Setter<TValue, TContext>, get: Getter<TValue>) => TAction;
export interface StateBuilder {
    <TValue, TContext = unknown>(): State<TValue | undefined, undefined, TContext>;
    <TValue, TContext = unknown>(initialValue: TValue): State<TValue, undefined, TContext>;
    <TValue, TMeta, TContext = unknown>(initialValue: TValue, actionBuilder: null | undefined, metadata: TMeta): State<TValue, TMeta, TContext>;
    <TValue, TAction, TContext = unknown>(initialValue: TValue, actionBuilder: ActionBuilder<TValue, TAction, TContext>): StateWithAction<TValue, TAction, undefined, TContext>;
    <TValue, TAction, TMeta, TContext = unknown>(initialValue: TValue, actionBuilder: ActionBuilder<TValue, TAction, TContext>, metadata: TMeta): StateWithAction<TValue, TAction, TMeta, TContext>;
}
export interface StateBuilderWithMeta<TStateMeta> {
    <TValue, TMeta extends TStateMeta, TContext = unknown>(initialValue: TValue, actionBuilder: null | undefined, metadata: TMeta): State<TValue, TMeta, TContext>;
    <TValue, TAction, TMeta extends TStateMeta, TContext = unknown>(initialValue: TValue, actionBuilder: ActionBuilder<TValue, TAction, TContext>, metadata: TMeta): StateWithAction<TValue, TAction, TMeta, TContext>;
}
export type SelectorListener = () => void;
export type SelectorSubscriber = (listener: SelectorListener) => Unsubscriber;
export interface Observable<TValue> {
    get: Getter<TValue>;
    subscribe: SelectorSubscriber;
}
export interface Selector<TValue, TMeta = unknown> extends Observable<TValue> {
    meta: () => TMeta;
}
export type Middleware<TStateMeta = never> = <TValue, TMeta extends TStateMeta, TContext = unknown>(state: State<TValue, TMeta, TContext>) => Setter<TValue, TContext>;
export interface Plugin<TSelectorMeta = never> {
    <TValue, TMeta extends TSelectorMeta>(selector: Selector<TValue, TMeta>): void;
}
export type SelectorArray = Selector<unknown>[];
export type SelectorValueArray<TArray extends SelectorArray> = {
    [index in keyof TArray]: ReturnType<TArray[index]['get']>;
};
export type SelectorFunc<TArray extends SelectorArray, TValue> = (...args: SelectorValueArray<TArray>) => TValue;
export type SelectorParams<TArray extends SelectorArray, TValue> = [
    ...TArray,
    SelectorFunc<TArray, TValue>
];
export interface SelectorBuilder {
    <TArray extends SelectorArray, TValue>(...items: SelectorParams<TArray, TValue>): Selector<TValue>;
    <TArray extends SelectorArray, TValue, TMeta>(...items: [...SelectorParams<TArray, TValue>, TMeta]): Selector<TValue>;
}
export interface SelectorBuilderWithMeta<TSelectorMeta> {
    <TArray extends SelectorArray, TValue, TMeta extends TSelectorMeta>(...items: [...SelectorParams<TArray, TValue>, TMeta]): Selector<TValue>;
}