// Copyright (C) 2003  Davis E. King (davis@dlib.net)
// License: Boost Software License   See LICENSE.txt for the full license.


#include <sstream>
#include <string>
#include <ctime>
#include <cstdlib>

#include <dlib/entropy_encoder.h>
#include <dlib/entropy_decoder.h>

#include "tester.h"

namespace  
{

    using namespace test; 
    using namespace std;
    using namespace dlib;

    logger dlog("test.entropy_coder");

    namespace entropy_coder_kernel_test_helpers 
    {
        template <
            typename encoder,
            typename decoder
            >
        std::string test (
            const std::string& input
        )
        /*!
            ensures
                - encodes the data from in and then tries to decode it and returns
                  "" if it was successfully decoded else it returns the decoded string
        !*/
        {
            ostringstream sout;
            istringstream sin;
            istringstream in;


            in.str(input);

            const unsigned long max_total = 65535;




            unsigned long counts[256];
            for (int i = 0; i < 256; ++i)
            {
                counts[i] = 1;
            }


            encoder e;

         

            DLIB_TEST(e.stream_is_set() == false);

            e.set_stream(sout);

            DLIB_TEST(e.stream_is_set() == true);
            DLIB_TEST(&e.get_stream() == &sout);

            unsigned char ch;
            
            unsigned long total = 256;

            while (in.read((char*)&ch,1))
            {
                if (total > max_total)
                {
                    total = 0;
                    for (int j = 0; j<256; ++j)
                    {
                        counts[j] >>= 1;
                        if (counts[j] == 0)
                            counts[j] = 1;
                        total += counts[j];

                    }
                }

                unsigned long low_count = 0;
                unsigned long high_count;
                for (int i = 0; i < ch; ++i)
                    low_count += counts[i];
                high_count = low_count + counts[ch];
               
                e.encode(low_count,high_count,total);
               

                ++total;
                counts[ch] += 1;
            }

            DLIB_TEST(e.stream_is_set() == true);
            DLIB_TEST(&e.get_stream() == &sout);
            


            e.clear();

            DLIB_TEST(e.stream_is_set() == false);


            // *****************************************

     
            decoder d;


            DLIB_TEST(d.stream_is_set() == false);
            DLIB_TEST(d.get_target_called() == false);

            sin.str(sout.str());
            sout.str("");

            d.set_stream(sin);

            DLIB_TEST(d.get_target_called() == false);

            DLIB_TEST(d.stream_is_set() == true);
            DLIB_TEST(&d.get_stream() == &sin);

            for (int i = 0; i < 256; ++i)
            {
                counts[i] = 1;
            }

            total = 256;

            for (string::size_type i = 0; i < input.size()  ; ++i)
            {
                if (total > max_total)
                {
                    total = 0;
                    for (int j = 0; j<256; ++j)
                    {
                        counts[j] >>= 1;
                        if (counts[j] == 0)
                            counts[j] = 1;
                        total += counts[j];

                    }
                }

                DLIB_TEST(d.get_target_called() == false);

                unsigned long target = d.get_target(total);

                DLIB_TEST(target < total);

                DLIB_TEST(d.get_target_called() == true);


                unsigned long low_count;
                unsigned long high_count = 0;
                
                unsigned long j;
                for (j = 0; high_count <= target; ++j)
                {
                    high_count += counts[j];
                }
                --j;
                low_count = high_count - counts[j];


                ch = static_cast<unsigned char>(j);


                sout.rdbuf()->sputn((char*)&ch,1);
         


                d.decode(low_count,high_count);
                DLIB_TEST(d.get_target_called() == false);
                ++total;
                counts[ch] += 1;

            }

            DLIB_TEST(d.stream_is_set() == true);
            DLIB_TEST(&d.get_stream() == &sin);

            d.clear();

            DLIB_TEST(d.stream_is_set() == false);
            DLIB_TEST_MSG(sout.str().size() == input.size(),"the test script is buggy");
            

            if (sout.str() == input)
                return "";
            else
                return sout.str();

