using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace com.alibaba.openapi.client.util
{
    public class SignatureUtil
    {
        public static byte[] hmacSha1(String path, Dictionary<String, Object> parameters, String signingKey)
        {
            List<String> lists = new List<String>();
            foreach (KeyValuePair<string, object> kvp in parameters)
            {
                lists.Add(kvp.Key + kvp.Value);
            }
            lists.Sort(StringComparer.Ordinal);
            StringBuilder sb = new StringBuilder();
            sb.Append(path);
            foreach (String param in lists)
            {
                sb.Append(param);
            }
            String contentToHmac = sb.ToString();
            byte[] byteToHmac = System.Text.Encoding.UTF8.GetBytes(contentToHmac);
            byte[] byteArray = System.Text.Encoding.UTF8.GetBytes(signingKey);
            HMACSHA1 hmac = new HMACSHA1(byteArray);
            byte[] hashValue = hmac.ComputeHash(byteToHmac, 0, byteToHmac.Length);
            return hashValue;
        }

        public static string toHex( byte[] bytes)
        {
            char[] c = new char[bytes.Length * 2];

            byte b;

            for (int bx = 0, cx = 0; bx < bytes.Length; ++bx, ++cx)
            {
                b = ((byte)(bytes[bx] >> 4));
                c[cx] = (char)(b > 9 ? b + 0x37 + 0x20 : b + 0x30);

                b = ((byte)(bytes[bx] & 0x0F));
                c[++cx] = (char)(b > 9 ? b + 0x37 + 0x20 : b + 0x30);
            }

            return new string(c).ToUpper();
        }

        public static byte[] hexToBytes( string str)
        {
            if (str.Length == 0 || str.Length % 2 != 0)
                return new byte[0];

            byte[] buffer = new byte[str.Length / 2];
            char c;
            for (int bx = 0, sx = 0; bx < buffer.Length; ++bx, ++sx)
            {
                // Convert first half of byte
                c = str[sx];
                buffer[bx] = (byte)((c > '9' ? (c > 'Z' ? (c - 'a' + 10) : (c - 'A' + 10)) : (c - '0')) << 4);

                // Convert second half of byte
                c = str[++sx];
                buffer[bx] |= (byte)(c > '9' ? (c > 'Z' ? (c - 'a' + 10) : (c - 'A' + 10)) : (c - '0'));
            }

            return buffer;
        }
    }
}