[v7.0/forgejo] Render inline file permalinks

Backport: https://codeberg.org/forgejo/forgejo/pulls/2669

(cherry picked from commit 1d3240887c)
(cherry picked from commit 781a37fbe1)
(cherry picked from commit 8309f008c2)
(cherry picked from commit fae8d9f70d)
(cherry picked from commit 6721cba75b)
(cherry picked from commit 562e5cdf32)
(cherry picked from commit d789d33229)
(cherry picked from commit 8218e80bfc)
(cherry picked from commit 10bca456a9)
(cherry picked from commit db6f6281fc)
(cherry picked from commit ed8e8a792e)
(cherry picked from commit d6428f92ce)
(cherry picked from commit 069d87b80f)
(cherry picked from commit 2b6546adc9)
(cherry picked from commit 4c7cb0a5d2)
(cherry picked from commit 7e0014dd13)
(cherry picked from commit 16a8658878)
(cherry picked from commit 6e98bacbbd)

custom/conf/app.example.ini

@@ -2338,6 +2338,8 @@ LEVEL = Info
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Set the maximum number of characters in a mermaid source. (Set to -1 to disable limits)
 ;MERMAID_MAX_SOURCE_CHARACTERS = 5000
+;; Set the maximum number of lines allowed for a filepreview. (Set to -1 to disable limits; set to 0 to disable the feature)
+;FILEPREVIEW_MAX_LINES = 50
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

