1 files changed, 50 insertions, 0 deletions

diff --git a/services/pull/merge_rebase.go b/services/pull/merge_rebase.go
new file mode 100644
index 000000000..d3bb86d4a
--- /dev/null
+++ b/services/pull/merge_rebase.go
@@ -0,0 +1,50 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package pull
+
+import (
+	"fmt"
+
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+)
+
+// doMergeStyleRebase rebaases the tracking branch on the base branch as the current HEAD with or with a merge commit to the original pr branch
+func doMergeStyleRebase(ctx *mergeContext, mergeStyle repo_model.MergeStyle, message string) error {
+	if err := rebaseTrackingOnToBase(ctx, mergeStyle); err != nil {
+		return err
+	}
+
+	// Checkout base branch again
+	if err := git.NewCommand(ctx, "checkout").AddDynamicArguments(baseBranch).
+		Run(ctx.RunOpts()); err != nil {
+		log.Error("git checkout base prior to merge post staging rebase %-v: %v\n%s\n%s", ctx.pr, err, ctx.outbuf.String(), ctx.errbuf.String())
+		return fmt.Errorf("git checkout base prior to merge post staging rebase  %v: %w\n%s\n%s", ctx.pr, err, ctx.outbuf.String(), ctx.errbuf.String())
+	}
+	ctx.outbuf.Reset()
+	ctx.errbuf.Reset()
+
+	cmd := git.NewCommand(ctx, "merge")
+	if mergeStyle == repo_model.MergeStyleRebase {
+		cmd.AddArguments("--ff-only")
+	} else {
+		cmd.AddArguments("--no-ff", "--no-commit")
+	}
+	cmd.AddDynamicArguments(stagingBranch)
+
+	// Prepare merge with commit
+	if err := runMergeCommand(ctx, mergeStyle, cmd); err != nil {
+		log.Error("Unable to merge staging into base: %v", err)
+		return err
+	}
+	if mergeStyle == repo_model.MergeStyleRebaseMerge {
+		if err := commitAndSignNoAuthor(ctx, message); err != nil {
+			log.Error("Unable to make final commit: %v", err)
+			return err
+		}
+	}
+
+	return nil
+}