Add `Copy` button to gists (#338)

extension/content.css

@@ -532,3 +532,8 @@ td.blob-code.blob-code-deletion:before {
 .diffbar > .diffstat {
 	float: right;
 }
+
+/* copy button for gists margin */
+.copy-btn {
+	margin: 0 10px 0 0;
+}

extension/content.js

@@ -1,4 +1,4 @@
-/* globals gitHubInjection, pageDetect, icons, diffFileHeader, addReactionParticipants, addFileCopyButton, enableCopyOnY, addBlameParentLinks, showRealNames, markUnread */
+/* globals gitHubInjection, pageDetect, icons, diffFileHeader, addReactionParticipants, addFileCopyButton, addGistCopyButton, enableCopyOnY, addBlameParentLinks, showRealNames, markUnread */
 
 'use strict';
 const {ownerName, repoName} = pageDetect.getOwnerAndRepo();
@@ -320,7 +320,9 @@ $(document).on('click', event => {
 document.addEventListener('DOMContentLoaded', () => {
 	const username = getUsername();
 
-	if (!pageDetect.isGist()) {
+	if (pageDetect.isGist()) {
+		addGistCopyButton();
+	} else {
 		addTrendingMenuItem();
 	}
 

extension/copy-gist.js

@@ -0,0 +1,26 @@
+/* globals utils */
+
+'use strict';
+
+window.addGistCopyButton = () => {
+	// Button already added (partial page nav), or non-text file
+	if ($('.copy-btn').length > 0) {
+		return;
+	}
+	const $gistsSibling = $('.file-actions > .btn.btn-sm');
+
+	for (let i = 0; i < $gistsSibling.length; i++) {
+		const commonContainer = $('.file')[i];
+		const isSourceCodeClass = commonContainer.children[1].classList.contains('blob-wrapper');
+		const gistUri = $gistsSibling[i].href;
+		if (isSourceCodeClass) {
+			$(`<a href="${gistUri}" class="btn btn-sm copy-btn">Copy</a>`).insertBefore($gistsSibling[i]);
+		}
+	}
+
+	$(document).on('click', '.copy-btn', e => {
+		e.preventDefault();
+		const fileContents = $(`#${e.currentTarget.offsetParent.id}`).find('.js-file-line-container')[0].innerText;
+		utils.copyToClipboard(fileContents);
+	});
+};

extension/manifest.json

@@ -33,6 +33,7 @@
 				"diffheader.js",
 				"reactions-avatars.js",
 				"copy-file.js",
+				"copy-gist.js",
 				"copy-on-y.js",
 				"show-names.js",
 				"content.js",