modules/markup/file_preview.go

@@ -0,0 +1,323 @@
+// Copyright The Forgejo Authors.
+// SPDX-License-Identifier: MIT
+
+package markup
+
+import (
+	"bufio"
+	"bytes"
+	"html/template"
+	"regexp"
+	"slices"
+	"strconv"
+	"strings"
+
+	"code.gitea.io/gitea/modules/charset"
+	"code.gitea.io/gitea/modules/highlight"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/translation"
+
+	"golang.org/x/net/html"
+	"golang.org/x/net/html/atom"
+)
+
+// filePreviewPattern matches "http://domain/org/repo/src/commit/COMMIT/filepath#L1-L2"
+var filePreviewPattern = regexp.MustCompile(`https?://((?:\S+/){3})src/commit/([0-9a-f]{4,64})/(\S+)#(L\d+(?:-L\d+)?)`)
+
+type FilePreview struct {
+	fileContent []template.HTML
+	subTitle    template.HTML
+	lineOffset  int
+	urlFull     string
+	filePath    string
+	start       int
+	end         int
+	isTruncated bool
+}
+
+func NewFilePreview(ctx *RenderContext, node *html.Node, locale translation.Locale) *FilePreview {
+	if setting.FilePreviewMaxLines == 0 {
+		// Feature is disabled
+		return nil
+	}
+
+	preview := &FilePreview{}
+
+	m := filePreviewPattern.FindStringSubmatchIndex(node.Data)
+	if m == nil {
+		return nil
+	}
+
+	// Ensure that every group has a match
+	if slices.Contains(m, -1) {
+		return nil
+	}
+
+	preview.urlFull = node.Data[m[0]:m[1]]
+
+	// Ensure that we only use links to local repositories
+	if !strings.HasPrefix(preview.urlFull, setting.AppURL+setting.AppSubURL) {
+		return nil
+	}
+
+	projPath := strings.TrimSuffix(node.Data[m[2]:m[3]], "/")
+
+	commitSha := node.Data[m[4]:m[5]]
+	preview.filePath = node.Data[m[6]:m[7]]
+	hash := node.Data[m[8]:m[9]]
+
+	preview.start = m[0]
+	preview.end = m[1]
+
+	projPathSegments := strings.Split(projPath, "/")
+	var language string
+	fileBlob, err := DefaultProcessorHelper.GetRepoFileBlob(
+		ctx.Ctx,
+		projPathSegments[len(projPathSegments)-2],
+		projPathSegments[len(projPathSegments)-1],
+		commitSha, preview.filePath,
+		&language,
+	)
+	if err != nil {
+		return nil
+	}
+
+	lineSpecs := strings.Split(hash, "-")
+
+	commitLinkBuffer := new(bytes.Buffer)
+	err = html.Render(commitLinkBuffer, createLink(node.Data[m[0]:m[5]], commitSha[0:7], "text black"))
+	if err != nil {
+		log.Error("failed to render commitLink: %v", err)
+	}
+
+	var startLine, endLine int
+
+	if len(lineSpecs) == 1 {
+		startLine, _ = strconv.Atoi(strings.TrimPrefix(lineSpecs[0], "L"))
+		endLine = startLine
+		preview.subTitle = locale.Tr(
+			"markup.filepreview.line", startLine,
+			template.HTML(commitLinkBuffer.String()),
+		)
+
+		preview.lineOffset = startLine - 1
+	} else {
+		startLine, _ = strconv.Atoi(strings.TrimPrefix(lineSpecs[0], "L"))
+		endLine, _ = strconv.Atoi(strings.TrimPrefix(lineSpecs[1], "L"))
+		preview.subTitle = locale.Tr(
+			"markup.filepreview.lines", startLine, endLine,
+			template.HTML(commitLinkBuffer.String()),
+		)
+
+		preview.lineOffset = startLine - 1
+	}
+
+	lineCount := endLine - (startLine - 1)
+	if startLine < 1 || endLine < 1 || lineCount < 1 {
+		return nil
+	}
+
+	if setting.FilePreviewMaxLines > 0 && lineCount > setting.FilePreviewMaxLines {
+		preview.isTruncated = true
+		lineCount = setting.FilePreviewMaxLines
+	}
+
+	dataRc, err := fileBlob.DataAsync()
+	if err != nil {
+		return nil
+	}
+	defer dataRc.Close()
+
+	reader := bufio.NewReader(dataRc)
+
+	// skip all lines until we find our startLine
+	for i := 1; i < startLine; i++ {
+		_, err := reader.ReadBytes('\n')
+		if err != nil {
+			return nil
+		}
+	}
+
+	// capture the lines we're interested in
+	lineBuffer := new(bytes.Buffer)
+	for i := 0; i < lineCount; i++ {
+		buf, err := reader.ReadBytes('\n')
+		if err != nil {
+			break
+		}
+		lineBuffer.Write(buf)
+	}
+
+	// highlight the file...
+	fileContent, _, err := highlight.File(fileBlob.Name(), language, lineBuffer.Bytes())
+	if err != nil {
+		log.Error("highlight.File failed, fallback to plain text: %v", err)
+		fileContent = highlight.PlainText(lineBuffer.Bytes())
+	}
+	preview.fileContent = fileContent
+
+	return preview
+}
+
