1 files changed, 59 insertions, 0 deletions
diff --git a/pkg/commands/git_commands/merged_branch_loader.go b/pkg/commands/git_commands/merged_branch_loader.go
new file mode 100644
index 000000000..a3b4843b6
--- /dev/null
+++ b/pkg/commands/git_commands/merged_branch_loader.go
@@ -0,0 +1,59 @@
+package git_commands
+
+import (
+	"github.com/jesseduffield/generics/set"
+	"github.com/jesseduffield/lazygit/pkg/utils"
+)
+
+// Returns a set of branch names which are merged into a main branch.
+// This
+type MergedBranchLoader struct {
+	c *GitCommon
+}
+
+func NewMergedBranchLoader(c *GitCommon) *MergedBranchLoader {
+	return &MergedBranchLoader{c: c}
+}
+
+// TODO: check against upstreams, and share code with commit loader that determines main branches
+func (self *MergedBranchLoader) Load() *set.Set[string] {
+	set := set.New[string]()
+
+	mainBranches := self.c.UserConfig.Git.MainBranches
+	results := utils.ConcurrentMap(mainBranches, func(mainBranch string) []string {
+		mergedBranches, err := self.GetMergedBranches(mainBranch)
+		if err != nil {
+			self.c.Log.Warnf("Failed to get merged branches for %s: %s", mainBranch, err)
+			return nil
+		}
+		return mergedBranches
+	})
+
+	for i := 0; i < len(mainBranches); i++ {
+		for _, mergedBranch := range results[i] {
+			set.Add(mergedBranch)
+		}
+	}
+
+	return set
+}
+
+func (self *MergedBranchLoader) GetMergedBranches(mainBranch string) ([]string, error) {
+	// git for-each-ref --merged master --format '%(refname)' refs/heads/
+	cmdArgs := NewGitCmd("for-each-ref").Arg(
+		"--merged",
+		mainBranch,
+		"--format",
+		"%(refname)",
+		"refs/heads/",
+	).ToArgv()
+
+	output, err := self.c.cmd.New(cmdArgs).DontLog().RunWithOutput()
+	if err != nil {
+		return nil, err
+	}
+
+	branches := utils.SplitLines(output)
+
+	return branches, nil
+}