When.cs

using System;
using System.Threading.Tasks;
using System.Xml;
using Waher.Content.Xml;
using Waher.Events;
using Waher.Persistence.Attributes;
using Waher.Service.IoTBroker.StateMachines.Model.Attributes;
 
namespace Waher.Service.IoTBroker.StateMachines.Model.Actions.Runtime
{
    public class When : StateMachineNode
    {
        private ScriptableDateTimeAttribute value;
        private ScriptableStringAttribute timeCoordinates;
 
        public When()
            : base()
        {
        }
 
        [DefaultValueNull]
        public string ValueDefinition
        {
            get => this.value?.Definition;
            set => this.value = new ScriptableDateTimeAttribute(value, this);
        }
 
        [DefaultValueNull]
        public string TimeCoordinatesDefinition
        {
            get => this.timeCoordinates?.Definition;
            set => this.timeCoordinates = new ScriptableStringAttribute(value, this);
        }
 
        public override string LocalName => nameof(When);
 
        public override IStateMachineNode Create()
        {
            return new When();
        }
 
        public override Task Parse(XmlElement Xml)
        {
            this.value = new ScriptableDateTimeAttribute(Xml.InnerText, this);
            this.timeCoordinates = new ScriptableStringAttribute(XML.Attribute(Xml, "timeCoordinates"), this);
 
            return base.Parse(Xml);
        }
 
        public async Task<DateTime> CalcWhenUtc(EvaluationArguments Arguments)
        {
            if (this.value is null)
                return DateTime.UtcNow;
            else
            {
                DateTime Value = await this.value.Evaluate(Arguments.Variables);
                string TimeCoordinates = await this.timeCoordinates.Evaluate(Arguments.Variables);
 
                if (!string.IsNullOrEmpty(TimeCoordinates))
                {
                    if (string.Equals(TimeCoordinates, "Local", StringComparison.OrdinalIgnoreCase))
                    {
                        if (Value.Kind == DateTimeKind.Unspecified)
                            Value = new DateTime(Value.Ticks, DateTimeKind.Local);
                    }
                    else if (string.Equals(TimeCoordinates, "UTC", StringComparison.OrdinalIgnoreCase))
                    {
                        if (Value.Kind == DateTimeKind.Unspecified)
                            Value = new DateTime(Value.Ticks, DateTimeKind.Utc);
                    }
                    else if (TimeCoordinates.StartsWith('-') &&
                        TimeSpan.TryParse(TimeCoordinates[1..], out TimeSpan TS))
                    {
                        if (Value.Kind == DateTimeKind.Unspecified)
                        {
                            Value = new DateTime(Value.Ticks, DateTimeKind.Utc);
                            Value = Value.Add(TS);
                        }
                    }
                    else if ((TimeCoordinates.StartsWith('+') &&
                        TimeSpan.TryParse(TimeCoordinates[1..], out TS)) ||
                        TimeSpan.TryParse(TimeCoordinates, out TS))
                    {
                        if (Value.Kind == DateTimeKind.Unspecified)
                        {
                            Value = new DateTime(Value.Ticks, DateTimeKind.Utc);
                            Value = Value.Subtract(TS);
                        }
                    }
                    else
                    {
                        Log.Error("Invalid Time Coordinates in State Machine When definition: " + TimeCoordinates,
                            Arguments.CurrentState.StateMachineId.Value);
                    }
                }
 
                return Value.ToUniversalTime();
            }
        }
 
    }
}