+func (p *FilePreview) CreateHTML(locale translation.Locale) *html.Node {
+	table := &html.Node{
+		Type: html.ElementNode,
+		Data: atom.Table.String(),
+		Attr: []html.Attribute{{Key: "class", Val: "file-preview"}},
+	}
+	tbody := &html.Node{
+		Type: html.ElementNode,
+		Data: atom.Tbody.String(),
+	}
+
+	status := &charset.EscapeStatus{}
+	statuses := make([]*charset.EscapeStatus, len(p.fileContent))
+	for i, line := range p.fileContent {
+		statuses[i], p.fileContent[i] = charset.EscapeControlHTML(line, locale, charset.FileviewContext)
+		status = status.Or(statuses[i])
+	}
+
+	for idx, code := range p.fileContent {
+		tr := &html.Node{
+			Type: html.ElementNode,
+			Data: atom.Tr.String(),
+		}
+
+		lineNum := strconv.Itoa(p.lineOffset + idx + 1)
+
+		tdLinesnum := &html.Node{
+			Type: html.ElementNode,
+			Data: atom.Td.String(),
+			Attr: []html.Attribute{
+				{Key: "class", Val: "lines-num"},
+			},
+		}
+		spanLinesNum := &html.Node{
+			Type: html.ElementNode,
+			Data: atom.Span.String(),
+			Attr: []html.Attribute{
+				{Key: "data-line-number", Val: lineNum},
+			},
+		}
+		tdLinesnum.AppendChild(spanLinesNum)
+		tr.AppendChild(tdLinesnum)
+
+		if status.Escaped {
+			tdLinesEscape := &html.Node{
+				Type: html.ElementNode,
+				Data: atom.Td.String(),
+				Attr: []html.Attribute{
+					{Key: "class", Val: "lines-escape"},
+				},
+			}
+
+			if statuses[idx].Escaped {
+				btnTitle := ""
+				if statuses[idx].HasInvisible {
+					btnTitle += locale.TrString("repo.invisible_runes_line") + " "
+				}
+				if statuses[idx].HasAmbiguous {
+					btnTitle += locale.TrString("repo.ambiguous_runes_line")
+				}
+
+				escapeBtn := &html.Node{
+					Type: html.ElementNode,
+					Data: atom.Button.String(),
+					Attr: []html.Attribute{
+						{Key: "class", Val: "toggle-escape-button btn interact-bg"},
+						{Key: "title", Val: btnTitle},
+					},
+				}
+				tdLinesEscape.AppendChild(escapeBtn)
+			}
+
+			tr.AppendChild(tdLinesEscape)
+		}
+
+		tdCode := &html.Node{
+			Type: html.ElementNode,
+			Data: atom.Td.String(),
+			Attr: []html.Attribute{
+				{Key: "class", Val: "lines-code chroma"},
+			},
+		}
+		codeInner := &html.Node{
+			Type: html.ElementNode,
+			Data: atom.Code.String(),
+			Attr: []html.Attribute{{Key: "class", Val: "code-inner"}},
+		}
+		codeText := &html.Node{
+			Type: html.RawNode,
+			Data: string(code),
+		}
+		codeInner.AppendChild(codeText)
+		tdCode.AppendChild(codeInner)
+		tr.AppendChild(tdCode)
+
+		tbody.AppendChild(tr)
+	}
+
+	table.AppendChild(tbody)
+
+	twrapper := &html.Node{
+		Type: html.ElementNode,
+		Data: atom.Div.String(),
+		Attr: []html.Attribute{{Key: "class", Val: "ui table"}},
+	}
+	twrapper.AppendChild(table)
+
+	header := &html.Node{
+		Type: html.ElementNode,
+		Data: atom.Div.String(),
+		Attr: []html.Attribute{{Key: "class", Val: "header"}},
+	}
+	afilepath := &html.Node{
+		Type: html.ElementNode,
+		Data: atom.A.String(),
+		Attr: []html.Attribute{
+			{Key: "href", Val: p.urlFull},
+			{Key: "class", Val: "muted"},
+		},
+	}
+	afilepath.AppendChild(&html.Node{
+		Type: html.TextNode,
+		Data: p.filePath,
+	})
+	header.AppendChild(afilepath)
+
+	psubtitle := &html.Node{
+		Type: html.ElementNode,
+		Data: atom.Span.String(),
+		Attr: []html.Attribute{{Key: "class", Val: "text small grey"}},
+	}
+	psubtitle.AppendChild(&html.Node{
+		Type: html.RawNode,
+		Data: string(p.subTitle),
+	})
+	header.AppendChild(psubtitle)
+
+	node := &html.Node{
+		Type: html.ElementNode,
+		Data: atom.Div.String(),
+		Attr: []html.Attribute{{Key: "class", Val: "file-preview-box"}},
+	}
+	node.AppendChild(header)
+
+	if p.isTruncated {
+		warning := &html.Node{
+			Type: html.ElementNode,
+			Data: atom.Div.String(),
+			Attr: []html.Attribute{{Key: "class", Val: "ui warning message tw-text-left"}},
+		}
+		warning.AppendChild(&html.Node{
+			Type: html.TextNode,
+			Data: locale.TrString("markup.filepreview.truncated"),
+		})
+		node.AppendChild(warning)
+	}
+
+	node.AppendChild(twrapper)
+
+	return node
+}

