using System;

#if NETFX_CORE

using Windows.Security.Cryptography;

using Windows.Security.Cryptography.Core;

using Windows.Security.Cryptography.Certificates;

using Windows.Storage.Streams;

using System.Runtime.InteropServices.WindowsRuntime;

#else

using System.Security.Cryptography;

#endif

using System.Collections.Generic;

using System.Text;

using System.Text.RegularExpressions;



namespace HigLabo.Net

{

    public partial class OAuth1Client

    {

#if SILVERLIGHT || NETFX_CORE

        private static readonly Encoding GenerateSignatureEncoding = Encoding.UTF8;

#else

        private static readonly Encoding GenerateSignatureEncoding = Encoding.GetEncoding("us-ascii");

#endif

        /// <summary>

        /// 

        /// </summary>

        public class Key

        {

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthVersionNo = "1.0";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthParameterPrefix = "oauth_";

            /// <summary>

            /// List of know and used oauth parameters' names 

            /// </summary>

            public static readonly String OAuthConsumerKey = "oauth_consumer_key";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthCallback = "oauth_callback";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthVersion = "oauth_version";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthSignatureMethod = "oauth_signature_method";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthSignature = "oauth_signature";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthTimestamp = "oauth_timestamp";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthNonce = "oauth_nonce";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthToken = "oauth_token";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String OAuthTokenSecret = "oauth_token_secret";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String HMACSHA1SignatureType = "HMAC-SHA1";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String PlainTextSignatureType = "PLAINTEXT";

            /// <summary>

            /// 

            /// </summary>

            public static readonly String RSASHA1SignatureType = "RSA-SHA1";

        }

        private static readonly Random Random = new Random();

        /// <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>

        protected static List<KeyValuePair<String, String>> GetQueryParameters(String parameters)

        {

            if (parameters.StartsWith("?"))

            {

                parameters = parameters.Remove(0, 1);

            }



            List<KeyValuePair<String, String>> result = new List<KeyValuePair<String, String>>();



            if (!String.IsNullOrEmpty(parameters))

            {

                String[] p = parameters.Split('&');

                foreach (String s in p)

                {

                    if (!String.IsNullOrEmpty(s) && !s.StartsWith(Key.OAuthParameterPrefix))

                    {

                        if (s.IndexOf('=') > -1)

                        {

                            String[] temp = s.Split('=');

                            result.Add(new KeyValuePair<String, String>(temp[0], temp[1]));

                        }

                        else

                        {

                            result.Add(new KeyValuePair<String, String>(s, String.Empty));

                        }

                    }

                }

            }



            return result;

        }

        /// <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 static String NormalizeRequestParameters(IList<KeyValuePair<String, String>> parameters)

        {

            StringBuilder sb = new StringBuilder(256);

            KeyValuePair<String, String> p;

            for (int i = 0; i < parameters.Count; i++)

            {

                p = parameters[i];

                sb.AppendFormat("{0}={1}", p.Key, p.Value);



                if (i < parameters.Count - 1)

                {

                    sb.Append("&");

                }

            }



            return sb.ToString();

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="url"></param>

        /// <param name="command"></param>

        /// <param name="signatureType"></param>

        /// <returns></returns>

        public static SignatureInfo GenerateSignature(Uri url, GetRequestTokenCommand command, OAuthSignatureTypes signatureType)

        {

            var cm = command;

            SignatureInfo si = new SignatureInfo();



            switch (signatureType)

            {

                case OAuthSignatureTypes.PLAINTEXT:

                    si.Signature = OAuth1Client.UrlEncode(String.Format("{0}&{1}", cm.ConsumerKeySecret, cm.TokenSecret));

                    return si;

                case OAuthSignatureTypes.HMACSHA1:

                    si = GenerateSignatureBase(url, cm, Key.HMACSHA1SignatureType);

                    String key = String.Format("{0}&{1}"

                        , OAuth1Client.UrlEncode(cm.ConsumerKeySecret), String.IsNullOrEmpty(cm.TokenSecret) ? "" : OAuth1Client.UrlEncode(cm.TokenSecret));

                    si.Signature = GenerateSignatureUsingHash(key, si.Signature);

                    return si;

                case OAuthSignatureTypes.RSASHA1: throw new NotImplementedException();

            }

            throw new ArgumentException("Unknown signature type", "signatureType");

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="url"></param>

        /// <param name="command"></param>

        /// <param name="signatureType"></param>

        /// <returns></returns>

        public static SignatureInfo GenerateSignatureBase(Uri url, GetRequestTokenCommand command, String signatureType)

        {

            SignatureInfo si = new SignatureInfo();

            var cm = command;



            if (String.IsNullOrEmpty(signatureType))

            {

                throw new ArgumentNullException("signatureType");

