using System.Security.Cryptography;
using System.Text;

namespace MP.MONO.Core
{
    /// <summary>
    /// Classe validazione valori
    /// </summary>
    public class MachineDataValidator
    {
        #region Public Constructors

        /// <summary>
        /// Init classe validatore
        /// </summary>
        /// <param name="currMachineData"></param>
        public MachineDataValidator()
        {
            // inizializzo info di base
            machTestData = setupData().Result;
        }

        #endregion Public Constructors

        #region Public Properties

        /// <summary>
        /// Restituisce HASH del codice impiego = payload utente
        /// </summary>
        /// <returns></returns>
        public string macHash
        {
            get => calcMachineHash();
        }

        #endregion Public Properties

        #region Public Methods

        /// <summary>
        /// Verifica validità info correnti
        /// </summary>
        /// <returns></returns>
        public static async Task<bool> testCurrInfo()
        {
            var cDV = new MachineDataValidator();
            return await cDV.testInfo();
        }

        #endregion Public Methods

        #region Private Fields

        /// <summary>
        /// Dati rispetto cui fare i calcoli di validazione
        /// </summary>
        private Dictionary<string, string> machTestData = new Dictionary<string, string>();

        #endregion Private Fields

        #region Private Methods

        /// <summary>
        /// Calcola HASH del codice impiego = payload utente
        /// </summary>
        /// <returns></returns>
        private string calcMachineHash()
        {
            string hash = "";
            string buffData = currBaseBuffer();
            if (!string.IsNullOrEmpty(buffData))
            {
                // hashing!
                
                using (var hAlgo = SHA512.Create())
                //using (var hAlgo = MD5.Create())
                {
                    byte[] InputBytes = Encoding.UTF8.GetBytes(buffData);
                    var byteHash = hAlgo.ComputeHash(InputBytes);
                    hash = BitConverter.ToString(byteHash).Replace("-", "").Replace("/", "").Replace("\\", "").ToLowerInvariant();
                }
            }
            return hash;
        }

        /// <summary>
        /// Calcola hash key da info PC
        /// </summary>
        /// <returns></returns>
        private string currBaseBuffer()
        {
            string answ = "????????????????????????????????????????????";
            StringBuilder sb = new StringBuilder();
            // calcolo hashKey da alcuni valori solamente
            sb.Append($"{machTestData["SystemName"]}|");
            sb.Append($"{machTestData["ProcessorId"]}|");
            sb.Append($"{machTestData["PartNumber"]}|");
            sb.Append($"{machTestData["MACAddress"]}|");
            sb.Append($"{machTestData["SerialNumber"]}|");
            sb.Append($"{machTestData["Architecture"]}|");
            sb.Append($"{machTestData["SoftwareElementID"]}|");
            sb.Append($"{machTestData["SystemBiosMajorVersion"]}|");
            sb.Append($"{machTestData["SystemBiosMinorVersion"]}|");
            if (sb.Length > 0)
            {
                answ = sb.ToString();
                // lo uso 2 volte dritto e reverse...
                answ += ReverseString(sb.ToString());
            }
            return answ;
        }

        /// <summary>
        /// Esegue reverse delal stringa
        /// </summary>
        /// <param name="myStr"></param>
        /// <returns></returns>
        private string ReverseString(string myStr)
        {
            char[] myArr = myStr.ToCharArray();
            Array.Reverse(myArr);
            return new string(myArr);
        }

        /// <summary>
        /// Legge la hash key dal file licenza salvato
        /// </summary>
        /// <returns></returns>
        /// <exception cref="NotImplementedException"></exception>
        private async Task<string> getSavedHash()
        {
            string answ = "############################################################";
            string filePath = "Conf/lic.file";
            if (File.Exists(filePath))
            {
                answ = await File.ReadAllTextAsync(filePath);
            }
            return answ;
        }

        /// <summary>
        /// Predispone elenco dati di test
        /// </summary>
        /// <returns></returns>
        private async Task<Dictionary<string, string>> setupData()
        { // creo un unico array di info
            Dictionary<string, string> testData = new Dictionary<string, string>();
            var biosInfo = await MachineInfo.GetInfo("BIOS");
            var cpuInfo = await MachineInfo.GetInfo("CPU");
            var netInfo = await MachineInfo.GetInfo("NET");
            var osInfo = await MachineInfo.GetInfo("OS");
            var ramInfo = await MachineInfo.GetInfo("RAM");
            testData = biosInfo.Concat(cpuInfo).Concat(netInfo).Concat(osInfo).Concat(ramInfo).GroupBy(ele => ele.Key).ToDictionary(ele => ele.Key, ele => ele.First().Value);
            return testData;
        }

        /// <summary>
        /// Effettua verifica putuale tra hash Key fornita ed hash key calcolata da info PC
        /// </summary>
        /// <returns></returns>
        private async Task<bool> testInfo()
        {
            // recupero hash key da conf applicativo (licenza)
            string fileHash = await getSavedHash();
            /// recupero hash calcolata
            string calcHash = calcMachineHash();
            // confronto con hashKey calcolata da info PC + dati...
            return fileHash.Equals(calcHash);
        }

        #endregion Private Methods
    }
}