modules/markup/html.go

@@ -171,6 +171,7 @@ type processor func(ctx *RenderContext, node *html.Node)
 var defaultProcessors = []processor{
 	fullIssuePatternProcessor,
 	comparePatternProcessor,
+	filePreviewPatternProcessor,
 	fullHashPatternProcessor,
 	shortLinkProcessor,
 	linkProcessor,
@@ -1054,6 +1055,47 @@ func comparePatternProcessor(ctx *RenderContext, node *html.Node) {
 	}
 }
 
+func filePreviewPatternProcessor(ctx *RenderContext, node *html.Node) {
+	if ctx.Metas == nil {
+		return
+	}
+	if DefaultProcessorHelper.GetRepoFileBlob == nil {
+		return
+	}
+
+	next := node.NextSibling
+	for node != nil && node != next {
+		locale, ok := ctx.Ctx.Value(translation.ContextKey).(translation.Locale)
+		if !ok {
+			locale = translation.NewLocale("en-US")
+		}
+
+		preview := NewFilePreview(ctx, node, locale)
+		if preview == nil {
+			return
+		}
+
+		previewNode := preview.CreateHTML(locale)
+
+		// Specialized version of replaceContent, so the parent paragraph element is not destroyed from our div
+		before := node.Data[:preview.start]
+		after := node.Data[preview.end:]
+		node.Data = before
+		nextSibling := node.NextSibling
+		node.Parent.InsertBefore(&html.Node{
+			Type: html.RawNode,
+			Data: "</p>",
+		}, nextSibling)
+		node.Parent.InsertBefore(previewNode, nextSibling)
+		node.Parent.InsertBefore(&html.Node{
+			Type: html.RawNode,
+			Data: "<p>" + after,
+		}, nextSibling)
+
+		node = node.NextSibling
+	}
+}
+
 // emojiShortCodeProcessor for rendering text like :smile: into emoji
 func emojiShortCodeProcessor(ctx *RenderContext, node *html.Node) {
 	start := 0

modules/markup/html_test.go

@@ -17,9 +17,11 @@ import (
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/markup/markdown"
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/translation"
 	"code.gitea.io/gitea/modules/util"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 var localMetas = map[string]string{
@@ -676,3 +678,68 @@ func TestIssue18471(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, "<a href=\"http://domain/org/repo/compare/783b039...da951ce\" class=\"compare\"><code class=\"nohighlight\">783b039...da951ce</code></a>", res.String())
 }
+
+func TestRender_FilePreview(t *testing.T) {
+	setting.StaticRootPath = "../../"
+	setting.Names = []string{"english"}
+	setting.Langs = []string{"en-US"}
+	translation.InitLocales(context.Background())
+
+	setting.AppURL = markup.TestAppURL
+	markup.Init(&markup.ProcessorHelper{
+		GetRepoFileBlob: func(ctx context.Context, ownerName, repoName, commitSha, filePath string, language *string) (*git.Blob, error) {
+			gitRepo, err := git.OpenRepository(git.DefaultContext, "./tests/repo/repo1_filepreview")
+			require.NoError(t, err)
+			defer gitRepo.Close()
+
+			commit, err := gitRepo.GetCommit("HEAD")
+			require.NoError(t, err)
+
+			blob, err := commit.GetBlobByPath("path/to/file.go")
+			require.NoError(t, err)
+
+			return blob, nil
+		},
+	})
+
+	sha := "190d9492934af498c3f669d6a2431dc5459e5b20"
+	commitFilePreview := util.URLJoin(markup.TestRepoURL, "src", "commit", sha, "path", "to", "file.go") + "#L2-L3"
+
+	test := func(input, expected string) {
+		buffer, err := markup.RenderString(&markup.RenderContext{
+			Ctx:          git.DefaultContext,
+			RelativePath: ".md",
+			Metas:        localMetas,
+		}, input)
+		assert.NoError(t, err)
+		assert.Equal(t, strings.TrimSpace(expected), strings.TrimSpace(buffer))
+	}
+
+	test(
+		commitFilePreview,
+		`<p></p>`+
+			`<div class="file-preview-box">`+
+			`<div class="header">`+
+			`<a href="http://localhost:3000/gogits/gogs/src/commit/190d9492934af498c3f669d6a2431dc5459e5b20/path/to/file.go#L2-L3" class="muted" rel="nofollow">path/to/file.go</a>`+
+			`<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>`,
+	)
+}

modules/markup/renderer.go

@@ -31,6 +31,7 @@ const (
 
 type ProcessorHelper struct {
 	IsUsernameMentionable func(ctx context.Context, username string) bool
+	GetRepoFileBlob       func(ctx context.Context, ownerName, repoName, commitSha, filePath string, language *string) (*git.Blob, error)
 
