survey/templates/router.ts

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/*
* Copyright (C) 2021 Aravinth Manivannan <realaravinth@batsense.net>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/** Removes trailing slash from URI */
const normalizeUri = (uri: string) => {
uri = uri.trim();
if (uri.length == 0) {
throw new Error("uri is empty");
}
const uriLength = uri.length;
if (uri[uriLength - 1] == "/") {
uri = uri.slice(0, uriLength - 1);
}
return uri;
};
/** URI<-> Fn mapping type */
type routeTuple = {
pattern: RegExp;
fn: () => void;
};
/**
* Router that selectively executes fucntions
* based on window.location.pathname
* */
export class Router {
routes: Array<routeTuple>;
constructor() {
this.routes = [];
}
/**
* registers a route-function pair with Router
* @param {string} uri - route to be registered
* @param {function} fn: - function to be registered when window.locatin.path
* matches uri
* */
register(uri: string, fn: () => void): void {
uri = normalizeUri(uri);
const pattern = new RegExp(`^${uri}$`);
const patterString = pattern.toString();
if (
this.routes.find((route) => {
if (route.pattern.toString() == patterString) {
return true;
} else {
return false;
}
})
) {
throw new Error("URI exists");
}
const route: routeTuple = {
pattern,
fn,
};
this.routes.push(route);
}
/**
* executes registered function with route
* matches window.pathname.location
* */
route(): void {
const path = normalizeUri(window.location.pathname);
let fn: undefined | (() => void);
if (
this.routes.find((route) => {
if (path.match(route.pattern)) {
fn = route.fn;
return true;
}
})
) {
if (fn === undefined) {
throw new Error("Route isn't registered");
} else {
return fn();
}
}
}
}