context: using System;
  using System.Security.Cryptography;
  using System.Collections.Generic;
  using System.Text;
  using System.Web;
  
  namespace uTorrentNotifier
  {
      public class OAuthBase
      {
  
          /// <summary>
          /// Provides a predefined set of algorithms that are supported officially by the protocol
          /// </summary>
          public enum SignatureTypes
          {
              HMACSHA1,
              Plaintext,
              RSASHA1
          }
  
          /// <summary>
          /// Provides an internal structure to sort the query parameter
          /// </summary>
          protected class QueryParameter
          {
              private string name = null;
              private string value = null;
  
              public QueryParameter(string name, string value)
              {
                  this.name = name;
                  this.value = value;
              }
  
              public string Name
              {
                  get { return name; }
              }
  
              public string Value
              {
                  get { return value; }
              }
          }
  
          /// <summary>
          /// Comparer class used to perform the sorting of the query parameters
          /// </summary>
          protected class QueryParameterComparer : IComparer<QueryParameter>
          {
  
              #region IComparer<QueryParameter> Members
  
              public int Compare(QueryParameter x, QueryParameter y)
              {
                  if (x.Name == y.Name)
                  {
                      return string.Compare(x.Value, y.Value);
                  }
                  else
                  {
                      return string.Compare(x.Name, y.Name);
                  }
              }
  
              #endregion
          }
  
          protected const string OAuthVersion = "1.0";
          protected const string OAuthParameterPrefix = "oauth_";
  
          //
          // List of know and used oauth parameters' names
          //        
          protected const string OAuthConsumerKeyKey = "oauth_consumer_key";
          protected const string OAuthCallbackKey = "oauth_callback";
          protected const string OAuthVersionKey = "oauth_version";
          protected const string OAuthSignatureMethodKey = "oauth_signature_method";
          protected const string OAuthSignatureKey = "oauth_signature";
          protected const string OAuthTimestampKey = "oauth_timestamp";
          protected const string OAuthNonceKey = "oauth_nonce";
          protected const string OAuthTokenKey = "oauth_token";
          protected const string OAuthTokenSecretKey = "oauth_token_secret";
          protected const string OAuthVerifierKey = "oauth_verifier"; // JDevlin
  
          protected const string HMACSHA1SignatureType = "HMAC-SHA1";
          protected const string PlaintextSignatureType = "PLAINTEXT";
          protected const string RSASHA1SignatureType = "RSA-SHA1";
  
          protected Random random = new Random();
  
          protected string unreservedChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.~";
  
          /// <summary>
          /// Helper function to compute a hash value
          /// </summary>
          /// <param name="hashAlgorithm">The hashing algoirhtm used. If that algorithm needs some initialization, like HMAC and its derivatives, they should be initialized prior to passing it to this function</param>
          /// <param name="data">The data to hash</param>
          /// <returns>a Base64 string of the hash value</returns>
          private string ComputeHash(HashAlgorithm hashAlgorithm, string data)
          {
              if (hashAlgorithm == null)
              {
                  throw new ArgumentNullException("hashAlgorithm");
              }
  
              if (string.IsNullOrEmpty(data))
              {
                  throw new ArgumentNullException("data");
              }
  
              byte[] dataBuffer = System.Text.Encoding.ASCII.GetBytes(data);
              byte[] hashBytes = hashAlgorithm.ComputeHash(dataBuffer);
  
              return Convert.ToBase64String(hashBytes);
          }
  
          /// <summary>
          /// Internal function to cut out all non oauth query string parameters (all parameters not begining with "oauth_")
          /// </summary>
          /// <param name="parameters">The query string part of the Url</param>
          /// <returns>A list of QueryParameter each containing the parameter name and value</returns>
          private List<QueryParameter> GetQueryParameters(string parameters)
          {
              if (parameters.StartsWith("?"))
              {
                  parameters = parameters.Remove(0, 1);
              }
  
