Move some functions to gitrepo package (#35503)

modules/gitrepo/diff.go

@@ -0,0 +1,62 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package gitrepo
+
+import (
+	"context"
+	"fmt"
+	"regexp"
+	"strconv"
+
+	"code.gitea.io/gitea/modules/git/gitcmd"
+)
+
+// GetDiffShortStatByCmdArgs counts number of changed files, number of additions and deletions
+// TODO: it can be merged with another "GetDiffShortStat" in the future
+func GetDiffShortStatByCmdArgs(ctx context.Context, repo Repository, trustedArgs gitcmd.TrustedCmdArgs, dynamicArgs ...string) (numFiles, totalAdditions, totalDeletions int, err error) {
+	// Now if we call:
+	// $ git diff --shortstat 1ebb35b98889ff77299f24d82da426b434b0cca0...788b8b1440462d477f45b0088875
+	// we get:
+	// " 9902 files changed, 2034198 insertions(+), 298800 deletions(-)\n"
+	cmd := gitcmd.NewCommand("diff", "--shortstat").AddArguments(trustedArgs...).AddDynamicArguments(dynamicArgs...)
+	stdout, err := runCmdString(ctx, repo, cmd)
+	if err != nil {
+		return 0, 0, 0, err
+	}
+
+	return parseDiffStat(stdout)
+}
+
+var shortStatFormat = regexp.MustCompile(
+	`\s*(\d+) files? changed(?:, (\d+) insertions?\(\+\))?(?:, (\d+) deletions?\(-\))?`)
+
+func parseDiffStat(stdout string) (numFiles, totalAdditions, totalDeletions int, err error) {
+	if len(stdout) == 0 || stdout == "\n" {
+		return 0, 0, 0, nil
+	}
+	groups := shortStatFormat.FindStringSubmatch(stdout)
+	if len(groups) != 4 {
+		return 0, 0, 0, fmt.Errorf("unable to parse shortstat: %s groups: %s", stdout, groups)
+	}
+
+	numFiles, err = strconv.Atoi(groups[1])
+	if err != nil {
+		return 0, 0, 0, fmt.Errorf("unable to parse shortstat: %s. Error parsing NumFiles %w", stdout, err)
+	}
+
+	if len(groups[2]) != 0 {
+		totalAdditions, err = strconv.Atoi(groups[2])
+		if err != nil {
+			return 0, 0, 0, fmt.Errorf("unable to parse shortstat: %s. Error parsing NumAdditions %w", stdout, err)
+		}
+	}
+
+	if len(groups[3]) != 0 {
+		totalDeletions, err = strconv.Atoi(groups[3])
+		if err != nil {
+			return 0, 0, 0, fmt.Errorf("unable to parse shortstat: %s. Error parsing NumDeletions %w", stdout, err)
+		}
+	}
+	return numFiles, totalAdditions, totalDeletions, err
+}