/*
 *
 * (c) Copyright Ascensio System Limited 2010-2018
 *
 * This program is freeware. You can redistribute it and/or modify it under the terms of the GNU 
 * General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html). 
 * In accordance with Section 7(a) of the GNU GPL its Section 15 shall be amended to the effect that 
 * Ascensio System SIA expressly excludes the warranty of non-infringement of any third-party rights.
 *
 * THIS PROGRAM IS DISTRIBUTED WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE. For more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
 *
 * You can contact Ascensio System SIA by email at sales@onlyoffice.com
 *
 * The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display 
 * Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
 *
 * Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains 
 * relevant author attributions when distributing the software. If the display of the logo in its graphic 
 * form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE" 
 * in every copy of the program you distribute. 
 * Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
 *
*/


#region Import

using ASC.CRM.Resources;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Reflection;

#endregion

namespace ASC.CRM.Classes
{

    public static class EnumExtension
    {
        public static String ToLocalizedString(this Enum value)
        {
            return LocalizedEnumConverter.ConvertToString(value);
        }

        public static bool TryParse<T>(string value, out T result)
   where T : struct // error CS0702: Constraint cannot be special class 'System.Enum'
        {
            return TryParse<T>(value, false, out result);
        }

        public static bool TryParse<T>(string value,  bool ignoreCase, out T result)
           where T : struct // error CS0702: Constraint cannot be special class 'System.Enum'
        {
            if (value == null)
                value = String.Empty;

            result = default(T);
            try
            {
                result = (T)Enum.Parse(typeof(T), value, ignoreCase);
                return true;
            }
            catch { }

            return false;
        }

   
    }

    public class LocalizedEnumConverter : EnumConverter
    {
        private class LookupTable : Dictionary<string, object> { }
        private Dictionary<CultureInfo, LookupTable> _lookupTables = new Dictionary<CultureInfo, LookupTable>();
        private System.Resources.ResourceManager _resourceManager;
        private bool _isFlagEnum = false;
        private Array _flagValues;

        /// <summary>
        /// GetList the lookup table for the given culture (creating if necessary)
        /// </summary>
        /// <param name="culture"></param>
        /// <returns></returns>
        private LookupTable GetLookupTable(CultureInfo culture)
        {
            LookupTable result = null;
            if (culture == null)
                culture = CultureInfo.CurrentCulture;

            if (!_lookupTables.TryGetValue(culture, out result))
            {
                result = new LookupTable();
                foreach (object value in GetStandardValues())
                {
                    string text = GetValueText(culture, value);
                    if (text != null)
                    {
                        result.Add(text, value);
                    }
                }
                _lookupTables.Add(culture, result);
            }
            return result;
        }

        /// <summary>
        /// Return the text to display for a simple value in the given culture
        /// </summary>
        /// <param name="culture">The culture to get the text for</param>
        /// <param name="value">The enum value to get the text for</param>
        /// <returns>The localized text</returns>
        private string GetValueText(CultureInfo culture, object value)
        {
            Type type = value.GetType();
            string resourceName = string.Format("{0}_{1}", type.Name, value.ToString());
            string result = _resourceManager.GetString(resourceName, culture);
            if (result == null)
                result = resourceName;
            return result;
        }

        /// <summary>
        /// Return true if the given value is can be represented using a single bit
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        private bool IsSingleBitValue(ulong value)
        {
            switch (value)
            {
                case 0:
                    return false;
                case 1:
                    return true;
            }
            return ((value & (value - 1)) == 0);
        }

        /// <summary>
        /// Return the text to display for a flag value in the given culture
        /// </summary>
        /// <param name="culture">The culture to get the text for</param>
        /// <param name="value">The flag enum value to get the text for</param>
        /// <returns>The localized text</returns>
        private string GetFlagValueText(CultureInfo culture, object value)
        {
            // if there is a standard value then use it
            //
            if (Enum.IsDefined(value.GetType(), value))
            {
                return GetValueText(culture, value);
            }

