//-----------------------------------------------------------------------------

//假设 存在一个核心操作 接收参数coreArg

//建立洋葱模型，包裹N层中间件

//要求：

// 在核心代码执行执之前必须要有序执行中间件

// 核心代码执行后层层返回

// 每个中间件都能接收到coreArg

function receiveMiddleware () {

//拿到中间件队列

let middlewareList = Array.prototype.slice.call(arguments);

//将中间件队列改造为函数层层嵌套形式

//[a,b,c,d] => a(b(c(d(core)))) By reduce

let tiggerPip = middlewareList.reduce((a, b) => (core) => a(b(core)));

let tiggerPipWitchCoreHandler = tiggerPip(() => { console.log('我是核心操作') });

return tiggerPipWitchCoreHandler;

}

const middleware1 = (next) => (lastMDarg) => {

console.log('lm 1 start')

next(lastMDarg);

console.log('lm 1 end')

};

const middleware2 = (next) => (lastMDarg) => {

console.log('lm 2 start')

next(lastMDarg);

console.log('lm 2 end')

};

const middleware3 = (next) => (lastMDarg) => {

console.log('lm 3 start')

next(lastMDarg);

console.log('lm 3 end')

};

let dispatch = receiveMiddleware(middleware1, middleware2, middleware3);

dispatch({ type: 'fff' });

//-----------------------------------------------------------------------------

//增加异步操作

const store = {

status: {name: 'zhangsan'},

getState: () => { return this.status },

dispatch: (arg) => {console.log(`我是核心操作,参数=${arg}`)}

};

function receiveMiddleware () {

//拿到中间件队列

let middlewareList = Array.prototype.slice.call(arguments);

let dispatch = store.dispatch;

let middlewareAPI = {

dispatch: (arg) => { dispatch(arg) },

getState: store.getState,

};

//判断中间件数量

if (middlewareList.length === 0) { return dispatch }

//将核心操作当作参数赋予每个中间件

middlewareList = middlewareList.map((middleware) => middleware(middlewareAPI));

//将中间件队列改造为函数层层嵌套形式

//[a,b,c,d] => a(b(c(d(core)))) By reduce

let tiggerPip = middlewareList.reduce((a, b) => (reallyDispatch) => a(b(reallyDispatch)));

//重写dispatch

dispatch = tiggerPip(store.dispatch);

return dispatch;

}

const middleware1 = (middlewareAPI) => (next) => (lastMDarg) => {

console.log('lm 1 start')

next(lastMDarg);

console.log('lm 1 end')

};

const middleware2 = (middlewareAPI) => (next) => (lastMDarg) => {

console.log('lm 2 start')

next(lastMDarg);

console.log('lm 2 end')

};

const middleware3 = (middlewareAPI) => (next) => (lastMDarg) => {

console.log('lm 3 start')

next(lastMDarg);

console.log('lm 3 end')

};

const supportAsyncMiddleware = (middlewareAPI) => (next) => (lastMDarg) => {

console.log('lm supportAsyncMiddleware start')

if (typeof lastMDarg === 'function') {

lastMDarg(middlewareAPI)

} else {

next(lastMDarg);

console.log('lm supportAsyncMiddleware end')

}

};

let dispatch = receiveMiddleware(middleware1,

middleware2,

middleware3,

supportAsyncMiddleware);

let asyncFun = (middlewareAPI) => {

setTimeout(() => {

let mockGetData = 'im mock data'

middlewareAPI.dispatch(mockGetData)

console.log(middlewareAPI.getState())

}, 3000)

}

dispatch(asyncFun)