feat(java): Implement Java catalog management and download features

- Added commands to fetch and refresh the Java catalog, cancel downloads, and manage pending downloads.
- Enhanced the Java download modal in the UI to support version selection, download progress, and pending downloads.
- Introduced new types for Java catalog, download progress, and pending downloads.
- Updated settings store to handle Java catalog state, download progress, and pending downloads.
- Improved user experience with loading states, error handling, and status notifications for Java installations.

1 files changed, 397 insertions, 3 deletions

diff --git a/src-tauri/src/core/downloader.rs b/src-tauri/src/core/downloader.rs
index d33c44d..bf6334f 100644
--- a/src-tauri/src/core/downloader.rs
+++ b/src-tauri/src/core/downloader.rs
@@ -2,10 +2,10 @@ use futures::StreamExt;
 use serde::{Deserialize, Serialize};
 use sha1::Digest as Sha1Digest;
 use std::path::PathBuf;
-use std::sync::atomic::{AtomicU64, AtomicUsize, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU64, AtomicUsize, Ordering};
 use std::sync::Arc;
-use tauri::{Emitter, Window};
-use tokio::io::AsyncWriteExt;
+use tauri::{AppHandle, Emitter, Manager, Window};
+use tokio::io::{AsyncSeekExt, AsyncWriteExt};
 use tokio::sync::Semaphore;
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -18,6 +18,400 @@ pub struct DownloadTask {
     pub sha256: Option<String>,
 }
 
+/// Metadata for resumable downloads stored in .part.meta file
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct DownloadMetadata {
+    pub url: String,
+    pub file_name: String,
+    pub total_size: u64,
+    pub downloaded_bytes: u64,
+    pub checksum: Option<String>,
+    pub timestamp: u64,
+    pub segments: Vec<DownloadSegment>,
+}
+
+/// A download segment for multi-segment parallel downloading
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct DownloadSegment {
+    pub start: u64,
+    pub end: u64,
+    pub downloaded: u64,
+    pub completed: bool,
+}
+
+/// Progress event for Java download
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct JavaDownloadProgress {
+    pub file_name: String,
+    pub downloaded_bytes: u64,
+    pub total_bytes: u64,
+    pub speed_bytes_per_sec: u64,
+    pub eta_seconds: u64,
+    pub status: String, // "Downloading", "Extracting", "Verifying", "Completed", "Paused", "Error"
+    pub percentage: f32,
+}
+
+/// Pending download task for queue persistence
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct PendingJavaDownload {
+    pub major_version: u32,
+    pub image_type: String,
+    pub download_url: String,
+    pub file_name: String,
+    pub file_size: u64,
+    pub checksum: Option<String>,
+    pub install_path: String,
+    pub created_at: u64,
+}
+
+/// Download queue for persistence
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct DownloadQueue {
+    pub pending_downloads: Vec<PendingJavaDownload>,
+}
+
+impl DownloadQueue {
+    /// Load download queue from file
+    pub fn load(app_handle: &AppHandle) -> Self {
+        let queue_path = app_handle
+            .path()
+            .app_data_dir()
+            .unwrap()
+            .join("download_queue.json");
+        if queue_path.exists() {
+            if let Ok(content) = std::fs::read_to_string(&queue_path) {
+                if let Ok(queue) = serde_json::from_str(&content) {
+                    return queue;
+                }
+            }
+        }
+        Self::default()
+    }
+
+    /// Save download queue to file
+    pub fn save(&self, app_handle: &AppHandle) -> Result<(), String> {
+        let queue_path = app_handle
+            .path()
+            .app_data_dir()
+            .unwrap()
+            .join("download_queue.json");
+        let content = serde_json::to_string_pretty(self).map_err(|e| e.to_string())?;
+        std::fs::write(&queue_path, content).map_err(|e| e.to_string())?;
+        Ok(())
+    }
+
+    /// Add a pending download
+    pub fn add(&mut self, download: PendingJavaDownload) {
+        // Remove existing download for same version/type
+        self.pending_downloads.retain(|d| {
+            !(d.major_version == download.major_version && d.image_type == download.image_type)
+        });
+        self.pending_downloads.push(download);
+    }
+
+    /// Remove a completed or cancelled download
+    pub fn remove(&mut self, major_version: u32, image_type: &str) {
+        self.pending_downloads.retain(|d| {
+            !(d.major_version == major_version && d.image_type == image_type)
+        });
+    }
+}
+
+/// Global cancel flag for Java downloads
+pub static JAVA_DOWNLOAD_CANCELLED: AtomicBool = AtomicBool::new(false);
+
+/// Reset the cancel flag
+pub fn reset_java_download_cancel() {
+    JAVA_DOWNLOAD_CANCELLED.store(false, Ordering::SeqCst);
+}
+
+/// Cancel the current Java download
+pub fn cancel_java_download() {
+    JAVA_DOWNLOAD_CANCELLED.store(true, Ordering::SeqCst);
+}
+
+/// Check if download is cancelled
+pub fn is_java_download_cancelled() -> bool {
+    JAVA_DOWNLOAD_CANCELLED.load(Ordering::SeqCst)
