#include<stdio.h>
#include<ctype.h>
#include<string.h>
#include<stdlib.h>
#include<pthread.h>
#define MAXLEN 4096

// This is what we had before:
//void print_decryption(char* text, int current_key, size_t textlen){

struct pd_param{
	char* text;
	int current_key;
	size_t textlen;
};

void* print_decryption(void* params){
	struct pd_param* p = (struct pd_param*)params;
	char valid = 0;
	// sizeof(char) is 1, but if this was an int or something it would matter
	// Ready for upgrade to unicode...
	// Except not because of character code issues...
	char* new_text = (char*)malloc(sizeof(char) * p->textlen);
	for(size_t i = 0; i < p->textlen; i++){
		if(islower(p->text[i])){
			new_text[i] = p->text[i] - p->current_key;
			if(new_text[i] < 97)
				new_text[i] += 26;
		} else if(isupper(p->text[i])){
			new_text[i] = p->text[i] - p->current_key;
			if(new_text[i] < 65)
				new_text[i] += 26;
		} else {
			new_text[i] = p->text[i];
		}
		if(i > 2)
			if(!strncmp(new_text+i-2, "the", 3))
				valid = 1;
	}
	if(valid)
		printf("Key %d:  %s\n", p->current_key, new_text);
}

int main(int argc, char ** argv){
	if(argc < 2){
		printf("Usage:  %s <filename>", argv[0]);
		return 1;
	}
	FILE *infile = fopen(argv[1], "r");
	char data[MAXLEN];
	size_t read_size = fread(data, 1, MAXLEN, infile);
	fclose(infile);

	pthread_t threads[25];
	struct pd_param params[25];
	for(char i = 0; i < 25; i++){
		params[i].text = data;
		params[i].current_key = i+1;
		params[i].textlen = read_size;
		// pd_param + i is the same as &(pd_param[i])
		pthread_create(threads + i, 0, print_decryption, params + i);
	}

	for(char i = 0; i < 25; i++)
		pthread_join(threads[i], 0);

	return 0;
}