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import React from 'dom-chef';
import select from 'select-dom';
import onetime from 'onetime';
import elementReady from 'element-ready';
import * as pageDetect from 'github-url-detection';
import features from '.';
import getDefaultBranch from '../github-helpers/get-default-branch';
import {getCleanPathname} from '../github-helpers';
function getType(): string {
return location.pathname.split('/').pop()!.includes('.') ? 'file' : 'object';
}
async function is404(url: string): Promise<boolean> {
const {status} = await fetch(url, {method: 'head'});
return status === 404;
}
function getStrikeThrough(text: string): HTMLElement {
return <del style={{color: '#6a737d'}}>{text}</del>;
}
async function checkAnchor(anchor: HTMLAnchorElement): Promise<void> {
if (await is404(anchor.href)) {
anchor.replaceWith(getStrikeThrough(anchor.textContent!));
}
}
function parseCurrentURL(): string[] {
const parts = getCleanPathname().split('/');
if (parts[2] === 'blob') { // Blob URLs are never useful
parts[2] = 'tree';
}
return parts;
}
// If the resource was deleted, link to the commit history
async function addCommitHistoryLink(bar: Element): Promise<void> {
const parts = parseCurrentURL();
parts[2] = 'commits';
const url = '/' + parts.join('/');
if (await is404(location.origin + url)) {
return;
}
bar.after(
<p className="container mt-4 text-center">
See also the {getType()}’s <a href={url}>commit history</a>.
</p>
);
}
// If the resource exists in the default branch, link to it
async function addDefaultBranchLink(bar: Element): Promise<void> {
const parts = getCleanPathname().split('/');
const branch = parts[3];
if (!branch) {
return;
}
const defaultBranch = await getDefaultBranch();
if (branch === defaultBranch) {
return;
}
parts[3] = defaultBranch; // Change branch
const url = '/' + parts.join('/');
if (await is404(location.origin + url)) {
return;
}
bar.after(
<p className="container mt-4 text-center">
The {getType()} exists on the <a href={url}>default branch</a>.
</p>
);
}
function init(): false | void {
const parts = parseCurrentURL();
if (parts.length <= 1 || !select.exists('[alt*="This is not the web page you are looking for"]')) {
return false;
}
const bar = <h2 className="container mt-4 text-center"/>;
for (const [i, part] of parts.entries()) {
if (i === 2 && ['tree', 'blob', 'edit'].includes(part)) {
// Exclude parts that don't exist as standalones
continue;
}
if (i === parts.length - 1) {
// The last part of the URL is a known 404
bar.append(' / ', getStrikeThrough(part));
} else {
const pathname = '/' + parts.slice(0, i + 1).join('/');
bar.append(i ? ' / ' : '', <a href={pathname}>{part}</a>);
}
}
select('main > :first-child, #parallax_illustration')!.after(bar);
// Check parts from right to left; skip the last part
for (let i = bar.children.length - 2; i >= 0; i--) {
void checkAnchor(bar.children[i] as HTMLAnchorElement);
}
if (['tree', 'blob'].includes(parts[2])) {
// Object might be 410 Gone
void addCommitHistoryLink(bar);
}
if (['tree', 'blob', 'edit'].includes(parts[2])) {
// File might not be available on the current branch
// GitHub already redirects /tree/ and /blob/ natively
void addDefaultBranchLink(bar);
}
}
async function initPRCommit(): Promise<void | false> {
const commitUrl = location.href.replace(/pull\/\d+\/commits/, 'commit');
if (await is404(commitUrl)) {
return false;
}
const blankSlateParagraph = await elementReady('.blankslate p');
blankSlateParagraph!.after(
<p>You can also try to <a href={commitUrl}>view the detached standalone commit</a>.</p>
);
}
void features.add(__filebasename, {
include: [
pageDetect.is404
],
init: onetime(init)
}, {
include: [
pageDetect.isPRCommit404
],
awaitDomReady: false,
init: onetime(initPRCommit)
});
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