using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Text;
using System.Security.Cryptography;

/// <summary>
/// Helper class to handle the payment integration with PayGate
/// </summary>
/// 

public enum PaymentResults { Pending, Approved, InsufficientFunds, Declined, InvalidCard }

public class PayGate
{
  public string PayGate_ID
  { get; set; }

  public string PayGate_Key
  { get; set; }

  public string Reference
  { get; set; }

  public float Amount
  { get; set; }

  public string Currency
  { get; set; }

  public string Return_URL
  { get; set; }

  public string UserEmail
  { get; set; }

  //private static string PayGate_Server = "https://www.paygate.co.za/paywebv2/process.trans";
  private static string PayGate_Server = "SendRequest.aspx";

  /****************************************************************************************************/
  /// <summary>
  /// Initializes a new instance of the <see cref="PayGate"/> class.
  /// </summary>
  public PayGate()
	{
    PayGate_ID = System.Configuration.ConfigurationManager.AppSettings.Get("PayGate_ID");
    PayGate_Key = System.Configuration.ConfigurationManager.AppSettings.Get("PayGate_Key");
    Currency = System.Configuration.ConfigurationManager.AppSettings.Get("PayGate_Currency");
    Return_URL = System.Configuration.ConfigurationManager.AppSettings.Get("PayGate_ReturnURL");
	}

  /****************************************************************************************************/
  /// <summary>
  /// Initializes a new instance of the <see cref="PayGate"/> class.
  /// </summary>
  /// <param name="PayGate_ID">The pay gate ID.</param>
  /// <param name="PayGate_Key">The pay gate encryption key.</param>
  /// <param name="PayGate_Currency">The pay gate currency.</param>
  /// <param name="PayGate_ReturnURL">The pay gate return URL.</param>
  public PayGate(string PayGate_ID, string PayGate_Key, string PayGate_Currency, string PayGate_ReturnURL)
  {
    this.PayGate_ID = PayGate_ID;
    this.PayGate_Key = PayGate_Key;
    this.Currency = PayGate_Currency;
    this.Return_URL = PayGate_ReturnURL;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Generates the PayGate MD5 checksum.
  /// </summary>
  /// <param name="Data">The data.</param>
  /// <returns></returns>
  private string GenerateChecksum(string Data)
  {
    ASCIIEncoding AE = new ASCIIEncoding();
    byte[] ByteSource = AE.GetBytes(Data);
    MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();
    byte[] Hash = MD5.ComputeHash(ByteSource);
    string Checksum = "";
    for (int i = 0; i < Hash.Length; i++)
    {
      Checksum += Hash[i].ToString("x2").ToUpper();
    }

    return Checksum;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Starts the payment process.
  /// </summary>
  public string StartPayment()
  {
    string TransDate = DateTime.Now.ToString("yyyy-MM-dd HH:mm");
    string TransAmnt = (Amount * 100).ToString("G0");
    string ChecksumSource = PayGate_ID + "|";
    ChecksumSource += Reference + "|";
    ChecksumSource += TransAmnt + "|";
    ChecksumSource += Currency + "|";
    ChecksumSource += Return_URL + "|";
    ChecksumSource += TransDate + "|";
    if (!string.IsNullOrEmpty(UserEmail))
      ChecksumSource += UserEmail + "|";
    ChecksumSource += PayGate_Key;

    //ASCIIEncoding AE = new ASCIIEncoding();
    //byte[] ByteSource = AE.GetBytes(ChecksumSource);
    //MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();
    //byte[] Hash = MD5.ComputeHash(ByteSource);
    //string Checksum = "";
    //for (int i = 0; i < Hash.Length; i++)
    //{
    //  Checksum += Hash[i].ToString("x2").ToUpper();
    //}

    string Checksum = GenerateChecksum(ChecksumSource);

    string PostUrl = PayGate_Server + "?";
    PostUrl += "PAYGATE_ID=" + PayGate_ID;
    PostUrl += "&REFERENCE=" + Reference;
    PostUrl += "&AMOUNT=" + TransAmnt;
    PostUrl += "&CURRENCY=" + Currency;
    PostUrl += "&TRANSACTION_DATE=" + TransDate;
    PostUrl += "&RETURN_URL=" + Return_URL;
    if (!string.IsNullOrEmpty(UserEmail))
      PostUrl += "&EMAIL=" + UserEmail;
    PostUrl += "&CHECKSUM=" + Checksum;

