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, 84 insertions, 0 deletions

diff --git a/crates/mozart-core/src/downloader/hg_downloader.rs b/crates/mozart-core/src/downloader/hg_downloader.rs
new file mode 100644
index 0000000..9fb918e
--- /dev/null
+++ b/crates/mozart-core/src/downloader/hg_downloader.rs
@@ -0,0 +1,84 @@
+use anyhow::Result;
+use std::path::Path;
+
+use crate::{downloader::VcsDownloader, vcs::util::hg::HgUtil};
+
+/// Mercurial downloader using clone/pull/update.
+pub struct HgDownloader {
+    hg_util: HgUtil,
+}
+
+impl HgDownloader {
+    pub fn new(hg_util: HgUtil) -> Self {
+        Self { hg_util }
+    }
+}
+
+impl VcsDownloader for HgDownloader {
+    fn download(&self, _url: &str, _reference: &str, _target: &Path) -> Result<()> {
+        Ok(())
+    }
+
+    fn install(&self, url: &str, reference: &str, target: &Path) -> Result<()> {
+        let target_str = target.to_string_lossy().to_string();
+        self.hg_util
+            .execute(&["clone", "--", url, &target_str], None)?;
+        self.hg_util
+            .execute(&["update", "-r", reference], Some(target))?;
+        Ok(())
+    }
+
+    fn update(&self, url: &str, _old_ref: &str, new_ref: &str, target: &Path) -> Result<()> {
+        self.hg_util.execute(&["pull", url], Some(target))?;
+        self.hg_util
+            .execute(&["update", "-r", new_ref], Some(target))?;
+        Ok(())
+    }
+
+    fn remove(&self, target: &Path) -> Result<()> {
+        if target.exists() {
+            std::fs::remove_dir_all(target)?;
+        }
+        Ok(())
+    }
+
+    fn get_local_changes(&self, target: &Path) -> Result<Option<String>> {
+        if !target.join(".hg").is_dir() {
+            return Ok(None);
+        }
+        let output = self.hg_util.execute(&["st"], Some(target))?;
+        let trimmed = output.stdout.trim();
+        if trimmed.is_empty() {
+            Ok(None)
+        } else {
+            Ok(Some(trimmed.to_string()))
+        }
+    }
+
+    fn commit_logs(&self, from: &str, to: &str, target: &Path) -> Result<String> {
+        let range = format!("{from}:{to}");
+        let output = self.hg_util.execute(
+            &[
+                "log",
+                "-r",
+                &range,
+                "--template",
+                "{rev}:{node|short} {desc|firstline}\\n",
+            ],
+            Some(target),
+        )?;
+        Ok(output.stdout)
+    }
+
+    fn is_change_report(&self) -> bool {
+        true
+    }
+
+    fn is_vcs_capable_downloader(&self) -> bool {
+        true
+    }
+
+    fn is_dvcs_downloader(&self) -> bool {
+        false
+    }
+}