feat: enhance Excel export functionality with improved styling and download handling

Components/Pages/MonthlySummary.razor

@@ -16,7 +16,7 @@
     <button class="btn btn-outline-secondary btn-sm" @onclick="PreviousMonth">&laquo; Prev</button>
     <h2 class="h5 mb-0">@currentMonth.ToString("MMMM yyyy")</h2>
     <button class="btn btn-outline-secondary btn-sm" @onclick="NextMonth">Next &raquo;</button>
-    <a class="btn btn-success btn-sm ms-auto" href="@GetExcelDownloadUrl()">Download Excel</a>
+    <button type="button" class="btn btn-success btn-sm ms-auto" @onclick="DownloadExcelAsync">Download Excel</button>
     <a class="btn btn-outline-primary btn-sm ms-auto" href="yearly-summary/@currentMonth.Year">Yearly Summary</a>
 </div>
 
@@ -278,6 +278,20 @@ else if (viewMode == SummaryViewMode.Timesheet && timesheet is not null)
         viewMode = mode;
     }
 
+    private async Task DownloadExcelAsync()
+    {
+        try
+        {
+            await JS.InvokeVoidAsync("workTrackerDownloads.downloadFromUrl", GetExcelDownloadUrl());
+        }
+        catch (JSDisconnectedException)
+        {
+        }
+        catch (TaskCanceledException)
+        {
+        }
+    }
+
     private string GetExcelDownloadUrl()
     {
         return $"/api/monthly-timesheet/{currentMonth.Year}/{currentMonth.Month}/excel?includePreview={includePreview.ToString().ToLowerInvariant()}";

Services/Exports/MonthlyTimesheetExcelExporter.cs

@@ -8,6 +8,8 @@ public sealed class MonthlyTimesheetExcelExporter : IMonthlyTimesheetExcelExport
     private const int DayHeaderRow = 1;
     private const int DayStartColumn = 3;
     private const int TemplateDayCount = 30;
+    private const int SaturdaySampleColumn = 6;
+    private const int SundayHolidaySampleColumn = 7;
 
     private static readonly IReadOnlyDictionary<string, int> TimesheetRowMap = new Dictionary<string, int>(StringComparer.Ordinal)
     {
@@ -37,9 +39,10 @@ public sealed class MonthlyTimesheetExcelExporter : IMonthlyTimesheetExcelExport
         workbook.DefinedNames.DeleteAll();
         var worksheet = workbook.Worksheet(1);
         var dayCount = timesheet.Days.Count;
+        var styleCatalog = CaptureDayStyleCatalog(worksheet);
 
         AdjustDayColumns(worksheet, dayCount);
-        ApplyDayHeaders(worksheet, timesheet.Days);
+        ApplyDayHeaders(worksheet, timesheet.Days, styleCatalog);
         ApplyRowValues(worksheet, timesheet.Rows, dayCount);
         ApplyTotalFormulas(worksheet, dayCount);
 
@@ -63,7 +66,7 @@ public sealed class MonthlyTimesheetExcelExporter : IMonthlyTimesheetExcelExport
         }
     }
 
-    private static void ApplyDayHeaders(IXLWorksheet worksheet, IReadOnlyList<MonthlyTimesheetDayModel> days)
+    private static void ApplyDayHeaders(IXLWorksheet worksheet, IReadOnlyList<MonthlyTimesheetDayModel> days, DayStyleCatalog styleCatalog)
     {
         var lastDayColumn = DayStartColumn + days.Count - 1;
 
@@ -74,11 +77,11 @@ public sealed class MonthlyTimesheetExcelExporter : IMonthlyTimesheetExcelExport
 
             var headerCell = worksheet.Cell(DayHeaderRow, column);
             headerCell.Value = day.Date.Day;
-            ApplyDayStyle(worksheet, headerCell, day, column, lastDayColumn, 1);
+            ApplyDayStyle(headerCell, day, column, lastDayColumn, 1, styleCatalog);
 
             foreach (var rowNumber in TimesheetRowMap.Values)
             {
-                ApplyDayStyle(worksheet, worksheet.Cell(rowNumber, column), day, column, lastDayColumn, rowNumber);
+                ApplyDayStyle(worksheet.Cell(rowNumber, column), day, column, lastDayColumn, rowNumber, styleCatalog);
             }
         }
     }
@@ -121,10 +124,32 @@ public sealed class MonthlyTimesheetExcelExporter : IMonthlyTimesheetExcelExport
         }
     }
 
