Add version detection via package.json

src/lib.rs

@@ -1,6 +1,6 @@
 use std::ffi::OsString;
 
-use consts::{DATA_DIR, VERSION_FILE_PATH};
+use consts::VERSION_FILE_PATH;
 use crossterm::style::Stylize;
 use mapper::Mapper;
 use repository::{config::Config, NodeVersion, Repository};
@@ -80,5 +80,5 @@ async fn get_repository() -> Result<Repository> {
 }
 
 async fn get_mapper() -> Result<Mapper> {
-    Ok(Mapper::new(get_repository().await?))
+    Ok(Mapper::load(get_repository().await?).await)
 }

src/mapper/mod.rs

@@ -8,11 +8,16 @@ use crate::{
     repository::{NodeVersion, Repository},
 };
 
-use self::{error::MapperError, mapped_command::MappedCommand, mapped_dir::map_node_bin};
+use self::{
+    error::MapperError, mapped_command::MappedCommand, mapped_dir::map_node_bin,
+    package_info::PackageInfo,
+};
 
 pub mod error;
 mod mapped_command;
 mod mapped_dir;
+mod package_info;
+
 /// Responsible for mapping to node executables
 /// and managing node versions
 pub struct Mapper {
@@ -21,9 +26,10 @@ pub struct Mapper {
 }
 
 impl Mapper {
-    pub fn new(repository: Repository) -> Self {
-        let version =
-            Self::get_version().unwrap_or_else(|| repository.config.default_version.to_owned());
+    pub async fn load(repository: Repository) -> Self {
+        let version = Self::get_version()
+            .await
+            .unwrap_or_else(|| repository.config.default_version.to_owned());
         Self {
             repo: repository,
             active_version: version,
@@ -77,10 +83,20 @@ impl Mapper {
         Ok(())
     }
 
-    fn get_version() -> Option<NodeVersion> {
-        env::var("NODE_VERSION")
+    async fn get_version() -> Option<NodeVersion> {
+        if let Some(version) = PackageInfo::find()
+            .await
             .ok()
-            .and_then(|v| NodeVersion::from_str(&v).ok())
+            .and_then(|i| i)
+            .and_then(|i| i.engines)
+            .and_then(|e| e.node)
+        {
+            Some(NodeVersion::Req(version))
+        } else {
+            env::var("NODE_VERSION")
+                .ok()
+                .and_then(|v| NodeVersion::from_str(&v).ok())
+        }
     }
 
     /// creates wrapper scripts for the current version

src/mapper/package_info.rs

@@ -0,0 +1,56 @@
+use std::{collections::HashMap, path::Path};
+
+use semver::VersionReq;
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use tokio::fs;
+
+use crate::error::LibResult;
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct PackageInfo {
+    pub engines: Option<EngineInfo>,
+
+    #[serde(flatten)]
+    other: HashMap<String, Value>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct EngineInfo {
+    pub node: Option<VersionReq>,
+
+    #[serde(flatten)]
+    other: HashMap<String, Value>,
+}
+
+impl PackageInfo {
+    pub async fn find() -> LibResult<Option<Self>> {
+        let mut dir = std::env::current_dir()?;
+        let file_path = dir.join("package.json");
+
+        if file_path.exists() {
+            let info = Self::load(&file_path).await?;
+
+            Ok(Some(info))
+        } else {
+            while let Some(parent) = dir.parent() {
+                dir = parent.to_owned();
+                let file_path = dir.join("package.json");
+
+                if file_path.exists() {
+                    let info = Self::load(&file_path).await?;
+                    return Ok(Some(info));
+                }
+            }
+            Ok(None)
+        }
+    }
+
+    /// Loads the package.json config file
+    pub async fn load(path: &Path) -> LibResult<Self> {
+        let file_content = fs::read_to_string(&path).await?;
+        let cfg = serde_json::from_str(&file_content)?;
+
+        Ok(cfg)
+    }
+}