重构批量下载逻辑，优化历史显示和下载管理

backend/services/task-manager.js

@@ -11,6 +11,10 @@ class TaskManager {
     this.tasksFile = path.join(dataPath, 'download_tasks.json');
     this.tasks = new Map(); // 内存中的任务状态
     this.initialized = false;
+    
+    // 配置
+    this.maxCompletedTasks = 100; // 最多保留100个已完成的任务
+    this.cleanupThreshold = 150; // 超过150个时开始清理
   }
 
   /**
@@ -20,8 +24,12 @@ class TaskManager {
     try {
       await fs.ensureDir(this.dataPath);
       await this.loadTasks();
+      
+      // 初始化时清理已完成的任务
+      await this.cleanupCompletedTasks();
+      
       this.initialized = true;
-      // 任务管理器初始化完成
+      console.log('任务管理器初始化完成');
     } catch (error) {
       console.error('任务管理器初始化失败:', error);
       this.initialized = false;
@@ -99,7 +107,14 @@ class TaskManager {
     }
 
     Object.assign(task, updates);
-    await this.saveTasks();
+    
+    // 如果任务完成，检查是否需要清理
+    if (['completed', 'failed', 'cancelled', 'partial'].includes(updates.status)) {
+      await this.checkAndCleanupTasks();
+    } else {
+      await this.saveTasks();
+    }
+    
     return true;
   }
 
@@ -121,6 +136,24 @@ class TaskManager {
     return Array.from(this.tasks.values());
   }
 
+  /**
+   * 获取活跃任务（下载中或暂停）
+   */
+  getActiveTasks() {
+    return Array.from(this.tasks.values()).filter(task => 
+      ['downloading', 'paused'].includes(task.status)
+    );
+  }
+
+  /**
+   * 获取已完成的任务
+   */
+  getCompletedTasks() {
+    return Array.from(this.tasks.values()).filter(task => 
+      ['completed', 'failed', 'cancelled', 'partial'].includes(task.status)
+    );
+  }
+
   /**
    * 获取指定状态的任务
    */
@@ -128,23 +161,45 @@ class TaskManager {
     return Array.from(this.tasks.values()).filter(task => task.status === status);
   }
 
+  /**
+   * 检查并清理任务
+   */
+  async checkAndCleanupTasks() {
+    const completedTasks = this.getCompletedTasks();
+    
+    if (completedTasks.length > this.cleanupThreshold) {
+      await this.cleanupCompletedTasks();
+    } else {
+      await this.saveTasks();
+    }
+  }
+
   /**
    * 清理已完成的任务
    */
   async cleanupCompletedTasks() {
     const completedStatuses = ['completed', 'failed', 'cancelled', 'partial'];
+    const completedTasks = Array.from(this.tasks.entries())
+      .filter(([_, task]) => completedStatuses.includes(task.status))
+      .sort((a, b) => new Date(b[1].end_time) - new Date(a[1].end_time)); // 按完成时间排序
+
+    if (completedTasks.length <= this.maxCompletedTasks) {
+      await this.saveTasks();
+      return 0;
+    }
+
+    // 删除超出限制的已完成任务
+    const tasksToDelete = completedTasks.slice(this.maxCompletedTasks);
     let cleanedCount = 0;
 
-    for (const [taskId, task] of this.tasks) {
-      if (completedStatuses.includes(task.status)) {
-        this.tasks.delete(taskId);
-        cleanedCount++;
-      }
+    for (const [taskId, _] of tasksToDelete) {
+      this.tasks.delete(taskId);
+      cleanedCount++;
     }
 
     if (cleanedCount > 0) {
       await this.saveTasks();
-      // 清理了已完成的任务
+      console.log(`清理已完成任务: ${cleanedCount} 个`);
     }
 
     return cleanedCount;
@@ -172,6 +227,43 @@ class TaskManager {
 
     return stats;
   }
+
+  /**
+   * 手动清理任务
+   */
+  async cleanupTasksManually(keepActive = true, keepCompleted = this.maxCompletedTasks) {
+    let cleanedCount = 0;
+    
+    if (keepActive) {
+      // 保留活跃任务
+      const activeTasks = this.getActiveTasks();
+      const completedTasks = this.getCompletedTasks()
+        .sort((a, b) => new Date(b.end_time) - new Date(a.end_time))
+        .slice(0, keepCompleted);
+      
+      // 重建任务Map
+      const newTasks = new Map();
+      
+      // 添加活跃任务
+      for (const task of activeTasks) {
+        newTasks.set(task.id, task);
+      }
+      
+      // 添加要保留的已完成任务
+      for (const task of completedTasks) {
+        newTasks.set(task.id, task);
+      }
+      
+      cleanedCount = this.tasks.size - newTasks.size;
+      this.tasks = newTasks;
+    } else {
+      // 清理所有已完成任务
+      cleanedCount = await this.cleanupCompletedTasks();
+    }
+    
+    await this.saveTasks();
+    return cleanedCount;
+  }
 }
 
 module.exports = TaskManager;