3 files changed, 84 insertions, 6 deletions
diff --git a/crates/shirabe/src/installer/installation_manager.rs b/crates/shirabe/src/installer/installation_manager.rs
index ac5f8e4..bee14cc 100644
--- a/crates/shirabe/src/installer/installation_manager.rs
+++ b/crates/shirabe/src/installer/installation_manager.rs
@@ -791,3 +791,78 @@ impl InstallationManager {
         }
     }
 }
+
+// Composer's PartialComposer::setInstallationManager() accepts any InstallationManager subclass, so
+// plugins may swap in a replacement. The interface captures the methods reached through Composer's
+// accessor and through the `&mut dyn InstallationManagerInterface` references fed from it.
+pub trait InstallationManagerInterface: std::fmt::Debug {
+    fn add_installer(&mut self, installer: Box<dyn InstallerInterface>);
+    fn remove_installer(&mut self, installer: &dyn InstallerInterface);
+    fn disable_plugins(&mut self);
+    fn is_package_installed(
+        &mut self,
+        repo: &dyn InstalledRepositoryInterface,
+        package: PackageInterfaceHandle,
+    ) -> Result<bool>;
+    fn ensure_binaries_presence(&mut self, package: PackageInterfaceHandle);
+    fn execute(
+        &mut self,
+        repo: &mut dyn InstalledRepositoryInterface,
+        operations: Vec<std::rc::Rc<dyn OperationInterface>>,
+        dev_mode: bool,
+        run_scripts: bool,
+        download_only: bool,
+    ) -> Result<()>;
+    fn get_install_path(&mut self, package: PackageInterfaceHandle) -> Option<String>;
+    fn set_output_progress(&mut self, output_progress: bool);
+    fn notify_installs(&mut self, io: std::rc::Rc<std::cell::RefCell<dyn IOInterface>>);
+}
+
+impl InstallationManagerInterface for InstallationManager {
+    fn add_installer(&mut self, installer: Box<dyn InstallerInterface>) {
+        self.add_installer(installer);
+    }
+
+    fn remove_installer(&mut self, installer: &dyn InstallerInterface) {
+        self.remove_installer(installer);
+    }
+
+    fn disable_plugins(&mut self) {
+        self.disable_plugins();
+    }
+
+    fn is_package_installed(
+        &mut self,
+        repo: &dyn InstalledRepositoryInterface,
+        package: PackageInterfaceHandle,
+    ) -> Result<bool> {
+        self.is_package_installed(repo, package)
+    }
+
+    fn ensure_binaries_presence(&mut self, package: PackageInterfaceHandle) {
+        self.ensure_binaries_presence(package);
+    }
+
+    fn execute(
+        &mut self,
+        repo: &mut dyn InstalledRepositoryInterface,
+        operations: Vec<std::rc::Rc<dyn OperationInterface>>,
+        dev_mode: bool,
+        run_scripts: bool,
+        download_only: bool,
+    ) -> Result<()> {
+        self.execute(repo, operations, dev_mode, run_scripts, download_only)
+    }
+
+    fn get_install_path(&mut self, package: PackageInterfaceHandle) -> Option<String> {
+        self.get_install_path(package)
+    }
+
+    fn set_output_progress(&mut self, output_progress: bool) {
+        self.set_output_progress(output_progress);
+    }
+
+    fn notify_installs(&mut self, io: std::rc::Rc<std::cell::RefCell<dyn IOInterface>>) {
+        self.notify_installs(io);
+    }
+}
diff --git a/crates/shirabe/src/installer/library_installer.rs b/crates/shirabe/src/installer/library_installer.rs
index e2c6c0c..e1c3aec 100644
--- a/crates/shirabe/src/installer/library_installer.rs
+++ b/crates/shirabe/src/installer/library_installer.rs
@@ -8,7 +8,7 @@ use shirabe_php_shim::{
 };
 
 use crate::composer::PartialComposerWeakHandle;
-use crate::downloader::DownloadManager;
+use crate::downloader::DownloadManagerInterface;
 use crate::installer::BinaryInstaller;
 use crate::installer::BinaryPresenceInterface;
 use crate::installer::InstallerInterface;
@@ -24,7 +24,8 @@ use crate::util::Silencer;
 pub struct LibraryInstaller {
     pub(crate) composer: PartialComposerWeakHandle,
     pub(crate) vendor_dir: String,
-    pub(crate) download_manager: Option<std::rc::Rc<std::cell::RefCell<DownloadManager>>>,
+    pub(crate) download_manager:
+        Option<std::rc::Rc<std::cell::RefCell<dyn DownloadManagerInterface>>>,
     pub(crate) io: std::rc::Rc<std::cell::RefCell<dyn IOInterface>>,
     pub(crate) r#type: Option<String>,
     pub(crate) filesystem: std::rc::Rc<std::cell::RefCell<Filesystem>>,
@@ -192,7 +193,9 @@ impl LibraryInstaller {
         self.vendor_dir = realpath(&self.vendor_dir).unwrap_or_default();
     }
 
-    pub(crate) fn get_download_manager(&self) -> &std::rc::Rc<std::cell::RefCell<DownloadManager>> {
+    pub(crate) fn get_download_manager(
+        &self,
+    ) -> &std::rc::Rc<std::cell::RefCell<dyn DownloadManagerInterface>> {
         // PHP: assert($this->downloadManager instanceof DownloadManager, new \LogicException(...))
         assert!(
             self.download_manager.is_some(),
diff --git a/crates/shirabe/src/installer/project_installer.rs b/crates/shirabe/src/installer/project_installer.rs
index 351fd35..83ffbb2 100644
--- a/crates/shirabe/src/installer/project_installer.rs
+++ b/crates/shirabe/src/installer/project_installer.rs
@@ -1,6 +1,6 @@
 //! ref: composer/src/Composer/Installer/ProjectInstaller.php
 
-use crate::downloader::DownloadManager;
+use crate::downloader::DownloadManagerInterface;
 use crate::installer::InstallerInterface;
 use crate::package::PackageInterfaceHandle;
 use crate::repository::InstalledRepositoryInterface;
@@ -10,14 +10,14 @@ use shirabe_php_shim::{InvalidArgumentException, PhpMixed};
 #[derive(Debug)]
 pub struct ProjectInstaller {
     install_path: String,
-    download_manager: std::rc::Rc<std::cell::RefCell<DownloadManager>>,
+    download_manager: std::rc::Rc<std::cell::RefCell<dyn DownloadManagerInterface>>,
     filesystem: std::rc::Rc<std::cell::RefCell<Filesystem>>,
 }
 
 impl ProjectInstaller {
     pub fn new(
         install_path: &str,
-        dm: std::rc::Rc<std::cell::RefCell<DownloadManager>>,
+        dm: std::rc::Rc<std::cell::RefCell<dyn DownloadManagerInterface>>,
         fs: std::rc::Rc<std::cell::RefCell<Filesystem>>,
     ) -> Self {
         let install_path = format!("{}/", install_path.replace('\\', "/").trim_end_matches('/'));