feat: home-manager configuration support

Closes https://github.com/getchoo/nix-forecast/issues/59

3 files changed, 46 insertions, 14 deletions

diff --git a/src/cli.rs b/src/cli.rs
index edfba5d..da8635b 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -11,6 +11,15 @@ pub struct Cli {
 	#[arg(short, long, conflicts_with("installables"))]
 	pub configuration: Option<String>,
 
+	/// Flake reference pointing to a standalone home-manager configuration
+	#[arg(
+		short = 'o',
+		long,
+		conflicts_with("configuration"),
+		conflicts_with("installables")
+	)]
+	pub home: Option<String>,
+
 	/// URLs of the substituters to check (can be passed more than once)
 	#[arg(
 		alias = "binary-cache",
diff --git a/src/command.rs b/src/command.rs
index be1dd4c..3d630ca 100644
--- a/src/command.rs
+++ b/src/command.rs
@@ -19,7 +19,10 @@ impl Run for crate::Cli {
 			resolve_installables(installables).await?
 		} else if let Some(configuration) = &self.configuration {
 			println!("❓ Indexing requisites of configuration closure");
-			nix::configuration_closure_paths(configuration)?
+			nix::system_configuration_closure_paths(configuration)?
+		} else if let Some(home) = &self.home {
+			println!("❓ Indexing requisites of home configuration closure");
+			nix::home_configuration_closure_paths(home)?
 		} else {
 			println!("❓ Indexing all installables of flake `{}`", self.flake);
 			let installables = nix::all_flake_installables(&self.flake)?;
diff --git a/src/nix.rs b/src/nix.rs
index 99e7f96..7132e8d 100644
--- a/src/nix.rs
+++ b/src/nix.rs
@@ -24,6 +24,18 @@ struct PathInfo {
 	path: String,
 }
 
+/// Strip derivations from a list of store paths
+fn strip_drvs(paths: Vec<String>) -> Vec<String> {
+	paths
+		.into_iter()
+		.filter(|path| {
+			std::path::Path::new(path)
+				.extension()
+				.is_some_and(|ext| !ext.eq_ignore_ascii_case("drv"))
+		})
+		.collect()
+}
+
 #[instrument(skip(installable))]
 pub fn dry_build_output(installable: &str) -> Result<Vec<u8>> {
 	event!(Level::TRACE, "Running command `nix build --extra-experimental-features 'nix-command flakes' --dry-run --json {installable}`");
@@ -105,22 +117,30 @@ pub fn closure_paths(store_path: &str, with_outputs: bool) -> Result<Vec<String>
 	}
 }
 
+/// Get all paths in an installable's closure
+#[instrument(skip(installable))]
+fn installable_closure_paths(installable: &str) -> Result<Vec<String>> {
+	let store_path = drv_path(&installable)?;
+	let paths = closure_paths(&store_path, true)?;
+	let out_paths = strip_drvs(paths);
+
+	Ok(out_paths)
+}
+
 /// Get all paths in a NixOS or nix-darwin configuration's closure
 #[instrument(skip(configuration_ref))]
-pub fn configuration_closure_paths(configuration_ref: &str) -> Result<Vec<String>> {
+pub fn system_configuration_closure_paths(configuration_ref: &str) -> Result<Vec<String>> {
 	let installable = format!("{configuration_ref}.config.system.build.toplevel");
-	let store_path = drv_path(&installable)?;
-	let paths = closure_paths(&store_path, true)?;
-	// Operate only on the out paths of requisites of the closure
-	let out_paths = paths
-		.iter()
-		.filter(|path| {
-			std::path::Path::new(path)
-				.extension()
-				.is_some_and(|ext| !ext.eq_ignore_ascii_case("drv"))
-		})
-		.map(ToString::to_string)
-		.collect();
+	let out_paths = installable_closure_paths(&installable)?;
+
+	Ok(out_paths)
+}
+
+/// Get all paths in a home-manager configuration's closure
+#[instrument(skip(configuration_ref))]
+pub fn home_configuration_closure_paths(configuration_ref: &str) -> Result<Vec<String>> {
+	let installable = format!("{configuration_ref}.activationPackage");
+	let out_paths = installable_closure_paths(&installable)?;
 
 	Ok(out_paths)
 }