git: Implement a basic repository selector (#23419)

This PR adds a rough-and-ready picker for selecting which of the
project's repositories the git panel should display.

Release Notes:

- N/A

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>
Co-authored-by: Nate <nate@zed.dev>

crates/project/src/git.rs

@@ -1,25 +1,55 @@
-use anyhow::{anyhow, Context as _};
+use crate::worktree_store::{WorktreeStore, WorktreeStoreEvent};
+use crate::{Project, ProjectPath};
+use anyhow::anyhow;
 use futures::channel::mpsc;
 use futures::{SinkExt as _, StreamExt as _};
 use git::{
     repository::{GitRepository, RepoPath},
     status::{GitSummary, TrackedSummary},
 };
-use gpui::{AppContext, Context as _, Model};
+use gpui::{
+    AppContext, Context as _, EventEmitter, Model, ModelContext, SharedString, Subscription,
+    WeakModel,
+};
 use language::{Buffer, LanguageRegistry};
 use settings::WorktreeId;
 use std::sync::Arc;
 use text::Rope;
-use worktree::RepositoryEntry;
+use util::maybe;
+use worktree::{RepositoryEntry, StatusEntry};
 
 pub struct GitState {
-    pub commit_message: Model<Buffer>,
-
-    /// When a git repository is selected, this is used to track which repository's changes
-    /// are currently being viewed or modified in the UI.
-    pub active_repository: Option<(WorktreeId, RepositoryEntry, Arc<dyn GitRepository>)>,
-
+    repositories: Vec<RepositoryHandle>,
+    active_index: Option<usize>,
     update_sender: mpsc::UnboundedSender<(Message, mpsc::Sender<anyhow::Error>)>,
+    languages: Arc<LanguageRegistry>,
+    _subscription: Subscription,
+}
+
+#[derive(Clone)]
+pub struct RepositoryHandle {
+    git_state: WeakModel<GitState>,
+    worktree_id: WorktreeId,
+    repository_entry: RepositoryEntry,
+    git_repo: Arc<dyn GitRepository>,
+    commit_message: Model<Buffer>,
+    update_sender: mpsc::UnboundedSender<(Message, mpsc::Sender<anyhow::Error>)>,
+}
+
+impl PartialEq<Self> for RepositoryHandle {
+    fn eq(&self, other: &Self) -> bool {
+        self.worktree_id == other.worktree_id
+            && self.repository_entry.work_directory_id()
+                == other.repository_entry.work_directory_id()
+    }
+}
+
+impl Eq for RepositoryHandle {}
+
+impl PartialEq<RepositoryEntry> for RepositoryHandle {
+    fn eq(&self, other: &RepositoryEntry) -> bool {
+        self.repository_entry.work_directory_id() == other.work_directory_id()
+    }
 }
 
 enum Message {
@@ -29,11 +59,21 @@ enum Message {
     Unstage(Arc<dyn GitRepository>, Vec<RepoPath>),
 }
 
+pub enum Event {
+    RepositoriesUpdated,
+}
+
+impl EventEmitter<Event> for GitState {}
+
 impl GitState {
-    pub fn new(languages: Arc<LanguageRegistry>, cx: &mut AppContext) -> Self {
+    pub fn new(
+        worktree_store: &Model<WorktreeStore>,
+        languages: Arc<LanguageRegistry>,
+        cx: &mut ModelContext<'_, Self>,
+    ) -> Self {
         let (update_sender, mut update_receiver) =
             mpsc::unbounded::<(Message, mpsc::Sender<anyhow::Error>)>();
-        cx.spawn(|cx| async move {
+        cx.spawn(|_, cx| async move {
             while let Some((msg, mut err_sender)) = update_receiver.next().await {
                 let result = cx
                     .background_executor()
@@ -57,39 +97,147 @@ impl GitState {
         })
         .detach();
 
-        let commit_message = cx.new_model(|cx| Buffer::local("", cx));
-        let markdown = languages.language_for_name("Markdown");
-        cx.spawn({
-            let commit_message = commit_message.clone();
-            |mut cx| async move {
-                let markdown = markdown.await.context("failed to load Markdown language")?;
-                commit_message.update(&mut cx, |commit_message, cx| {
-                    commit_message.set_language(Some(markdown), cx)
-                })
-            }
-        })
-        .detach_and_log_err(cx);
+        let _subscription = cx.subscribe(worktree_store, Self::on_worktree_store_event);
 
         GitState {
-            commit_message,
-            active_repository: None,
+            languages,
+            repositories: vec![],
+            active_index: None,
             update_sender,
+            _subscription,
         }
     }
 
-    pub fn activate_repository(
-        &mut self,
-        worktree_id: WorktreeId,
-        active_repository: RepositoryEntry,
-        git_repo: Arc<dyn GitRepository>,
-    ) {
-        self.active_repository = Some((worktree_id, active_repository, git_repo));
+    pub fn active_repository(&self) -> Option<RepositoryHandle> {
+        self.active_index
+            .map(|index| self.repositories[index].clone())
     }
 