+}
+
+/// Determine optimal segment count based on file size
+fn get_segment_count(file_size: u64) -> usize {
+    if file_size < 20 * 1024 * 1024 {
+        1 // < 20MB: single segment
+    } else if file_size < 100 * 1024 * 1024 {
+        4 // 20-100MB: 4 segments
+    } else {
+        8 // > 100MB: 8 segments
+    }
+}
+
+/// Download a large file with resume support and progress events
+pub async fn download_with_resume(
+    app_handle: &AppHandle,
+    url: &str,
+    dest_path: &PathBuf,
+    checksum: Option<&str>,
+    total_size: u64,
+) -> Result<(), String> {
+    reset_java_download_cancel();
+
+    let part_path = dest_path.with_extension(
+        dest_path
+            .extension()
+            .map(|e| format!("{}.part", e.to_string_lossy()))
+            .unwrap_or_else(|| "part".to_string()),
+    );
+    let meta_path = PathBuf::from(format!("{}.meta", part_path.display()));
+    let file_name = dest_path
+        .file_name()
+        .unwrap_or_default()
+        .to_string_lossy()
+        .to_string();
+
+    // Load or create metadata
+    let mut metadata = if meta_path.exists() {
+        let content = tokio::fs::read_to_string(&meta_path)
+            .await
+            .map_err(|e| e.to_string())?;
+        serde_json::from_str(&content).unwrap_or_else(|_| create_new_metadata(url, &file_name, total_size, checksum))
+    } else {
+        create_new_metadata(url, &file_name, total_size, checksum)
+    };
+
+    // Create parent directory
+    if let Some(parent) = dest_path.parent() {
+        tokio::fs::create_dir_all(parent)
+            .await
+            .map_err(|e| e.to_string())?;
+    }
+
+    // Open or create part file
+    let file = tokio::fs::OpenOptions::new()
+        .create(true)
+        .write(true)
+        .read(true)
+        .open(&part_path)
+        .await
+        .map_err(|e| format!("Failed to open part file: {}", e))?;
+
+    let file = Arc::new(tokio::sync::Mutex::new(file));
+    let client = reqwest::Client::new();
+    let progress = Arc::new(AtomicU64::new(metadata.downloaded_bytes));
+    let start_time = std::time::Instant::now();
+    let last_progress_bytes = Arc::new(AtomicU64::new(metadata.downloaded_bytes));
+
+    // Download segments concurrently
+    let segment_count = metadata.segments.len();
+    let semaphore = Arc::new(Semaphore::new(segment_count.min(8)));
+    let mut handles = Vec::new();
+
+    for (idx, segment) in metadata.segments.iter().enumerate() {
+        if segment.completed {
+            continue;
+        }
+
+        let client = client.clone();
+        let url = url.to_string();
+        let file = file.clone();
+        let progress = progress.clone();
+        let semaphore = semaphore.clone();
+        let segment_start = segment.start + segment.downloaded;
+        let segment_end = segment.end;
+        let app_handle = app_handle.clone();
+        let file_name = file_name.clone();
+        let total_size = total_size;
+        let last_progress_bytes = last_progress_bytes.clone();
+        let start_time = start_time.clone();
+
+        let handle = tokio::spawn(async move {
+            let _permit = semaphore.acquire().await.unwrap();
+
+            if is_java_download_cancelled() {
+                return Err("Download cancelled".to_string());
+            }
+
+            // Send Range request
+            let range = format!("bytes={}-{}", segment_start, segment_end);
+            let response = client
+                .get(&url)
+                .header("Range", &range)
+                .send()
+                .await
+                .map_err(|e| format!("Request failed: {}", e))?;
+
+            if !response.status().is_success() && response.status() != reqwest::StatusCode::PARTIAL_CONTENT {
+                return Err(format!("Server returned error: {}", response.status()));
+            }
+
+            let mut stream = response.bytes_stream();
+            let mut current_pos = segment_start;
+
+            while let Some(chunk_result) = stream.next().await {
+                if is_java_download_cancelled() {
+                    return Err("Download cancelled".to_string());
+                }
+
+                let chunk = chunk_result.map_err(|e| format!("Stream error: {}", e))?;
+                let chunk_len = chunk.len() as u64;
+
+                // Write to file at correct position
+                {
+                    let mut file_guard = file.lock().await;
+                    file_guard
+                        .seek(std::io::SeekFrom::Start(current_pos))
+                        .await
+                        .map_err(|e| format!("Seek error: {}", e))?;
+                    file_guard
+                        .write_all(&chunk)
+                        .await
+                        .map_err(|e| format!("Write error: {}", e))?;
+                }
+
+                current_pos += chunk_len;
+                let total_downloaded = progress.fetch_add(chunk_len, Ordering::Relaxed) + chunk_len;
+
+                // Emit progress event (throttled)
