public DxSchedulerMapping TimeZoneId { get; set; }

@using System.Globalization;

<DxScheduler StartDate="@DateTime.Today"
             DataStorage="@DataStorage"
             GroupType="SchedulerGroupType.Resource"
             VisibleResourcesDataSource="VisibleResources">
    <DxSchedulerDayView DayCount="1" ShowWorkTimeOnly="true"></DxSchedulerDayView>
    <DxSchedulerWeekView ShowWorkTimeOnly="true"></DxSchedulerWeekView>
    <DxSchedulerWorkWeekView ShowWorkTimeOnly="true"></DxSchedulerWorkWeekView>
    <DxSchedulerMonthView ShowWorkDaysOnly="true" MonthCount="1"></DxSchedulerMonthView>
    <DxSchedulerTimelineView Duration="@TimeSpan.FromHours(48)" CellMinWidth="80">
        <Scales>
            <DxSchedulerTimeScale Unit="@SchedulerTimeScaleUnit.Day" UnitCount="1"></DxSchedulerTimeScale>
            <DxSchedulerTimeScale Unit="@SchedulerTimeScaleUnit.Hour" UnitCount="2"></DxSchedulerTimeScale>
        </Scales>
    </DxSchedulerTimelineView>
</DxScheduler>

<p></p>

<DxComboBox Data="timeZones" Value=selectedTimeZone ValueChanged="@((string t) => OnValueChanged(t))"></DxComboBox>

@code {
    List<string> timeZones = new List<string>() { 
        "UTC", "Egypt Standard Time", "Turkey Standard Time", "Caucasus Standard Time" 
    };
    string selectedTimeZone { get; set; } = "UTC";
    System.Collections.ObjectModel.ReadOnlyCollection<TimeZoneInfo> zones = TimeZoneInfo.GetSystemTimeZones();
    DxSchedulerDataStorage DataStorage = null;

    protected override void OnInitialized() {
        base.OnInitialized();
        DataStorage = new DxSchedulerDataStorage() {
                AppointmentsSource = AppointmentCollection.GetAppointments(),
                AppointmentMappings = new DxSchedulerAppointmentMappings() {
                    Id = "AppointmentID",
                    Type = "AppointmentType",
                    Start = "StartDate",
                    End = "EndDate",
                    Subject = "Caption",
                    AllDay = "AllDay",
                    Location = "Location",
                    Description = "Description",
                    LabelId = "Label",
                    StatusId = "Status",
                    RecurrenceInfo = "Recurrence",
                    ResourceId = "ResourceId",
                    TimeZoneId = "TimeZone"
                },
                ResourcesSource = ResourceCollection.GetResourcesForGrouping(),
                ResourceMappings = new DxSchedulerResourceMappings() {
                    Id = "Id",
                    Caption = "Name",
                    BackgroundCssClass = "BackgroundCss",
                    TextCssClass = "TextCss"
                },
                TimeZone = TimeZoneInfo.GetSystemTimeZones().FirstOrDefault(tz => tz.Id == selectedTimeZone)
            };
        DataStorage.RefreshData();
    }

    void OnValueChanged(string newTZ) {
        selectedTimeZone = newTZ;
        DataStorage.TimeZone = TimeZoneInfo.GetSystemTimeZones().FirstOrDefault(tz => tz.Id == selectedTimeZone);
        DataStorage.RefreshData();
    }

    List<Resource> VisibleResources = ResourceCollection.GetResources().Take(2).ToList();
}

public class Appointment {
    public Appointment() { }
    public int AppointmentID { get; set; }
    public int AppointmentType { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }
    public string Caption { get; set; }
    public string Description { get; set; }
    public string Location { get; set; }
    public int? Label { get; set; }
    public int Status { get; set; }
    public bool AllDay { get; set; }
    public string Recurrence { get; set; }
    public int? ResourceId { get; set; }
    public bool Accepted { get; set; }
    public string TimeZone { get; set; }
}

