///
/// Copyright (c) 2021 Sensus Slovensko a.s.
///
using System;
using System.Collections.Generic;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Xml.Serialization;

namespace OrderManagement
{
    /// <summary>
    /// Class to be serialized to an XML file...
    /// </summary>
    [XmlRootAttribute("SNPrinting")]
    public class LocalSettings
    {
        static XmlSerializer serializer = XmlSerializer.FromTypes(new[] { typeof(LocalSettings) })[0];

        /// Configuration file ecryption/decryption key and initialization vector
        static byte[] key = new byte[] { 83, 254, 105, 64, 184, 201, 195, 127, 52, 99, 77, 45, 252, 132, 163, 156 };
        static byte[] IV = new byte[] { 189, 23, 137, 56, 204, 241, 242, 118, 28, 89, 9, 198, 224, 111, 186, 125 };

        public Mode Mode;
        public string Language;             /// User interface language used as CultureInfo(..) constructor argument
        public bool IsUserLoginRequired;    /// true = require user login on program start-up
        public bool IsShowPredefinedOrders; /// true = show predefined orders with nr. <= 1000
        public bool IsShowFinishedOrders;   /// true = show finished orders
        public string TracingDBConnString;  /// Connection string to MySQL database with production tracing records
        public string UsersDBConnString;    /// Connection string to MySQL database with authorized users
        public string[] SapNumberHistory;   /// SAP number history
        public string[] SeparatorHistory;   /// Separator history
        public int CurrentSNTrail;          /// Serial number trail to be printed now
        public int RemainingSNsCount;       /// Remaining count of serial numbers to be printed in this session


        /// Parameterless constructor required by serialization
        public LocalSettings() { }

        public LocalSettings(bool createNew)
        {
            if (createNew)
            {
                Mode = Mode.Standalone;
                Language = "EN";
                IsUserLoginRequired = false;
                IsShowPredefinedOrders = false;
                IsShowFinishedOrders = false;
#if DEBUG
                TracingDBConnString = "SERVER=localhost; DATABASE=nanjingshared; UID=root; PASSWORD=kraken; CHARSET=utf8;";
#else
                TracingDBConnString = "SERVER=10.116.192.200; DATABASE=nanjingshared; UID=nanjingshared; PASSWORD=C1ern4V0d4; CHARSET=utf8;";
#endif
                UsersDBConnString = TracingDBConnString;
                SapNumberHistory = new string[] { };
                SeparatorHistory = new string[] { "7VQ" };
                CurrentSNTrail = 1;
                RemainingSNsCount = 0;
            }
        }

        /// <summary>
        /// Load public fields of this class from the XML file.
        /// </summary>
		/// <returns>LocalSettings object or null when Load() fails</returns>
		public static LocalSettings Load(string fileName)
        {
            try
            {
                bool isEncrypted = true;
                using (StreamReader reader = new StreamReader(fileName))
                {
                    isEncrypted = !reader.ReadLine().StartsWith("<?xml version=");
                    reader.Close();
                }

                if (isEncrypted)
                {
                    /// Write settings to a string
                    StringBuilder plain = new StringBuilder();

                    using (RijndaelManaged aes = new RijndaelManaged { Padding = PaddingMode.Zeros })
                    {
                        using (FileStream fsCrypt = new FileStream(fileName, FileMode.Open))
                        {
                            using (ICryptoTransform decryptor = aes.CreateDecryptor(key, IV))
                            {
                                using (CryptoStream cs = new CryptoStream(fsCrypt, decryptor, CryptoStreamMode.Read))
                                {
                                    using (MemoryStream mStream = new MemoryStream())
                                    {
                                        using (var writer = new BinaryWriter(mStream))
                                        {
                                            int data;
                                            while ((data = cs.ReadByte()) != -1)
                                            {
                                                if (data != 0) writer.Write((byte)data);
                                            }
                                            writer.Flush();
                                            mStream.Position = 0;

                                            using (var reader = new StreamReader(mStream))
                                            {
                                                return serializer.Deserialize(reader) as LocalSettings;
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
                else
                {
                    using (StreamReader reader = new StreamReader(fileName))
                    {
                        return serializer.Deserialize(reader) as LocalSettings;
                    }
                }
            }
            catch (Exception e)
            {
                string msg = e.Message;
                return null;
            }
        }

        /// <summary>
        /// Save public fields of this class to the XML file.
        /// </summary>
        public void Save()
        {
            try
            {
                /// Encrypt and write to file 'Program.LocalSettingsFileName'
                using (RijndaelManaged aes = new RijndaelManaged { Padding = PaddingMode.Zeros })
                {
                    using (FileStream fsCrypt = new FileStream(Program.LocalSettingsFileName, FileMode.Create))
                    {
                        using (ICryptoTransform encryptor = aes.CreateEncryptor(key, IV))
                        {
                            using (CryptoStream cs = new CryptoStream(fsCrypt, encryptor, CryptoStreamMode.Write))
                            {
                                using (MemoryStream mStream = new MemoryStream())
                                {
                                    using (var writer = new StreamWriter(mStream))
                                    {
                                        /// Serialize and write settings to a memory stream
                                        serializer.Serialize(writer, this);
                                        writer.Flush();
                                        mStream.Position = 0;

                                        using (var reader = new StreamReader(mStream))
                                        {
                                            /// Encrypt and write to file 'Program.LocalSettingsFileName'
                                            int data;
                                            while ((data = mStream.ReadByte()) != -1) cs.WriteByte((byte)data);
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
            catch (Exception e)
            {
                string msg = e.Message;
            }
        }

		/// <summary>
		/// Updates history stored in a string array by a new latest string.
		/// </summary>
		/// <param name="lastStrValue">Last entered string</param>
		/// <returns>true = history updated</returns>
		public static bool UpdateHistory(string lastStrValue, ref string[] history)
		{
			const int MaxHistoryLen = 10;

			if (string.IsNullOrEmpty(lastStrValue)) return false;

			int currentHistoryLength = (history != null) ? history.Length : 0;

			int match = -1;
			for (int i = 0; i < currentHistoryLength; i++)
			{
				if (history[i] == lastStrValue)
				{
					match = i;
					break;
				}
			}

			if (match >= 0 || currentHistoryLength >= MaxHistoryLen)
			{
				/// History does not have to be extended (because of a match) or should not be extended (because of the lenght)
				if (match < 0) match = currentHistoryLength - 1;

				for (int j = match; j > 0; j--)
				{
					history[j] = history[j - 1];
				}
				history[0] = lastStrValue;
			}
			else
			{
				/// History wiil be extended, new item inserted at the beginning
				string[] newHistory = new string[currentHistoryLength + 1];
				newHistory[0] = lastStrValue;
				for (int j = 1; j <= currentHistoryLength; j++)
				{
					newHistory[j] = history[j - 1];
				}
				history = newHistory;
			}

            return true;
		}

        /// <summary>
        /// Load Purchase order combo box items from the LocalSettings PurchaseOrderHistory array
        /// </summary>
        /// <param name="comboBox">Puchase order ComboBox</param>
        public static void PrepareCombo(string[] history, System.Windows.Forms.ComboBox comboBox)
        {
            if (history != null)
            {
                for (int i = 0; i < history.Length; i++)
                {
                    comboBox.Items.Add(history[i]);
                }
            }

            if (comboBox.Items.Count > 0)
            {
                comboBox.Text = comboBox.Items[0].ToString();
            }
        }
    }


    public enum Mode
    {
        Standalone,
        WithDatabase,
    }
}