              List<QueryParameter> result = new List<QueryParameter>();
  
              if (!string.IsNullOrEmpty(parameters))
              {
                  string[] p = parameters.Split('&');
                  foreach (string s in p)
                  {
                      // jmd: don't strip out oauth_verifier
                      if (!string.IsNullOrEmpty(s) && !s.StartsWith(OAuthParameterPrefix))
                      {
                          if (s.IndexOf('=') > -1)
                          {
                              string[] temp = s.Split('=');
                              result.Add(new QueryParameter(temp[0], temp[1]));
                          }
                          else
                          {
                              result.Add(new QueryParameter(s, string.Empty));
                          }
                      }
                  }
              }
  
              return result;
          }
  
          /// <summary>
          /// This is a different Url Encode implementation since the default .NET one outputs the percent encoding in lower case.
          /// While this is not a problem with the percent encoding spec, it is used in upper case throughout OAuth
          /// </summary>
          /// <param name="value">The value to Url encode</param>
          /// <returns>Returns a Url encoded string</returns>
          protected string UrlEncode(string value)
          {
              StringBuilder result = new StringBuilder();
  
              foreach (char symbol in value)
              {
                  if (unreservedChars.IndexOf(symbol) != -1)
                  {
                      result.Append(symbol);
                  }
                  else
                  {
                      result.Append('%' + String.Format("{0:X2}", (int)symbol));
                  }
              }
  
              return result.ToString();
          }
  
          /// <summary>
          /// Normalizes the request parameters according to the spec
          /// </summary>
          /// <param name="parameters">The list of parameters already sorted</param>
          /// <returns>a string representing the normalized parameters</returns>
          protected string NormalizeRequestParameters(IList<QueryParameter> parameters)
          {
              StringBuilder sb = new StringBuilder();
              QueryParameter p = null;
              for (int i = 0; i < parameters.Count; i++)
              {
                  p = parameters[i];
                  sb.AppendFormat("{0}={1}", p.Name, p.Value);
  
                  if (i < parameters.Count - 1)
                  {
                      sb.Append("&");
                  }
              }
  
              return sb.ToString();
          }
  
          /// <summary>
          /// Generate the signature base that is used to produce the signature
          /// </summary>
          /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
          /// <param name="consumerKey">The consumer key</param>        
          /// <param name="token">The token, if available. If not available pass null or an empty string</param>
          /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
          /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
          /// <param name="signatureType">The signature type. To use the default values use <see cref="OAuthBase.SignatureTypes">OAuthBase.SignatureTypes</see>.</param>
          /// <returns>The signature base</returns>
          public string GenerateSignatureBase(Uri url, string consumerKey, string token, string tokenSecret, string httpMethod, string timestamp, string nonce, string pin, string signatureType, out string normalizedUrl, out string normalizedRequestParameters)
          {
              if (token == null)
              {
                  token = string.Empty;
              }
  
              if (tokenSecret == null)
              {
                  tokenSecret = string.Empty;
              }
  
              if (string.IsNullOrEmpty(consumerKey))
              {
                  throw new ArgumentNullException("consumerKey");
              }
  
              if (string.IsNullOrEmpty(httpMethod))
              {
                  throw new ArgumentNullException("httpMethod");
              }
  
              if (string.IsNullOrEmpty(signatureType))
              {
                  throw new ArgumentNullException("signatureType");
              }
  
              normalizedUrl = null;
              normalizedRequestParameters = null;
  
              List<QueryParameter> parameters = GetQueryParameters(url.Query);
              parameters.Add(new QueryParameter(OAuthVersionKey, OAuthVersion));
              parameters.Add(new QueryParameter(OAuthNonceKey, nonce));
              parameters.Add(new QueryParameter(OAuthTimestampKey, timestamp));
              parameters.Add(new QueryParameter(OAuthSignatureMethodKey, signatureType));
              parameters.Add(new QueryParameter(OAuthConsumerKeyKey, consumerKey));
  
              if (!string.IsNullOrEmpty(token))
              {
                  parameters.Add(new QueryParameter(OAuthTokenKey, token));
              }
  