+                let last_bytes = last_progress_bytes.load(Ordering::Relaxed);
+                if total_downloaded - last_bytes > 100 * 1024 || total_downloaded >= total_size {
+                    last_progress_bytes.store(total_downloaded, Ordering::Relaxed);
+
+                    let elapsed = start_time.elapsed().as_secs_f64();
+                    let speed = if elapsed > 0.0 {
+                        (total_downloaded as f64 / elapsed) as u64
+                    } else {
+                        0
+                    };
+                    let remaining = total_size.saturating_sub(total_downloaded);
+                    let eta = if speed > 0 { remaining / speed } else { 0 };
+                    let percentage = (total_downloaded as f32 / total_size as f32) * 100.0;
+
+                    let _ = app_handle.emit(
+                        "java-download-progress",
+                        JavaDownloadProgress {
+                            file_name: file_name.clone(),
+                            downloaded_bytes: total_downloaded,
+                            total_bytes: total_size,
+                            speed_bytes_per_sec: speed,
+                            eta_seconds: eta,
+                            status: "Downloading".to_string(),
+                            percentage,
+                        },
+                    );
+                }
+            }
+
+            Ok::<usize, String>(idx)
+        });
+
+        handles.push(handle);
+    }
+
+    // Wait for all segments
+    let mut all_success = true;
+    for handle in handles {
+        match handle.await {
+            Ok(Ok(idx)) => {
+                metadata.segments[idx].completed = true;
+            }
+            Ok(Err(e)) => {
+                all_success = false;
+                if e.contains("cancelled") {
+                    // Save progress for resume
+                    metadata.downloaded_bytes = progress.load(Ordering::Relaxed);
+                    let meta_content = serde_json::to_string_pretty(&metadata).map_err(|e| e.to_string())?;
+                    tokio::fs::write(&meta_path, meta_content).await.ok();
+                    return Err(e);
+                }
+            }
+            Err(e) => {
+                all_success = false;
+                eprintln!("Segment task panicked: {}", e);
+            }
+        }
+    }
+
+    if !all_success {
+        // Save progress
+        metadata.downloaded_bytes = progress.load(Ordering::Relaxed);
+        let meta_content = serde_json::to_string_pretty(&metadata).map_err(|e| e.to_string())?;
+        tokio::fs::write(&meta_path, meta_content).await.ok();
+        return Err("Some segments failed".to_string());
+    }
+
+    // Verify checksum if provided
+    if let Some(expected) = checksum {
+        let _ = app_handle.emit(
+            "java-download-progress",
+            JavaDownloadProgress {
+                file_name: file_name.clone(),
+                downloaded_bytes: total_size,
+                total_bytes: total_size,
+                speed_bytes_per_sec: 0,
+                eta_seconds: 0,
+                status: "Verifying".to_string(),
+                percentage: 100.0,
+            },
+        );
+
+        let data = tokio::fs::read(&part_path)
+            .await
+            .map_err(|e| format!("Failed to read file for verification: {}", e))?;
+        
+        if !verify_checksum(&data, Some(expected), None) {
+            // Checksum failed, delete files and retry
+            tokio::fs::remove_file(&part_path).await.ok();
+            tokio::fs::remove_file(&meta_path).await.ok();
+            return Err("Checksum verification failed".to_string());
+        }
+    }
+
+    // Rename part file to final destination
+    tokio::fs::rename(&part_path, dest_path)
+        .await
+        .map_err(|e| format!("Failed to rename file: {}", e))?;
+
+    // Clean up metadata file
+    tokio::fs::remove_file(&meta_path).await.ok();
+
+    Ok(())
+}
+
+/// Create new download metadata with segments
+fn create_new_metadata(url: &str, file_name: &str, total_size: u64, checksum: Option<&str>) -> DownloadMetadata {
+    let segment_count = get_segment_count(total_size);
+    let segment_size = total_size / segment_count as u64;
+    let mut segments = Vec::new();
+
+    for i in 0..segment_count {
+        let start = i as u64 * segment_size;
+        let end = if i == segment_count - 1 {
+            total_size - 1
+        } else {
+            (i as u64 + 1) * segment_size - 1
+        };
+        segments.push(DownloadSegment {
+            start,
+            end,
+            downloaded: 0,
+            completed: false,
+        });
+    }
+
+    DownloadMetadata {
+        url: url.to_string(),
+        file_name: file_name.to_string(),
+        total_size,
+        downloaded_bytes: 0,
+        checksum: checksum.map(|s| s.to_string()),
+        timestamp: std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_secs(),
+        segments,
+    }
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ProgressEvent {
     pub file: String,