// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.ComponentModel.Design.Serialization;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Reflection;

namespace System.ComponentModel
{
    /// <summary>
    /// Provides a type converter to convert globally unique identifier objects to and from various
    /// other representations.
    /// </summary>
    public class GuidConverter : TypeConverter
    {
        /// <summary>
        /// Gets a value indicating whether this converter can convert an object in the given source
        /// type to a globally unique identifier object using the context.
        /// </summary>
        public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
        {
            return sourceType == typeof(string) || base.CanConvertFrom(context, sourceType);
        }

        /// <summary>
        /// Gets a value indicating whether this converter can convert an object to
        /// the given destination type using the context.
        /// </summary>
        public override bool CanConvertTo(ITypeDescriptorContext? context, [NotNullWhen(true)] Type? destinationType)
        {
            return destinationType == typeof(InstanceDescriptor) || base.CanConvertTo(context, destinationType);
        }

        /// <summary>
        /// Converts the given object to a globally unique identifier object.
        /// </summary>
        public override object? ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
        {
            if (value is string text)
            {
                return new Guid(text);
            }

            return base.ConvertFrom(context, culture, value);
        }

        /// <summary>
        /// Converts the given object to another type. The most common types to convert
        /// are to and from a string object. The default implementation will make a call
        /// to ToString on the object if the object is valid and if the destination
        /// type is string. If this cannot convert to the destination type, this will
        /// throw a NotSupportedException.
        /// </summary>
        public override object? ConvertTo(ITypeDescriptorContext? context, CultureInfo? culture, object? value, Type destinationType)
        {
            if (destinationType == typeof(InstanceDescriptor) && value is Guid)
            {
                ConstructorInfo? ctor = typeof(Guid).GetConstructor(new Type[] { typeof(string) });
                Debug.Assert(ctor != null, "Expected constructor to exist.");
                return new InstanceDescriptor(ctor, new object?[] { value.ToString() });
            }

            return base.ConvertTo(context, culture, value, destinationType);
        }
    }
}