        }

    }


    

    template <
        typename encoder,
        typename decoder
        >
    void entropy_coder_kernel_test (
    )
    /*!
        requires
            - encoder is an implementation of entropy_encoder/entropy_encoder_kernel_abstract.h
            - decoder is an implementation of entropy_decoder/entropy_decoder_kernel_abstract.h
        ensures
            - runs tests on encoder and decoder for compliance with the specs 
    !*/
    {        
        using namespace entropy_coder_kernel_test_helpers;

        dlog << LTRACE << 1;

        print_spinner();
        string temp, temp2;

        srand(static_cast<int>(time(0)));

        for (int k = 0; k < 10000; ++k)
        {
            string temp;
            istringstream sin;
            ostringstream sout;
            decoder d;
            encoder e;

            e.set_stream(sout);

            int num = ::rand() %200;
            unsigned long total[200];
            unsigned long high_count[200];
            unsigned long low_count[200];
            for (int i = 0; i < num; ++i)
            {
                total[i] = ::rand()%256 + 20;
                high_count[i] = ::rand()%total[i] + 1;
                low_count[i] = ::rand()%high_count[i];

                e.encode(low_count[i],high_count[i],total[i]);
            }

            e.clear();

            sout.rdbuf()->sputc('a');

            sin.str(sout.str());


            d.set_stream(sin);


            for (int i = 0; i < num; ++i)
            {
                unsigned long N = d.get_target(total[i]);                
                DLIB_TEST(low_count[i] <= N && N < high_count[i]);
                d.decode(low_count[i],high_count[i]);
            }






            DLIB_TEST_MSG(sin.rdbuf()->sgetc() != EOF,"num: " << num);
            DLIB_TEST_MSG(sin.rdbuf()->sgetc() == 'a',
                         "sin.rdbuf()->sgetc() == " << (char)sin.rdbuf()->sgetc() <<
                         "\nnum: " << num
            );
            DLIB_TEST(sin.rdbuf()->sbumpc() == 'a');
            DLIB_TEST(sin.rdbuf()->sgetc() == EOF);

        } // for (int k = 0; k < 10000; ++k)

        dlog << LTRACE << 2;

        print_spinner();

        // the point of this block is to make sure that the return value
        // from decoder.get_target(total) is a always less than total
        for (int k = 0; k < 20; ++k)
        {
            string temp;
            temp.push_back(static_cast<char>(::rand()&0xff));
            istringstream sin(temp);
            decoder d;
            d.set_stream(sin);
            unsigned long total = ::rand()%256 + 20;
            unsigned long target = d.get_target(total);
            DLIB_TEST(target<total);

            for (int i = 0; i < 30; ++i)
            {
                unsigned long high_count = ::rand()%total + 1;
                unsigned long low_count = ::rand()%high_count;
                if (high_count <= target)
                    high_count = target+1;
                if (low_count > target)
                    low_count = target;

                d.decode(low_count,high_count);
                target = d.get_target(total);
                DLIB_TEST_MSG(target<total,"target: " << target << "    total: " << total);
            }
        }

        print_spinner();


        dlog << LTRACE << 3;

        for (int k = 0; k < 10; ++k)
        {
            unsigned long seed1 = 1064644658, seed2 = 1064543921;
            //unsigned long seed1 = 1064682621, seed2 = 1064543921;

            // make array be an array with each element in the range 0 to 255
            // and have the probability of seeing each number in the array
            // not be the same
            //seed1 = static_cast<unsigned long>(time(0));
            srand(seed1 );
            int array[65536];
            for (int i = 0; i < 65536; ++i)
            {
                array[i] = ::rand()%256;
            }
            for (int i = 0; i < 60; ++i)
            {
                int idx = ::rand()%65536;
                int radius = 35;
                if (idx > radius && idx <65536-radius)
                {
                    for (int j = idx-radius; j < idx+radius; ++j)
                        array[j] = array[idx];
                }
            }

            // test with 3 random strings of length 10000 
            // but use the above array to bias the random numbers
            for (int j = 0; j < 3; ++j)
            {
                print_spinner();
                temp = "";
                //seed2 = static_cast<unsigned long>(time(0));
                srand(seed2 );
                for ( int i = 0; i < 10000; ++i)
                {
                    int a = array[::rand()%65536];
                    temp += (unsigned char)a;                
                }               
                string temp2;
                temp2 = test<encoder,decoder>(temp);  
                if (temp2 != "")
                {

                    int k = 0;
                    DLIB_TEST(temp != temp2);
                    while (temp[k] == temp2[k])++k;
                }


                DLIB_TEST_MSG(temp2 == "","")  
            }
        }

        print_spinner();


        dlog << LTRACE << 4;




        // test with a large string which contains all the same character
        temp = "eeeeeeeeee";
        for (int i = 0; i < 13; ++i)
        {
            temp = temp + temp;
        }
        temp = test<encoder,decoder>(temp); 
        if (temp != "")
        {   
            // crop off all the e's until we find the part that is messed up
            string::size_type pos = temp.find_first_not_of("e");
            temp = temp.substr(pos);
        }
        DLIB_TEST_MSG(temp == "","decoded string: \"" << temp << "\"") /**/


            dlog << LTRACE << 5;

        print_spinner();

        temp = "davis";
        temp = test<encoder,decoder>(temp);  DLIB_TEST_MSG(temp == "","decoded string: \"" << temp << "\"")

            temp = "";
        temp = test<encoder,decoder>(temp);  DLIB_TEST_MSG(temp == "","decoded string: \"" << temp << "\"")