    return PostUrl;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Confirms the checksum result.
  /// </summary>
  /// <param name="rxAmount">The rx amount.</param>
  /// <param name="Transaction_Status">The transaction_ status.</param>
  /// <param name="Result_Code">The result_ code.</param>
  /// <param name="Result_Desc">The result_ desc.</param>
  /// <param name="Auth_Code">The auth_ code.</param>
  /// <param name="Transaction_Id">The transaction_ id.</param>
  /// <param name="Risk_Indicator">The risk_ indicator.</param>
  /// <param name="Checksum">The checksum.</param>
  /// <returns></returns>
  public bool ConfirmChecksumResult(string rxAmount, string Transaction_Status, string Result_Code, string Result_Desc, string Auth_Code, string Transaction_Id, string Risk_Indicator, string rxChecksum)
  {
    bool result = false;

    string ChecksumSource = PayGate_ID + "|";
    ChecksumSource += Reference + "|";
    ChecksumSource += Transaction_Status + "|";
    ChecksumSource += Result_Code + "|";
    ChecksumSource += Auth_Code + "|";
    ChecksumSource += rxAmount + "|";
    ChecksumSource += Result_Desc + "|";
    ChecksumSource += Transaction_Id + "|";

    if (!string.IsNullOrEmpty(Risk_Indicator))
      ChecksumSource += Risk_Indicator + "|";
    ChecksumSource += PayGate_Key;

    result = rxChecksum.ToUpper().Equals(GenerateChecksum(ChecksumSource));

    return result;
  }

  /****************************************************************************************************/
  public string GetChecksumResult(string rxAmount, string Transaction_Status, string Result_Code, string Result_Desc, string Auth_Code, string Transaction_Id, string Risk_Indicator, string rxChecksum)
  {
    string result = "";

    string ChecksumSource = PayGate_ID + "|";
    ChecksumSource += Reference + "|";
    ChecksumSource += Transaction_Status + "|";
    ChecksumSource += Result_Code + "|";
    ChecksumSource += Auth_Code + "|";
    ChecksumSource += rxAmount + "|";
    ChecksumSource += Result_Desc + "|";
    ChecksumSource += Transaction_Id + "|";

    if (!string.IsNullOrEmpty(Risk_Indicator))
      ChecksumSource += Risk_Indicator + "|";
    ChecksumSource += PayGate_Key;

    result = GenerateChecksum(ChecksumSource);

    return result;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Gets the transaction status.
  /// </summary>
  /// <param name="Status">The status.</param>
  /// <returns></returns>
  public string GetTransactionStatus(int Status)
  {
    string result = "";
    switch (Status)
    {
      case 0:
        result = "Pending";
        break;
      case 1:
        result = "Approved";
        break;
      case 2:
        result = "Declined";
        break;
    }
    return result;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Gets the result code.
  /// </summary>
  /// <param name="Code">The code.</param>
  /// <returns></returns>
  public string GetResultCode(int Code)
  {
    string result = "";
    switch (Code)
    {
      case 0:
        result = "N/A";
        break;
      case 990017:
        result = "Approved Transaction";
        break;
      case 900003:
        result = "Insufficient Funds";
        break;
      case 900007:
        result = "Declined Transaction";
        break;
      case 900004:
        result = "Invalid Card Number";
        break;
      case 990022:
        result = "Unprocessed Transaction";
        break;
    }
    return result;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Gets the risk indicator.
  /// </summary>
  /// <param name="Status">The status.</param>
  /// <returns></returns>
  public string GetRiskIndicator(string Status)
  {
    string result = "";
    switch (Status.ToUpper())
    {
      case "AX":
        result = "Authenticated";
        break;
      case "NX":
        result = "Not Authenticated";
        break;
      default:
        result = "N/A";
        break;
    }
    return result;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Return the results code as a status code.
  /// </summary>
  /// <param name="Code">The code.</param>
  /// <returns></returns>
  public int ResultCodeAsStatus(int Code)
  {
    int result = 0;
    switch (Code)
    {
      case 0:
        result = (int)PaymentResults.Pending;
        break;
      case 990017:
        result = (int)PaymentResults.Approved;
        break;
      case 900003:
        result = (int)PaymentResults.InsufficientFunds;
        break;
      case 900007:
        result = (int)PaymentResults.Declined;
        break;
      case 900004:
        result = (int)PaymentResults.InvalidCard;
        break;
      case 990022:
        result = (int)PaymentResults.Pending;
        break;
    }
    return result;
  }

  /****************************************************************************************************/
}