// 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 <see cref='decimal'/>
    /// objects to and from various other representations.
    /// </summary>
    public class DecimalConverter : BaseNumberConverter
    {
        /// <summary>
        /// Determines whether this editor will attempt to convert hex (0x or #) strings
        /// </summary>
        internal override bool AllowHex => false;

        /// <summary>
        /// The Type this converter is targeting (e.g. Int16, UInt32, etc.)
        /// </summary>
        internal override Type TargetType => typeof(decimal);

        /// <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 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 decimal decimalValue)
            {
                ConstructorInfo? ctor = typeof(decimal).GetConstructor(new Type[] { typeof(int[]) });
                Debug.Assert(ctor != null, "Expected constructor to exist.");
                return new InstanceDescriptor(ctor, new object[] { decimal.GetBits(decimalValue) });
            }

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

        /// <summary>
        /// Convert the given value to a string using the given radix
        /// </summary>
        internal override object FromString(string value, int radix)
        {
            return Convert.ToDecimal(value, CultureInfo.CurrentCulture);
        }

        /// <summary>
        /// Convert the given value to a string using the given formatInfo
        /// </summary>
        internal override object FromString(string value, NumberFormatInfo? formatInfo)
        {
            return decimal.Parse(value, NumberStyles.Float, formatInfo);
        }

        /// <summary>
        /// Convert the given value from a string using the given formatInfo
        /// </summary>
        internal override string ToString(object value, NumberFormatInfo? formatInfo)
        {
            return ((decimal)value).ToString("G", formatInfo);
        }
    }
}