Add support for parsing the flake.lock.

src/nix_util/lock_parser.rs

@@ -0,0 +1,150 @@
+use std::collections::BTreeMap;
+use std::path::Path;
+
+use serde::Deserialize;
+use serde::Serialize;
+
+use crate::Result;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub(crate) struct FlakeLock {
+    pub(crate) root: String,
+    pub(crate) version: u8,
+    pub(crate) nodes: BTreeMap<String, FlakeLockNode>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub(crate) struct FlakeLockNode {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub(crate) locked: Option<FlakeLockNodeLocked>,
+
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub(crate) original: Option<FlakeLockNodeOriginal>,
+
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub(crate) inputs: Option<BTreeMap<String, FlakeLockInputValue>>,
+
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub(crate) flake: Option<bool>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub(crate) struct FlakeLockNodeLocked {
+    #[serde(rename = "lastModified")]
+    pub(crate) last_modified: i64,
+
+    #[serde(rename = "narHash")]
+    pub(crate) nar_hash: String,
+
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub(crate) url: Option<String>,
+
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub(crate) owner: Option<String>,
+
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub(crate) repo: Option<String>,
+
+    #[serde(rename = "ref", default, skip_serializing_if = "Option::is_none")]
+    pub(crate) git_ref: Option<String>,
+
+    pub(crate) rev: String,
+
+    #[serde(rename = "revCount", default, skip_serializing_if = "Option::is_none")]
+    pub(crate) rev_count: Option<i64>,
+
+    #[serde(rename = "type")]
+    pub(crate) repo_type: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(tag = "type", rename_all = "lowercase", deny_unknown_fields)]
+pub(crate) enum FlakeLockNodeOriginal {
+    Github {
+        owner: String,
+
+        repo: String,
+
+        #[serde(rename = "ref", default, skip_serializing_if = "Option::is_none")]
+        git_ref: Option<String>,
+
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        rev: Option<String>,
+    },
+    Git {
+        url: String,
+    },
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(untagged, deny_unknown_fields)]
+pub(crate) enum FlakeLockInputValue {
+    String(String),
+    List(Vec<String>),
+}
+
+pub(crate) async fn parse_flake_lock<F>(flake_path: F) -> Result<FlakeLock>
+where
+    F: AsRef<Path>,
+{
+    let lock_file_path = flake_path.as_ref().join("flake.lock");
+    let contents = tokio::fs::read_to_string(&lock_file_path).await?;
+    let parsed_flake_lock = serde_json::from_str(&contents)?;
+    Ok(parsed_flake_lock)
+}
+
+impl FlakeLock {
+    pub(crate) fn get_root_node(&self) -> Result<&FlakeLockNode> {
+        let root_node = self.nodes.get(&self.root).ok_or("Root node not found.")?;
+        Ok(root_node)
+    }
+
+    pub(crate) fn get_inputs<'lock>(
+        &'lock self,
+        source_node: &'lock FlakeLockNode,
+    ) -> Result<BTreeMap<&'lock String, &'lock FlakeLockNode>> {
+        let direct_inputs = match &source_node.inputs {
+            Some(inputs) => inputs,
+            None => {
+                return Ok(BTreeMap::new());
+            }
+        };
+        let mut inputs = BTreeMap::new();
+
+        for (input_name, input_id_or_path) in direct_inputs.iter() {
+            inputs.insert(input_name, self.resolve_path(input_id_or_path)?);
+        }
+
+        Ok(inputs)
+    }
+
+    fn resolve_path<'lock>(
+        &'lock self,
+        input_id_or_path: &'lock FlakeLockInputValue,
+    ) -> Result<&'lock FlakeLockNode> {
+        match input_id_or_path {
+            FlakeLockInputValue::String(input_id) => {
+                // If the input value is a plain string, then it refers to a node.
+                let node = self.nodes.get(input_id).ok_or("Input not found.")?;
+                Ok(node)
+            }
+            FlakeLockInputValue::List(items) => {
+                // If the input value is a list, then it refers to a path to an input.
+                let mut current_node = self.get_root_node()?;
+                for step in items {
+                    let child_input_id_or_path = current_node
+                        .inputs
+                        .as_ref()
+                        .ok_or("Node without inputs while walking input tree.")?
+                        .get(step)
+                        .ok_or("Step not found in inputs while walking input tree")?;
+                    current_node = self.resolve_path(child_input_id_or_path)?;
+                }
+                Ok(current_node)
+            }
+        }
+    }
+}