public class Resource {        
        public int Id { get; set; }
        public int? GroupId { get; set; }
        public string Name { get; set; }
        public bool IsGroup { get; set; }
        public string TextCss { get; set; }
        public string BackgroundCss { get; set; }
        public string ImageFileName => $"employees/{Id + 1}.jpg";
        public override bool Equals(object obj) {
            Resource resource = obj as Resource;
            return resource != null && resource.Id == Id;
        }
        public override int GetHashCode() {
            return Id;
        }
    }

public static partial class AppointmentCollection {
    public static List<Appointment> GetAppointments() {
        DateTime date = DateTime.Today;
        return new List<Appointment>() {
            new Appointment {
                AppointmentID = 1,
                AppointmentType = 0,
                Caption = "Watercolor Landscape (13:00 - TimeZone+2)",
                Label = 5,
                StartDate = date + (new TimeSpan(13, 0, 0)),
                EndDate = date + (new TimeSpan(16, 0, 0)),
                ResourceId = 0,
                TimeZone = "Egypt Standard Time"
            },
            new Appointment {
                AppointmentID = 2,
                AppointmentType = 0,
                Caption = "Oil Painting for Beginners (13:00 - TimeZone+3)",
                Label = 2,
                StartDate = date + (new TimeSpan(13, 0, 0)),
                EndDate = date + (new TimeSpan(16, 0, 0)),
                ResourceId = 0,
                TimeZone = "Turkey Standard Time"
            },
            new Appointment {
                AppointmentID = 3,
                AppointmentType = 0,
                Caption = "Testing (13:00 - TimeZone+4)",
                Label = 8,
                StartDate = date + (new TimeSpan(13, 0, 0)),
                EndDate = date + (new TimeSpan(16, 0, 0)),
                ResourceId = 0,
                TimeZone = "Caucasus Standard Time"
            }
        };
    }
    private static string ToString(DateTime dateTime) {
        return dateTime.ToString(CultureInfo.InvariantCulture);
    }
}

public static partial class ResourceCollection {
    public static List<Resource> GetResourcesForGrouping() {
        return GetResources().Take(3).ToList();
    }
    public static List<Resource> GetResources() {
        return new List<Resource>() {
            new Resource() { Id=0 , Name="Nancy Davolio", GroupId=100, BackgroundCss="dxbl-green-color", TextCss="text-white" },
            new Resource() { Id=1 , Name="Andrew Fuller", GroupId=101, BackgroundCss="dxbl-orange-color", TextCss="text-white" },
            new Resource() { Id=2 , Name="Janet Leverling", GroupId=100, BackgroundCss="dxbl-purple-color", TextCss="text-white" },
            new Resource() { Id=3 , Name="Margaret Peacock", GroupId=101, BackgroundCss="dxbl-indigo-color", TextCss="text-white" },
            new Resource() { Id=4 , Name="Steven Buchanan", GroupId=100, BackgroundCss="dxbl-red-color", TextCss="text-white" }
        };
    }
    public static List<Resource> GetResourceGroups() {
        return new List<Resource>() {
            new Resource() { Id=100, Name="Sales and Marketing", IsGroup=true },
            new Resource() { Id=101, Name="Engineering", IsGroup=true }
        };
    }
}

public static class DateTimeUtils {
    public static DateTime GetWeekStart(DateTime date) {
        return date.DayOfWeek == DayOfWeek.Sunday ? ValidWeekStart(date.Date) : ValidWeekStart(date.Date - CreateWeekOffset(date, DayOfWeek.Sunday));
    }
    public static DateTime GetBeginOfMonth(DateTime date) {
        return new DateTime(date.Year, date.Month, 1);
    }
    static DateTime ValidWeekStart(DateTime date) {
        TimeSpan weekSpan = new TimeSpan(7, 0, 0, 0);
        DateTime baseDate = date.Date;
        if (DateTime.MaxValue - date < weekSpan)
            return baseDate - weekSpan;
        return baseDate;
    }
    static TimeSpan CreateWeekOffset(DateTime date, DayOfWeek firstDayOfWeek) {
        int offset = (date.DayOfWeek + 7 - firstDayOfWeek) % 7;
        TimeSpan result = TimeSpan.FromDays(offset);
        if (date.Ticks < result.Ticks)
            result = TimeSpan.FromDays(offset - 7);
        return result;
    }
}