From e9494787547ec75f714a47aa1e9830518a5f4bf9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christina=20S=C3=B8rensen?= <christina@cafkafk.com>
Date: Thu, 12 Sep 2024 11:56:04 +0200
Subject: [PATCH] feat: parse installables
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Signed-off-by: Christina Sørensen <christina@cafkafk.com>
---
 crates/nix-weather/src/cli.rs  |  5 ++++-
 crates/nix-weather/src/main.rs |  6 +++++-
 crates/nix-weather/src/nix.rs  | 29 +++++++++++++++++++++++++----
 3 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/crates/nix-weather/src/cli.rs b/crates/nix-weather/src/cli.rs
index 9f35095..78b8d0d 100644
--- a/crates/nix-weather/src/cli.rs
+++ b/crates/nix-weather/src/cli.rs
@@ -6,12 +6,15 @@
 use clap::{arg, command, crate_authors, value_parser, ArgAction, Command};
 
 const DEFAULT_CACHE: &str = "cache.nixos.org";
+const DEFAULT_INSTALLABLE: &str = "./#nixosConfigurations.{}.config.system.build.toplevel";
 
 pub fn build_cli() -> Command {
   command!()
     .author(crate_authors!("\n"))
+    // TODO: parse multiple installables, like e.g. build does?
+    .arg(arg!([installable] "A nix installable").required(false))
     .arg(
-      arg!(--cache <CACHE> "check a specific cache")
+      arg!(--cache <CACHE> "Check a specific cache")
         .required(false)
         .default_value(DEFAULT_CACHE),
     )
diff --git a/crates/nix-weather/src/main.rs b/crates/nix-weather/src/main.rs
index d69c3b1..e0ba065 100644
--- a/crates/nix-weather/src/main.rs
+++ b/crates/nix-weather/src/main.rs
@@ -103,7 +103,11 @@ async fn main() -> io::Result<()> {
     .build()
     .unwrap();
 
-  let binding = get_requisites(&host_name, &config_dir);
+  let binding = get_requisites(
+    &host_name,
+    &config_dir,
+    matches.get_one::<String>("installable").cloned(),
+  );
 
   let get_requisites_duration = initial_time.elapsed().as_secs();
 
diff --git a/crates/nix-weather/src/nix.rs b/crates/nix-weather/src/nix.rs
index fe8c6ac..bc89f15 100644
--- a/crates/nix-weather/src/nix.rs
+++ b/crates/nix-weather/src/nix.rs
@@ -9,8 +9,9 @@ use std::{
   process::{Command, Stdio},
 };
 
-pub fn get_requisites(host: &str, config_dir: &str) -> String {
-  let get_drv_path = Command::new("nix")
+/// Get nixosConfiguration derivation path
+fn get_config_drv_path(host: &str, config_dir: &str) -> std::io::Result<std::process::Output> {
+  Command::new("nix")
     .current_dir(Path::new(config_dir))
     .args([
       "build",
@@ -23,10 +24,30 @@ pub fn get_requisites(host: &str, config_dir: &str) -> String {
       "--json",
     ])
     .output()
-    .unwrap();
+}
+
+/// Get installable derivation path
+fn get_installable_drv_path(
+  host: &str,
+  config_dir: &str,
+  installable: &str,
+) -> std::io::Result<std::process::Output> {
+  Command::new("nix")
+    .current_dir(Path::new(config_dir))
+    .args(["build", "--quiet", installable, "--dry-run", "--json"])
+    .output()
+}
+
+pub fn get_requisites(host: &str, config_dir: &str, installable: Option<String>) -> String {
+  let mut drv_path;
+  if let Some(installable) = installable {
+    drv_path = get_installable_drv_path(host, config_dir, &installable).unwrap();
+  } else {
+    drv_path = get_config_drv_path(host, config_dir).unwrap();
+  }
 
   let drv_path_json: Value =
-    serde_json::from_str(&String::from_utf8(get_drv_path.stdout).unwrap()).unwrap();
+    serde_json::from_str(&String::from_utf8(drv_path.stdout).unwrap()).unwrap();
   let drv_path = drv_path_json[0]["drvPath"].clone();
 
   log::debug!("drv_path: {}", &drv_path);