refactor(downloader): introduce top-level downloader module

Move VCS downloaders and DownloadManager out of vcs/repository into a
new top-level downloader module mirroring Composer\Downloader, and add
stub types for the remaining Composer downloader hierarchy (file,
archive variants, path, perforce, fossil, exceptions, interfaces) so
future ports have a home.

1 files changed, 55 insertions, 0 deletions

diff --git a/crates/mozart-core/src/downloader/vcs_downloader.rs b/crates/mozart-core/src/downloader/vcs_downloader.rs
new file mode 100644
index 0000000..ce56d41
--- /dev/null
+++ b/crates/mozart-core/src/downloader/vcs_downloader.rs
@@ -0,0 +1,55 @@
+/// The VCS downloader interface.
+///
+/// Corresponds to Composer's `VcsDownloader` hierarchy.
+pub trait VcsDownloader {
+    /// Prepare for installation (e.g., sync mirror cache).
+    fn download(&self, url: &str, reference: &str, target: &std::path::Path) -> anyhow::Result<()>;
+
+    /// Install (clone/checkout) the source to the target directory.
+    fn install(&self, url: &str, reference: &str, target: &std::path::Path) -> anyhow::Result<()>;
+
+    /// Update the source at target to a new reference.
+    fn update(
+        &self,
+        url: &str,
+        old_ref: &str,
+        new_ref: &str,
+        target: &std::path::Path,
+    ) -> anyhow::Result<()>;
+
+    /// Remove the source from the target directory.
+    fn remove(&self, target: &std::path::Path) -> anyhow::Result<()>;
+
+    /// Detect local changes in the working copy.
+    /// Returns `None` if clean, `Some(diff)` if modified.
+    /// Mirrors `Composer\Downloader\ChangeReportInterface::getLocalChanges`.
+    fn get_local_changes(&self, target: &std::path::Path) -> anyhow::Result<Option<String>>;
+
+    /// Detect commits present locally but not on the tracking remote.
+    /// Returns `None` if there are no unpushed commits or the concept does
+    /// not apply (only `GitDownloader` implements this in Composer's
+    /// `DvcsDownloaderInterface`).
+    fn unpushed_changes(&self, _target: &std::path::Path) -> anyhow::Result<Option<String>> {
+        Ok(None)
+    }
+
+    /// Resolve the working copy's current VCS reference (e.g. commit hash).
+    /// Returns `None` if no reference can be determined. Mirrors
+    /// `Composer\Downloader\VcsCapableDownloaderInterface::getVcsReference`.
+    fn vcs_reference(&self, _target: &std::path::Path) -> anyhow::Result<Option<String>> {
+        Ok(None)
+    }
+
+    /// Get commit log between two references.
+    fn commit_logs(&self, from: &str, to: &str, target: &std::path::Path)
+    -> anyhow::Result<String>;
+
+    /// instanceof ChangeReportInterface
+    fn is_change_report(&self) -> bool;
+
+    /// instanceof VcsCapableDownloaderInterface
+    fn is_vcs_capable_downloader(&self) -> bool;
+
+    /// instanceof DvcsDownloaderInterface
+    fn is_dvcs_downloader(&self) -> bool;
+}