1 files changed, 119 insertions, 0 deletions
diff --git a/services/markup/renderhelper_codepreview.go b/services/markup/renderhelper_codepreview.go
new file mode 100644
index 0000000000..170c70c409
--- /dev/null
+++ b/services/markup/renderhelper_codepreview.go
@@ -0,0 +1,119 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package markup
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"html/template"
+	"strings"
+
+	"code.gitea.io/gitea/models/perm/access"
+	"code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/modules/charset"
+	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/indexer/code"
+	"code.gitea.io/gitea/modules/markup"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/util"
+	gitea_context "code.gitea.io/gitea/services/context"
+	"code.gitea.io/gitea/services/repository/files"
+)
+
+func renderRepoFileCodePreview(ctx context.Context, opts markup.RenderCodePreviewOptions) (template.HTML, error) {
+	opts.LineStop = max(opts.LineStop, opts.LineStart)
+	lineCount := opts.LineStop - opts.LineStart + 1
+	if lineCount <= 0 || lineCount > 140 /* GitHub at most show 140 lines */ {
+		lineCount = 10
+		opts.LineStop = opts.LineStart + lineCount
+	}
+
+	dbRepo, err := repo.GetRepositoryByOwnerAndName(ctx, opts.OwnerName, opts.RepoName)
+	if err != nil {
+		return "", err
+	}
+
+	webCtx, ok := ctx.Value(gitea_context.WebContextKey).(*gitea_context.Context)
+	if !ok {
+		return "", fmt.Errorf("context is not a web context")
+	}
+	doer := webCtx.Doer
+
+	perms, err := access.GetUserRepoPermission(ctx, dbRepo, doer)
+	if err != nil {
+		return "", err
+	}
+	if !perms.CanRead(unit.TypeCode) {
+		return "", util.ErrPermissionDenied
+	}
+
+	gitRepo, err := gitrepo.OpenRepository(ctx, dbRepo)
+	if err != nil {
+		return "", err
+	}
+	defer gitRepo.Close()
+
+	commit, err := gitRepo.GetCommit(opts.CommitID)
+	if err != nil {
+		return "", err
+	}
+
+	language, _ := files.TryGetContentLanguage(gitRepo, opts.CommitID, opts.FilePath)
+	blob, err := commit.GetBlobByPath(opts.FilePath)
+	if err != nil {
+		return "", err
+	}
+
+	if blob.Size() > setting.UI.MaxDisplayFileSize {
+		return "", fmt.Errorf("file is too large")
+	}
+
+	dataRc, err := blob.DataAsync()
+	if err != nil {
+		return "", err
+	}
+	defer dataRc.Close()
+
+	reader := bufio.NewReader(dataRc)
+	for i := 1; i < opts.LineStart; i++ {
+		if _, err = reader.ReadBytes('\n'); err != nil {
+			return "", err
+		}
+	}
+
+	lineNums := make([]int, 0, lineCount)
+	lineCodes := make([]string, 0, lineCount)
+	for i := opts.LineStart; i <= opts.LineStop; i++ {
+		line, err := reader.ReadString('\n')
+		if err != nil && line == "" {
+			break
+		}
+
+		lineNums = append(lineNums, i)
+		lineCodes = append(lineCodes, line)
+	}
+	realLineStop := max(opts.LineStart, opts.LineStart+len(lineNums)-1)
+	highlightLines := code.HighlightSearchResultCode(opts.FilePath, language, lineNums, strings.Join(lineCodes, ""))
+
+	escapeStatus := &charset.EscapeStatus{}
+	lineEscapeStatus := make([]*charset.EscapeStatus, len(highlightLines))
+	for i, hl := range highlightLines {
+		lineEscapeStatus[i], hl.FormattedContent = charset.EscapeControlHTML(hl.FormattedContent, webCtx.Base.Locale, charset.RuneNBSP)
+		escapeStatus = escapeStatus.Or(lineEscapeStatus[i])
+	}
+
+	return webCtx.RenderToHTML("base/markup_codepreview", map[string]any{
+		"FullURL":          opts.FullURL,
+		"FilePath":         opts.FilePath,
+		"LineStart":        opts.LineStart,
+		"LineStop":         realLineStop,
+		"RepoLink":         dbRepo.Link(),
+		"CommitID":         opts.CommitID,
+		"HighlightLines":   highlightLines,
+		"EscapeStatus":     escapeStatus,
+		"LineEscapeStatus": lineEscapeStatus,
+	})
+}