-    pub fn active_repository(
-        &self,
-    ) -> Option<&(WorktreeId, RepositoryEntry, Arc<dyn GitRepository>)> {
-        self.active_repository.as_ref()
+    fn on_worktree_store_event(
+        &mut self,
+        worktree_store: Model<WorktreeStore>,
+        _event: &WorktreeStoreEvent,
+        cx: &mut ModelContext<'_, Self>,
+    ) {
+        // TODO inspect the event
+
+        let mut new_repositories = Vec::new();
+        let mut new_active_index = None;
+        let this = cx.weak_model();
+
+        worktree_store.update(cx, |worktree_store, cx| {
+            for worktree in worktree_store.worktrees() {
+                worktree.update(cx, |worktree, cx| {
+                    let snapshot = worktree.snapshot();
+                    let Some(local) = worktree.as_local() else {
+                        return;
+                    };
+                    for repo in snapshot.repositories().iter() {
+                        let Some(local_repo) = local.get_local_repo(repo) else {
+                            continue;
+                        };
+                        let existing = self
+                            .repositories
+                            .iter()
+                            .enumerate()
+                            .find(|(_, existing_handle)| existing_handle == &repo);
+                        let handle = if let Some((index, handle)) = existing {
+                            if self.active_index == Some(index) {
+                                new_active_index = Some(new_repositories.len());
+                            }
+                            // Update the statuses but keep everything else.
+                            let mut existing_handle = handle.clone();
+                            existing_handle.repository_entry = repo.clone();
+                            existing_handle
+                        } else {
+                            let commit_message = cx.new_model(|cx| Buffer::local("", cx));
+                            cx.spawn({
+                                let commit_message = commit_message.downgrade();
+                                let languages = self.languages.clone();
+                                |_, mut cx| async move {
+                                    let markdown = languages.language_for_name("Markdown").await?;
+                                    commit_message.update(&mut cx, |commit_message, cx| {
+                                        commit_message.set_language(Some(markdown), cx);
+                                    })?;
+                                    anyhow::Ok(())
+                                }
+                            })
+                            .detach_and_log_err(cx);
+                            RepositoryHandle {
+                                git_state: this.clone(),
+                                worktree_id: worktree.id(),
+                                repository_entry: repo.clone(),
+                                git_repo: local_repo.repo().clone(),
+                                commit_message,
+                                update_sender: self.update_sender.clone(),
+                            }
+                        };
+                        new_repositories.push(handle);
+                    }
+                })
+            }
+        });
+
+        if new_active_index == None && new_repositories.len() > 0 {
+            new_active_index = Some(0);
+        }
+
+        self.repositories = new_repositories;
+        self.active_index = new_active_index;
+
+        cx.emit(Event::RepositoriesUpdated);
+    }
+
+    pub fn all_repositories(&self) -> Vec<RepositoryHandle> {
+        self.repositories.clone()
+    }
+}
+
+impl RepositoryHandle {
+    pub fn display_name(&self, project: &Project, cx: &AppContext) -> SharedString {
+        maybe!({
+            let path = self.unrelativize(&"".into())?;
+            Some(
+                project
+                    .absolute_path(&path, cx)?
+                    .file_name()?
+                    .to_string_lossy()
+                    .to_string()
+                    .into(),
+            )
+        })
+        .unwrap_or("".into())
+    }
+
+    pub fn activate(&self, cx: &mut AppContext) {
+        let Some(git_state) = self.git_state.upgrade() else {
+            return;
+        };
+        git_state.update(cx, |git_state, cx| {
+            let Some((index, _)) = git_state
+                .repositories
+                .iter()
+                .enumerate()
+                .find(|(_, handle)| handle == &self)
+            else {
+                return;
+            };
+            git_state.active_index = Some(index);
+            cx.emit(Event::RepositoriesUpdated);
+        });
+    }
+
+    pub fn status(&self) -> impl '_ + Iterator<Item = StatusEntry> {
+        self.repository_entry.status()
+    }
+
+    pub fn unrelativize(&self, path: &RepoPath) -> Option<ProjectPath> {
+        let path = self.repository_entry.unrelativize(path)?;
+        Some((self.worktree_id, path).into())
+    }
+
+    pub fn commit_message(&self) -> Model<Buffer> {
+        self.commit_message.clone()
     }
 
