1 files changed, 153 insertions, 0 deletions
diff --git a/src/nix.rs b/src/nix.rs
new file mode 100644
index 0000000..a2268a2
--- /dev/null
+++ b/src/nix.rs
@@ -0,0 +1,153 @@
+/// Abstractions over Nix's CLI
+use crate::Error;
+
+use std::{collections::HashMap, process::Command};
+
+use anyhow::{Context, Result};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use tracing::{event, instrument, Level};
+
+/// JSON output of `nix path-info`
+#[derive(Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct PathInfo {
+	path: String,
+}
+
+/// JSON output of `nix build`
+#[derive(Clone, Debug, Eq, PartialEq, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct Build {
+	drv_path: String,
+	/// Derivation output names and their path
+	outputs: HashMap<String, String>,
+}
+
+#[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}`");
+	let output = Command::new("nix")
+		.args([
+			"--extra-experimental-features",
+			"nix-command flakes",
+			"build",
+			"--dry-run",
+			"--json",
+			installable,
+		])
+		.output()?;
+
+	if output.status.success() {
+		Ok(output.stdout)
+	} else {
+		let code = output.status.code().unwrap_or(1);
+		let stderr = String::from_utf8(output.stderr.clone()).unwrap_or_default();
+
+		Err(Error::Nix { code, stderr }.into())
+	}
+}
+
+/// Get the `outPath` (store path) of an installable
+#[instrument(skip(installable))]
+pub fn out_path(installable: &str) -> Result<String> {
+	let dry_build_output = dry_build_output(installable)?;
+	let data: Vec<Build> = serde_json::from_slice(&dry_build_output)?;
+
+	let out_path = data
+		.first()
+		.context("Unable to parse `nix build` output!")?
+		.outputs
+		.get("out")
+		.with_context(|| format!("Unable to find output `out` for installable {installable}"))?;
+
+	Ok(out_path.to_string())
+}
+
+/// Get the `drvPath` (derivation path) of an installable
+#[instrument(skip(installable))]
+pub fn drv_path(installable: &str) -> Result<String> {
+	let dry_build_output = dry_build_output(installable)?;
+	let data: Vec<Build> = serde_json::from_slice(&dry_build_output)?;
+
+	let drv_path = &data
+		.first()
+		.context("Unable to parse `nix build` output!")?
+		.drv_path;
+
+	Ok(drv_path.to_string())
+}
+
+/// Get all paths in a closure at the given store path
+#[instrument(skip(store_path))]
+pub fn closure_paths(store_path: &str) -> Result<Vec<String>> {
+	event!(Level::TRACE, "Running command `nix --extra-experimental-features 'nix-command flakes' path-info --json --recursive {store_path}`");
+	let output = Command::new("nix")
+		.args([
+			"--extra-experimental-features",
+			"nix-command flakes",
+			"path-info",
+			"--json",
+			"--recursive",
+			store_path,
+		])
+		.output()?;
+
+	if output.status.success() {
+		let path_infos: Vec<PathInfo> = serde_json::from_slice(&output.stdout)?;
+		let paths = path_infos
+			.into_iter()
+			.map(|path_info| path_info.path)
+			.collect();
+		Ok(paths)
+	} else {
+		let code = output.status.code().unwrap_or(1);
+		let stderr = String::from_utf8(output.stderr.clone()).unwrap_or_default();
+
+		Err(Error::Nix { code, stderr }.into())
+	}
+}
+
+/// 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>> {
+	let installable = format!("{configuration_ref}.config.system.build.toplevel");
+	let store_path = drv_path(&installable)?;
+	let paths = closure_paths(&store_path)?;
+
+	Ok(paths)
+}
+
+/// Get all installables available in a given Flake
+#[instrument(skip(flake_ref))]
+pub fn all_flake_installables(flake_ref: &str) -> Result<Vec<String>> {
+	event!(
+		Level::TRACE,
+		"Running command `nix --extra-experimental-features 'nix-command flakes' search --json {flake_ref} .`"
+	);
+	let output = Command::new("nix")
+		.args([
+			"--extra-experimental-features",
+			"nix-command flakes",
+			"search",
+			"--json",
+			flake_ref,
+			".",
+		])
+		.output()?;
+
+	if output.status.success() {
+		let search_results: HashMap<String, Value> = serde_json::from_slice(&output.stdout)?;
+		let package_names = search_results
+			.keys()
+			.map(|name| format!("{flake_ref}#{name}"))
+			.collect::<Vec<_>>();
+
+		Ok(package_names)
+	} else {
+		let code = output.status.code().unwrap_or(1);
+		let stderr = String::from_utf8(output.stderr.clone()).unwrap_or_default();
+
+		Err(Error::Nix { code, stderr }.into())
+	}
+}