#include <stdlib.h>
#include <stdio.h>
#include <limits.h>
#include "my.qsort.h"

#define TYPE char
#define MEM_AVAILIBLE 4096
#define LARGE  (MEM_AVAILIBLE / sizeof(TYPE))
#define FILES 8

typedef unsigned int uint;

int main(int argc, char** argv){
    FILE* input = fopen("Weetabix.mp4", "rb");
    FILE* files[FILES * 2];
    uint how_many;

    char buf[LARGE];
    char filename[] = "0.bin";
    char from = 'a';
    char to = 'a' + FILES;
    char* buffers[FILES];
    char* brick;

    uint files_active = FILES;

    for(char c = from; c < to; ++c){
        filename[0] = c;
        files[c - 'a'] = fopen(filename, "wb");
    }

    char cur = 0;

    while(!feof(input)){
        /* first time. read from source file */

        how_many = fread(&buf, sizeof(TYPE), LARGE, input);
        my::qsort(buf, how_many);

        fwrite(&buf, sizeof(TYPE), how_many, files[cur]);

        if(++cur == FILES) cur = 0;
    }
    fcloseall();

    while(true){
        uint block_size = LARGE / (files_active + 1);
        uint brick_size = LARGE - block_size * files_active;
        brick = (char*) calloc(brick_size, sizeof(char));

        for(char c = from; c <  from + files_active; ++c)
            filename[0] = c, files[c - 'a'] = fopen(filename, "rb");

        for(char c = to; c < to + files_active; ++c)
            filename[0] = c, files[c - 'a'] = fopen(filename, "wb");

        bool flag = true;

        for(uint i = from - 'a'; i < from + files_active - 'a'; ++i){
            buffers[i] = buf + i * files_active;
            fread(buffers[i], sizeof(TYPE), block_size, files[i]);
            my::qsort(buffers[i], block_size);
        }

        uint where_i_am[FILES] = {0};
        uint to_cur = to;

        while(true){

            for(uint i = 0; i < brick_size; ++i){
                for(uint j = from + 1; j < from + files_active; ++j){
                    if(where_i_am[j] < from + files_active &&
                       buffers[where_i_am[j]] < buffers[to_cur]){
                        to_cur = j;
                    }
                }
                ++where_i_am[to_cur];
            }
        }


        while(false){

        }


        char tmp = from;
        from = to;
        to = tmp;

        fcloseall();

        free(brick);
        break;
    }
}