#pragma once

#include <string>
#include <sstream>
#include <openssl/hmac.h>
#include <stdexcept>
#include <iomanip>
#include <cstddef>
#include <cctype>
#include <cstring>
#include <cstdlib>

namespace agora { namespace tools {
    const uint32_t HMAC_LENGTH = 20;
    const uint32_t SIGNATURE_LENGTH = 40;
    const uint32_t APP_ID_LENGTH = 32;
    const uint32_t UNIX_TS_LENGTH = 10;
    const uint32_t RANDOM_INT_LENGTH = 8;
    const uint32_t UID_LENGTH = 10;
    const uint32_t VERSION_LENGTH = 3;
    const std::string  RECORDING_SERVICE = "ARS"; 
    const std::string  PUBLIC_SHARING_SERVICE = "APSS"; 
    const std::string  MEDIA_CHANNEL_SERVICE = "ACS";

    template <class T>
        class singleton
        {
            public:
                static T* instance()
                {
                    static T inst;
                    return &inst;
                }
            protected:
                singleton(){}
                virtual ~singleton(){}
            private:
                singleton(const singleton&);
                singleton& operator = (const singleton& rhs);
        };

    class crypto : public singleton<crypto>
    {
        public:
            // HMAC
            std::string hmac_sign(const std::string& message)
            {
                return hmac_sign2(hmac_key_, message, 20);
            }

            std::string hmac_sign2(const std::string& appCertificate, const std::string& message, uint32_t signSize)
            {
                if (appCertificate.empty()) {
                    /*throw std::runtime_error("empty hmac key");*/
                    return "";
                }
                return std::string((char *)HMAC(EVP_sha1()
                            , (const unsigned char*)appCertificate.data()
                            , appCertificate.length()
                            , (const unsigned char*)message.data()
                            , message.length(), NULL, NULL)
                        , signSize);
            }

            bool hmac_verify(const std::string & message, const std::string & signature)
            {
                return signature == hmac_sign(message);
            }
        private:
            std::string hmac_key_;
    };

    inline std::string toupper(const std::string& in)
    {
        std::string out;
        for (char x : in) {
            int u = std::toupper(x);
            out.push_back((char)u);
        }
        return out;
    }

    inline std::string stringToHEX(const std::string& in)
    {
        static const char hexTable[]= "0123456789ABCDEF";

        if (in.empty()) {
            return std::string();
        }
        std::string out(in.size()*2, '\0');
        for (uint32_t i = 0; i < in.size(); ++i){
            out[i*2 + 0] = hexTable[(in[i] >> 4) & 0x0F];
            out[i*2 + 1] = hexTable[(in[i]     ) & 0x0F];
        }
        return out;
    }

    inline std::string stringToHex(const std::string& in)
    {
        static const char hexTable[]= "0123456789abcdef";

        if (in.empty()) {
            return std::string();
        }
        std::string out(in.size()*2, '\0');
        for (uint32_t i = 0; i < in.size(); ++i){
            out[i*2 + 0] = hexTable[(in[i] >> 4) & 0x0F];
            out[i*2 + 1] = hexTable[(in[i]     ) & 0x0F];
        }
        return out;
    }

    inline std::string hexDecode(const std::string& hex)
    {
        if (hex.length() % 2 != 0) {
            return "";
        }

        size_t count = hex.length() / 2;
        std::string out(count, '\0');
        for (size_t i = 0; i < count; ++i) {
            std::string one = hex.substr(i * 2, 2);
            out[i] = ::strtol(one.c_str(), 0, 16);
        }
        return out;
    }

    static const char base64_chars[] =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "abcdefghijklmnopqrstuvwxyz"
        "0123456789+/";

    static char * base64_encode(const unsigned char *input, int length)
    {
        /* http://www.adp-gmbh.ch/cpp/common/base64.html */
        int i=0, j=0, s=0;
        unsigned char char_array_3[3], char_array_4[4];

        int b64len = (length+2 - ((length+2)%3))*4/3;
        char *b64str = new char[b64len + 1];

        while (length--) {
            char_array_3[i++] = *(input++);
            if (i == 3) {
                char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
                char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
                char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
                char_array_4[3] = char_array_3[2] & 0x3f;

                for (i = 0; i < 4; i++)
                    b64str[s++] = base64_chars[char_array_4[i]];

                i = 0;
            }
        }
        if (i) {
            for (j = i; j < 3; j++)
                char_array_3[j] = '\0';

            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;

            for (j = 0; j < i + 1; j++)
                b64str[s++] = base64_chars[char_array_4[j]];

            while (i++ < 3)
                b64str[s++] = '=';
        }
        b64str[b64len] = '\0';

        return b64str;
    }

    static inline bool is_base64(unsigned char c) {
        return (isalnum(c) || (c == '+') || (c == '/'));
    }

    static unsigned char * base64_decode(const char *input, int length, int *outlen)
    {
        int i = 0;
        int j = 0;
        int r = 0;
        int idx = 0;
        unsigned char char_array_4[4], char_array_3[3];
        unsigned char *output = new unsigned char[length*3/4];

        while (length-- && input[idx] != '=') {
            //skip invalid or padding based chars
            if (!is_base64(input[idx])) {
                idx++;
                continue;
            }
            char_array_4[i++] = input[idx++];
            if (i == 4) {
                for (i = 0; i < 4; i++)
                    char_array_4[i] = strchr(base64_chars, char_array_4[i]) - base64_chars;

                char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
                char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
                char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

                for (i = 0; (i < 3); i++)
                    output[r++] = char_array_3[i];
                i = 0;
            }
        }

        if (i) {
            for (j = i; j <4; j++)
                char_array_4[j] = 0;

            for (j = 0; j <4; j++)
                char_array_4[j] = strchr(base64_chars, char_array_4[j]) - base64_chars;

            char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

            for (j = 0; (j < i - 1); j++)
                output[r++] = char_array_3[j];
        }

        *outlen = r;

        return output;
    }

    static std::string base64Encode(const std::string& data)
    {
        char* r = base64_encode((const unsigned char*)data.data(), data.length());
        std::string s(r);
        delete r;
        return s;
    }

    static std::string base64Decode(const std::string& data)
    {
        int length = 0;
        const unsigned char* r = base64_decode(data.data(), data.length(), &length);
        std::string s((const char*)r, (size_t)length);
        delete r;
        return s;
    }

}}