 	ElementDir string // the direction of the elements, eg: "ltr", "rtl", "auto", default to no direction attribute
 }

modules/markup/sanitizer.go

@@ -113,6 +113,23 @@ func createDefaultPolicy() *bluemonday.Policy {
 	// Allow 'color' and 'background-color' properties for the style attribute on text elements.
 	policy.AllowStyles("color", "background-color").OnElements("span", "p")
 
+	// Allow classes for file preview links...
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^(lines-num|lines-code chroma)$")).OnElements("td")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^code-inner$")).OnElements("code")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^file-preview-box$")).OnElements("div")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^ui table$")).OnElements("div")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^header$")).OnElements("div")
+	policy.AllowAttrs("data-line-number").Matching(regexp.MustCompile("^[0-9]+$")).OnElements("span")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^text small grey$")).OnElements("span")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^file-preview*")).OnElements("table")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^lines-escape$")).OnElements("td")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^toggle-escape-button btn interact-bg$")).OnElements("button")
+	policy.AllowAttrs("title").OnElements("button")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^ambiguous-code-point$")).OnElements("span")
+	policy.AllowAttrs("data-tooltip-content").OnElements("span")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("muted|(text black)")).OnElements("a")
+	policy.AllowAttrs("class").Matching(regexp.MustCompile("^ui warning message tw-text-left$")).OnElements("div")
+
 	// Allow generally safe attributes
 	generalSafeAttrs := []string{
 		"abbr", "accept", "accept-charset",

modules/markup/tests/repo/repo1_filepreview/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/master

modules/markup/tests/repo/repo1_filepreview/config

@@ -0,0 +1,6 @@
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = true
+[remote "origin"]
+	url = /home/mai/projects/codeark/forgejo/forgejo/modules/markup/tests/repo/repo1_filepreview/../../__test_repo

modules/markup/tests/repo/repo1_filepreview/description

@@ -0,0 +1 @@
+Unnamed repository; edit this file 'description' to name the repository.

modules/markup/tests/repo/repo1_filepreview/info/exclude

@@ -0,0 +1,6 @@
+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~

modules/markup/tests/repo/repo1_filepreview/objects/ee/2b1253d9cf407796e2e724926cbe3a974b214d

@@ -0,0 +1 @@
+x
+)JMU06e040031QHËÌIÕKÏghQºÂ/TX'·7潊ç·såË#3
‹ô

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

@@ -0,0 +1 @@
+190d9492934af498c3f669d6a2431dc5459e5b20

modules/setting/markup.go

@@ -15,6 +15,7 @@ var (
 	ExternalMarkupRenderers    []*MarkupRenderer
 	ExternalSanitizerRules     []MarkupSanitizerRule
 	MermaidMaxSourceCharacters int
+	FilePreviewMaxLines        int
 )
 
 const (
@@ -62,6 +63,7 @@ func loadMarkupFrom(rootCfg ConfigProvider) {
 	mustMapSetting(rootCfg, "markdown", &Markdown)
 
 	MermaidMaxSourceCharacters = rootCfg.Section("markup").Key("MERMAID_MAX_SOURCE_CHARACTERS").MustInt(5000)
+	FilePreviewMaxLines = rootCfg.Section("markup").Key("FILEPREVIEW_MAX_LINES").MustInt(50)
 	ExternalMarkupRenderers = make([]*MarkupRenderer, 0, 10)
 	ExternalSanitizerRules = make([]MarkupSanitizerRule, 0, 10)
 

options/locale/locale_en-US.ini

@@ -3725,3 +3725,8 @@ normal_file = Normal file
 executable_file = Executable file
 symbolic_link = Symbolic link
 submodule = Submodule
+
+[markup]
+filepreview.line = Line %[1]d in %[2]s
+filepreview.lines = Lines %[1]d to %[2]d in %[3]s
+filepreview.truncated = Preview has been truncated

services/markup/processorhelper.go

@@ -5,10 +5,18 @@ package markup
 
 import (
 	"context"
+	"fmt"
 
