using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Xml.Linq;
using System.Xml.Schema;
using Thermo.Active.Model.DTOModels;
using static Thermo.Active.Model.Constants;

namespace Thermo.Active.Utils
{
    public static class LanguageController
    {
        private static bool FileIsValid = true;

        public static bool LanguageIsAvailable(string language)
        {
            // Create a valid language
            CultureInfo lang = CultureInfo.CreateSpecificCulture(language);
            // File path with 2 letter iso language
            string filePath = LANGUAGE_PACK_DIRECTORY + lang.TwoLetterISOLanguageName + ".xml";

            if (!File.Exists(filePath))
                return false;

            return true;
        }

        public static Dictionary<string, string> GetTranslationsFromFile(string language)
        {
            CultureInfo lang = CultureInfo.CreateSpecificCulture(language);

            // File path with 2 letter iso language
            string filePath = LANGUAGE_PACK_DIRECTORY + lang.TwoLetterISOLanguageName + ".xml";

            // Open file reader
            XDocument xmlLanguageFile = XDocument.Load(filePath);

            //if (!ValidateTranslationsFile(xmlLanguageFile, LANGUAGE_SCHEMA_PATH))
            //    return null;

            // Read file content
            return xmlLanguageFile
                .Root?
                .Elements()
                .ToDictionary(x => x.Name.ToString(), x => x.Value); // Populate dictionary
        }

        public static List<DTOLanguageModel> GetLanguageListFromDirectory()
        {
            // Check if directory exists
            if (Directory.Exists(LANGUAGE_PACK_DIRECTORY))
            {
                // Check if directory is empty
                if (Directory.EnumerateFileSystemEntries(LANGUAGE_PACK_DIRECTORY).Any())
                {
                    // Read all the files in the lang directory
                    return Directory.GetFiles(LANGUAGE_PACK_DIRECTORY, "*.xml", SearchOption.TopDirectoryOnly)
                         .Select(Path.GetFileNameWithoutExtension) // Get only fileName without extensions
                         .Where(x => IsValidLanguage(x)) // Filter file names by valid language
                         .Select(x =>
                         {
                             CultureInfo info = new CultureInfo(x);
                             DTOLanguageModel language = new DTOLanguageModel() // Create language model
                             {
                                 IsoId = info.TwoLetterISOLanguageName,
                                 Name = char.ToUpper(info.NativeName[0]) + info.NativeName.Substring(1)
                             };
                             return language;
                         })
                         .ToList();
                }
            }

            return null;
        }

        public static bool IsValidLanguage(string language)
        {
            CultureInfo info = CultureInfo
                .GetCultures(CultureTypes.AllCultures)
                .FirstOrDefault(l => l.TwoLetterISOLanguageName == language.ToLower()); // Find user language from system language

            if (info == null)
                return false;

            return true;
        }

        private static bool ValidateTranslationsFile(XDocument xmlLanguageFile, string validatorFilePath)
        {
            FileIsValid = true;

            // Read validation file
            XmlSchemaSet readerSettings = new XmlSchemaSet();

            // Add Schema
            readerSettings.Add(null, validatorFilePath);

            // Validate file
            xmlLanguageFile.Validate(readerSettings, ValidationHandler);

            return FileIsValid;
        }

        // Validation XML Callback
        private static void ValidationHandler(object sender, ValidationEventArgs e)
        {
            if (e.Severity == XmlSeverityType.Error)
                FileIsValid = false;
        }
    }
}