#region License

// Copyright 2005-2019 Paul Kohler (https://github.com/paulkohler/minisqlquery). All rights reserved.
// This source code is made available under the terms of the GNU Lesser General Public License v3.0
// https://github.com/paulkohler/minisqlquery/blob/master/LICENSE

#endregion

using System.Collections.Generic;
using System.IO;

namespace MiniSqlQuery.Core
{
    /// <summary>
    /// 	Given a file name or extention the service will work out the most appropriate editor to use.
    /// </summary>
    /// <remarks>
    /// 	The editors need to be registered using the <see cref = "Register" /> method.
    /// 	<example>
    /// 		<code>
    /// 			IEditor editor = resolver.ResolveEditorInstance("c:\data.sql");
    /// 			// will resolve to the SQL editor
    /// 
    /// 			IEditor editor = resolver.ResolveEditorInstance("c:\foo.txt");
    /// 			// will resolve to the basic text editor</code>
    /// 	</example>
    /// </remarks>
    public class FileEditorResolverService : IFileEditorResolver
    {
        /// <summary>
        /// 	The extention map of files types to descriptors.
        /// </summary>
        private readonly Dictionary<string, FileEditorDescriptor> _extentionMap;

        /// <summary>
        /// 	The file editor descriptors.
        /// </summary>
        private readonly List<FileEditorDescriptor> _fileEditorDescriptors;

        /// <summary>
        /// 	The application services.
        /// </summary>
        private readonly IApplicationServices _services;

        /// <summary>
        /// 	Initializes a new instance of the <see cref = "FileEditorResolverService" /> class.
        /// </summary>
        /// <param name = "services">The application services.</param>
        public FileEditorResolverService(IApplicationServices services)
        {
            _services = services;
            _extentionMap = new Dictionary<string, FileEditorDescriptor>();
            _fileEditorDescriptors = new List<FileEditorDescriptor>();
        }

        /// <summary>
        /// 	Gets an array of the file descriptiors.
        /// </summary>
        /// <returns>An array of <see cref = "FileEditorDescriptor" /> objects.</returns>
        public FileEditorDescriptor[] GetFileTypes()
        {
            return _fileEditorDescriptors.ToArray();
        }

        /// <summary>
        /// 	Registers the specified file editor descriptor.
        /// 	It is recommended to use the <see cref = "IApplicationServices.RegisterEditor{TEditor}" /> method to
        /// 	set up the container correctly.
        /// </summary>
        /// <param name = "fileEditorDescriptor">The file editor descriptor.</param>
        public void Register(FileEditorDescriptor fileEditorDescriptor)
        {
            _fileEditorDescriptors.Add(fileEditorDescriptor);
            if (fileEditorDescriptor.Extensions == null || fileEditorDescriptor.Extensions.Length == 0)
            {
                _extentionMap.Add("*", fileEditorDescriptor);
            }
            else
            {
                // create a map of all ext to editors
                foreach (string extention in fileEditorDescriptor.Extensions)
                {
                    _extentionMap.Add(extention, fileEditorDescriptor);
                }
            }
        }

        /// <summary>
        /// 	Resolves the editor instance from the container based on the filename.
        /// </summary>
        /// <param name = "filename">The filename.</param>
        /// <returns>An editor.</returns>
        public IEditor ResolveEditorInstance(string filename)
        {
            string ext = Path.GetExtension(filename);
            string editorName = ResolveEditorNameByExtension(ext);
            return _services.Resolve<IEditor>(editorName);
        }

        /// <summary>
        /// 	Works out the "name" of the editor to use based on the <paramref name = "extension" />.
        /// </summary>
        /// <param name = "extension">The extention ("sql", "txt"/".txt" etc).</param>
        /// <returns>The name of an editor in the container.</returns>
        public string ResolveEditorNameByExtension(string extension)
        {
            string editorName = _extentionMap["*"].EditorKeyName;

            if (extension != null)
            {
                if (extension.StartsWith("."))
                {
                    extension = extension.Substring(1);
                }

                // is there a specific editor for this file type
                if (_extentionMap.ContainsKey(extension))
                {
                    editorName = _extentionMap[extension].EditorKeyName;
                }
            }

            return editorName;
        }
    }
}