+	"code.gitea.io/gitea/models/perm/access"
+	"code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unit"
 	"code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/markup"
 	gitea_context "code.gitea.io/gitea/services/context"
+	file_service "code.gitea.io/gitea/services/repository/files"
 )
 
 func ProcessorHelper() *markup.ProcessorHelper {
@@ -29,5 +37,51 @@ func ProcessorHelper() *markup.ProcessorHelper {
 			// when using gitea context (web context), use user's visibility and user's permission to check
 			return user.IsUserVisibleToViewer(giteaCtx, mentionedUser, giteaCtx.Doer)
 		},
+		GetRepoFileBlob: func(ctx context.Context, ownerName, repoName, commitSha, filePath string, language *string) (*git.Blob, error) {
+			repo, err := repo.GetRepositoryByOwnerAndName(ctx, ownerName, repoName)
+			if err != nil {
+				return nil, err
+			}
+
+			var user *user.User
+
+			giteaCtx, ok := ctx.(*gitea_context.Context)
+			if ok {
+				user = giteaCtx.Doer
+			}
+
+			perms, err := access.GetUserRepoPermission(ctx, repo, user)
+			if err != nil {
+				return nil, err
+			}
+			if !perms.CanRead(unit.TypeCode) {
+				return nil, fmt.Errorf("cannot access repository code")
+			}
+
+			gitRepo, err := gitrepo.OpenRepository(ctx, repo)
+			if err != nil {
+				return nil, err
+			}
+			defer gitRepo.Close()
+
+			commit, err := gitRepo.GetCommit(commitSha)
+			if err != nil {
+				return nil, err
+			}
+
+			if language != nil {
+				*language, err = file_service.TryGetContentLanguage(gitRepo, commitSha, filePath)
+				if err != nil {
+					log.Error("Unable to get file language for %-v:%s. Error: %v", repo, filePath, err)
+				}
+			}
+
+			blob, err := commit.GetBlobByPath(filePath)
+			if err != nil {
+				return nil, err
+			}
+
+			return blob, nil
+		},
 	}
 }

web_src/css/index.css

@@ -40,6 +40,7 @@
 @import "./markup/content.css";
 @import "./markup/codecopy.css";
 @import "./markup/asciicast.css";
+@import "./markup/filepreview.css";
 
 @import "./chroma/base.css";
 @import "./codemirror/base.css";

web_src/css/markup/content.css

@@ -451,7 +451,8 @@
   text-decoration: inherit;
 }
 
-.markup pre > code {
+.markup pre > code,
+.markup .file-preview code {
   padding: 0;
   margin: 0;
   font-size: 100%;

web_src/css/markup/filepreview.css

@@ -0,0 +1,41 @@
+.markup table.file-preview {
+  margin-bottom: 0;
+}
+
+.markup table.file-preview td {
+  padding: 0 10px !important;
+  border: none !important;
+}
+
+.markup table.file-preview tr {
+  border-top: none;
+  background-color: inherit !important;
+}
+
+.markup .file-preview-box {
+  margin-bottom: 16px;
+}
+
+.markup .file-preview-box .header {
+  padding: .5rem;
+  padding-left: 1rem;
+  border: 1px solid var(--color-secondary);
+  border-bottom: none;
+  border-radius: 0.28571429rem 0.28571429rem 0 0;
+  background: var(--color-box-header);
+}
+
+.markup .file-preview-box .warning {
+  border-radius: 0;
+  margin: 0;
+  padding: .5rem .5rem .5rem 1rem;
+}
+
+.markup .file-preview-box .header > a {
+  display: block;
+}
+
+.markup .file-preview-box .table {
+  margin-top: 0;
+  border-radius: 0 0 0.28571429rem 0.28571429rem;
+}

web_src/css/repo/linebutton.css

@@ -1,4 +1,5 @@
-.code-view .lines-num:hover {
+.code-view .lines-num:hover,
+.file-preview .lines-num:hover {
   color: var(--color-text-dark) !important;
 }
 

web_src/js/features/repo-unicode-escape.js

@@ -7,8 +7,8 @@ export function initUnicodeEscapeButton() {
 
     e.preventDefault();
 
-    const fileContent = btn.closest('.file-content, .non-diff-file-content');
+    const fileContent = btn.closest('.file-content, .non-diff-file-content, .file-preview-box');
-    const fileView = fileContent?.querySelectorAll('.file-code, .file-view');
+    const fileView = fileContent?.querySelectorAll('.file-code, .file-view, .file-preview');
     if (btn.matches('.escape-button')) {
       for (const el of fileView) el.classList.add('unicode-escaped');
       hideElem(btn);