            }



            List<KeyValuePair<String, String>> parameters = OAuth1Client.GetQueryParameters(url.Query);

            parameters.Add(new KeyValuePair<String, String>(Key.OAuthVersion, Key.OAuthVersionNo));

            parameters.Add(new KeyValuePair<String, String>(Key.OAuthNonce, cm.Nonce));

            parameters.Add(new KeyValuePair<String, String>(Key.OAuthTimestamp, cm.TimeStamp));

            parameters.Add(new KeyValuePair<String, String>(Key.OAuthSignatureMethod, signatureType));

            parameters.Add(new KeyValuePair<String, String>(Key.OAuthConsumerKey, cm.ConsumerKey));



            if (!String.IsNullOrEmpty(cm.Token))

            {

                parameters.Add(new KeyValuePair<String, String>(Key.OAuthToken, cm.Token));

            }



            parameters.Sort(CompareQueryString);



            si.NormalizedUrl = String.Format("{0}://{1}", url.Scheme, url.Host);

            if (!((url.Scheme == "http" && url.Port == 80) || (url.Scheme == "https" && url.Port == 443)))

            {

                si.NormalizedUrl += ":" + url.Port;

            }

            si.NormalizedUrl += url.AbsolutePath;

            si.NormalizedRequestParameters = NormalizeRequestParameters(parameters);



            StringBuilder sb = new StringBuilder(1000);

            sb.AppendFormat("{0}&", cm.MethodName.ToString().ToUpper());

            sb.AppendFormat("{0}&", OAuth1Client.UrlEncode(si.NormalizedUrl));

            sb.AppendFormat("{0}", OAuth1Client.UrlEncode(si.NormalizedRequestParameters));

            si.Signature = sb.ToString();

            return si;

        }

        private static int CompareQueryString(KeyValuePair<String, String> x, KeyValuePair<String, String> y)

        {

            if (x.Key == y.Key)

            {

                return String.Compare(x.Value, y.Value);

            }

            return String.Compare(x.Key, y.Key);

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="key"></param>

        /// <param name="data"></param>

        /// <returns></returns>

#if NETFX_CORE

        public static String GenerateSignatureUsingHash(String key, String data)

        {

            MacAlgorithmProvider hash = MacAlgorithmProvider.OpenAlgorithm(MacAlgorithmNames.HmacSha1);

            BinaryStringEncoding encoding = BinaryStringEncoding.Utf8;

            var dataBuffer = CryptographicBuffer.ConvertStringToBinary(data, encoding);

            IBuffer buffKeyMaterial = CryptographicBuffer.GenerateRandom(hash.MacLength);

            var hmacKey = hash.CreateKey(OAuth1Client.GenerateSignatureEncoding.GetBytes(key).AsBuffer());

            var hashBytes = CryptographicEngine.Sign(hmacKey, dataBuffer);

            // Verify that the HMAC length is correct for the selected algorithm

            if (hashBytes.Length != hash.MacLength)

            {

                throw new Exception("Error computing digest");

            }

            return Convert.ToBase64String(hashBytes.ToArray());

        }

#else

        public static String GenerateSignatureUsingHash(String key, String data)

        {

            if (String.IsNullOrEmpty(data))

            {

                throw new ArgumentNullException("data");

            }

            HMACSHA1 hash = new HMACSHA1();

            hash.Key = OAuth1Client.GenerateSignatureEncoding.GetBytes(key);



            byte[] dataBuffer = OAuth1Client.GenerateSignatureEncoding.GetBytes(data);

            byte[] hashBytes = hash.ComputeHash(dataBuffer);



            return Convert.ToBase64String(hashBytes);

        }

#endif

        /// <summary>

        /// 

        /// </summary>

        /// <param name="url"></param>

        /// <param name="command"></param>

        /// <returns></returns>

        public static SignatureInfo GenerateSignature(Uri url, GetRequestTokenCommand command)

        {

            return GenerateSignature(url, command, OAuthSignatureTypes.HMACSHA1);

        }

        /// <summary>

        /// Generate the timestamp for the signature        

        /// </summary>

        /// <returns></returns>

        internal static String GenerateTimeStamp()

        {

            // Default implementation of UNIX time of the current UTC time

            TimeSpan ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);

            return Convert.ToInt64(ts.TotalSeconds).ToString();

        }

        /// <summary>

        /// 

        /// </summary>

        /// <returns></returns>

        internal static String GenerateNonce()

        {

            return GenerateNonce1();

        }

        /// <summary>

        /// Generate a nonce

        /// </summary>

        /// <returns></returns>

        private static String GenerateNonce0()

        {

            // Just a simple implementation of a random number between 123400 and 9999999

            return Random.Next(123400, 9999999).ToString();

        }

        /// <summary>

        /// 

        /// </summary>

        /// <returns></returns>

        private static String GenerateNonce1()

        {

            String letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

            StringBuilder result = new StringBuilder(8);

            Random random = new Random();

            for (int i = 0; i < 8; ++i)

            {

                result.Append(letters[random.Next(letters.Length)]);

            }

            return result.ToString();

        }

    }

}