src/Lucene.Net.QueryParser/Flexible/Messages/NLS.cs

using Lucene.Net.Support;
using Lucene.Net.Util;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Reflection;
using System.Resources;

namespace Lucene.Net.QueryParsers.Flexible.Messages
{
    /*
     * Licensed to the Apache Software Foundation (ASF) under one or more
     * contributor license agreements.  See the NOTICE file distributed with
     * this work for additional information regarding copyright ownership.
     * The ASF licenses this file to You under the Apache License, Version 2.0
     * (the "License"); you may not use this file except in compliance with
     * the License.  You may obtain a copy of the License at
     *
     *     http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */

    /// <summary>
    /// MessageBundles classes extend this class, to implement a bundle.
    /// 
    /// For Native Language Support (NLS), system of software internationalization.
    /// 
    /// This interface is similar to the NLS class in eclipse.osgi.util.NLS class -
    /// initializeMessages() method resets the values of all static strings, should
    /// only be called by classes that extend from NLS (see TestMessages.java for
    /// reference) - performs validation of all message in a bundle, at class load
    /// time - performs per message validation at runtime - see NLSTest.java for
    /// usage reference
    /// 
    /// MessageBundle classes may subclass this type.
    /// </summary>
    public class NLS
    {
        /// <summary>
        /// LUCENENET specific factory reference to inject instances of <see cref="ResourceManager"/>
        /// into this class.
        /// </summary>
        private static IResourceManagerFactory resourceManagerFactory = new BundleResourceManagerFactory();
        private static IDictionary<string, Type> bundles = new Dictionary<string, Type>(0);

        protected NLS()
        {
            // Do not instantiate
        }

        /// <summary>
        /// Gets the static <see cref="IResourceManagerFactory"/> instance responsible
        /// for creating <see cref="ResourceManager"/> instances in this class. LUCENENET specific.
        /// </summary>
        // LUCENENET NOTE: Don't make this into a property in case we need to make it into an extension method
        // in a centralized DI configuration builder.
        public static IResourceManagerFactory GetResourceManagerFactory()
        {
            return resourceManagerFactory;
        }

        /// <summary>
        /// Sets the <see cref="IResourceManagerFactory"/> used to create instances of <see cref="ResourceManager"/>
        /// for retrieving localized resources. Defaults to <see cref="BundleResourceManagerFactory"/> if not set. LUCENENET specific.
        /// </summary>
        /// <param name="resourceManagerFactory">The <see cref="IResourceManagerFactory"/> instance. Cannot be <c>null</c>.</param>
        // LUCENENET NOTE: Don't make this into a property in case we need to make it into an extension method
        // in a centralized DI configuration builder.
        public static void SetResourceManagerFactory(IResourceManagerFactory resourceManagerFactory)
        {
            if (resourceManagerFactory == null)
            {
                throw new ArgumentNullException("resourceManagerFactory");
            }
            NLS.resourceManagerFactory = resourceManagerFactory;
        }

        public static string GetLocalizedMessage(string key)
        {
            return GetLocalizedMessage(key, CultureInfo.InvariantCulture);
        }

        public static string GetLocalizedMessage(string key, CultureInfo locale)
        {
            string message = GetResourceBundleObject(key, locale);
            if (message == null)
            {
                return "Message with key:" + key + " and locale: " + locale
                    + " not found.";
            }
            return message;
        }

        public static string GetLocalizedMessage(string key, CultureInfo locale,
            params object[] args)
        {
            string str = GetLocalizedMessage(key, locale);

            if (args.Length > 0)
            {
                str = string.Format(locale, str, args);
            }

            return str;
        }

        public static string GetLocalizedMessage(string key, params object[] args)
        {
            return GetLocalizedMessage(key, CultureInfo.CurrentUICulture, args);
        }

        /// <summary>
        /// Initialize a given class with the message bundle Keys Should be called from
        /// a class that extends NLS in a static block at class load time.
        /// </summary>
        /// <param name="bundleName">Property file with that contains the message bundle</param>
        /// <param name="clazz">where constants will reside</param>
        protected static void InitializeMessages(string bundleName, Type clazz)
        {
            try
            {
                Load(clazz);
                if (!bundles.ContainsKey(bundleName))
                    bundles[bundleName] = clazz;
            }
#pragma warning disable 168
            catch (Exception e)
#pragma warning restore 168
            {
                // ignore all errors and exceptions
                // because this function is supposed to be called at class load time.
            }
        }

        private static string GetResourceBundleObject(string messageKey, CultureInfo locale)
        {
            // slow resource checking
            // need to loop thru all registered resource bundles
            foreach(var key in bundles.Keys)
            {
                Type clazz = bundles[key];
                ResourceManager resourceBundle = resourceManagerFactory.Create(clazz);
                if (resourceBundle != null)
                {
                    try
                    {
                        string obj = resourceBundle.GetString(messageKey, locale);
                        if (obj != null)
                            return obj;
                    }
#pragma warning disable 168
                    catch (MissingManifestResourceException e)
#pragma warning restore 168
                    {
                        // just continue it might be on the next resource bundle
                    }
                    finally
                    {
                        resourceManagerFactory.Release(resourceBundle);
                    }
                }
            }
            // if resource is not found
            return null;
        }

        private static void Load(Type clazz)
        {
            FieldInfo[] fieldArray = clazz.GetFields();

            // build a map of field names to Field objects
            int len = fieldArray.Length;
            IDictionary<string, FieldInfo> fields = new Dictionary<string, FieldInfo>(len * 2);
            for (int i = 0; i < len; i++)
            {
                fields[fieldArray[i].Name] = fieldArray[i];
                LoadFieldValue(fieldArray[i], clazz);
            }
        }

        private static void LoadFieldValue(FieldInfo field, Type clazz)
        {
            field.SetValue(null, field.Name);
            ValidateMessage(field.Name, clazz);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="key">Message Key</param>
        /// <param name="clazz"></param>
        private static void ValidateMessage(string key, Type clazz)
        {
            // Test if the message is present in the resource bundle
            try
            {
                ResourceManager resourceBundle = resourceManagerFactory.Create(clazz);
                if (resourceBundle != null)
                {
                    try
                    {
                        string obj = resourceBundle.GetString(key);
                        //if (obj == null)
                        //  System.err.println("WARN: Message with key:" + key + " and locale: "
                        //      + Locale.getDefault() + " not found.");
                    }
                    finally
                    {
                        resourceManagerFactory.Release(resourceBundle);
                    }
                }
            }
#pragma warning disable 168
            catch (MissingManifestResourceException e)
#pragma warning restore 168
            {
                //System.err.println("WARN: Message with key:" + key + " and locale: "
                //    + Locale.getDefault() + " not found.");
            }
#pragma warning disable 168
            catch (Exception e)
#pragma warning restore 168
            {
                // ignore all other errors and exceptions
                // since this code is just a test to see if the message is present on the
                // system
            }
        }
    }
}