              // JDevlin: support for PIN-based auth
              if (!String.IsNullOrEmpty(pin))
              {
                  parameters.Add(new QueryParameter(OAuthVerifierKey, pin));
              }
  
              parameters.Sort(new QueryParameterComparer());
  
              normalizedUrl = string.Format("{0}://{1}", url.Scheme, url.Host);
              if (!((url.Scheme == "http" && url.Port == 80) || (url.Scheme == "https" && url.Port == 443)))
              {
                  normalizedUrl += ":" + url.Port;
              }
  
              normalizedUrl += url.AbsolutePath;
              normalizedRequestParameters = NormalizeRequestParameters(parameters);
  
              StringBuilder signatureBase = new StringBuilder();
              signatureBase.AppendFormat("{0}&", httpMethod.ToUpper());
              signatureBase.AppendFormat("{0}&", UrlEncode(normalizedUrl));
              signatureBase.AppendFormat("{0}", UrlEncode(normalizedRequestParameters));
  
              return signatureBase.ToString();
          }
  
          /// <summary>
          /// Generate the signature value based on the given signature base and hash algorithm
          /// </summary>
          /// <param name="signatureBase">The signature based as produced by the GenerateSignatureBase method or by any other means</param>
          /// <param name="hash">The hash algorithm used to perform the hashing. If the hashing algorithm requires initialization or a key it should be set prior to calling this method</param>
          /// <returns>A base64 string of the hash value</returns>
          public string GenerateSignatureUsingHash(string signatureBase, HashAlgorithm hash)
          {
              return ComputeHash(hash, signatureBase);
          }
  
          /// <summary>
          /// Generates a signature using the HMAC-SHA1 algorithm
          /// </summary>		
          /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
          /// <param name="consumerKey">The consumer key</param>
          /// <param name="consumerSecret">The consumer seceret</param>
          /// <param name="token">The token, if available. If not available pass null or an empty string</param>
          /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
          /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
          /// <returns>A base64 string of the hash value</returns>
          public string GenerateSignature(Uri url, string consumerKey, string consumerSecret, string token, string tokenSecret, string httpMethod, string timestamp, string nonce, /* JDevlin*/ string pin, out string normalizedUrl, out string normalizedRequestParameters)
          {
              return GenerateSignature(url, consumerKey, consumerSecret, token, tokenSecret, httpMethod, timestamp, nonce, pin, SignatureTypes.HMACSHA1, out normalizedUrl, out normalizedRequestParameters);
          }
  
          /// <summary>
          /// Generates a signature using the specified signatureType 
          /// </summary>		
          /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
          /// <param name="consumerKey">The consumer key</param>
          /// <param name="consumerSecret">The consumer seceret</param>
          /// <param name="token">The token, if available. If not available pass null or an empty string</param>
          /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
          /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
          /// <param name="signatureType">The type of signature to use</param>
          /// <returns>A base64 string of the hash value</returns>
          public string GenerateSignature(Uri url, string consumerKey, string consumerSecret, string token, string tokenSecret, string httpMethod, string timestamp, string nonce, string pin /*JDevlin*/, SignatureTypes signatureType, out string normalizedUrl, out string normalizedRequestParameters)
          {
              normalizedUrl = null;
              normalizedRequestParameters = null;
  
              switch (signatureType)
              {
                  case SignatureTypes.Plaintext:
                      return HttpUtility.UrlEncode(string.Format("{0}&{1}", consumerSecret, tokenSecret));
                  case SignatureTypes.HMACSHA1:
                      string signatureBase = GenerateSignatureBase(url, consumerKey, token, tokenSecret, httpMethod, timestamp, nonce, pin, HMACSHA1SignatureType, out normalizedUrl, out normalizedRequestParameters);
  
                      HMACSHA1 hmacsha1 = new HMACSHA1();
                      hmacsha1.Key = Encoding.ASCII.GetBytes(string.Format("{0}&{1}", UrlEncode(consumerSecret), string.IsNullOrEmpty(tokenSecret) ? "" : UrlEncode(tokenSecret)));
  
                      return GenerateSignatureUsingHash(signatureBase, hmacsha1);
                  case SignatureTypes.RSASHA1:
  
gt:                     throw new NotImplementedException();