From 3cb0a735f6c5a2c39a9214aa8798966e2761d4dc Mon Sep 17 00:00:00 2001
From: Abhinav Gupta <mail@abhinavg.net>
Date: Sat, 1 Jun 2024 12:29:59 -0700
Subject: [PATCH] branch rename: Support <old> <new> form (#139)

With this, 'branch rename' supports the following three forms:

    branch rename <old> <new>
    branch rename <new> # old = current
    branch rename       # old = current, new = prompt
---
 .../unreleased/Added-20240601-122230.yaml     |  3 ++
 branch_rename.go                              | 44 ++++++++++++++-----
 doc/reference.md                              | 18 ++++++--
 testdata/script/branch_rename_old_new.txt     | 26 +++++++++++
 4 files changed, 75 insertions(+), 16 deletions(-)
 create mode 100644 .changes/unreleased/Added-20240601-122230.yaml
 create mode 100644 testdata/script/branch_rename_old_new.txt

diff --git a/.changes/unreleased/Added-20240601-122230.yaml b/.changes/unreleased/Added-20240601-122230.yaml
new file mode 100644
index 00000000..15f09548
--- /dev/null
+++ b/.changes/unreleased/Added-20240601-122230.yaml
@@ -0,0 +1,3 @@
+kind: Added
+body: 'branch rename: Support renaming another branch by name with the `branch rename <old> <new>` form of the command.'
+time: 2024-06-01T12:22:30.93713-07:00
diff --git a/branch_rename.go b/branch_rename.go
index 0e746579..3578e7c9 100644
--- a/branch_rename.go
+++ b/branch_rename.go
@@ -7,22 +7,31 @@ import (
 
 	"github.com/charmbracelet/log"
 	"go.abhg.dev/gs/internal/git"
+	"go.abhg.dev/gs/internal/must"
 	"go.abhg.dev/gs/internal/spice"
 	"go.abhg.dev/gs/internal/text"
 	"go.abhg.dev/gs/internal/ui"
 )
 
 type branchRenameCmd struct {
-	// TODO: optional old name
-
-	Name string `arg:"" optional:"" help:"New name of the branch"`
+	OldName string `arg:"" optional:"" help:"Old name of the branch"`
+	NewName string `arg:"" optional:"" help:"New name of the branch"`
 }
 
 func (*branchRenameCmd) Help() string {
 	return text.Dedent(`
-		Renames a tracked branch, updating internal references to it.
+		The following modes are supported:
+
+			# Rename <old> to <new>
+			gs branch rename <old> <new>
+
+			# Rename current branch to <new>
+			gs branch rename <new>
 
-		If you renamed a branch without using this command,
+			# Rename current branch interactively
+			gs branch rename
+
+		If you renamed a branch without this command,
 		track the new branch name with 'gs branch track',
 		and untrack the old name with 'gs branch untrack'.
 	`)
@@ -36,15 +45,23 @@ func (cmd *branchRenameCmd) Run(ctx context.Context, log *log.Logger, opts *glob
 		return fmt.Errorf("open repository: %w", err)
 	}
 
-	// TODO: support: rename [old] new
-	oldName, err := repo.CurrentBranch(ctx)
-	if err != nil {
-		return fmt.Errorf("get current branch: %w", err)
+	oldName, newName := cmd.OldName, cmd.NewName
+	// For "gs branch rename <new>",
+	// we'll actually get oldName = <new> and newName = "".
+	if oldName != "" && newName == "" {
+		oldName, newName = "", oldName
 	}
 
-	if cmd.Name == "" {
+	if oldName == "" {
+		oldName, err = repo.CurrentBranch(ctx)
+		if err != nil {
+			return fmt.Errorf("get current branch: %w", err)
+		}
+	}
+
+	if newName == "" {
 		prompt := ui.NewInput().
-			WithValue(&cmd.Name).
+			WithValue(&newName).
 			WithTitle("New branch name").
 			WithDescription(fmt.Sprintf("Renaming branch: %v", oldName)).
 			WithValidate(func(s string) error {
@@ -59,13 +76,16 @@ func (cmd *branchRenameCmd) Run(ctx context.Context, log *log.Logger, opts *glob
 		}
 	}
 
+	must.NotBeBlankf(oldName, "old branch name must be set")
+	must.NotBeBlankf(newName, "new branch name must be set")
+
 	store, err := ensureStore(ctx, repo, log, opts)
 	if err != nil {
 		return err
 	}
 
 	svc := spice.NewService(repo, store, log)
-	if err := svc.RenameBranch(ctx, oldName, cmd.Name); err != nil {
+	if err := svc.RenameBranch(ctx, oldName, newName); err != nil {
 		return fmt.Errorf("rename branch: %w", err)
 	}
 
diff --git a/doc/reference.md b/doc/reference.md
index c1c54747..5374e1d4 100644
--- a/doc/reference.md
+++ b/doc/reference.md
@@ -413,20 +413,30 @@ will be restacked.
 ## gs branch rename
 
 ```
-gs branch (b) rename (rn,mv) [<name>]
+gs branch (b) rename (rn,mv) [<old-name> [<new-name>]]
 ```
 
 Rename a branch
 
-Renames a tracked branch, updating internal references to it.
+The following modes are supported:
 
-If you renamed a branch without using this command,
+	# Rename <old> to <new>
+	gs branch rename <old> <new>
+
+	# Rename current branch to <new>
+	gs branch rename <new>
+
+	# Rename current branch interactively
+	gs branch rename
+
+If you renamed a branch without this command,
 track the new branch name with 'gs branch track',
 and untrack the old name with 'gs branch untrack'.
 
 **Arguments**
 
-* `name`: New name of the branch
+* `old-name`: Old name of the branch
+* `new-name`: New name of the branch
 
 ## gs branch restack
 
diff --git a/testdata/script/branch_rename_old_new.txt b/testdata/script/branch_rename_old_new.txt
new file mode 100644
index 00000000..b301efbe
--- /dev/null
+++ b/testdata/script/branch_rename_old_new.txt
@@ -0,0 +1,26 @@
+# Renaming a branch by name.
+
+as 'Test <test@example.com>'
+at '2024-06-01T12:15:12Z'
+
+mkdir repo
+cd repo
+git init
+git commit --allow-empty -m 'Initial commit'
+gs repo init
+
+git add foo.txt
+gs branch create oldname -m 'Do things'
+gs trunk
+
+gs branch rename oldname newname
+git graph --branches
+cmp stdout $WORK/golden/graph.txt
+
+
+-- repo/foo.txt --
+whatever
+
+-- golden/graph.txt --
+* 1f8dc81 (newname) Do things
+* 0cfef96 (HEAD -> main) Initial commit