From 62450f7757ec121698331095e947ae8eb68c824e Mon Sep 17 00:00:00 2001
From: Michael Schuett <mschuett@ext.uber.com>
Date: Thu, 1 Jul 2021 18:34:35 -0500
Subject: [PATCH] Reparent branches

---
 lib/git/parent.go | 16 ++++++++++++----
 lib/git/raw.go    | 16 ++++++++++++++++
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/lib/git/parent.go b/lib/git/parent.go
index 22bef80..2fe623d 100644
--- a/lib/git/parent.go
+++ b/lib/git/parent.go
@@ -31,13 +31,21 @@ func ReparentBranches(repo *gogit.Repository,
 
 	localRepoPreDelete := preRemovedState.FullGraphBeforeDelete.BranchMap
 	for _, deletedBranch := range preRemovedState.BranchesForRemoval {
-		rmedNode := localRepoPreDelete[deletedBranch.Name]
-		newParent := getFirstLivingParent(rmedNode, preRemovedState.BranchesForRemoval)
 
-		fmt.Println(newParent)
+		rmedNode := localRepoPreDelete[deletedBranch.Name]
+		for _, upstream := range rmedNode.Downstream {
+
+			newParent := getFirstLivingParent(upstream.Upstream, preRemovedState.BranchesForRemoval)
+			if newParent != "" && !isDeletedBranch(upstream.Name, preRemovedState.BranchesForRemoval) {
+				err := SetBranchUpstream(upstream.Name, newParent)
+				if err != nil {
+					return nil, fmt.Errorf("Unable to set git branch -u %s %s"+err.Error(), newParent, upstream.Name)
+				}
+			}
+		}
 	}
 
-	return nil, nil
+	return &ReparentBranchesStatus{}, nil
 }
 
 // Find the first upstream branch of a given node provided it doesn't exist in the deletedBranches list
diff --git a/lib/git/raw.go b/lib/git/raw.go
index 0374c02..7a07593 100644
--- a/lib/git/raw.go
+++ b/lib/git/raw.go
@@ -123,3 +123,19 @@ func DeleteBranch(branch string) error {
 
 	return nil
 }
+
+func SetBranchUpstream(branch string, upstream string) error {
+	// cmd := exec.Command("git", "branch", "--delete", branch)
+	cmd := exec.Command("git", "branch", "-u", upstream, branch)
+
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return err
+	}
+
+	if cmd.ProcessState.ExitCode() != 0 {
+		return fmt.Errorf(string(output))
+	}
+
+	return nil
+}