// 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.
 
 
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Globalization;
 
namespace System.ServiceModel
{
    public class FaultReason
    {
        public FaultReason(FaultReasonText translation)
        {
            if (translation == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull(nameof(translation));
            }
 
            Init(translation);
        }
 
        public FaultReason(string text)
        {
            // Let FaultReasonText constructor throw
            Init(new FaultReasonText(text));
        }
 
        internal FaultReason(string text, string xmlLang)
        {
            // Let FaultReasonText constructor throw
            Init(new FaultReasonText(text, xmlLang));
        }
 
        internal FaultReason(string text, CultureInfo cultureInfo)
        {
            // Let FaultReasonText constructor throw
            Init(new FaultReasonText(text, cultureInfo));
        }
 
        public FaultReason(IEnumerable<FaultReasonText> translations)
        {
            if (translations == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException(nameof(translations)));
            }
 
            int count = 0;
            foreach (FaultReasonText faultReasonText in translations)
            {
                count++;
            }
 
            if (count == 0)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SRP.AtLeastOneFaultReasonMustBeSpecified, "translations"));
            }
 
            FaultReasonText[] array = new FaultReasonText[count];
            int index = 0;
            foreach (FaultReasonText faultReasonText in translations)
            {
                array[index++] = faultReasonText ?? throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgument("translations", SRP.NoNullTranslations);
            }
            Init(array);
        }
 
        private void Init(FaultReasonText translation)
        {
            Init(new FaultReasonText[] { translation });
        }
 
        private void Init(FaultReasonText[] translations)
        {
            Translations = new SynchronizedReadOnlyCollection<FaultReasonText>(new object(), new ReadOnlyCollection<FaultReasonText>(translations));
        }
 
        public FaultReasonText GetMatchingTranslation()
        {
            return GetMatchingTranslation(CultureInfo.CurrentCulture);
        }
 
        public FaultReasonText GetMatchingTranslation(CultureInfo cultureInfo)
        {
            if (cultureInfo == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException(nameof(cultureInfo)));
            }
 
            // If there's only one translation, use it
            if (Translations.Count == 1)
            {
                return Translations[0];
            }
 
            // Search for an exact match
            for (int i = 0; i < Translations.Count; i++)
            {
                if (Translations[i].Matches(cultureInfo))
                {
                    return Translations[i];
                }
            }
 
            // If no exact match is found, proceed by looking for the a translation with a language that is a parent of the current culture
 
            if (Translations.Count == 0)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SRP.NoMatchingTranslationFoundForFaultText));
            }
 
            // Search for a more general language
            string localLang = cultureInfo.Name;
            while (true)
            {
                int idx = localLang.LastIndexOf('-');
 
                // We don't want to accept xml:lang=""
                if (idx == -1)
                {
                    break;
                }
 
                // Clip off the last subtag and look for a match
                localLang = localLang.Substring(0, idx);
 
                for (int i = 0; i < Translations.Count; i++)
                {
                    if (Translations[i].XmlLang == localLang)
                    {
                        return Translations[i];
                    }
                }
            }
 
            // Return the first translation if no match is found
            return Translations[0];
        }
 
        public SynchronizedReadOnlyCollection<FaultReasonText> Translations { get; private set; }
 
        public override string ToString()
        {
            if (Translations.Count == 0)
            {
                return string.Empty;
            }
 
            return GetMatchingTranslation().Text;
        }
    }
}