From a09763f340a9b8208a5191a1049c287457ea6a0f Mon Sep 17 00:00:00 2001
From: Martin von Zweigbergk <martinvonz@google.com>
Date: Thu, 24 Nov 2022 08:45:49 -0800
Subject: [PATCH] git: in export code, work with branch names (not ref names) a
 bit longer

I'm going to make the export skip branches that we fail to update in
the Git repo. For that, we need to know the branch name while
interacting with the `git2::Repository` object. This little
refactoring prepares for that.
---
 lib/src/git.rs | 37 +++++++++++++++++++------------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/lib/src/git.rs b/lib/src/git.rs
index 235337341..3a06d323a 100644
--- a/lib/src/git.rs
+++ b/lib/src/git.rs
@@ -187,8 +187,8 @@ fn export_changes(
     let old_branches: HashSet<_> = old_view.branches().keys().cloned().collect();
     let new_branches: HashSet<_> = new_view.branches().keys().cloned().collect();
     let mut exported_view = old_view.store_view().clone();
-    let mut refs_to_update = BTreeMap::new();
-    let mut refs_to_delete = BTreeSet::new();
+    let mut branches_to_update = BTreeMap::new();
+    let mut branches_to_delete = BTreeSet::new();
     // First find the changes we want need to make without modifying mut_repo
     for branch_name in old_branches.union(&new_branches) {
         let old_branch = old_view.get_local_branch(branch_name);
@@ -196,7 +196,6 @@ fn export_changes(
         if new_branch == old_branch {
             continue;
         }
-        let git_ref_name = format!("refs/heads/{}", branch_name);
         if let Some(new_branch) = new_branch {
             match new_branch {
                 RefTarget::Normal(id) => {
@@ -207,10 +206,8 @@ fn export_changes(
                             remote_targets: Default::default(),
                         },
                     );
-                    refs_to_update.insert(
-                        git_ref_name.clone(),
-                        Oid::from_bytes(id.as_bytes()).unwrap(),
-                    );
+                    branches_to_update
+                        .insert(branch_name.clone(), Oid::from_bytes(id.as_bytes()).unwrap());
                 }
                 RefTarget::Conflict { .. } => {
                     // Skip conflicts and leave the old value in `exported_view`
@@ -219,32 +216,36 @@ fn export_changes(
             }
         } else {
             exported_view.branches.remove(branch_name);
-            refs_to_delete.insert(git_ref_name.clone());
+            branches_to_delete.insert(branch_name.clone());
         }
     }
     // TODO: Also check other worktrees' HEAD.
     if let Ok(head_ref) = git_repo.find_reference("HEAD") {
-        if let (Some(head_target), Ok(current_git_commit)) =
+        if let (Some(head_git_ref), Ok(current_git_commit)) =
             (head_ref.symbolic_target(), head_ref.peel_to_commit())
         {
-            let detach_head = if let Some(new_target) = refs_to_update.get(head_target) {
-                *new_target != current_git_commit.id()
-            } else {
-                refs_to_delete.contains(head_target)
-            };
-            if detach_head {
-                git_repo.set_head_detached(current_git_commit.id())?;
+            if let Some(branch_name) = head_git_ref.strip_prefix("refs/heads/") {
+                let detach_head = if let Some(new_target) = branches_to_update.get(branch_name) {
+                    *new_target != current_git_commit.id()
+                } else {
+                    branches_to_delete.contains(branch_name)
+                };
+                if detach_head {
+                    git_repo.set_head_detached(current_git_commit.id())?;
+                }
             }
         }
     }
-    for (git_ref_name, new_target) in refs_to_update {
+    for (branch_name, new_target) in branches_to_update {
+        let git_ref_name = format!("refs/heads/{}", branch_name);
         git_repo.reference(&git_ref_name, new_target, true, "export from jj")?;
         mut_repo.set_git_ref(
             git_ref_name,
             RefTarget::Normal(CommitId::from_bytes(new_target.as_bytes())),
         );
     }
-    for git_ref_name in refs_to_delete {
+    for branch_name in branches_to_delete {
+        let git_ref_name = format!("refs/heads/{}", branch_name);
         if let Ok(mut git_ref) = git_repo.find_reference(&git_ref_name) {
             git_ref.delete()?;
         }