import { UnsubscribeFunc } from "./types.js" ; type Listener < State > = ( state : State ) => void ; type Action < State > = ( state : State , ... args : any [ ] ) => Partial < State > | Promise < Partial < State > > | null ; type BoundAction < State > = ( ... args : any [ ] ) => void ; export type Store < State > = { state : State | undefined ; action ( action ) : BoundAction < State > ; setState ( update , overwrite ? ) : void ; subscribe ( listener ) : UnsubscribeFunc ; } ; export const createStore = < State > ( state ? ) : Store < State > => { let listeners = [ ] ; function unsubscribe ( listener ) { let out = [ ] ; for ( let i = 0 ; i < listeners . length ; i ++ ) { if ( listeners [ i ] === listener ) { listener = null ; } else { out . push ( listeners [ i ] ) ; } } listeners = out ; } function setState ( update , overwrite ) { state = overwrite ? ( update as State ) : { ... state ! , ... update } ; let currentListeners = listeners ; for ( let i = 0 ; i < currentListeners . length ; i ++ ) { currentListeners [ i ] ( state ) ; } } /**
     * An observable state container, returned from  createStore name return { get state ( ) { return state ; } , param { Function } action returns { Function } action ( action ) { function apply ( result ) { setState ( result , false ) ; } return function ( ) { let args = [ state ] ; for ( let i = 0 ; i < arguments . length ; i ++ ) args . push ( arguments [ i ] ) ; let ret = action . apply ( this , args ) ; if ( ret != null ) { return ret instanceof Promise ? ret . then ( apply ) : apply ( ret ) ; } } ; } , param { Object } update param { Boolean } overwrite setState , param { Function } listener returns { Function } subscribe ( listener ) { listeners . push ( listener ) ; return ( ) => { unsubscribe ( listener ) ; } ; } , } ; } ;