下载非内核

src-tauri/src/download_engine/storage.rs

@@ -0,0 +1,82 @@
+use serde::{Deserialize, Serialize};
+use std::fs;
+use std::path::PathBuf;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+use super::task::{DownloadTask, DownloaderSettings};
+
+/// 引擎持久化状态（序列化到 engine_state.json）
+#[derive(Serialize, Deserialize)]
+pub struct EngineState {
+    /// 所有任务（active + queued + paused + complete + error）
+    #[serde(default)]
+    pub tasks: Vec<DownloadTask>,
+    /// 下载设置
+    #[serde(default)]
+    pub settings: DownloaderSettings,
+    /// 自增 ID 计数器（不序列化为 hex，存原始数字）
+    #[serde(default)]
+    pub next_id: u64,
+}
+
+impl Default for EngineState {
+    fn default() -> Self {
+        Self {
+            tasks: Vec::new(),
+            settings: DownloaderSettings::default(),
+            next_id: 1,
+        }
+    }
+}
+
+/// 存储管理器：负责加载/保存引擎状态到 JSON 文件
+pub struct Storage {
+    state_path: PathBuf,
+    /// ID 计数器（内存中维护，与 EngineState.next_id 同步）
+    pub id_counter: AtomicU64,
+}
+
+impl Storage {
+    pub fn new(data_dir: PathBuf) -> Self {
+        let state_path = data_dir.join("engine_state.json");
+        let existing = Self::load_raw(&state_path);
+        let next_id = existing.as_ref().map(|s| s.next_id).unwrap_or(1);
+        Self {
+            state_path,
+            id_counter: AtomicU64::new(next_id),
+        }
+    }
+
+    /// 生成下一个任务 ID（16 位 hex 字符串）
+    pub fn next_task_id(&self) -> String {
+        let id = self.id_counter.fetch_add(1, Ordering::SeqCst);
+        format!("{:016x}", id)
+    }
+
+    /// 从磁盘加载状态
+    fn load_raw(path: &PathBuf) -> Option<EngineState> {
+        let raw = fs::read_to_string(path).ok()?;
+        serde_json::from_str::<EngineState>(&raw).ok()
+    }
+
+    /// 加载完整状态（若文件不存在返回默认值）
+    pub fn load(&self) -> EngineState {
+        Self::load_raw(&self.state_path).unwrap_or_default()
+    }
+
+    /// 保存状态到磁盘
+    pub fn save(&self, mut state: EngineState) {
+        // 同步 ID 计数器
+        state.next_id = self.id_counter.load(Ordering::SeqCst);
+        match serde_json::to_string_pretty(&state) {
+            Ok(json) => {
+                if let Err(e) = fs::write(&self.state_path, json) {
+                    eprintln!("[download_engine] 保存状态失败: {}", e);
+                }
+            }
+            Err(e) => {
+                eprintln!("[download_engine] 序列化状态失败: {}", e);
+            }
+        }
+    }
+}