index.js

import { cloneElement, h, Component } from 'preact';
import { exec, pathRankSort, assign, segmentize } from './util';

let customHistory = null;

const ROUTERS = [];

const subscribers = [];

const EMPTY = {};

function isPreactElement(node) {
	return node.__preactattr_!=null || typeof Symbol!=='undefined' && node[Symbol.for('preactattr')]!=null;
}

function setUrl(url, type='push') {
	if (customHistory && customHistory[type]) {
		customHistory[type](url);
	}
	else if (typeof history!=='undefined' && history[type+'State']) {
		history[type+'State'](null, null, url);
	}
}


function getCurrentUrl() {
	let url;
	if (customHistory && customHistory.location) {
		url = customHistory.location;
	}
	else if (customHistory && customHistory.getCurrentLocation) {
		url = customHistory.getCurrentLocation();
	}
	else {
		url = typeof location!=='undefined' ? location : EMPTY;
	}
	return `${url.pathname || ''}${url.search || ''}`;
}



function route(url, replace=false) {
	if (typeof url!=='string' && url.url) {
		replace = url.replace;
		url = url.url;
	}

	// only push URL into history if we can handle it
	if (canRoute(url)) {
		setUrl(url, replace ? 'replace' : 'push');
	}

	return routeTo(url);
}


/** Check if the given URL can be handled by any router instances. */
function canRoute(url) {
	for (let i=ROUTERS.length; i--; ) {
		if (ROUTERS[i].canRoute(url)) return true;
	}
	return false;
}


/** Tell all router instances to handle the given URL.  */
function routeTo(url) {
	let didRoute = false;
	for (let i=0; i<ROUTERS.length; i++) {
		if (ROUTERS[i].routeTo(url)===true) {
			didRoute = true;
		}
	}
	for (let i=subscribers.length; i--; ) {
		subscribers[i](url);
	}
	return didRoute;
}


function routeFromLink(node) {
	// only valid elements
	if (!node || !node.getAttribute) return;

	let href = node.getAttribute('href'),
		target = node.getAttribute('target');

	// ignore links with targets and non-path URLs
	if (!href || !href.match(/^\//g) || (target && !target.match(/^_?self$/i))) return;

	// attempt to route, if no match simply cede control to browser
	return route(href);
}


function handleLinkClick(e) {
	if (e.button==0) {
		routeFromLink(e.currentTarget || e.target || this);
		return prevent(e);
	}
}


function prevent(e) {
	if (e) {
		if (e.stopImmediatePropagation) e.stopImmediatePropagation();
		if (e.stopPropagation) e.stopPropagation();
		e.preventDefault();
	}
	return false;
}


function delegateLinkHandler(e) {
	// ignore events the browser takes care of already:
	if (e.ctrlKey || e.metaKey || e.altKey || e.shiftKey || e.button!==0) return;

	let t = e.target;
	do {
		if (String(t.nodeName).toUpperCase()==='A' && t.getAttribute('href') && isPreactElement(t)) {
			if (t.hasAttribute('native')) return;
			// if link is handled by the router, prevent browser defaults
			if (routeFromLink(t)) {
				return prevent(e);
			}
		}
	} while ((t=t.parentNode));
}


let eventListenersInitialized = false;

function initEventListeners() {
	if (eventListenersInitialized){
		return;
	}

	if (typeof addEventListener==='function') {
		if (!customHistory) {
			addEventListener('popstate', () => routeTo(getCurrentUrl()));
		}
		addEventListener('click', delegateLinkHandler);
	}
	eventListenersInitialized = true;
}


class Router extends Component {
	constructor(props, context) {
		super(props);
		this.baseUrl = this.props.base || '';
		if (props.path) {
			let segments = segmentize(props.path);
			segments.forEach(segment => {
				if (segment.indexOf(':') == -1) {
					this.baseUrl = this.baseUrl + '/' + segment;
				}
			});
		}
		if (props.history) {
			customHistory = props.history;
		}
		if (context && context['preact-router-base'] && !this.props.base) {
			this.baseUrl = context['preact-router-base'] + this.baseUrl;
		}
		this.state = {
			url: props.url || getCurrentUrl()
		};

		initEventListeners();
	}

	getChildContext() {
		let result = {['preact-router-base']: this.baseUrl};
		return result;
	}

	shouldComponentUpdate(props) {
		if (props.static!==true) return true;
		return props.url!==this.props.url || props.onChange!==this.props.onChange;
	}

	/** Check if the given URL can be matched against any children */
	canRoute(url) {
		return this.getMatchingChildren(this.props.children, url, false).length > 0;
	}

	/** Re-render children with a new URL to match against. */
	routeTo(url) {
		this._didRoute = false;
		this.setState({ url });

		// if we're in the middle of an update, don't synchronously re-route.
		if (this.updating) return this.canRoute(url);

		this.forceUpdate();
		return this._didRoute;
	}

	componentWillMount() {
		ROUTERS.push(this);
		this.updating = true;
	}

	componentDidMount() {
		if (customHistory) {
			this.unlisten = customHistory.listen((location) => {
				this.routeTo(`${location.pathname || ''}${location.search || ''}`);
			});
		}
		this.updating = false;
	}

	componentWillUnmount() {
		if (typeof this.unlisten==='function') this.unlisten();
		ROUTERS.splice(ROUTERS.indexOf(this), 1);
	}

	componentWillUpdate() {
		this.updating = true;
	}

	componentDidUpdate() {
		this.updating = false;
	}

	getMatchingChildren(children, url, invoke) {
		return children.slice().sort(pathRankSort).map( vnode => {
			let attrs = vnode.attributes || {},
				path = this.baseUrl + attrs.path,
				matches = exec(url, path, attrs);
			if (matches) {
				if (invoke!==false) {
					let newProps = { url, matches };
					assign(newProps, matches);
					return cloneElement(vnode, newProps);
				}
				return vnode;
			}
			return false;
		}).filter(Boolean);
	}

	render({ children, onChange }, { url }) {
		let active = this.getMatchingChildren(children, url, true);

		let current = active[0] || null;
		this._didRoute = !!current;

		let previous = this.previousUrl;
		if (url!==previous) {
			this.previousUrl = url;
			if (typeof onChange==='function') {
				onChange({
					router: this,
					url,
					previous,
					active,
					current
				});
			}
		}

		return current;
	}
}

const Link = (props) => (
	h('a', assign({ onClick: handleLinkClick }, props))
);

const Route = props => h(props.component, props);

Router.subscribers = subscribers;
Router.getCurrentUrl = getCurrentUrl;
Router.route = route;
Router.Router = Router;
Router.Route = Route;
Router.Link = Link;

export { subscribers, getCurrentUrl, route, Router, Route, Link };
export default Router;