Add summary statistics endpoint and UI integration

- Introduced a new API endpoint `GET /stats/summary` to retrieve detailed smoking statistics for users, including daily and global averages.
- Updated the API client to support fetching summary statistics.
- Enhanced the statistics page with a new tab for summary statistics, featuring key metrics and visualizations for user comparison.
- Implemented error handling and loading states for the summary statistics fetch operation.
- Refactored the statistics page to separate daily and summary statistics into distinct components for improved organization and readability.

stubs/api/index.js

@@ -5,9 +5,16 @@ const timer = (time = 300) => (req, res, next) => setTimeout(next, time);
 router.use(timer());
 
 // In-memory storage for demo
-const users = [];
+const users = [
+  {
+    id: '1',
+    login: 'testuser',
+    password: 'test1234',
+    created: new Date('2024-01-01T00:00:00.000Z').toISOString()
+  }
+];
 const cigarettes = [];
-let userIdCounter = 1;
+let userIdCounter = 2;
 let cigaretteIdCounter = 1;
 
 // Simple token generation (for demo purposes only)
@@ -191,4 +198,108 @@ router.get('/stats/daily', authMiddleware, (req, res) => {
   });
 });
 
+// GET /stats/summary
+router.get('/stats/summary', authMiddleware, (req, res) => {
+  const { from, to } = req.query;
+  
+  // Default: 30 days ago to now
+  const fromDate = from ? new Date(from) : new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
+  const toDate = to ? new Date(to) : new Date();
+
+  // Helper function to get day name in Russian
+  const getDayName = (dayOfWeek) => {
+    const names = ['', 'Воскресенье', 'Понедельник', 'Вторник', 'Среда', 'Четверг', 'Пятница', 'Суббота'];
+    return names[dayOfWeek];
+  };
+
+  // Helper function to calculate stats for a set of cigarettes
+  const calculateStats = (cigs) => {
+    // Daily stats
+    const dailyStats = {};
+    cigs.forEach(c => {
+      const date = c.smokedAt.split('T')[0];
+      dailyStats[date] = (dailyStats[date] || 0) + 1;
+    });
+
+    const daily = Object.entries(dailyStats)
+      .map(([date, count]) => ({ date, count }))
+      .sort((a, b) => a.date.localeCompare(b.date));
+
+    // Weekday stats (1=Sunday, 2=Monday, ..., 7=Saturday)
+    const weekdayStats = {};
+    cigs.forEach(c => {
+      const date = new Date(c.smokedAt);
+      const dayOfWeek = date.getDay() + 1; // JS getDay() returns 0-6, we want 1-7
+      weekdayStats[dayOfWeek] = (weekdayStats[dayOfWeek] || 0) + 1;
+    });
+
+    // Count occurrences of each weekday in the period
+    const weekdayCounts = {};
+    let current = new Date(fromDate);
+    while (current <= toDate) {
+      const dayOfWeek = current.getDay() + 1;
+      weekdayCounts[dayOfWeek] = (weekdayCounts[dayOfWeek] || 0) + 1;
+      current.setDate(current.getDate() + 1);
+    }
+
+    const weekday = Object.entries(weekdayStats)
+      .map(([dayOfWeek, count]) => {
+        const dow = parseInt(dayOfWeek);
+        const occurrences = weekdayCounts[dow] || 1;
+        return {
+          dayOfWeek: dow,
+          dayName: getDayName(dow),
+          count,
+          average: (count / occurrences).toFixed(2)
+        };
+      })
+      .sort((a, b) => a.dayOfWeek - b.dayOfWeek);
+
+    const total = cigs.length;
+    const daysWithData = Object.keys(dailyStats).length;
+    const averagePerDay = daysWithData > 0 ? total / daysWithData : 0;
+
+    return {
+      daily,
+      averagePerDay: parseFloat(averagePerDay.toFixed(2)),
+      weekday,
+      total,
+      daysWithData
+    };
+  };
+
+  // User cigarettes
+  const userCigarettes = cigarettes.filter(c => {
+    if (c.userId !== req.userId) return false;
+    const smokedDate = new Date(c.smokedAt);
+    return smokedDate >= fromDate && smokedDate <= toDate;
+  });
+
+  // Global cigarettes (all users)
+  const globalCigarettes = cigarettes.filter(c => {
+    const smokedDate = new Date(c.smokedAt);
+    return smokedDate >= fromDate && smokedDate <= toDate;
+  });
+
+  // Count active users
+  const activeUsers = new Set(globalCigarettes.map(c => c.userId)).size;
+
+  // Calculate stats
+  const userStats = calculateStats(userCigarettes);
+  const globalStats = calculateStats(globalCigarettes);
+  globalStats.activeUsers = activeUsers;
+
+  res.json({
+    success: true,
+    body: {
+      user: userStats,
+      global: globalStats,
+      period: {
+        from: fromDate.toISOString(),
+        to: toDate.toISOString()
+      }
+    }
+  });
+});
+
 module.exports = router;