using System;
using System.IO;
using System.Net;
using System.Security.Cryptography;
using System.Text;
using System.Web;

namespace PDF_Alchemy
{
    class Download
    {
        const string accessKeyId = "xxxxxxxxxxxxxxxxxxxx";
        const string secretAccessKey = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";

        // Downloads the next document from PDF Alchemy.
        // Returns the documentId on success, or null on failure.
        static private string DownloadNext()
        {
            // Generate the HMAC-SHA1 signature.
            string date = DateTime.UtcNow.ToString("r");
            string request = '/' + accessKeyId + "/outqueue/next";
            string clearText = "GET\n" + accessKeyId + '\n' + date + '\n' + request;
            HMACSHA1 hmac = new HMACSHA1(ASCIIEncoding.UTF8.GetBytes(secretAccessKey));
            string signature = Convert.ToBase64String(hmac.ComputeHash(ASCIIEncoding.UTF8.GetBytes(clearText)));

            // Request the next document from PDF Alchemy.
            HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create("http://www.pdfalchemy.com" + request);
            req.Headers.Add("X-PDF-Alchemy-Date", date);
            req.Headers.Add("X-PDF-Alchemy-Signature", signature);
            try
            {
                HttpWebResponse response = (HttpWebResponse)req.GetResponse();
                Stream responseStream = response.GetResponseStream();
                string filename = response.Headers.Get("Content-Disposition").Split(new char[] { '"' })[1];
                FileStream file = File.OpenWrite(filename);
                byte[] buffer = new Byte[4096];
                int bytesRead;
                while ((bytesRead = responseStream.Read(buffer, 0, buffer.Length)) > 0)
                    file.Write(buffer, 0, bytesRead);
                responseStream.Close();
                response.Close();
                file.Close();
                Console.WriteLine("Downloaded '{0}'.", filename);
                return response.Headers.Get("X-PDF-Alchemy-ID");
            }
            catch (System.Net.WebException e)
            {
                Console.Write(e.Message);
            }
            return null;
        }

        // Removes documentId from the PDF Alchemy outqueue.
        static private void DeleteDocument(string documentId)
        {
            // Generate the HMAC-SHA1 signature.
            string date = DateTime.UtcNow.ToString("r");
            string request = '/' + accessKeyId + "/outqueue/" + HttpUtility.UrlEncode(documentId);
            string clearText = "DELETE\n" + accessKeyId + '\n' + date + '\n' + request;
            HMACSHA1 hmac = new HMACSHA1(ASCIIEncoding.UTF8.GetBytes(secretAccessKey));
            string signature = Convert.ToBase64String(hmac.ComputeHash(ASCIIEncoding.UTF8.GetBytes(clearText)));

            // Remove the document from PDF Alchemy.
            HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create("http://www.pdfalchemy.com" + request);
            req.Method = "DELETE";
            req.Headers.Add("X-PDF-Alchemy-Date", date);
            req.Headers.Add("X-PDF-Alchemy-Signature", signature);
            try
            {
                ((HttpWebResponse)req.GetResponse()).Close();
                Console.WriteLine("Removed '{0}' from PDF Alchemy.", documentId);
            }
            catch (System.Net.WebException e)
            {
                Console.Write(e.Message);
            }
        }

        static void Main(string[] args)
        {
            string documentId;
            while ((documentId = DownloadNext()) != null)
                DeleteDocument(documentId);
        }
    }
}