using System;
using System.ComponentModel;
using System.Globalization;
using System.Windows;
using System.Windows.Controls;

namespace CustomControls
{
    [DesignTimeVisible(false)]
    public partial class DateTimePicker : DatePicker, INotifyPropertyChanged
    {
        public string CustomFormat
        {
            get { return (string)GetValue(CustomFormatProperty); }
            set { SetValue(CustomFormatProperty, value); }
        }
        public readonly static DependencyProperty CustomFormatProperty = DependencyProperty.Register(
            "CustomFormat", typeof(string), typeof(DateTimePicker), new UIPropertyMetadata(""));

        public event PropertyChangedEventHandler PropertyChanged;

        private DateTime? _value;
        internal DateTime? Value
        {
            get => SelectedDate;
            set
            {
                _value = value;
                SelectedDate = value;
            }
        }

        public string FormattedValue
        {
            get
            {
                if (SelectedDate == null)
                    return null;
                DateTime dateTime = SelectedDate.Value;
                if (_value != null)
                {
                    DateTime timePart = _value.Value;
                    dateTime = new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, timePart.Hour, timePart.Minute, timePart.Second, timePart.Millisecond);
                }
                return dateTime.ToString(CustomFormat);
            }
            set => Value = DateTime.ParseExact(value, CustomFormat, CultureInfo.CurrentCulture);
        }

        protected override void OnPropertyChanged(DependencyPropertyChangedEventArgs e)
        {
            base.OnPropertyChanged(e);
            if (e.Property.Name == "SelectedDate" || e.Property.Name == "CustomFormat")
            {
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("FormattedValue"));
            }
        }

        public DateTimePicker()
        {
            InitializeComponent();
            Padding = new Thickness(2, 2, 0, 3);
        }
    }
}