// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#nullable disable

using System.ComponentModel;
using System.Globalization;

namespace System.Windows.Forms
{
    /// <summary>
    ///  OpacityConverter is a class that can be used to convert opacity values from one
    ///  data type to another. Access this class through the TypeDescriptor.
    /// </summary>
    public class OpacityConverter : TypeConverter
    {
        /// <summary>
        ///  Determines if this converter can convert an object in the given source
        ///  type to the native type of the converter.
        /// </summary>
        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
        {
            if (sourceType == typeof(string))
            {
                return true;
            }

            return base.CanConvertFrom(context, sourceType);
        }

        /// <summary>
        ///  Converts the given object to the converter's native type.
        /// </summary>
        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
        {
            if (value is string valueString)
            {
                string text = valueString.Replace('%', ' ').Trim();
                double val = double.Parse(text, CultureInfo.CurrentCulture);
                int indexOfPercent = valueString.IndexOf('%');
                if (indexOfPercent > 0 && (val >= 0.0 && val <= 1.0))
                {
                    val /= 100.0;
                    text = val.ToString(CultureInfo.CurrentCulture);
                }

                double percent = 1.0;
                try
                {
                    percent = (double)TypeDescriptor.GetConverter(typeof(double)).ConvertFrom(context, culture, text);

                    // Assume they meant a percentage if it is > 1.0, else they actually
                    // typed the correct double.
                    if (percent > 1.0)
                    {
                        percent /= 100.0;
                    }
                }
                catch (FormatException e)
                {
                    throw new FormatException(string.Format(SR.InvalidBoundArgument,
                                                                    "Opacity",
                                                                    text,
                                                                    "0%",
                                                                    "100%"), e);
                }

                // Now check to see if it is within our bounds.
                if (percent < 0.0 || percent > 1.0)
                {
                    throw new FormatException(string.Format(SR.InvalidBoundArgument,
                                                                    "Opacity",
                                                                    text,
                                                                    "0%",
                                                                    "100%"));
                }

                return percent;
            }

            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 (value is double val && destinationType == typeof(string))
            {
                int perc = (int)(val * 100.0);
                return perc.ToString(CultureInfo.CurrentCulture) + "%";
            }

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