Implement chain submissions API and update frontend to utilize new endpoint; enhance submissions page with feature flag for API selection, participant progress display, and improved filtering logic.

stubs/api/index.js

@@ -461,4 +461,116 @@ router.get('/challenge/user/:userId/submissions', (req, res) => {
   respond(res, filtered);
 });
 
+// GET /api/challenge/chain/:chainId/submissions
+router.get('/challenge/chain/:chainId/submissions', (req, res) => {
+  const chains = getChains();
+  const submissions = getSubmissions();
+  const users = getUsers();
+  
+  const chainId = req.params.chainId;
+  const userId = req.query.userId;
+  const status = req.query.status;
+  const limit = parseInt(req.query.limit) || 100;
+  const offset = parseInt(req.query.offset) || 0;
+  
+  // Найти цепочку
+  const chain = chains.find(c => c.id === chainId);
+  if (!chain) {
+    return respondError(res, 'Chain not found', 404);
+  }
+  
+  // Получить taskIds из цепочки
+  const taskIds = new Set(chain.tasks.map(t => t.id));
+  
+  // Фильтровать submissions по taskIds цепочки
+  let filteredSubmissions = submissions.filter(s => {
+    const taskId = typeof s.task === 'object' ? s.task.id : s.task;
+    return taskIds.has(taskId);
+  });
+  
+  // Применить фильтр по userId если указан
+  if (userId) {
+    filteredSubmissions = filteredSubmissions.filter(s => {
+      const subUserId = typeof s.user === 'object' ? s.user.id : s.user;
+      return subUserId === userId;
+    });
+  }
+  
+  // Применить фильтр по status если указан
+  if (status) {
+    filteredSubmissions = filteredSubmissions.filter(s => s.status === status);
+  }
+  
+  // Получить уникальных участников
+  const participantMap = new Map();
+  
+  filteredSubmissions.forEach(sub => {
+    const subUserId = typeof sub.user === 'object' ? sub.user.id : sub.user;
+    const subUserNickname = typeof sub.user === 'object' ? sub.user.nickname : '';
+    
+    // Найти nickname если не заполнен
+    let nickname = subUserNickname;
+    if (!nickname) {
+      const user = users.find(u => u.id === subUserId);
+      nickname = user ? user.nickname : subUserId;
+    }
+    
+    if (!participantMap.has(subUserId)) {
+      participantMap.set(subUserId, {
+        userId: subUserId,
+        nickname: nickname,
+        completedTasks: new Set(),
+        totalTasks: chain.tasks.length,
+      });
+    }
+    
+    // Если статус accepted, добавляем taskId в completedTasks
+    if (sub.status === 'accepted') {
+      const taskId = typeof sub.task === 'object' ? sub.task.id : sub.task;
+      participantMap.get(subUserId).completedTasks.add(taskId);
+    }
+  });
+  
+  // Преобразовать в массив и рассчитать прогресс
+  const participants = Array.from(participantMap.values()).map(p => ({
+    userId: p.userId,
+    nickname: p.nickname,
+    completedTasks: p.completedTasks.size,
+    totalTasks: p.totalTasks,
+    progressPercent: p.totalTasks > 0 
+      ? Math.round((p.completedTasks.size / p.totalTasks) * 100) 
+      : 0,
+  }));
+  
+  // Сортировать submissions по дате (новые сначала)
+  filteredSubmissions.sort((a, b) => 
+    new Date(b.submittedAt) - new Date(a.submittedAt)
+  );
+  
+  // Применить пагинацию
+  const total = filteredSubmissions.length;
+  const paginatedSubmissions = filteredSubmissions.slice(offset, offset + limit);
+  
+  // Формируем ответ
+  const response = {
+    chain: {
+      id: chain.id,
+      name: chain.name,
+      tasks: chain.tasks.map(t => ({
+        id: t.id,
+        title: t.title,
+      })),
+    },
+    participants: participants,
+    submissions: paginatedSubmissions,
+    pagination: {
+      total: total,
+      limit: limit,
+      offset: offset,
+    },
+  };
+  
+  respond(res, response);
+});
+
 module.exports = router;