-    private static void ApplyDayStyle(IXLWorksheet worksheet, IXLCell targetCell, MonthlyTimesheetDayModel day, int column, int lastDayColumn, int rowNumber)
+    private static DayStyleCatalog CaptureDayStyleCatalog(IXLWorksheet worksheet)
     {
-        var baseCell = worksheet.Cell(GetBaseStyleRowAddress(rowNumber), GetBaseStyleColumn(column, lastDayColumn));
+        return new DayStyleCatalog(
-        var baseStyle = baseCell.Style;
+            CaptureStylesForColumn(worksheet, DayStartColumn),
+            CaptureStylesForColumn(worksheet, DayStartColumn + 1),
+            CaptureStylesForColumn(worksheet, DayStartColumn + TemplateDayCount - 1),
+            CaptureStylesForColumn(worksheet, SaturdaySampleColumn),
+            CaptureStylesForColumn(worksheet, SundayHolidaySampleColumn));
+    }
+
+    private static IReadOnlyDictionary<int, IXLStyle> CaptureStylesForColumn(IXLWorksheet worksheet, int column)
+    {
+        var rowNumbers = new[] { 1, 2, 4, 12 };
+        var styles = new Dictionary<int, IXLStyle>(rowNumbers.Length);
+
+        foreach (var rowNumber in rowNumbers)
+        {
+            styles[rowNumber] = worksheet.Cell(rowNumber, column).Style;
+        }
+
+        return styles;
+    }
+
+    private static void ApplyDayStyle(IXLCell targetCell, MonthlyTimesheetDayModel day, int column, int lastDayColumn, int rowNumber, DayStyleCatalog styleCatalog)
+    {
+        var baseStyle = styleCatalog.GetBaseStyle(rowNumber, column == DayStartColumn, column == lastDayColumn);
 
         if (!ShouldHighlight(day))
         {
@@ -132,9 +157,7 @@ public sealed class MonthlyTimesheetExcelExporter : IMonthlyTimesheetExcelExport
             return;
         }
 
-        var sampleColumn = GetHighlightSampleColumn(day, rowNumber);
+        var sampleStyle = styleCatalog.GetHighlightStyle(rowNumber, day);
-        var sampleCell = worksheet.Cell(GetSampleStyleRow(rowNumber), sampleColumn);
-        var sampleStyle = sampleCell.Style;
 
         targetCell.Style = sampleStyle;
         targetCell.Style.Border.LeftBorder = baseStyle.Border.LeftBorder;
@@ -152,7 +175,7 @@ public sealed class MonthlyTimesheetExcelExporter : IMonthlyTimesheetExcelExport
         return day.IsWeekend || day.IsHoliday;
     }
 
-    private static int GetBaseStyleRowAddress(int rowNumber)
+    private static int GetStyleRow(int rowNumber)
     {
         return rowNumber switch
         {
@@ -164,67 +187,42 @@ public sealed class MonthlyTimesheetExcelExporter : IMonthlyTimesheetExcelExport
         };
     }
 
-    private static int GetSampleStyleRow(int rowNumber)
+    private sealed class DayStyleCatalog(
+        IReadOnlyDictionary<int, IXLStyle> firstColumnStyles,
+        IReadOnlyDictionary<int, IXLStyle> middleColumnStyles,
+        IReadOnlyDictionary<int, IXLStyle> lastColumnStyles,
+        IReadOnlyDictionary<int, IXLStyle> saturdayStyles,
+        IReadOnlyDictionary<int, IXLStyle> sundayHolidayStyles)
     {
-        return rowNumber switch
+        public IXLStyle GetBaseStyle(int rowNumber, bool isFirstColumn, bool isLastColumn)
         {
-            1 => 1,
+            var styleRow = GetStyleRow(rowNumber);
-            2 => 2,
-            4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 => 4,
-            12 => 12,
-            _ => rowNumber
-        };
-    }
 
-    private static int GetBaseStyleColumn(int column, int lastDayColumn)
+            if (isFirstColumn)
-    {
-        if (column == DayStartColumn)
-        {
-            return DayStartColumn;
-        }
-
-        if (column == lastDayColumn)
-        {
-            return lastDayColumn == DayStartColumn + TemplateDayCount - 1
-                ? DayStartColumn + TemplateDayCount - 1
-                : DayStartColumn + 1;
-        }
-
-        return DayStartColumn + 1;
-    }
-
-    private static int GetHighlightSampleColumn(MonthlyTimesheetDayModel day, int rowNumber)
-    {
-        if (rowNumber == 1)
-        {
-            if (day.IsHoliday || day.Date.DayOfWeek == DayOfWeek.Sunday)
             {
-                return 7;
+                return firstColumnStyles[styleRow];
             }
 
