refined-github · fregante · Jun 18, 2020 · Jun 12, 2020 · Jun 14, 2020 · Jun 14, 2020
diff --git a/readme.md b/readme.md
@@ -137,6 +137,7 @@ Thanks for contributing! 🦋🙌
 - [](# "repo-age") [Adds the age of the repository to the statistics bar.](https://user-images.githubusercontent.com/3848317/69494069-7d2b1180-0eb7-11ea-9aa1-d4194e566340.png)
 - [](# "show-open-prs-of-forks") [In your forked repos, shows number of your open PRs to the original repo.](https://user-images.githubusercontent.com/1922624/76398271-e0648500-637c-11ea-8210-53dda1be9d51.png)
 - [](# "go-to-action-from-file") [Adds a link to access the past runs of a GitHub Action workflow when seeing the workflow configuration file.](https://user-images.githubusercontent.com/1402241/80146153-ab6d6400-85b1-11ea-9f38-e87950692a62.png)
+- [](# "fork-source-link-same-view") [Points the “Forked from user/repository” link to current folder or file in the upstream repository.](https://user-images.githubusercontent.com/1402241/84795784-3722d000-aff8-11ea-9b34-97c01acf4fd4.png)
 
 <!-- Refer to style guide above. Keep this message between sections. -->
 

diff --git a/source/features/fork-source-link-same-view.tsx b/source/features/fork-source-link-same-view.tsx
@@ -0,0 +1,37 @@
+import select from 'select-dom';
+import * as pageDetect from 'github-url-detection';
+
+import features from '.';
+import GitHubURL from '../github-helpers/github-url';
+import doesFileExist from '../github-helpers/does-file-exist';
+import getDefaultBranch from '../github-helpers/get-default-branch';
+import {getRepositoryInfo, getForkedRepo} from '../github-helpers';
+
+async function init(): Promise<void> {
+	const forkedRepository = getRepositoryInfo(getForkedRepo());
+	const sameViewUrl = new GitHubURL(location.href).assign({
+		user: forkedRepository.owner,
+		repository: forkedRepository.name,
+		branch: await getDefaultBranch(forkedRepository)
+	});
+
+	if (await doesFileExist(sameViewUrl)) {
+		select<HTMLAnchorElement>('.fork-flag .text a')!.pathname = sameViewUrl.pathname;
+	}
+}
+
+void features.add({
+	id: __filebasename,
+	description: 'Points the “Forked from user/repository” link to current folder or file in the upstream repository.',
+	screenshot: 'https://user-images.githubusercontent.com/1402241/84795784-3722d000-aff8-11ea-9b34-97c01acf4fd4.png'
+}, {
+	include: [
+		pageDetect.isSingleFile,
+		pageDetect.isRepoTree
+	],
+	exclude: [
+		() => !pageDetect.isForkedRepo(),
+		() => pageDetect.isRepoRoot()
+	],
+	init
+});
diff --git a/source/github-helpers/does-file-exist.tsx b/source/github-helpers/does-file-exist.tsx
@@ -0,0 +1,14 @@
+import * as api from './api';
+import GitHubURL from './github-url';
+
+export default async function doesFileExist(url: GitHubURL): Promise<boolean> {
+	const {repository} = await api.v4(`
+		repository(owner: "${url.user}", name: "${url.repository}") {
+			file: object(expression: "${url.branch}:${url.filePath}") {
+				id
+			}
+		}
+	`);
+
+	return Boolean(repository.file);
+}
diff --git a/source/refined-github.ts b/source/refined-github.ts
@@ -182,6 +182,7 @@ import './features/prevent-pr-commit-link-loss';
 import './features/first-published-tag-for-merged-pr';
 import './features/show-associated-branch-prs-on-fork';
 import './features/faster-reviews';
+import './features/fork-source-link-same-view';
 
 // Add global for easier debugging
 (window as any).select = select;