1 files changed, 86 insertions, 0 deletions

diff --git a/services/pull/merge_squash.go b/services/pull/merge_squash.go
new file mode 100644
index 0000000..197d810
--- /dev/null
+++ b/services/pull/merge_squash.go
@@ -0,0 +1,86 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package pull
+
+import (
+	"fmt"
+
+	repo_model "code.gitea.io/gitea/models/repo"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/container"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+// doMergeStyleSquash gets a commit author signature for squash commits
+func getAuthorSignatureSquash(ctx *mergeContext) (*git.Signature, error) {
+	if err := ctx.pr.Issue.LoadPoster(ctx); err != nil {
+		log.Error("%-v Issue[%d].LoadPoster: %v", ctx.pr, ctx.pr.Issue.ID, err)
+		return nil, err
+	}
+
+	// Try to get an signature from the same user in one of the commits, as the
+	// poster email might be private or commits might have a different signature
+	// than the primary email address of the poster.
+	gitRepo, closer, err := gitrepo.RepositoryFromContextOrOpenPath(ctx, ctx.tmpBasePath)
+	if err != nil {
+		log.Error("%-v Unable to open base repository: %v", ctx.pr, err)
+		return nil, err
+	}
+	defer closer.Close()
+
+	commits, err := gitRepo.CommitsBetweenIDs(trackingBranch, "HEAD")
+	if err != nil {
+		log.Error("%-v Unable to get commits between: %s %s: %v", ctx.pr, "HEAD", trackingBranch, err)
+		return nil, err
+	}
+
+	uniqueEmails := make(container.Set[string])
+	for _, commit := range commits {
+		if commit.Author != nil && uniqueEmails.Add(commit.Author.Email) {
+			commitUser, _ := user_model.GetUserByEmail(ctx, commit.Author.Email)
+			if commitUser != nil && commitUser.ID == ctx.pr.Issue.Poster.ID {
+				return commit.Author, nil
+			}
+		}
+	}
+
+	return ctx.pr.Issue.Poster.NewGitSig(), nil
+}
+
+// doMergeStyleSquash squashes the tracking branch on the current HEAD (=base)
+func doMergeStyleSquash(ctx *mergeContext, message string) error {
+	sig, err := getAuthorSignatureSquash(ctx)
+	if err != nil {
+		return fmt.Errorf("getAuthorSignatureSquash: %w", err)
+	}
+
+	cmdMerge := git.NewCommand(ctx, "merge", "--squash").AddDynamicArguments(trackingBranch)
+	if err := runMergeCommand(ctx, repo_model.MergeStyleSquash, cmdMerge); err != nil {
+		log.Error("%-v Unable to merge --squash tracking into base: %v", ctx.pr, err)
+		return err
+	}
+
+	if setting.Repository.PullRequest.AddCoCommitterTrailers && ctx.committer.String() != sig.String() {
+		// add trailer
+		message += fmt.Sprintf("\nCo-authored-by: %s\nCo-committed-by: %s\n", sig.String(), sig.String())
+	}
+	cmdCommit := git.NewCommand(ctx, "commit").
+		AddOptionFormat("--author='%s <%s>'", sig.Name, sig.Email).
+		AddOptionFormat("--message=%s", message)
+	if ctx.signKeyID == "" {
+		cmdCommit.AddArguments("--no-gpg-sign")
+	} else {
+		cmdCommit.AddOptionFormat("-S%s", ctx.signKeyID)
+	}
+	if err := cmdCommit.Run(ctx.RunOpts()); err != nil {
+		log.Error("git commit %-v: %v\n%s\n%s", ctx.pr, err, ctx.outbuf.String(), ctx.errbuf.String())
+		return fmt.Errorf("git commit [%s:%s -> %s:%s]: %w\n%s\n%s", ctx.pr.HeadRepo.FullName(), ctx.pr.HeadBranch, ctx.pr.BaseRepo.FullName(), ctx.pr.BaseBranch, err, ctx.outbuf.String(), ctx.errbuf.String())
+	}
+	ctx.outbuf.Reset()
+	ctx.errbuf.Reset()
+	return nil
+}