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// Copyright 2019-2020 Yusuke Sakurai. All rights reserved. MIT license.import { findLongestAndNearestMatches } from "./_matcher.ts";import { ServeHandler, ServerRequest } from "./server.ts";import { RoutingError } from "./error.ts";import {  acceptable,  acceptWebSocket,  WebSocket,} from "./vendor/https/deno.land/std/ws/mod.ts";import { assert } from "./vendor/https/deno.land/std/testing/asserts.ts";
/** Router handler */export interface RouteHandler {  (req: ServerRequest):    | void    | Promise<void>;}
/** WebSocket Handler */export interface WebSocketHandler {  (    sock: WebSocket,    req: ServerRequest,  ): void | Promise<void>;}
/** Global error handler for requests */export interface ErrorHandler {  (    e: any | RoutingError,    req: ServerRequest,  ): void | Promise<void>;}
export interface Route {  // internal  handleRoute(prefix: string, req: ServerRequest): Promise<void>;}
function isRoute(x: any): x is Route {  return typeof x?.handleRoute === "function";}
export interface Router extends Route {  /**   * Set global middleware.   * It will be called for each request on any routes.   * */  use(...handlers: ServeHandler[]): void;
  /**   * Register route with given pattern.   * It will be called for every http method,   * Examples:   *   router.handle("/", ...)   => Called if request path exactly matches "/".   *   router.handle(/^\//, ...) => Called if request path matches given regexp.   * */  handle(pattern: string | RegExp, ...handlers: RouteHandler[]): void;
  /**   * Register route with given prefixer.   * This is similar to router.handle() but different in several points:   *  - Only string prefix can be passed.   *  - Handlers will be called if req.path STARTS WITH prefix   *  - route() doesn't designate a single route handler set before dispatching.   *    This means it will keep calling all handler sets that matches prefixer until someone responds.   *  - route can accept Router   * Examples   *   router.route("/users", ...)   => Called if request path STARTS WITH "/users".   */  route(prefix: string, ...handlers: (RouteHandler | Router)[]): void;
  /**   * Register GET/HEAD route. This is shortcut for handle();   * */  get(pattern: string | RegExp, ...handlers: RouteHandler[]): void;
  /** Register POST route. This is shortcut for handle() */  post(pattern: string | RegExp, ...handlers: RouteHandler[]): void;
  /** Register PUT route  */  put(pattern: string | RegExp, ...handlers: RouteHandler[]): void;
  /** Register DELETE route  */  delete(pattern: string | RegExp, ...handlers: RouteHandler[]): void;
  /** Register OPTIONS route */  options(pattern: string | RegExp, ...handlers: RouteHandler[]): void;
  /** Accept ws upgrade */  ws(pattern: string | RegExp, handler: WebSocketHandler): void;  ws(    pattern: string | RegExp,    handlers: RouteHandler[],    handler: WebSocketHandler,  ): void;
  /**   * Set global error handler.   * All unhandled promise rejections occured on processing requests will be passed .   * Only one handler can be set for one router.   */  catch(handler: ErrorHandler): void;
  /**   * Set global finalizer.   * Every request will reach this handler.   * Note that request may already has been responded by other handlers.   * Only one handler can be set for one router.   */  finally(handler: ServeHandler): void;}
export function createRouter(): Router {  const middlewareList: ServeHandler[] = [];  const routes: {    pattern: string | RegExp;    methods?: string[];    handlers: RouteHandler[];    wsHandler?: WebSocketHandler;  }[] = [];  const prefixers: {    prefix: string;    handlers: RouteHandler[];  }[] = [];
  let errorHandler: ErrorHandler | undefined;  let finalHandler: ServeHandler | undefined;
  function handle(pattern: string | RegExp, ...handlers: RouteHandler[]) {    routes.push({ pattern, handlers });  }
  function route(prefix: string, ...handlers: RouteHandler[]) {    prefixers.push({ prefix, handlers });  }
  function get(pattern: string | RegExp, ...handlers: RouteHandler[]) {    routes.push({      pattern,      methods: ["GET", "HEAD"],      handlers,    });  }
  function post(pattern: string | RegExp, ...handlers: RouteHandler[]) {    routes.push({ pattern, methods: ["POST"], handlers });  }
  function put(pattern: string | RegExp, ...handlers: RouteHandler[]) {    routes.push({ pattern, methods: ["PUT"], handlers });  }
  function _delete(pattern: string | RegExp, ...handlers: RouteHandler[]) {    routes.push({ pattern, methods: ["DELETE"], handlers });  }
  function options(pattern: string | RegExp, ...handlers: RouteHandler[]) {    routes.push({ pattern, methods: ["OPTIONS"], handlers });  }
  function use(...handlers: ServeHandler[]) {    middlewareList.push(...handlers);  }
  function ws(pattern: string | RegExp, ...args: any[]) {    if (Array.isArray(args[0])) {      routes.push({ pattern, handlers: args[0], wsHandler: args[1] });    } else if (typeof args[0] === "function") {      routes.push({ pattern, handlers: [], wsHandler: args[0] });    } else {      throw new Error("invalid function arguments");    }  }
  function _catch(handler: ErrorHandler) {    errorHandler = handler;  }
  function _finally(handler: ServeHandler) {    finalHandler = handler;  }
  async function chainRoutes(    prefix: string,    req: ServerRequest,    handlers: (RouteHandler | Router)[],  ): Promise<boolean> {    for (const handler of handlers) {      if (isRoute(handler)) {        await handler.handleRoute(prefix, req);      } else {        await handler(req);      }      if (req.isResponded()) {        return true;      }    }    return false;  }  async function handleRouteInternal(    parentMatch: string,    req: ServerRequest,  ): Promise<void> {    for (const handler of middlewareList) {      await handler(req);      if (req.isResponded()) {        return;      }    }    const subpath = req.path.slice(parentMatch.length) || "/";    for (const { prefix, handlers } of prefixers) {      if (subpath.startsWith(prefix)) {        const match = subpath.match(new RegExp(`^${prefix}`));        assert(match != null);        req.match = match;        if (await chainRoutes(parentMatch + prefix, req, handlers)) {          return;        }      }    }    const matches = findLongestAndNearestMatches(      subpath,      routes.map((v) => v.pattern),    );    if (matches.length > 0) {      for (const [i, match] of matches) {        const { methods, handlers, wsHandler } = routes[i];        if (methods && !methods.includes(req.method)) {          continue;        }        req.match = match;        if (await chainRoutes(parentMatch + match, req, handlers)) {          return;        }        if (wsHandler && acceptable(req)) {          const sock = await acceptWebSocket(req);          req.markAsResponded(101);          wsHandler(sock, req);        }      }      if (!req.isResponded()) {        throw new RoutingError(404);      }    } else {      throw new RoutingError(404);    }  }  const handleRoute = async (parentMatch: string, req: ServerRequest) => {    try {      await handleRouteInternal(parentMatch, req);    } catch (e) {      if (errorHandler) {        await errorHandler(e, req);        if (!req.isResponded()) {          throw e;        }      } else {        throw e;      }    } finally {      finalHandler?.(req);    }  };  return {    handleRoute,    use,    handle,    route,    get,    post,    options,    put,    delete: _delete,    ws,    catch: _catch,    finally: _finally,  };}