TransportResource.DecisionModel.cs

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Xml.Serialization;
using LotSizingDataModel.Core.Common;
using LotSizingDataModel.Core.DecisionModel;
using LotSizingDataModel.Core.DecisionModel.Constraints;
using LotSizingDataModel.Core.DecisionModel.Costs;
 
namespace LotSizingDataModel.Core.PhysicalModel;
 
/// <summary>
/// Adds the optional decision-model parameters associated
/// with a transport resource.
/// </summary>
public sealed partial class TransportResource :
    IPlanningHorizonAware
{
    private CapacityConstraint? _capacityConstraint;
    private AdditionalCapacity? _additionalCapacity;
    private FixedUsageCost? _fixedUsageCost;
    private AdditionalCapacityCost? _additionalCapacityCost;
 
    /// <summary>
    /// Gets or sets the maximum regular capacity available
    /// for the transport resource during each planning period.
    ///
    /// A null value means that no global capacity constraint
    /// is active for this transport resource.
    /// </summary>
    [XmlElement("capacityConstraint")]
    public CapacityConstraint? CapacityConstraint
    {
        get => _capacityConstraint;
        set => SetDecisionParameter(
            ref _capacityConstraint,
            value,
            nameof(CapacityConstraint));
    }
 
    /// <summary>
    /// Gets or sets the maximum additional capacity that may
    /// be allocated to the transport resource during each period.
    ///
    /// This parameter should only be defined when a regular
    /// capacity constraint is also defined.
    /// </summary>
    [XmlElement("additionalCapacity")]
    public AdditionalCapacity? AdditionalCapacity
    {
        get => _additionalCapacity;
        set => SetDecisionParameter(
            ref _additionalCapacity,
            value,
            nameof(AdditionalCapacity));
    }
 
    /// <summary>
    /// Gets or sets the fixed cost incurred when the transport
    /// resource is used during a planning period.
    /// </summary>
    [XmlElement("fixedUsageCost")]
    public FixedUsageCost? FixedUsageCost
    {
        get => _fixedUsageCost;
        set => SetDecisionParameter(
            ref _fixedUsageCost,
            value,
            nameof(FixedUsageCost));
    }
 
    /// <summary>
    /// Gets or sets the cost of using one unit of additional
    /// transport capacity during each planning period.
    ///
    /// This parameter should only be defined when additional
    /// capacity is authorized.
    /// </summary>
    [XmlElement("additionalCapacityCost")]
    public AdditionalCapacityCost? AdditionalCapacityCost
    {
        get => _additionalCapacityCost;
        set => SetDecisionParameter(
            ref _additionalCapacityCost,
            value,
            nameof(AdditionalCapacityCost));
    }
 
    /// <summary>
    /// Gets the planning horizon represented by the first
    /// active period-dependent parameter.
    ///
    /// Returns zero when no decision parameter is active.
    /// </summary>
    [XmlIgnore]
    public int PlanningHorizon
    {
        get
        {
            // Return the first active parameter's horizon.
            foreach (IPlanningHorizonAware parameter
                     in GetDecisionParameters())
            {
                return parameter.PlanningHorizon;
            }
 
            // No active parameter → horizon is zero.
            return 0;
        }
    }
 
    /// <summary>
    /// Gets a value indicating whether at least one
    /// decision-model parameter is active.
    /// </summary>
    [XmlIgnore]
    public bool HasDecisionParameters =>
        CapacityConstraint is not null ||
        AdditionalCapacity is not null ||
        FixedUsageCost is not null ||
        AdditionalCapacityCost is not null;
 
    /// <summary>
    /// Gets a value indicating whether all active parameters
    /// use the same planning horizon.
    /// </summary>
    [XmlIgnore]
    public bool HasConsistentPlanningHorizon
    {
        get
        {
            int? expectedHorizon = null;
 
            // Compare each active parameter's horizon against the first.
            foreach (IPlanningHorizonAware parameter
                     in GetDecisionParameters())
            {
                if (expectedHorizon is null)
                {
                    expectedHorizon =
                        parameter.PlanningHorizon;
 
                    continue;
                }
 
                if (parameter.PlanningHorizon !=
                    expectedHorizon.Value)
                {
                    return false;
                }
            }
 
            return true;
        }
    }
 
    /// <summary>
    /// Gets a value indicating whether the dependencies between
    /// the capacity-related parameters are respected.
    /// </summary>
    [XmlIgnore]
    public bool HasValidCapacityConfiguration =>
        (AdditionalCapacity is null ||
         CapacityConstraint is not null) &&
 
