[v10.0/forgejo] Fix inline file preview for rendered files (#6685)

**Backport:** https://codeberg.org/forgejo/forgejo/pulls/6572

### What?

This fixes the inline file preview for rendered files (e.g., markdown). [Here, a live issue in v11](https://v11.next.forgejo.org/mahlzahn/test-inline-file-preview/issues/1) and [the same in v7 (with even more bugs)](https://v7.next.forgejo.org/mahlzahn/test-inline-file-preview/issues/1).

It fixes
1. the inline preview for possibly rendered files, when the link is specified with `?display=source`. This happens, e.g., if you are watching a (e.g., markdown) file in source and then want to link some of its lines.
2. the link to the source file inside the inline preview for possible rendered files (currently it links to the rendered version and then the `#L…` cannot point to the correct lines). This is done by always adding `?display=source` to the link.

### Screenshots
<details><summary>

#### Before

</summary>

![image](/attachments/898f82d5-d116-465a-89e2-ed83da189762)

</details>
<details><summary>

#### After

</summary>

![image](/attachments/41058620-47f3-4f6a-b427-66ef33c1a07f)

</details>

### Tests

- I added test coverage for Go changes...
  - [x] in their respective `*_test.go` for unit tests.
  - [ ] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
  - [ ] in `web_src/js/*.test.js` if it can be unit tested.
  - [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).

I think that this minor edit does not need special tests. Some backend tests have been updated to reflect the addition of URL parameters.

#### Manual testing
- create a repository with a file that can be rendered with couple of lines inside, e.g., a markdown README.md
- go to the source of this file (e.g., `…/src/branch/main/README.md`)
- click on the `<> View Source` button (or add `?display=source` to the URL)
- click on one of the lines, then on the three dots, then on ”Reference in a new issue“
- continue creating the issue

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] I do not want this change to show in the release notes.
- [ ] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

Co-authored-by: Robert Wolff <mahlzahn@posteo.de>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/6685
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>
Co-committed-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>

modules/markup/file_preview.go

@@ -77,6 +77,12 @@ func newFilePreview(ctx *RenderContext, node *html.Node, locale translation.Loca
 
 	commitSha := node.Data[m[4]:m[5]]
 	filePath := node.Data[m[6]:m[7]]
+	urlFullSource := urlFull
+	if strings.HasSuffix(filePath, "?display=source") {
+		filePath = strings.TrimSuffix(filePath, "?display=source")
+	} else if Type(filePath) != "" {
+		urlFullSource = node.Data[m[0]:m[6]] + filePath + "?display=source#" + node.Data[m[8]:m[1]]
+	}
 	hash := node.Data[m[8]:m[9]]
 
 	preview.start = m[0]
@@ -113,7 +119,7 @@ func newFilePreview(ctx *RenderContext, node *html.Node, locale translation.Loca
 		titleBuffer.WriteString(" – ")
 	}
 
-	err = html.Render(titleBuffer, createLink(urlFull, filePath, "muted"))
+	err = html.Render(titleBuffer, createLink(urlFullSource, filePath, "muted"))
 	if err != nil {
 		log.Error("failed to render filepathLink: %v", err)
 	}