            // otherwise find the combination of flag bit values
            // that makes up the value
            //
            ulong lValue = Convert.ToUInt32(value);
            string result = null;
            foreach (object flagValue in _flagValues)
            {
                ulong lFlagValue = Convert.ToUInt32(flagValue);
                if (IsSingleBitValue(lFlagValue))
                {
                    if ((lFlagValue & lValue) == lFlagValue)
                    {
                        string valueText = GetValueText(culture, flagValue);
                        if (result == null)
                        {
                            result = valueText;
                        }
                        else
                        {
                            result = string.Format("{0}, {1}", result, valueText);
                        }
                    }
                }
            }
            return result;
        }

        /// <summary>
        /// Return the Enum value for a simple (non-flagged enum)
        /// </summary>
        /// <param name="culture">The culture to convert using</param>
        /// <param name="text">The text to convert</param>
        /// <returns>The enum value</returns>
        private object GetValue(CultureInfo culture, string text)
        {
            LookupTable lookupTable = GetLookupTable(culture);
            object result = null;
            lookupTable.TryGetValue(text, out result);
            return result;
        }
        
        private object GetFlagValue(CultureInfo culture, string text)
        {
            LookupTable lookupTable = GetLookupTable(culture);
            string[] textValues = text.Split(',');
            ulong result = 0;
            foreach (string textValue in textValues)
            {
                object value = null;
                string trimmedTextValue = textValue.Trim();
                if (!lookupTable.TryGetValue(trimmedTextValue, out value))
                {
                    return null;
                }
                result |= Convert.ToUInt32(value);
            }
            return Enum.ToObject(EnumType, result);
        }

        public LocalizedEnumConverter(Type type)
            : base(type)
        {
            _resourceManager = CRMEnumResource.ResourceManager;
            object[] flagAttributes = type.GetCustomAttributes(typeof(FlagsAttribute), true);
            _isFlagEnum = flagAttributes.Length > 0;
            if (_isFlagEnum)
            {
                _flagValues = Enum.GetValues(type);
            }
        }

        public override object ConvertFrom(System.ComponentModel.ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
        {
            if (value is string)
            {
                object result = (_isFlagEnum) ?
                    GetFlagValue(culture, (string)value) : GetValue(culture, (string)value);
                if (result == null)
                {
                    result = base.ConvertFrom(context, culture, value);
                }
                return result;
            }
            
            return base.ConvertFrom(context, culture, value);

        }

        public override object ConvertTo(System.ComponentModel.ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destinationType)
        {
            if (value != null && destinationType == typeof(string))
            {
                object result = (_isFlagEnum) ?
                    GetFlagValueText(culture, value) : GetValueText(culture, value);
                return result;
            }
            else
            {
                return base.ConvertTo(context, culture, value, destinationType);
            }
        }

        public static string ConvertToString(Enum value)
        {
            TypeConverter converter = TypeDescriptor.GetConverter(value.GetType());
            return converter.ConvertToString(value);
        }

        public static List<KeyValuePair<Enum, string>> GetValues(Type enumType, CultureInfo culture)
        {
            List<KeyValuePair<Enum, string>> result = new List<KeyValuePair<Enum, string>>();
            TypeConverter converter = TypeDescriptor.GetConverter(enumType);
            foreach (Enum value in Enum.GetValues(enumType))
            {
                KeyValuePair<Enum, string> pair = new KeyValuePair<Enum, string>(value, converter.ConvertToString(null, culture, value));
                result.Add(pair);
            }
            return result;
        }

        public static List<KeyValuePair<Enum, string>> GetValues(Type enumType)
        {
            return GetValues(enumType, CultureInfo.CurrentUICulture);
        }

        public static List<String> GetLocalizedValues(Type enumType)
        {
            var converter = TypeDescriptor.GetConverter(enumType);

            return (from Enum value in Enum.GetValues(enumType) 
                    select converter.ConvertToString(null, CultureInfo.CurrentUICulture, value)).ToList();

        }
    }
}