        (AdditionalCapacityCost is null ||
         AdditionalCapacity is not null);
 
    /// <summary>
    /// Resizes every active period-dependent parameter.
    ///
    /// Existing values are preserved.
    /// </summary>
    /// <param name="periodCount">
    /// New number of planning periods.
    /// </param>
    public void ResizeTimeSeries(int periodCount)
    {
        if (periodCount < 0)
        {
            throw new ArgumentOutOfRangeException(
                nameof(periodCount),
                periodCount,
                "The planning horizon cannot be negative.");
        }
 
        // Resize every active decision parameter.
        foreach (IPlanningHorizonAware parameter
                 in GetDecisionParameters())
        {
            parameter.ResizeTimeSeries(periodCount);
        }
 
        // Notify dependent computed properties.
        OnPropertyChanged(nameof(PlanningHorizon));
        OnPropertyChanged(
            nameof(HasConsistentPlanningHorizon));
    }
 
    /// <summary>
    /// Removes all decision-model parameters from
    /// this transport resource.
    ///
    /// The transport lanes are preserved.
    /// </summary>
    public void ClearDecisionParameters()
    {
        CapacityConstraint = null;
        AdditionalCapacity = null;
        FixedUsageCost = null;
        AdditionalCapacityCost = null;
    }
 
    private void SetDecisionParameter<T>(
        ref T? field,
        T? value,
        string propertyName)
        where T : ModelObject, IPlanningHorizonAware
    {
        if (ReferenceEquals(field, value))
        {
            return;
        }
 
        // Unsubscribe from old parameter.
        if (field is not null)
        {
            field.PropertyChanged -=
                OnDecisionParameterPropertyChanged;
        }
 
        field = value;
 
        // Subscribe to new parameter.
        if (field is not null)
        {
            field.PropertyChanged +=
                OnDecisionParameterPropertyChanged;
        }
 
        // Notify the specific property plus all dependent ones.
        OnPropertyChanged(propertyName);
        OnPropertyChanged(nameof(PlanningHorizon));
        OnPropertyChanged(nameof(HasDecisionParameters));
        OnPropertyChanged(
            nameof(HasConsistentPlanningHorizon));
        OnPropertyChanged(
            nameof(HasValidCapacityConfiguration));
    }
 
    private IEnumerable<IPlanningHorizonAware>
        GetDecisionParameters()
    {
        if (CapacityConstraint is not null)
        {
            yield return CapacityConstraint;
        }
 
        if (AdditionalCapacity is not null)
        {
            yield return AdditionalCapacity;
        }
 
        if (FixedUsageCost is not null)
        {
            yield return FixedUsageCost;
        }
 
        if (AdditionalCapacityCost is not null)
        {
            yield return AdditionalCapacityCost;
        }
    }
 
    private void OnDecisionParameterPropertyChanged(
        object? sender,
        PropertyChangedEventArgs e)
    {
        // Forward notification for the specific parameter that changed.
        if (ReferenceEquals(sender, CapacityConstraint))
        {
            OnPropertyChanged(nameof(CapacityConstraint));
        }
        else if (ReferenceEquals(sender, AdditionalCapacity))
        {
            OnPropertyChanged(nameof(AdditionalCapacity));
        }
        else if (ReferenceEquals(sender, FixedUsageCost))
        {
            OnPropertyChanged(nameof(FixedUsageCost));
        }
        else if (ReferenceEquals(
                     sender,
                     AdditionalCapacityCost))
        {
            OnPropertyChanged(
                nameof(AdditionalCapacityCost));
        }
 
        // Update all computed properties that may be affected.
        OnPropertyChanged(nameof(PlanningHorizon));
        OnPropertyChanged(
            nameof(HasConsistentPlanningHorizon));
        OnPropertyChanged(
            nameof(HasValidCapacityConfiguration));
    }
}