90 # 实现 express 请求处理

const http = require("http");
const Router = require("./router");
function Application() {
    this._router = new Router();
}
Application.prototype.get = function (path, ...handlers) {
    this._router.get(path, handlers);
};
Application.prototype.listen = function () {
    const server = http.createServer((req, res) => {
        function done() {
            res.end(`kaimo-express Cannot ${req.method} ${req.url}`);
        }
        this._router.handle(req, res, done);
    });
    server.listen(...arguments);
};
module.exports = Application;

const url = require("url");
const Route = require("./route");
const Layer = require("./layer");
function Router() {
    // 维护所有的路由
    this.stack = [];
}
Router.prototype.route = function (path) {
    // 产生 route
    let route = new Route();
    // 产生 layer 让 layer 跟 route 进行关联
    let layer = new Layer(path, route.dispatch.bind(route));
    // 每个路由都具备一个 route 属性，稍后路径匹配到后会调用 route 中的每一层
    layer.route = route;
    // 把 layer 放到路由的栈中
    this.stack.push(layer);
    return route;
};
// 用户调用 get 时，传入的 handler 不一定是一个
Router.prototype.get = function (path, handlers) {
    // 1.用户调用 get 时，需要保存成一个 layer 当道栈中
    // 2.产生一个 Route 实例和当前的 layer 创造关系
    // 3.要将 route 的 dispatch 方法存到 layer 上
    let route = this.route(path);
    // 让 route 记录用户传入的 handler 并且标记这个 handler 是什么方法
    route.get(handlers);
};
Router.prototype.handle = function (req, res, out) {
    console.log("请求到了");
    // 需要取出路由系统中 Router 存放的 layer 依次执行
    const { pathname } = url.parse(req.url);
    let idx = 0;
    let next = () => {
        // 遍历完后没有找到就直接走出路由系统
        if (idx >= this.stack.length) return out();
        let layer = this.stack[idx++];
        // 需要判断 layer 上的 path 和当前请求路由是否一致，一致就执行 dispatch 方法
        if (layer.path === pathname) {
            // 将遍历路由系统中下一层的方法传入
            layer.handler(req, res, next);
        } else {
            next();
        }
    };
    next();
};
module.exports = Router;

const Layer = require("./layer");
function Route() {
    this.stack = [];
}
Route.prototype.dispatch = function (req, res, out) {
    // 稍后调用此方法时，回去栈中拿出对应的 handler 依次执行
    let idx = 0;
    console.log("this.stack----->", this.stack);
    let next = () => {
        // 遍历完后没有找到就直接走出路由系统
        if (idx >= this.stack.length) return out();
        let layer = this.stack[idx++];
        if (layer.method === req.method.toLowerCase()) {
            layer.handler(req, res, next);
        } else {
            next();
        }
    };
    next();
};
Route.prototype.get = function (handlers) {
    console.log("handlers----->", handlers);
    handlers.forEach((handler) => {
        // 这里的路径没有意义
        let layer = new Layer("/", handler);
        layer.method = "get";
        this.stack.push(layer);
    });
};
module.exports = Route;

const express = require("./kaimo-express");
const app = express();
app.get(
    "/",
    (req, res, next) => {
        console.log(1);
        setTimeout(() => {
            next();
        }, 1000);
    },
    (req, res, next) => {
        console.log(11);
        next();
    },
    (req, res, next) => {
        console.log(111);
        next();
    }
);
app.get("/", (req, res, next) => {
    console.log(2);
    res.end("end");
});
app.listen(3000, () => {
    console.log(`server start 3000`);
    console.log(`在线访问地址：http://localhost:3000/`);
});