//------------------------------------------------------------------------------
// <copyright file="FontUnitConverter.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
//------------------------------------------------------------------------------

namespace System.Web.UI.WebControls {

    using System;
    using System.Collections;
    using System.ComponentModel;
    using System.ComponentModel.Design.Serialization;
    using System.Globalization;
    using System.Reflection;
    using System.Web.Util;


    /// <devdoc>
    /// <para>Converts a <see cref='System.Web.UI.WebControls.FontUnit'/> to and from a specified data type.</para>
    /// </devdoc>
    public class FontUnitConverter : TypeConverter {
        private StandardValuesCollection values;


        /// <devdoc>
        /// <para>Determines if the specified data type can be converted to a <see cref='System.Web.UI.WebControls.FontUnit'/>.</para>
        /// </devdoc>
        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType) {
            if (sourceType == typeof(string)) {
                return true;
            }
            else {
                return base.CanConvertFrom(context, sourceType);
            }
        }


        /// <devdoc>
        /// <para>Converts the specified <see cref='System.Object' qualify='true'/> into a <see cref='System.Web.UI.WebControls.FontUnit'/>.</para>
        /// </devdoc>
        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value) {
            if (value == null)
                return null;

            string stringValue = value as string;
            if (stringValue != null) {
                string textValue = stringValue.Trim();
                if (textValue.Length == 0) {
                    return FontUnit.Empty;
                }
                return FontUnit.Parse(textValue, culture);
            }
            else {
                return base.ConvertFrom(context, culture, value);
            }
        }


        /// <internalonly/>
        /// <devdoc>
        ///   Returns a value indicating whether the converter can
        ///   convert to the specified destination type.
        /// </devdoc>
        public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType) {
            if ((destinationType == typeof(string)) ||
                (destinationType == typeof(InstanceDescriptor))) {
                return true;
            }
            else {
                return base.CanConvertTo(context, destinationType);
            }
        }


        /// <devdoc>
        /// <para>Converts the specified <see cref='System.Web.UI.WebControls.FontUnit'/> into the specified <see cref='System.Type' qualify='true'/>. </para>
        /// </devdoc>
        public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType) {
            if (destinationType == typeof(string)) {
                if ((value == null) || (((FontUnit)value).Type == FontSize.NotSet))
                    return String.Empty;
                else
                    return ((FontUnit)value).ToString(culture);
            }
            else if ((destinationType == typeof(InstanceDescriptor)) && (value != null)) {
                FontUnit u = (FontUnit)value;
                MemberInfo member = null;
                object[] args = null;

                if (u.IsEmpty) {
                    member = typeof(FontUnit).GetField("Empty");
                }
                else if (u.Type != FontSize.AsUnit) {
                    string fieldName = null;
                    switch (u.Type) {
                        case FontSize.Smaller:
                            fieldName = "Smaller";
                            break;
                        case FontSize.Larger:
                            fieldName = "Larger";
                            break;
                        case FontSize.XXSmall:
                            fieldName = "XXSmall";
                            break;
                        case FontSize.XSmall:
                            fieldName = "XSmall";
                            break;
                        case FontSize.Small:
                            fieldName = "Small";
                            break;
                        case FontSize.Medium:
                            fieldName = "Medium";
                            break;
                        case FontSize.Large:
                            fieldName = "Large";
                            break;
                        case FontSize.XLarge:
                            fieldName = "XLarge";
                            break;
                        case FontSize.XXLarge:
                            fieldName = "XXLarge";
                            break;
                    }
                    Debug.Assert(fieldName != null, "Invalid FontSize type");
                    if (fieldName != null) {
                        member = typeof(FontUnit).GetField(fieldName);
                    }
                }
                else {
                    member = typeof(FontUnit).GetConstructor(new Type[] { typeof(Unit) });
                    args = new object[] { u.Unit };
                }

                Debug.Assert(member != null, "Looks like we're missing FontUnit static fields or FontUnit::ctor(Unit)");
                if (member != null) {
                    return new InstanceDescriptor(member, args);
                }
                else {
                    return null;
                }
            }
            else {
                return base.ConvertTo(context, culture, value, destinationType);
            }
        }


        /// <devdoc>
        /// <para>Returns a <see cref='System.ComponentModel.TypeConverter.StandardValuesCollection' qualify='true'/> 
        /// containing standard <see cref='System.Web.UI.WebControls.FontUnit'/> values.</para>
        /// </devdoc>
        public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context) {
            if (values == null) {
                object[] namedUnits = new object[] {
                    FontUnit.Smaller,
                    FontUnit.Larger,
                    FontUnit.XXSmall,
                    FontUnit.XSmall,
                    FontUnit.Small,
                    FontUnit.Medium,
                    FontUnit.Large,
                    FontUnit.XLarge,
                    FontUnit.XXLarge
                };

                values = new StandardValuesCollection(namedUnits);
            }
            return values;
        }


        /// <devdoc>
        ///    <para>Indicates whether the specified context contains exclusive standard 
        ///       values.</para>
        /// </devdoc>
        public override bool GetStandardValuesExclusive(ITypeDescriptorContext context) {
            return false;
        }


        /// <devdoc>
        ///    <para>Indicates whether the specified context contains suppurted standard 
        ///       values.</para>
        /// </devdoc>
        public override bool GetStandardValuesSupported(ITypeDescriptorContext context) {
            return true;
        }
    }
}