3rdpartylibs/fastreports.wpf/FastReport.Forms.WPF/Controls/MonthCalendar.cs

namespace System.Windows.Forms
{
    public class MonthCalendar : Control
    {
        protected new CustomControls.Calendar control { get; }

        public DateTime MinDate
        {
            get => control.DisplayDateStart ?? DateTime.MinValue;
            set => control.DisplayDateStart = value;
        }

        public DateTime MaxDate
        {
            get => control.DisplayDateEnd ?? DateTime.MaxValue;
            set => control.DisplayDateEnd = value;
        }

        private DateTime selectionStart = DateTime.MinValue;
        public DateTime SelectionStart
        {
            get => selectionStart;
            set
            {
                selectionStart = value;
                UpdateSelectionRange();
            }
        }

        private DateTime selectionEnd;
        public DateTime SelectionEnd
        {
            get => selectionEnd;
            set
            {
                selectionEnd = value;
                UpdateSelectionRange();
            }
        }
        
        public SelectionRange SelectionRange
        {
            get => GetSelectedRange();
            set
            {
                SelectionStart = value.Start;
                SelectionEnd = value.End;
            }
        }

        public int MaxSelectionCount { get; set; } // TODO?

        public Drawing.Size CalendarDimensions { get; set; } // TODO?

        public Day FirstDayOfWeek
        {
            get
            {
                return control.ReadLocalValue(System.Windows.Controls.Calendar.FirstDayOfWeekProperty) == DependencyProperty.UnsetValue ?
                    Day.Default : Helper.GetDay(control.FirstDayOfWeek);
            }
            set
            {
                if (value == Day.Default)
                    control.ClearValue(System.Windows.Controls.Calendar.FirstDayOfWeekProperty);
                else
                    control.FirstDayOfWeek = Helper.GetDayOfWeek(value);
            }
        }

        public bool ShowToday
        {
            get => control.IsTodayHighlighted;
            set => control.IsTodayHighlighted = value;
        }

        public bool ShowTodayCircle { get; set; } // nope

        public bool ShowWeekNumbers { get; set; } // nope

        public DateTime TodayDate { get; set; } // nope

        public DateTime[] AnnuallyBoldedDates
        {
            get => control.AnnualDates;
            set => control.AnnualDates = value;
        }

        public DateTime[] MonthlyBoldedDates
        {
            get => control.MonthDates;
            set => control.MonthDates = value;
        }

        public DateTime[] BoldedDates
        {
            get => control.Dates;
            set => control.Dates = value;
        }


        public event DateRangeEventHandler DateChanged;

        public event DateRangeEventHandler DateSelected;

        private void UpdateSelectionRange()
        {
            control.SelectedDates.Clear();
            var start = SelectionStart;
            var end = SelectionEnd;
            if (start >= MinDate && start <= MaxDate &&
                end >= MinDate && end <= MaxDate &&
                start <= end)
            {
                control.SelectedDates.AddRange(SelectionStart, SelectionEnd);
            }
        }

        private SelectionRange GetSelectedRange()
        {
            var start = DateTime.MaxValue;
            var end = DateTime.MinValue;
            foreach (var date in control.SelectedDates)
            {
                if (date > end)
                    end = date;
                if (date < start)
                    start = date;
            }
            return new SelectionRange(start, end.Add(new TimeSpan(23, 59, 59)));
        }

        protected virtual void OnDateSelected(DateRangeEventArgs e)
        {
            DateChanged?.Invoke(this, e);
            DateSelected?.Invoke(this, e);
        }

        public MonthCalendar()
        {
            control = new();
            SetControl(control);
            AutoSize = true;
            control.SelectionMode = Windows.Controls.CalendarSelectionMode.SingleRange;

            control.SelectedDatesChanged += (s, e) =>
            {
                var range = GetSelectedRange();
                selectionStart = range.Start;
                selectionEnd = range.End;
                OnDateSelected(new DateRangeEventArgs(selectionStart, selectionEnd));
            };
        }
    }
}