using System;
using System.IO;
using System.Resources;
using JD.LogService;

namespace JD.TeaBoxAddinSystem.Addins.Description.FileReferences
{
    /// <summary>
    /// A reference to a resource file.
    /// </summary>
    /// FIXME: This class doesn't support loading/unloading well, i.e. once the resources are loaded, they remain loaded.
    public class ResourceFileReference : FileReference
    {
        #region Variables

        /// <summary>
        /// Extension of recognized resource files.
        /// </summary>
        protected const string ResourcesExtension = ".resources";

        private ResourceManager m_resources;
        private bool m_resourcesLoaded;

        #endregion

        #region Constructor

        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="filename"></param>
        public ResourceFileReference(string filename)
            : base(filename)
        {
        }

        #endregion

        #region Properties

        internal ResourceManager Resources
        {
            get
            {
                Load();
                return m_resources;
            }
        }

        #endregion

        #region Methods

        private void Load()
        {
            if (!m_resourcesLoaded)
            {
                m_resourcesLoaded = true;
                m_resources = LoadImpl();

                if (m_resources == null)
                {
                    AddinManager.Log(new Error(LogCategory.Error, "Unable to create resource from file '{0}'", Filename));
                    m_resources = null;
                }
                else
                {
                    try
                    {
                        m_resources.GetObject(string.Empty);
                    }
                    catch (MissingManifestResourceException)
                    {
                        // No resources available
                        AddinManager.Log(new Error(LogCategory.Error, "Could not load resources {0}.", Filename) { Origin = FileLocation.GetValueOrDefault() });
                        m_resources = null;
                    }
                }
            }
        }

        /// <summary>
        /// Loads the resources.
        /// </summary>
        /// <returns></returns>        
        protected virtual ResourceManager LoadImpl()
        {
            if (Addin != null)
            {
                string directory = Addin.FileLocation.GetValueOrDefault().FileName;

                if (!string.IsNullOrEmpty(directory))
                {
                    string fullname = Path.Combine(directory, Filename);
                    directory = Path.GetDirectoryName(fullname);

                    string baseName = Path.GetFileName(Filename);
                    if (baseName.EndsWith(ResourcesExtension, StringComparison.OrdinalIgnoreCase))
                    {
                        baseName = baseName.Substring(0, baseName.Length - ResourcesExtension.Length);
                    }

                    return ResourceManager.CreateFileBasedResourceManager(baseName, directory, null);
                }
            }

            return null;
        }

        #endregion
    }
}