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import { Middleware, Response, Request, NextFunction, Mith } from 'https://deno.land/x/mith@v0.6.1/mod.ts'import { match, MatchFunction } from 'https://raw.githubusercontent.com/pillarjs/path-to-regexp/master/src/index.ts'
interface RouterMiddleware extends Middleware {  isRouter: boolean}
type methods = 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH' | 'OPTIONS'
const state: {  [key: number]: string} = {}
/** Router state handlers * they are used to keep track of the current state of the matcher during deep routing * this is cleaned when the request ends */
 /** Sets the router state * @param id connection id from Deno request object * @param path string containing the currently matched path * @return void */const setStatePath = (id: number, path: string) => {  return state[id] = path}
/** Get a router state * @param id connection id from Deno request object * @return current state for the id */const getStatePath = (id: number) => {  return state[id]}
/** Delete a router state * @param id connection id from Deno request object * @return void */const deleteStatePath = (id: number) => {  delete state[id]}
/** A class which registers middleware (via `.use()`) and then processes * inbound requests against that middleware (via `.getRoutes()`). */export class Router {  private paths: {    [key in methods]: {      [key: string]: {        middleware: Mith,        isRouter: boolean,        matcher: MatchFunction,        route: string      }    }  } = {    GET: {},    POST: {},    PUT: {},    DELETE: {},    PATCH: {},    OPTIONS: {}  }
  private savedPaths: {    [key in methods]: string[]  } = {    GET: [],    POST: [],    PUT: [],    DELETE: [],    PATCH: [],    OPTIONS: []  }
  /** Register middleware to be used with the router.   * @param methods http method   * @param path path that will be matched with the requested url   * @param middleware   * @return void  */  use(method: methods, path: string, middleware: Middleware | RouterMiddleware | Array<Middleware | RouterMiddleware>) {    const subApp = new Mith()    subApp.use(middleware)    let isRouter = false    if (Array.isArray(middleware)) {      isRouter = middleware.filter(        (item) => {          return (item as RouterMiddleware).isRouter        }      ).length > 0    } else {      isRouter = (middleware as RouterMiddleware).isRouter    }    this.paths[method][path] = {      middleware: subApp,      isRouter,      matcher: match(path, { end: !isRouter }),      route: path,    }    this.savedPaths[method] = Object.keys(this.paths[method])    return this  }
  /** Returns a middleware that will trigger the routing system   * @return middleware  */  getRoutes(): RouterMiddleware {    const router: RouterMiddleware = (req: Request, res: Response, next: NextFunction) => {      let matchedRoute = false      const connectionId = req.serverRequest.conn.rid      const statePath = getStatePath(connectionId)      const {        method,        url      } = req.serverRequest      for (const savedPath of this.savedPaths[method as methods]) {        const route = this.paths[method as methods][savedPath]        const matched = route.matcher(url.replace(statePath, '') || '/')        if (matched) {          matchedRoute = true          req.params = {            ...req.params,            ...matched.params          }          if (route.isRouter) {            if (matched.path !== '/') {              setStatePath(connectionId, (statePath || '') + matched.path)            }          } else {            req.requestHandled = true            deleteStatePath(connectionId)          }          route.middleware.dispatch(req, res, 'main', 0, next)          return        }      }      if (!matchedRoute) {        deleteStatePath(connectionId)        next()      }    }
    router.isRouter = true    return router  }}