Set up the flake repo directory.

src/command/build/runner.rs

@@ -2,6 +2,10 @@ use crate::cli::parameters::BuildArgs;
 use crate::config::Config;
 use crate::config::TargetConfig;
 use crate::error::CustomError;
+use crate::fs_util::assert_directory;
+use crate::fs_util::is_git_repo;
+use crate::git_util::git_force_into_state;
+use crate::git_util::git_init_at_rev;
 
 pub(crate) async fn run_build(args: BuildArgs) -> Result<(), CustomError> {
     println!("{:?}", args);
@@ -18,12 +22,41 @@ pub(crate) async fn run_build(args: BuildArgs) -> Result<(), CustomError> {
             }
         };
 
-        prepare_flake_repo(target_config).await?;
+        prepare_flake_repo(&config, target_config).await?;
     }
 
     Ok(())
 }
 
-async fn prepare_flake_repo(target_config: &TargetConfig) -> Result<(), CustomError> {
-    todo!()
+async fn prepare_flake_repo(
+    config_root: &Config,
+    target_config: &TargetConfig,
+) -> Result<(), CustomError> {
+    let flake_directory = target_config.get_flake_directory(config_root)?;
+    assert_directory!(
+        &flake_directory,
+        "Creating flake directory {}",
+        (&flake_directory).to_string_lossy()
+    );
+
+    if is_git_repo(&flake_directory).await? {
+        // Clean up the existing clone
+        git_force_into_state(
+            &flake_directory,
+            target_config.get_branch()?,
+            "origin",
+            target_config.get_repo()?,
+            target_config.get_revision()?,
+        )
+        .await?;
+    } else {
+        git_init_at_rev(
+            &flake_directory,
+            target_config.get_branch()?,
+            target_config.get_repo()?,
+            target_config.get_revision()?,
+        )
+        .await?;
+    }
+    Ok(())
 }