#include "sha-2/sha-256.h"
#include<stdio.h>
#include<fcntl.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/stat.h>
#include<sys/mman.h>
#include<sys/time.h>
#include<pthread.h>

void print_hash(uint8_t *hash){
	for(int i = 0; i < 32; i++)
		printf("%02x", hash[i]);
	puts("");
}
// Return true if they're the same
char compare_hashes(uint8_t *a, uint8_t *b){
	for(int i = 0; i < 32; i++)
		if(a[i] != b[i])
			return 0;
	return 1;
}

double timediff(struct timeval* start, struct timeval* end) {
	double s_diff = end->tv_sec - start->tv_sec;
	double us_diff = end->tv_usec - start->tv_usec;
	s_diff += us_diff / 1000000;
	return s_diff;
}

struct range {
	char* data;
	size_t start_idx;
	size_t end_idx;
	uint8_t *target_hash;
};

char done = 0;
void *check_range(void *p){
	struct range *r = p;
	char *savepoint;
	uint8_t current_hash[32];
	char* word;
	word = strtok_r(r->data + r->start_idx, "\n", &savepoint);
	while(!done && word && word < (r->data + r->end_idx)) {
		calc_sha_256(current_hash, word, strlen(word));
		if(compare_hashes(current_hash, r->target_hash)) {
			printf("The word was %s\n", word);
			done = 1;
			break;
		}
		word = strtok_r(0, "\n", &savepoint);
	}
}
	

int main(){
	int fd = open("/usr/share/dict/american-english", O_RDONLY);
	struct stat stats;
	fstat(fd, &stats);	
	printf("File size is %d bytes\n", stats.st_size);
	char *ro_data = mmap(0, stats.st_size, PROT_READ, MAP_SHARED, fd, 0);
	char *file_data = malloc(stats.st_size);
	memcpy(file_data, ro_data, stats.st_size);
	munmap(file_data, stats.st_size);
	close(fd);
	
	char *target_as_string = "4ea511963388132dd56b3b23fdfa1a25b952a8fe958afc7938622a33156bebf3";
	uint8_t target_hash[32];
	for(int i = 0; i < 32; i++){
		char byte[5] = "0x";
		byte[4] = 0;
		memcpy(byte + 2, target_as_string + 2*i, 2);
/*
 * This part was broke at the end of class
 * I changed to using strtol, as Aiden suggested
 * It does exactly what I hoped atoi would do
 */
		target_hash[i] = strtol(byte, 0, 0);
	}

	print_hash(target_hash);
	

	struct timeval start, end;
	gettimeofday(&start, NULL);
	int thread_count = 8;
	pthread_t threads[thread_count];
	struct range parameters[thread_count];
	for(int i = 0; i < thread_count; i++){
		parameters[i].data = file_data;
		parameters[i].target_hash = target_hash;
		parameters[i].start_idx = i * (stats.st_size / thread_count);
		parameters[i].end_idx = (i+1) * (stats.st_size / thread_count);
		pthread_create(&threads[i], 0, check_range, &parameters[i]);
	}
	for(int i = 0; i < thread_count; i++){
		pthread_join(threads[i], 0);
	}
	gettimeofday(&end, NULL);
	printf("Password Finding Time: %lf\n",  timediff(&start, &end));		

	return 0;
}