#include <iostream>
#include <fstream>
#include <stdio.h>
using namespace std;

int main (int argc, char ** argv) {
	unsigned long maxSize = 0;
	unsigned long evenSize = 0;
	unsigned long oddSize= 0;
	unsigned long fileSize= 0;
	long long evenP = 0;
	long long oddP = 0;
	long long p;
	long long r;
	bool isEven;
	char* tableXor;
	char* tableInter;
	int pCoef[4];
	char* hashUsed; // Needed since data can be 0 

	// Spit out the usage if not enough args
	if(argc < 4){
		cout << "Usage: ddec inputFile outputFile \"passphrase\" \n";
		return 1;
	}
	ifstream inF(argv[1], ios::in|ios::binary);
	ofstream outF(argv[2], ios::out|ios::binary);
	srand(time(NULL));

        // Find the coefficients from the passwords 
	cout << argv[3] << "\n";
	pCoef[0] = argv[3][0];
	pCoef[1] = argv[3][1];
	pCoef[2] = argv[3][2];
	pCoef[3] = argv[3][3];
	p = pCoef[0] + pCoef[1] + pCoef[2] + pCoef[3];
	cout << p << "\n";

        inF.read(reinterpret_cast<char*>(&maxSize), sizeof(unsigned long));
	cout << maxSize << "\n";
        inF.read(reinterpret_cast<char*>(&evenP), sizeof(long long));
	cout << evenP << "\n";
        inF.read(reinterpret_cast<char*>(&oddP), sizeof(long long));
	cout << oddP << "\n";
        inF.read(reinterpret_cast<char*>(&evenSize), sizeof(unsigned long));
	cout << evenSize << "\n";
        inF.read(reinterpret_cast<char*>(&oddSize), sizeof(unsigned long));
	cout << oddSize << "\n";
	hashUsed = (char*) calloc(1, maxSize);
	tableXor = (char*) calloc(1, maxSize);
	tableInter = (char*) calloc(1, maxSize);
        inF.read(tableXor, maxSize);
        inF.read(tableInter, maxSize);
	
	// Check which interleaved data set to use
	if( p == evenP ) {
		isEven = true;
		fileSize = evenSize;
	} else if ( p == oddP ) {
		isEven = false;
		fileSize = oddSize;
	} else {
		cerr << "Failed to decrypt\n";
		return -1;
	}

	// Decrypt
	for(int i = 0; i < fileSize; i ++){
           p = pCoef[0] + pCoef[1] * i + pCoef[2] * i * i + pCoef[3] * i*i*i;
	   if( p < 0 ) p = -p;
	   while(hashUsed[p%maxSize]) p++;
	   r = p % maxSize;
	   hashUsed[r] = true;
	   if( ((!(r%2) && isEven) || ((r%2) && !isEven))) 
	   	outF.put(tableInter[r]);
           else 
	   	outF.put(tableInter[r] ^ tableXor[r]);
	}
	outF.close();
	return 0;
}