#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "hash_helper.h"
//funkce na výpoèet crc232 hashe
void crc32b(unsigned char *message, unsigned int *crc, size_t bytes) {
   unsigned int i = 0;
   int j;
   unsigned int byte, mask;
   while (i < bytes) {
      byte = message[i];            // Get next byte.
      *crc = *crc ^ byte;
      for (j = 7; j >= 0; j--) {    // Do eight times.
         mask = -(*crc & 1);
         *crc = (*crc >> 1) ^ (0xEDB88320 & mask);
      }
      i = i + 1;
   }
}
//funkce na výpoèet xor hashe
void xor_hash(unsigned char *message, unsigned int *xor, size_t bytes){
    for(unsigned int i=0;i<bytes;i++){
        *xor = *xor^message[i];
    }
}
int main(int argc, char *argv[])
{
    unsigned int md5=0, c16=0, c32=0, xor=0, hex=0;
    FILE *file = stdin;
    MD5_CTX md5_struct;
    MD5_Init(&md5_struct);
    crc16_context c16_struct;
    crc16_init(&c16_struct);
    unsigned char input[1];
    int counter = 1;
    int lenght = 0;
    unsigned int crc = 0xFFFFFFFF;
    unsigned int xor_result = 0;
    for(int i=0;i<argc;i++){
        //pøepínaè md5
        if(strcmp(argv[i],"-md5") == 0){
            md5 = 1;
        }
        //pøepínaè crc16
        else if(strcmp(argv[i],"-c16") == 0){
            c16 = 1;
        }
        //pøepínaè crc32
        else if(strcmp(argv[i],"-c32") == 0){
            c32 = 1;
        }
        //pøepínaè xor
        else if(strcmp(argv[i],"-xor") == 0){
            xor = 1;
        }
        //pøepínaè hex
        else if(strcmp(argv[i],"-hex") == 0){
            hex = 1;
        }
        //pøepínaè f file
        else if(strcmp(argv[i],"-f") == 0){
            if ((i+1) >= argc){
                fprintf(stderr,"Nezadali jste soubor!");
                return 1;
            }
            else {
                file = fopen(argv[i+1],"rb");
                i++;
                if (file == NULL){
                    fprintf(stderr,"Nejde otevrit!");
                    return 1;
                }
            }
        }
    }
    if (!md5 && !c16 && !c32 && !xor){
            fprintf(stderr,"Nezadali jste zadny hash!");
            return 1;
        }
    while(counter == 1){
        counter = fread(input,1,1,file);
        if(counter == 0) break;
        lenght += counter;
        //volání md5
        if(md5 == 1){
            MD5_Update(&md5_struct,input,counter);
        }
        //volání crc16
        if(c16 == 1){
            crc16_update(&c16_struct,input[0]);
        }
        //volání crc32
        if(c32 == 1){
            crc32b(input,&crc,counter);
        }
        //volání xor
        if(xor == 1){
            xor_hash(input,&xor_result,counter);
        }
    }
    printf("Length: %d bytes\n", lenght);
    //výpis xor
    if(xor == 1){
        printf("XOR: ");
        if(hex == 1){
            printf("0x%x\n",xor_result);
        }
        else printf("%d\n",xor_result);
    }
    //výpis crc16
    if(c16 == 1){
        printf("CRC-16: ");
        if(hex == 1){
            printf("0x%x\n",c16_struct.crc);
        }
        else printf("%d\n",c16_struct.crc);
    }
    //výpis crc32
    if(c32 == 1){
        crc = ~crc;
        if(hex == 1){
            printf("CRC-32: 0x%08x\n",crc);
        }
        else printf("CRC-32: %u\n",crc);
    }
    //výpis md5
    if(md5 == 1){
        unsigned char result[16];
        MD5_Final(result,&md5_struct);
        printf("MD5: ");
        for(int i=0;i<16;i++){
            printf("%02x",result[i]);
        }
        printf("\n");
    }
    fclose(file);
    return 0;
}