-            if (day.Date.DayOfWeek == DayOfWeek.Saturday)
+            if (isLastColumn)
             {
-                return 6;
+                return lastColumnStyles[styleRow];
             }
 
-            return 7;
+            return middleColumnStyles[styleRow];
         }
 
-        if (rowNumber == 2)
+        public IXLStyle GetHighlightStyle(int rowNumber, MonthlyTimesheetDayModel day)
         {
-            if (day.IsHoliday || day.Date.DayOfWeek == DayOfWeek.Sunday)
+            var styleRow = GetStyleRow(rowNumber);
+
+            if (rowNumber is 1 or 2)
             {
-                return 7;
+                return day.IsHoliday || day.Date.DayOfWeek == DayOfWeek.Sunday
+                    ? sundayHolidayStyles[styleRow]
+                    : saturdayStyles[styleRow];
             }
 
-            if (day.Date.DayOfWeek == DayOfWeek.Saturday)
+            return saturdayStyles[styleRow];
-            {
-                return 6;
-            }
-
-            return 7;
         }
-
-        return 6;
     }
 }

tests/WorkTracker.Tests/MonthlyTimesheetExcelExporterTests.cs

@@ -42,6 +42,43 @@ public sealed class MonthlyTimesheetExcelExporterTests
         Assert.Equal("TOTALE", worksheet.Cell("AH1").GetString());
     }
 
+    [Fact]
+    public void Export_ForMonthWhereSecondDayIsWeekend_OnlyHighlightsWeekendAndHolidayDays()
+    {
+        var exporter = new MonthlyTimesheetExcelExporter();
+        var timesheet = CreateTimesheet(new DateOnly(2026, 5, 1), new HashSet<DateOnly>
+        {
+            new(2026, 5, 4)
+        });
+        var templatePath = GetTemplatePath();
+
+        using var templateStream = File.OpenRead(templatePath);
+        var workbookBytes = exporter.Export(timesheet, templateStream);
+
+        using var workbook = new XLWorkbook(new MemoryStream(workbookBytes));
+        var worksheet = workbook.Worksheet(1);
+
+        var headerRegularFill = GetFillSignature(worksheet.Cell("C1"));
+        var headerSaturdayFill = GetFillSignature(worksheet.Cell("D1"));
+        var headerSundayFill = GetFillSignature(worksheet.Cell("E1"));
+        var headerHolidayFill = GetFillSignature(worksheet.Cell("F1"));
+        var headerNextWeekdayFill = GetFillSignature(worksheet.Cell("G1"));
+
+        Assert.NotEqual(headerRegularFill, headerSaturdayFill);
+        Assert.NotEqual(headerRegularFill, headerSundayFill);
+        Assert.Equal(headerSundayFill, headerHolidayFill);
+        Assert.Equal(headerRegularFill, headerNextWeekdayFill);
+
+        var bodyRegularFill = GetFillSignature(worksheet.Cell("C4"));
+        var bodySaturdayFill = GetFillSignature(worksheet.Cell("D4"));
+        var bodyHolidayFill = GetFillSignature(worksheet.Cell("F4"));
+        var bodyNextWeekdayFill = GetFillSignature(worksheet.Cell("G4"));
+
+        Assert.NotEqual(bodyRegularFill, bodySaturdayFill);
+        Assert.Equal(bodySaturdayFill, bodyHolidayFill);
+        Assert.Equal(bodyRegularFill, bodyNextWeekdayFill);
+    }
+
     private static MonthlyTimesheetModel CreateTimesheet(DateOnly monthStart, ISet<DateOnly> holidays)
     {
         var lastDay = monthStart.AddMonths(1).AddDays(-1);
@@ -116,4 +153,26 @@ public sealed class MonthlyTimesheetExcelExporterTests
 
         throw new DirectoryNotFoundException("Unable to locate the WorkTracker repository root.");
     }
+
+    private static string GetFillSignature(IXLCell cell)
+    {
+        var fill = cell.Style.Fill;
+
+        return string.Join(
+            "|",
+            fill.PatternType,
+            DescribeColor(fill.BackgroundColor),
+            DescribeColor(fill.PatternColor));
+    }
+
+    private static string DescribeColor(XLColor color)
+    {
+        return color.ColorType switch
+        {
+            XLColorType.Color => $"rgb:{color.Color.ToArgb()}",
+            XLColorType.Indexed => $"indexed:{color.Indexed}",
+            XLColorType.Theme => $"theme:{color.ThemeColor}:{Math.Round(color.ThemeTint, 12)}",
+            _ => color.ColorType.ToString()
+        };
+    }
 }