modules/markup/html_test.go

@@ -1026,4 +1026,107 @@ func TestRender_FilePreview(t *testing.T) {
 			localMetas,
 		)
 	})
+
+	commitFileURL := util.URLJoin(markup.TestRepoURL, "src", "commit", "c9913120ed2c1e27c1d7752ecdb7a504dc7cf6be", "path", "to", "file.md")
+
+	t.Run("rendered file with ?display=source", func(t *testing.T) {
+		testRender(
+			commitFileURL+"?display=source"+"#L1-L2",
+			`<p></p>`+
+				`<div class="file-preview-box">`+
+				`<div class="header">`+
+				`<div>`+
+				`<a href="http://localhost:3000/gogits/gogs/src/commit/c9913120ed2c1e27c1d7752ecdb7a504dc7cf6be/path/to/file.md?display=source#L1-L2" class="muted" rel="nofollow">path/to/file.md</a>`+
+				`</div>`+
+				`<span class="text small grey">`+
+				`Lines 1 to 2 in <a href="http://localhost:3000/gogits/gogs/src/commit/c9913120ed2c1e27c1d7752ecdb7a504dc7cf6be" class="text black" rel="nofollow">c991312</a>`+
+				`</span>`+
+				`</div>`+
+				`<div class="ui table">`+
+				`<table class="file-preview">`+
+				`<tbody>`+
+				`<tr>`+
+				`<td class="lines-num"><span data-line-number="1"></span></td>`+
+				`<td class="lines-code chroma"><code class="code-inner"><span class="gh"># A`+"\n"+`</span></code></td>`+
+				`</tr>`+
+				`<tr>`+
+				`<td class="lines-num"><span data-line-number="2"></span></td>`+
+				`<td class="lines-code chroma"><code class="code-inner"><span class="gh"></span>B`+"\n"+`</code></td>`+
+				`</tr>`+
+				`</tbody>`+
+				`</table>`+
+				`</div>`+
+				`</div>`+
+				`<p></p>`,
+			localMetas,
+		)
+	})
+
+	t.Run("rendered file without ?display=source", func(t *testing.T) {
+		testRender(
+			commitFileURL+"#L1-L2",
+			`<p></p>`+
+				`<div class="file-preview-box">`+
+				`<div class="header">`+
+				`<div>`+
+				`<a href="http://localhost:3000/gogits/gogs/src/commit/c9913120ed2c1e27c1d7752ecdb7a504dc7cf6be/path/to/file.md?display=source#L1-L2" class="muted" rel="nofollow">path/to/file.md</a>`+
+				`</div>`+
+				`<span class="text small grey">`+
+				`Lines 1 to 2 in <a href="http://localhost:3000/gogits/gogs/src/commit/c9913120ed2c1e27c1d7752ecdb7a504dc7cf6be" class="text black" rel="nofollow">c991312</a>`+
+				`</span>`+
+				`</div>`+
+				`<div class="ui table">`+
+				`<table class="file-preview">`+
+				`<tbody>`+
+				`<tr>`+
+				`<td class="lines-num"><span data-line-number="1"></span></td>`+
+				`<td class="lines-code chroma"><code class="code-inner"><span class="gh"># A`+"\n"+`</span></code></td>`+
+				`</tr>`+
+				`<tr>`+
+				`<td class="lines-num"><span data-line-number="2"></span></td>`+
+				`<td class="lines-code chroma"><code class="code-inner"><span class="gh"></span>B`+"\n"+`</code></td>`+
+				`</tr>`+
+				`</tbody>`+
+				`</table>`+
+				`</div>`+
+				`</div>`+
+				`<p></p>`,
+			localMetas,
+		)
+	})
+
+	commitFileURL = util.URLJoin(markup.TestRepoURL, "src", "commit", "190d9492934af498c3f669d6a2431dc5459e5b20", "path", "to", "file.go")
+
+	t.Run("normal file with ?display=source", func(t *testing.T) {
+		testRender(
+			commitFileURL+"?display=source"+"#L2-L3",
+			`<p></p>`+
+				`<div class="file-preview-box">`+
+				`<div class="header">`+
+				`<div>`+
+				`<a href="http://localhost:3000/gogits/gogs/src/commit/190d9492934af498c3f669d6a2431dc5459e5b20/path/to/file.go?display=source#L2-L3" class="muted" rel="nofollow">path/to/file.go</a>`+
+				`</div>`+
+				`<span class="text small grey">`+
+				`Lines 2 to 3 in <a href="http://localhost:3000/gogits/gogs/src/commit/190d9492934af498c3f669d6a2431dc5459e5b20" class="text black" rel="nofollow">190d949</a>`+
+				`</span>`+
+				`</div>`+
+				`<div class="ui table">`+
+				`<table class="file-preview">`+
+				`<tbody>`+
+				`<tr>`+
+				`<td class="lines-num"><span data-line-number="2"></span></td>`+
+				`<td class="lines-code chroma"><code class="code-inner"><span class="nx">B</span>`+"\n"+`</code></td>`+
+				`</tr>`+
+				`<tr>`+
+				`<td class="lines-num"><span data-line-number="3"></span></td>`+
+				`<td class="lines-code chroma"><code class="code-inner"><span class="nx">C</span>`+"\n"+`</code></td>`+
+				`</tr>`+
+				`</tbody>`+
+				`</table>`+
+				`</div>`+
+				`</div>`+
+				`<p></p>`,
+			localMetas,
+		)
+	})
 }

modules/markup/tests/repo/repo1_filepreview/objects/72/1f0ce13d83f93d431b849a554a62948b85f573

@@ -0,0 +1 @@
+x
•ŽKŠ1@]çµ$¿J¥aæz€JRÁ@w+éØsýõ®ÞâñàåÛ²´
ÖÛÃè"@VL&J
3%f-ÑGDÒq2>FçjBOEݹË:ÀgÃ\1¤œ¦ê¦’kÀêªEM6DÔ,Ÿ\‚âǸÞ:\6é¾OülmÈ©­;Ï­|ƒ!GäŒE‚£6Z«üzòY¥Î²
¨m¸wÙ›üÂÿi‘.x-o³ò"›úŒLÌ

modules/markup/tests/repo/repo1_filepreview/refs/heads/master

@@ -1 +1 @@
-4c1aaf56bcb9f39dcf65f3f250726850aed13cd6
+c9913120ed2c1e27c1d7752ecdb7a504dc7cf6be