feat(java): Enhance Java detection and error handling

- Added support for detecting Java installations from SDKMAN! in `find_sdkman_java`.
- Improved `run_which_command_with_timeout` to handle command timeouts gracefully.
- Introduced a unified `JavaError` enum for consistent error handling across Java operations.
- Updated functions to return `Result` types instead of `Option` for better error reporting.
- Enhanced `load_cached_catalog` and `save_catalog_cache` to use `JavaError`.
- Refactored `fetch_java_catalog`, `fetch_java_release`, and `fetch_available_versions` to return `JavaError`.
- Improved validation functions to return detailed errors when checking Java installations.
- Added tests for version parsing and compatibility checks.
- Updated `resolve_java_for_launch` to handle instance-specific and global Java paths.

1 files changed, 28 insertions, 4 deletions

diff --git a/src-tauri/src/core/java/provider.rs b/src-tauri/src/core/java/provider.rs
index 1b79681..8aa0a0d 100644
--- a/src-tauri/src/core/java/provider.rs
+++ b/src-tauri/src/core/java/provider.rs
@@ -1,23 +1,47 @@
-use crate::core::java::{ImageType, JavaCatalog, JavaDownloadInfo};
+use crate::core::java::{ImageType, JavaCatalog, JavaDownloadInfo, JavaError};
 use tauri::AppHandle;
 
+/// Trait for Java distribution providers (e.g., Adoptium, Corretto)
+///
+/// Implementations handle fetching Java catalogs and release information
+/// from different distribution providers.
 pub trait JavaProvider: Send + Sync {
     /// Fetch the Java catalog (all available versions for this provider)
+    ///
+    /// # Arguments
+    /// * `app_handle` - The Tauri app handle for cache access
+    /// * `force_refresh` - If true, bypass cache and fetch fresh data
+    ///
+    /// # Returns
+    /// * `Ok(JavaCatalog)` with available versions
+    /// * `Err(JavaError)` if fetch or parsing fails
     async fn fetch_catalog(
         &self,
         app_handle: &AppHandle,
         force_refresh: bool,
-    ) -> Result<JavaCatalog, String>;
+    ) -> Result<JavaCatalog, JavaError>;
 
     /// Fetch a specific Java release
+    ///
+    /// # Arguments
+    /// * `major_version` - The major version number (e.g., 17, 21)
+    /// * `image_type` - Whether to fetch JRE or JDK
+    ///
+    /// # Returns
+    /// * `Ok(JavaDownloadInfo)` with download details
+    /// * `Err(JavaError)` if fetch or parsing fails
     async fn fetch_release(
         &self,
         major_version: u32,
         image_type: ImageType,
-    ) -> Result<JavaDownloadInfo, String>;
+    ) -> Result<JavaDownloadInfo, JavaError>;
 
     /// Get list of available major versions
-    async fn available_versions(&self) -> Result<Vec<u32>, String>;
+    ///
+    /// # Returns
+    /// * `Ok(Vec<u32>)` with available major versions
+    /// * `Err(JavaError)` if fetch fails
+    async fn available_versions(&self) -> Result<Vec<u32>, JavaError>;
 
     /// Get provider name (e.g., "adoptium", "corretto")
     #[allow(dead_code)]