[v7.0/forgejo] Render inline file permalinks

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

(cherry picked from commit 1d3240887c519a04c13bcd7e852c6d6ad1cb00b5)
(cherry picked from commit 781a37fbe18c223763f51968862f1c8f61e7e260)
(cherry picked from commit 8309f008c2721e313e1949ce42ed410e844c16e7)
(cherry picked from commit fae8d9f70d31704af91cbf37bcefcc4772830695)
(cherry picked from commit 6721cba75b4997448b618a4b00ef25f142924de0)
(cherry picked from commit 562e5cdf324597882b7e6971be1b9a148bbc7839)
(cherry picked from commit d789d33229b3998bb33f1505d122504c8039f23d)
(cherry picked from commit 8218e80bfc3a1f9ba02ce60f1acafdc0e57c5ae0)
(cherry picked from commit 10bca456a9140519e95559aa7bac2221e1156c5b)
(cherry picked from commit db6f6281fcf568ae8e35330a4a93c9be1cb46efd)
(cherry picked from commit ed8e8a792e75b930074cd3cf1bab580a09ff8485)
(cherry picked from commit d6428f92ce7ce67d127cbd5bb4977aa92abf071c)
(cherry picked from commit 069d87b80f909e91626249afbb240a1df339a8fd)
(cherry picked from commit 2b6546adc954d450a9c6befccd407ce2ca1636a0)
(cherry picked from commit 4c7cb0a5d20e8973b03e35d91119cf917eed125e)
(cherry picked from commit 7e0014dd1391e123d95f2537c3b2165fef7122ef)
(cherry picked from commit 16a8658878a2656cb131453b728b65a89271f11f)
(cherry picked from commit 6e98bacbbd3c089b2ccfa725c58184f4dfe5e7fe)

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 fileView = fileContent?.querySelectorAll('.file-code, .file-view');
+    const fileContent = btn.closest('.file-content, .non-diff-file-content, .file-preview-box');
+    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);