using System;
using System.Collections.Generic;
using System.ComponentModel;

namespace DynamicDescriptors;

/// <summary>
/// A dictionary-backed implementation of <see cref="PropertyDescriptor"/>.
/// </summary>
internal sealed class DictionaryPropertyDescriptor : PropertyDescriptor
{
    /// <summary>
    /// A dictionary mapping property names to property values.
    /// </summary>
    private readonly IDictionary<string, object> _data;

    /// <summary>
    /// The name of the property.
    /// </summary>
    private readonly string _propertyName;

    /// <summary>
    /// The type of the property.
    /// </summary>
    private readonly Type _propertyType;

    /// <summary>
    /// Initializes a new instance of the <see cref="DictionaryPropertyDescriptor"/> class.
    /// </summary>
    /// <param name="data">The dictionary that backs this property descriptor.</param>
    /// <param name="propertyName">The name of the property.</param>
    /// <param name="propertyType">The type of the property.</param>
    public DictionaryPropertyDescriptor(IDictionary<string, object> data, string propertyName, Type propertyType)
        : base(Preconditions.CheckNotNullOrEmpty(propertyName, nameof(propertyName)), null)
    {
        _data = data ?? throw new ArgumentNullException(nameof(data));
        _propertyName = propertyName;
        _propertyType = propertyType ?? throw new ArgumentNullException(nameof(propertyType));
    }

    /// <summary>
    /// Returns a value indicating returns whether resetting an object changes its value.
    /// </summary>
    /// <param name="component">The component to test for reset capability.</param>
    /// <returns>true if resetting the component changes its value; otherwise, false.</returns>
    public override bool CanResetValue(object component)
    {
        return false;
    }

    /// <summary>
    /// Gets the type of the component this property is bound to.
    /// </summary>
    public override Type ComponentType => null;

    /// <summary>
    /// Returns the current value of the property on a component.
    /// </summary>
    /// <param name="component">
    /// The component with the property for which to retrieve the value.
    /// </param>
    /// <returns>The value of a property for a given component.</returns>
    public override object GetValue(object component)
    {
        return _data[_propertyName];
    }

    /// <summary>
    /// Gets a value indicating whether this property is read-only.
    /// </summary>
    public override bool IsReadOnly => false;

    /// <summary>
    /// Gets the type of the property.
    /// </summary>
    public override Type PropertyType => _propertyType;

    /// <summary>
    /// Resets the value for this property of the component to the default value.
    /// </summary>
    /// <param name="component">
    /// The component with the property value that is to be reset to the default value.
    /// </param>
    public override void ResetValue(object component)
    {
        _data[_propertyName] = null;
        OnValueChanged(component, EventArgs.Empty);
    }

    /// <summary>
    /// Sets the value of the component to a different value.
    /// </summary>
    /// <param name="component">
    /// The component with the property value that is to be set.
    /// </param>
    /// <param name="value">
    /// The new value.
    /// </param>
    public override void SetValue(object component, object value)
    {
        _data[_propertyName] = value;
        OnValueChanged(component, EventArgs.Empty);
    }

    /// <summary>
    /// Determines a value indicating whether the value of this property needs to be
    /// persisted.
    /// </summary>
    /// <param name="component">
    /// The component with the property to be examined for persistence.
    /// </param>
    /// <returns>true if the property should be persisted; otherwise, false.</returns>
    public override bool ShouldSerializeValue(object component)
    {
        return false;
    }
}