#include "sha1.h"
#include <errno.h>

uint32_t leftRotate(uint32_t n, unsigned int d)
{
    return (n << d) | (n >> (32 - d));
}

SHA1_Result sha1file(char *filename){
  FILE* file;

  SHA1_Result r;
  uint32_t number_of_chuncks = 0;
  uint32_t size_in_bytes = 0;
  uint64_t size_in_bits = 0;
  
  uint32_t h0 = 1742612993;
  uint32_t h1 = 3137593996;
  uint32_t h2 = 18805212;
  uint32_t h3 = 2459167202;
  uint32_t h4 = 3455001513;

  file = fopen(filename,"r");
  if(errno != 0){
    fprintf(stderr, "\nErrno : %d\n", errno);
    perror(filename);
    return r;
  }
  
  size_t bytes_read;
  char buffer[64];
  
  while(1){
    bytes_read = fread(buffer, 1, 64, file);
    number_of_chuncks++;
    if(bytes_read != 64){
      // * We need to convert to 512 bit * //
      // printf("\nWe read %d bytes", bytes_read);
      size_in_bytes += bytes_read; // the final size is done here
      size_in_bits = size_in_bytes * 8;

      //padding
      buffer[bytes_read] = 0x80;
      bytes_read += 1;

      for(int i = bytes_read; i <= 55; i++)
	buffer[i] = 0x00;

      //adding size to end
      for(int i = 63; i >= 56; i--){
	buffer[i] = size_in_bits % 256;
	size_in_bits /= 256;
      }

      /////////////////////// ****************************************** ////////////////////////////////////////////
      //continue how we do for 512 bit chunck
      uint32_t w[80];
      for(int i = 0; i < 16; i++)
	w[i] = buffer[i] + buffer[i+1] * 256 + buffer[i+2] * 65536 + buffer[i+3] * 16777216;
      for(int i = 16; i < 80; i++)
	w[i] = leftRotate( w[i-3] ^ w[i-8] ^ w[i-14] ^ w[i - 16] , 1 );

      uint32_t a = h0;
      uint32_t b = h1;
      uint32_t c = h2;
      uint32_t d = h3;
      uint32_t e = h4;

      uint32_t f;
      uint32_t k;
      
      // The 80 iterations
      for(int i = 0; i < 80; i++){
	if(i >= 0 && i <= 19){
	  f = (b & c) ^ (( ~ b ) & d);
	  k = 1518500249;
	}else if ( i >= 20 && i <= 39){
	  f = b ^ c ^ d;
	  k = 1859775393;
	}else if (i >= 40 && i <= 59){
	  f = (b & c) ^ (b & d) ^ (c & d);
	  k = 2400959708;
	}else if (i >= 60 && i <= 79){
	  f = b ^ c ^ d;
	  k = 3395469782;
	}

	uint32_t temp = leftRotate(a,5) + f + e + k + w[i];
	e = d;
	d = c;
	c = leftRotate(b, 30);
	b = a;
	a = temp;
      }

      // Add this chunk's hash result
      h0 += a;
      h1 += b;
      h2 += c;
      h3 += d;
      h4 += e;
      /////////////////////// ****************************************** ////////////////////////////////////////////
      break;
    }
    else{
      // * We got a 512 bit chunk * //
      // printf("\nWe read 64 bytes");
      size_in_bytes += 64;

      /////////////////////// ****************************************** ////////////////////////////////////////////
      uint32_t w[80];
      for(int i = 0; i < 16; i++)
	w[i] = buffer[i] + buffer[i+1] * 256 + buffer[i+2] * 65536 + buffer[i+3] * 16777216;
      for(int i = 16; i < 80; i++)
	w[i] = leftRotate( w[i-3] ^ w[i-8] ^ w[i-14] ^ w[i - 16] , 1 );

      uint32_t a = h0;
      uint32_t b = h1;
      uint32_t c = h2;
      uint32_t d = h3;
      uint32_t e = h4;

      uint32_t f;
      uint32_t k;
      
      // The 80 iterations
      for(int i = 0; i < 80; i++){
	if(i >= 0 && i <= 19){
	  f = (b & c) ^ (( ~ b ) & d);
	  k = 1518500249;
	}else if ( i >= 20 && i <= 39){
	  f = b ^ c ^ d;
	  k = 1859775393;
	}else if (i >= 40 && i <= 59){
	  f = (b & c) ^ (b & d) ^ (c & d);
	  k = 2400959708;
	}else if (i >= 60 && i <= 79){
	  f = b ^ c ^ d;
	  k = 3395469782;
	}

	uint32_t temp = leftRotate(a,5) + f + e + k + w[i];
	e = d;
	d = c;
	c = leftRotate(b, 30);
	b = a;
	a = temp;
      }

      // Add this chunk's hash result
      h0 += a;
      h1 += b;
      h2 += c;
      h3 += d;
      h4 += e;
      /////////////////////// ****************************************** ////////////////////////////////////////////
    }
  }

  // printf("\nFinal result %x%x%x%x%x", h0, h1, h2, h3, h4);
  r.h0 = h0;
  r.h1 = h1;
  r.h2 = h2;
  r.h3 = h3;
  r.h4 = h4;

  return r;
}