using System;
using System.Data;
using System.Globalization;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Security.Cryptography;
using System.Text.RegularExpressions;
using Sensor.Gateway.DataXfer;

public partial class GatewayFileSubmit : System.Web.UI.Page
{
    // Keys used in the Xfer service
    string secretKey = "Secret";
    string storeKey = "SensorStore";
    string dbKey = "DBConnection";
    string absPath = "AbsStorePath";

    // Params used
    string sigParam = "signature";
    string stageName = "Stage";

    // variables used
    string fileSHA1;
    string connString;
    string path, storePath;

    protected void Page_Load(object sender, EventArgs e)
    {
        try
        {
            // Get the params needed
            fileSHA1 = Request[sigParam];
            if (fileSHA1 == null) { throw new ArgumentNullException("fileSHA1"); }
        }
        catch
        {
            Response.Write("Incorrect parameters. Check signature");
            return;
        }
        HttpFileCollection uploadFiles = Request.Files;
        // Build HTML listing the files received.
        string summary = "";

        // Loop over the uploaded files and save to disk.
        int i;
        for (i = 0; i < uploadFiles.Count; i++)
        {
            HttpPostedFile postedFile = uploadFiles[i];
            SetEnvironment(postedFile.FileName);

            // Access the uploaded file's content in-memory:
            System.IO.Stream inStream = postedFile.InputStream;
            byte[] fileData = new byte[postedFile.ContentLength];
            inStream.Read(fileData, 0, postedFile.ContentLength);

            // Check the SHA-1 of the file
            if (fileSHA1 == null)
            {
                Response.Write("SHA-1 absent ... aborting");
                return;
            }
            // append date to the filename
            string fname = AppendDateToFilename(postedFile.FileName);
            
            // bool fileIntegrity = CheckFileSha1(fileData, fileSHA1, postedFile.FileName);
            //Test
            bool fileIntegrity = true;
            if (fileIntegrity)
            {
                // Process File
               
                int bytes = postedFile.ContentLength;
                if (CheckEmptyFile(bytes))
                {
                    Response.Write(fname + " file is empty. Nothing to do ...");
                    return;
                }

                // Save the posted file in our "data" virtual directory.
                // if the file passes the check.
                //TODO: uncomment
                postedFile.SaveAs(Server.MapPath(storePath) + fname);
                //connString = "Data Source=LEMON\\LEMON;Initial Catalog=BrazilStage;User Id=koala;Password=koala123;";
                GatewayFileProcessor fp = new GatewayFileProcessor(path, fname, bytes, connString);
                summary += fp.ProcessFile();
            }
            else
            {
                Response.Write("SHA-1 does not match ... aborting");
                return;
            }
        }
        Response.Write(summary);
    }

    #region Helper Functions

    /// <summary>
    /// compares the SHA-1 of the file recieved
    /// with the signature sent by the sender
    /// </summary>
    /// <param name="fileData"></param>
    /// <param name="fileSHA1"></param>
    /// <returns></returns>
    public bool CheckFileSha1 (byte[] fileData, string fileSHA1, string filename)
    {
        byte[] secretPhrase = AppendSecretPhrase (fileData, filename);
        string shaResult;
        SHA1 sha = new SHA1CryptoServiceProvider();
        shaResult = Bytes2String(sha.ComputeHash(secretPhrase));
        return ShaCompare(shaResult, fileSHA1);
    }
    /// <summary>
    /// Compares the SHA-1 strings
    /// </summary>
    /// <param name="shaResult"></param>
    /// <param name="fileSHA"></param>
    /// <returns></returns>
    public bool ShaCompare(string shaResult, string fileSHA)
    {
        if (shaResult.CompareTo(fileSHA) == 0)
        {
            return true;
        }
        return false;
    }
    /// <summary>
    /// The secret phrase is appended to the data file
    /// using the BlockCopy function. The resulting
    /// array is returned
    /// </summary>
    /// <param name="fileData"></param>
    /// <returns></returns>
    public byte[] AppendSecretPhrase (byte[] fileData, string filename)
    {
        byte[] concat;
        // Get the secret phrase
        string secret = filename + System.Configuration.ConfigurationManager.AppSettings[secretKey];
        byte[] secretBytes = new System.Text.ASCIIEncoding().GetBytes(secret);
        // append the secret phrase
        concat = new byte[fileData.Length + secretBytes.Length];
        System.Buffer.BlockCopy(fileData, 0, concat, 0, fileData.Length);
        System.Buffer.BlockCopy(secretBytes, 0, concat, fileData.Length, secretBytes.Length);
        return concat;
    }
    /// <summary>
    /// Helper function that converts Bytes to String 
    /// and prints it in hex format
    /// </summary>
    /// <param name="input"></param>
    /// <returns></returns>
    public string Bytes2String(byte[] input)
    {
        string hex = BitConverter.ToString(input);
        hex = hex.Replace("-", "");
        return hex;
    }
    /// <summary>
    /// Appends the system date to the name of the file.
    /// </summary>
    /// <param name="fname"></param>
    /// <returns></returns>
    public string AppendDateToFilename(string fname)
    {
        // Get the current time from the system.
        DateTime dt = DateTime.Now;
        string currDt = dt.ToString("s", DateTimeFormatInfo.InvariantInfo);
        currDt = currDt.Replace(":", "-");
        string storeName = fname + "." + currDt;
        return storeName;
    }
    public bool CheckEmptyFile(int numBytes)
    {
        if (numBytes < 8)
            return true;
        else
            return false;

    }
    public void SetEnvironment(string fname)
    {
        string[] tmp = fname.Split('.');
        string dbName = tmp[0];
        string stage = dbName + stageName;

        // Build up the key for the required DB
        connString = System.Configuration.ConfigurationManager.AppSettings[dbKey];
        // Replace DB name in connString
        connString = connString.Replace("XXX", stage);

        // obtain the store location
        path = System.Configuration.ConfigurationManager.AppSettings[absPath] + dbName;
        storePath = System.Configuration.ConfigurationManager.AppSettings[storeKey] + dbName + "/";
    }

    #endregion Helper functions
}