export const createStore = (reducer,enhancer)=>{
	if(enhancer) {
		return enhancer(createStore)(reducer)
	}
	let currentState = {}
	let currentListeners = []

	const getState = ()=>currentState
	const subscribe = (listener)=>{
		currentListeners.push(listener)
	}
	const dispatch = action=>{
		currentState = reducer(currentState, action)
		currentListeners.forEach(v=>v())
		return action
	}
	dispatch({type:'@@INIT'})
	return {getState,subscribe,dispatch}
}

//中间件实现
export applyMiddleWare(...middlewares){
	return createStore=>...args=>{
		const store = createStore(...args)
		let dispatch = store.dispatch

		const midApi = {
			getState:store.getState,
			dispatch:...args=>dispatch(...args)
		}
		const middlewaresChain = middlewares.map(middleware=>middleware(midApi))
		dispatch = compose(...middlewaresChain)(store.dispatch)
		return {
			...store,
			dispatch
		}
	}

// fn1(fn2(fn3())) 把函数嵌套依次调用
export function compose(...funcs){
	if(funcs.length===0){
		return arg=>arg
	}
	if(funs.length===1){
		return funs[0]
	}
	return funcs.reduce((ret,item)=>(...args)=>ret(item(...args)))
}


//bindActionCreator实现

function bindActionCreator(creator,dispatch){
    return ...args=>dispatch(creator(...args))
}
function bindActionCreators(creators,didpatch){
    //let bound = {}
    //Object.keys(creators).forEach(v=>{
   //     let creator = creator[v]
     //   bound[v] = bindActionCreator(creator,dispatch)
    //})
    //return bound
    
    return Object.keys(creators).reduce((ret,item)=>{
	    ret[item] = bindActionCreator(creators[item],dispatch)
    	return ret
    },{})
}