     pub fn stage_entries(
@@ -100,11 +248,8 @@ impl GitState {
         if entries.is_empty() {
             return Ok(());
         }
-        let Some((_, _, git_repo)) = self.active_repository.as_ref() else {
-            return Err(anyhow!("No active repository"));
-        };
         self.update_sender
-            .unbounded_send((Message::Stage(git_repo.clone(), entries), err_sender))
+            .unbounded_send((Message::Stage(self.git_repo.clone(), entries), err_sender))
             .map_err(|_| anyhow!("Failed to submit stage operation"))?;
         Ok(())
     }
@@ -117,20 +262,15 @@ impl GitState {
         if entries.is_empty() {
             return Ok(());
         }
-        let Some((_, _, git_repo)) = self.active_repository.as_ref() else {
-            return Err(anyhow!("No active repository"));
-        };
         self.update_sender
-            .unbounded_send((Message::Unstage(git_repo.clone(), entries), err_sender))
+            .unbounded_send((Message::Unstage(self.git_repo.clone(), entries), err_sender))
             .map_err(|_| anyhow!("Failed to submit unstage operation"))?;
         Ok(())
     }
 
     pub fn stage_all(&self, err_sender: mpsc::Sender<anyhow::Error>) -> anyhow::Result<()> {
-        let Some((_, entry, _)) = self.active_repository.as_ref() else {
-            return Err(anyhow!("No active repository"));
-        };
-        let to_stage = entry
+        let to_stage = self
+            .repository_entry
             .status()
             .filter(|entry| !entry.status.is_staged().unwrap_or(false))
             .map(|entry| entry.repo_path.clone())
@@ -140,10 +280,8 @@ impl GitState {
     }
 
     pub fn unstage_all(&self, err_sender: mpsc::Sender<anyhow::Error>) -> anyhow::Result<()> {
-        let Some((_, entry, _)) = self.active_repository.as_ref() else {
-            return Err(anyhow!("No active repository"));
-        };
-        let to_unstage = entry
+        let to_unstage = self
+            .repository_entry
             .status()
             .filter(|entry| entry.status.is_staged().unwrap_or(true))
             .map(|entry| entry.repo_path.clone())
@@ -155,23 +293,15 @@ impl GitState {
     /// Get a count of all entries in the active repository, including
     /// untracked files.
     pub fn entry_count(&self) -> usize {
-        self.active_repository
-            .as_ref()
-            .map_or(0, |(_, entry, _)| entry.status_len())
+        self.repository_entry.status_len()
     }
 
     fn have_changes(&self) -> bool {
-        let Some((_, entry, _)) = self.active_repository.as_ref() else {
-            return false;
-        };
-        entry.status_summary() != GitSummary::UNCHANGED
+        self.repository_entry.status_summary() != GitSummary::UNCHANGED
     }
 
     fn have_staged_changes(&self) -> bool {
-        let Some((_, entry, _)) = self.active_repository.as_ref() else {
-            return false;
-        };
-        entry.status_summary().index != TrackedSummary::UNCHANGED
+        self.repository_entry.status_summary().index != TrackedSummary::UNCHANGED
     }
 
     pub fn can_commit(&self, commit_all: bool, cx: &AppContext) -> bool {
@@ -185,36 +315,33 @@ impl GitState {
     }
 
     pub fn commit(
-        &mut self,
+        &self,
         err_sender: mpsc::Sender<anyhow::Error>,
-        cx: &AppContext,
+        cx: &mut AppContext,
     ) -> anyhow::Result<()> {
         if !self.can_commit(false, cx) {
             return Err(anyhow!("Unable to commit"));
         }
-        let Some((_, _, git_repo)) = self.active_repository() else {
-            return Err(anyhow!("No active repository"));
-        };
-        let git_repo = git_repo.clone();
         let message = self.commit_message.read(cx).as_rope().clone();
         self.update_sender
-            .unbounded_send((Message::Commit(git_repo, message), err_sender))
+            .unbounded_send((Message::Commit(self.git_repo.clone(), message), err_sender))
             .map_err(|_| anyhow!("Failed to submit commit operation"))?;
+        self.commit_message.update(cx, |commit_message, cx| {
+            commit_message.set_text("", cx);
+        });
         Ok(())
     }
 
     pub fn commit_all(
-        &mut self,
+        &self,
         err_sender: mpsc::Sender<anyhow::Error>,
-        cx: &AppContext,
+        cx: &mut AppContext,
     ) -> anyhow::Result<()> {
         if !self.can_commit(true, cx) {
             return Err(anyhow!("Unable to commit"));
         }
-        let Some((_, entry, git_repo)) = self.active_repository.as_ref() else {
-            return Err(anyhow!("No active repository"));
-        };
-        let to_stage = entry
+        let to_stage = self
+            .repository_entry
             .status()
             .filter(|entry| !entry.status.is_staged().unwrap_or(false))
             .map(|entry| entry.repo_path.clone())
@@ -222,10 +349,13 @@ impl GitState {
         let message = self.commit_message.read(cx).as_rope().clone();
         self.update_sender
             .unbounded_send((
-                Message::StageAndCommit(git_repo.clone(), message, to_stage),
+                Message::StageAndCommit(self.git_repo.clone(), message, to_stage),
                 err_sender,
             ))
             .map_err(|_| anyhow!("Failed to submit commit operation"))?;
+        self.commit_message.update(cx, |commit_message, cx| {
+            commit_message.set_text("", cx);
+        });
         Ok(())
     }
 }