Pre-fill suggested New File 'name' and 'content' with Query Params (#16556)

* feature: add (GitHub-style) querystrings for pre-filling new file content

* docs: add query parameters for new files

3 files changed, 35 insertions, 3 deletions

diff --git a/docs/content/doc/developers/integrations.en-us.md b/docs/content/doc/developers/integrations.en-us.md
index 8a111a3a8d..15d5e7e59e 100644
--- a/docs/content/doc/developers/integrations.en-us.md
+++ b/docs/content/doc/developers/integrations.en-us.md
@@ -24,3 +24,22 @@ If you are looking for [CI/CD](https://gitea.com/gitea/awesome-gitea#user-conten
 an [SDK](https://gitea.com/gitea/awesome-gitea#user-content-sdk),
 or even some extra [themes](https://gitea.com/gitea/awesome-gitea#user-content-themes),
 you can find them listed in the [awesome-gitea](https://gitea.com/gitea/awesome-gitea) repository!
+
+## Pre-Fill New File name and contents
+
+If you'd like to open a new file with a given name and contents,
+you can do so with query parameters:
+
+```txt
+GET /{{org}}/{{repo}}/_new/{{filepath}}
+    ?filename={{filename}}
+    &value={{content}}
+```
+
+For example:
+
+```txt
+GET https://git.example.com/johndoe/bliss/_new/articles/
+    ?filename=hello-world.md
+    &value=Hello%2C%20World!
+```
diff --git a/routers/web/repo/editor.go b/routers/web/repo/editor.go
index 792258da84..a99c1c7c61 100644
--- a/routers/web/repo/editor.go
+++ b/routers/web/repo/editor.go
@@ -81,7 +81,11 @@ func editFile(ctx *context.Context, isNewFile bool) {
 		return
 	}
 
-	treeNames, treePaths := getParentTreeFields(ctx.Repo.TreePath)
+	// Check if the filename (and additional path) is specified in the querystring
+	// (filename is a misnomer, but kept for compatibility with Github)
+	filePath, fileName := path.Split(ctx.Req.URL.Query().Get("filename"))
+	filePath = strings.Trim(filePath, "/")
+	treeNames, treePaths := getParentTreeFields(path.Join(ctx.Repo.TreePath, filePath))
 
 	if !isNewFile {
 		entry, err := ctx.Repo.Commit.GetTreeEntryByPath(ctx.Repo.TreePath)
@@ -136,7 +140,8 @@ func editFile(ctx *context.Context, isNewFile bool) {
 			ctx.Data["FileContent"] = content
 		}
 	} else {
-		treeNames = append(treeNames, "") // Append empty string to allow user name the new file.
+		// Append filename from query, or empty string to allow user name the new file.
+		treeNames = append(treeNames, fileName)
 	}
 
 	ctx.Data["TreeNames"] = treeNames
diff --git a/web_src/js/index.js b/web_src/js/index.js
index 6156429deb..4900d37f3f 100644
--- a/web_src/js/index.js
+++ b/web_src/js/index.js
@@ -1825,7 +1825,7 @@ async function initEditor() {
   const $editArea = $('.repository.editor textarea#edit_area');
   if (!$editArea.length) return;
 
-  await createCodeEditor($editArea[0], $editFilename[0], previewFileModes);
+  const editor = await createCodeEditor($editArea[0], $editFilename[0], previewFileModes);
 
   // Using events from https://github.com/codedance/jquery.AreYouSure#advanced-usage
   // to enable or disable the commit button
@@ -1849,6 +1849,14 @@ async function initEditor() {
     }
   });
 
+  // Update the editor from query params, if available,
+  // only after the dirtyFileClass initialization
+  const params = new URLSearchParams(window.location.search);
+  const value = params.get('value');
+  if (value) {
+    editor.setValue(value);
+  }
+
   $commitButton.on('click', (event) => {
     // A modal which asks if an empty file should be committed
     if ($editArea.val().length === 0) {