From d60296aebdff4afc23f9f5d4911c9a892e596eb6 Mon Sep 17 00:00:00 2001
From: SmartRootsSrl <glicciardello@smart-roots.net>
Date: Wed, 27 May 2026 18:24:39 +0200
Subject: [PATCH] fix: X-axis dates now use month-based intervals (fixes
 missing dates for short/long date ranges)

---
 .../Implementations/SkiaChartRendererV2.cs    | 65 ++++++++++++++-----
 1 file changed, 48 insertions(+), 17 deletions(-)

diff --git a/CertReports.Syncfusion/Services/Implementations/SkiaChartRendererV2.cs b/CertReports.Syncfusion/Services/Implementations/SkiaChartRendererV2.cs
index e6145ff..59f8d87 100644
--- a/CertReports.Syncfusion/Services/Implementations/SkiaChartRendererV2.cs
+++ b/CertReports.Syncfusion/Services/Implementations/SkiaChartRendererV2.cs
@@ -270,15 +270,17 @@ public static class SkiaChartRendererV2
             canvas.DrawLine(area.Left, y, area.Right, y, gridPaint);
         }
 
-        var totalDays = (maxDate - minDate).TotalDays;
-        int step = totalDays > 1000 ? 365 : totalDays > 500 ? 180 : 90;
-        var d = new DateTime(minDate.Year, minDate.Month > 6 ? 7 : 1, 1);
-        while (d <= maxDate)
+        int intervalMonths = XAxisIntervalMonths(minDate, maxDate);
+        if (intervalMonths > 0)
         {
-            float x = DateToX(d, area, minDate, maxDate);
-            if (x >= area.Left && x <= area.Right)
-                canvas.DrawLine(x, area.Top, x, area.Bottom, gridPaint);
-            d = d.AddDays(step);
+            var d = XAxisStart(minDate, intervalMonths);
+            while (d <= maxDate)
+            {
+                float x = DateToX(d, area, minDate, maxDate);
+                if (x >= area.Left && x <= area.Right)
+                    canvas.DrawLine(x, area.Top, x, area.Bottom, gridPaint);
+                d = d.AddMonths(intervalMonths);
+            }
         }
     }
 
@@ -300,18 +302,26 @@ public static class SkiaChartRendererV2
             canvas.DrawText($"{val:F0} %", area.Left - 55, y + 4, SKTextAlign.Left, font, paint);
         }
 
-        var totalDays = (maxDate - minDate).TotalDays;
-        int step = totalDays > 1000 ? 365 : totalDays > 500 ? 180 : 90;
-        var d = new DateTime(minDate.Year, minDate.Month > 6 ? 7 : 1, 1);
-        while (d <= maxDate)
+        double totalDays = (maxDate - minDate).TotalDays;
+        int intervalMonths = XAxisIntervalMonths(minDate, maxDate);
+        string fmt = totalDays > 365 ? "MMM yy" : "dd/MM/yy";
+
+        if (intervalMonths > 0)
         {
-            float x = DateToX(d, area, minDate, maxDate);
-            if (x >= area.Left && x <= area.Right)
+            var d = XAxisStart(minDate, intervalMonths);
+            while (d <= maxDate)
             {
-                string text = totalDays > 500 ? d.ToString("yyyy") : d.ToString("MMM yyyy");
-                canvas.DrawText(text, x, area.Bottom + 20, SKTextAlign.Center, font, paint);
+                float x = DateToX(d, area, minDate, maxDate);
+                if (x >= area.Left && x <= area.Right)
+                    canvas.DrawText(d.ToString(fmt), x, area.Bottom + 20, SKTextAlign.Center, font, paint);
+                d = d.AddMonths(intervalMonths);
             }
-            d = d.AddDays(step);
+        }
+        else
+        {
+            // Range < 30gg: mostra solo data inizio e fine
+            canvas.DrawText(minDate.ToString("dd/MM/yy"), area.Left,  area.Bottom + 20, SKTextAlign.Left,  font, paint);
+            canvas.DrawText(maxDate.ToString("dd/MM/yy"), area.Right, area.Bottom + 20, SKTextAlign.Right, font, paint);
         }
     }
 
@@ -425,6 +435,27 @@ public static class SkiaChartRendererV2
     // Conversioni coordinate
     // ═══════════════════════════════════════════════════════════════════
 
+    /// <summary>Intervallo in mesi per l'asse X in base alla durata del range.</summary>
+    private static int XAxisIntervalMonths(DateTime minDate, DateTime maxDate)
+    {
+        double days = (maxDate - minDate).TotalDays;
+        if (days > 1000) return 12;
+        if (days > 365)  return 6;
+        if (days > 90)   return 3;
+        if (days > 30)   return 1;
+        return 0; // range < 30gg: gestito a parte (inizio/fine)
+    }
+
+    /// <summary>Prima data "tonda" (primo del mese) dentro il range, allineata all'intervallo scelto.</summary>
+    private static DateTime XAxisStart(DateTime minDate, int intervalMonths)
+    {
+        // Parte dal primo del mese di minDate
+        var d = new DateTime(minDate.Year, minDate.Month, 1);
+        // Se è prima di minDate avanza di un intervallo
+        if (d < minDate) d = d.AddMonths(intervalMonths);
+        return d;
+    }
+
     private static float DateToX(DateTime date, SKRect area, DateTime minDate, DateTime maxDate)
     {
         double totalDays = (maxDate - minDate).TotalDays;