            // test for each single character
            for ( int i = 0; i <= 255; ++i)
            {
                temp = (unsigned char)i;
                temp = test<encoder,decoder>(temp);  DLIB_TEST_MSG(temp == "","decoded string: \"" << temp << "\"")                  
            } 

        dlog << LTRACE << 6;

        // test with a long string with the same thing repeated many times
        temp = "davis ";
        for (int i = 0; i < 10; ++i)
        {
            temp = temp + temp;
        }
        temp = test<encoder,decoder>(temp);  DLIB_TEST_MSG(temp == "","decoded string: \"" << temp << "\"")

            dlog << LTRACE << 7;

        // test with 10 random strings of length 1000 
        for (int j = 0; j < 10; ++j)
        {
            temp = "";
            srand(static_cast<unsigned int>(time(0)));
            for ( int i = 0; i < 1000; ++i)
            {
                int a = ::rand()%256;
                temp += (unsigned char)a;                
            } 
            temp = test<encoder,decoder>(temp);  DLIB_TEST_MSG(temp == "","decoded string: \"" << temp << "\"")                    
        }


        dlog << LTRACE << 8;

        print_spinner();

        // test with 15 random strings of length 30000 
        for (int j = 0; j < 15; ++j)
        {
            print_spinner();
            temp = "";
            unsigned long seed = static_cast<unsigned int>(time(0));
            srand(seed);
            for ( int i = 0; i < 30000; ++i)
            {
                int a = ::rand()%256;
                temp += (unsigned char)a;                
            }               
            temp = test<encoder,decoder>(temp);  DLIB_TEST_MSG(temp == "","seed: " << seed)  
        }


        dlog << LTRACE << 9;

        print_spinner();

        // test with a large string which contains all the same character
        temp = "         ";
        for (int i = 0; i < 10; ++i)
        {
            temp = temp + temp;
        }
        temp = test<encoder,decoder>(temp); 
        if (temp != "")
        {   
            // crop off all the spacess until we find the part that is messed up
            string::size_type pos = temp.find_first_not_of(" ");
            temp = temp.substr(pos);
        }
        DLIB_TEST_MSG(temp == "","decoded string: \"" << temp << "\"")/**/






            dlog << LTRACE << 10;






        // test with a large string which contains a bunch of a's followed by a
        // bunch of z's
        temp = "aaaaaaaa";
        temp2 = "zzzzzzzz";
        for (int i = 0; i < 12; ++i)
        {
            temp = temp + temp;
            temp2 = temp2 + temp2;
        }
        temp += temp2;
        print_spinner();
        temp = test<encoder,decoder>(temp); 
        DLIB_TEST(temp == "");



        dlog << LTRACE << 11;



    }




    class entropy_coder_tester : public tester
    {
    public:
        entropy_coder_tester (
        ) :
            tester ("test_entropy_coder",
                    "Runs tests on the entropy_coder component.")
        {}

        void perform_test (
        )
        {
            dlog << LINFO << "testing kernel_1a 1";
            entropy_coder_kernel_test<
                entropy_encoder::kernel_1a,
                entropy_decoder::kernel_1a
                >();

            dlog << LINFO << "testing kernel_1a_c 2";
            entropy_coder_kernel_test<
                entropy_encoder::kernel_1a_c,
                entropy_decoder::kernel_1a_c
                >();

            dlog << LINFO << "testing kernel_1a 3";
            entropy_coder_kernel_test<
                entropy_encoder::kernel_2a,
                entropy_decoder::kernel_2a
                >();

            dlog << LINFO << "testing kernel_1a_c 4";
            entropy_coder_kernel_test<
                entropy_encoder::kernel_2a_c,
                entropy_decoder::kernel_2a_c
                >();

            dlog << LINFO << "testing kernel_1a 5";
            entropy_coder_kernel_test<
                entropy_encoder::kernel_1a,
                entropy_decoder::kernel_1a_c
                >();

            dlog << LINFO << "testing kernel_1a_c 6";
            entropy_coder_kernel_test<
                entropy_encoder::kernel_1a_c,
                entropy_decoder::kernel_1a
                >();

            dlog << LINFO << "testing kernel_1a 7";
            entropy_coder_kernel_test<
                entropy_encoder::kernel_2a,
                entropy_decoder::kernel_2a_c
                >();

            dlog << LINFO << "testing kernel_1a_c 8";
            entropy_coder_kernel_test<
                entropy_encoder::kernel_2a_c,
                entropy_decoder::kernel_2a
                >();

        }
    } a;




}