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#ifndef PRIMEFINDER_H
#define PRIMEFINDER_H

#include "primeapp.h"

#include <QLCDNumber>
#include <QThread>

class PrimeApp;

class PrimeFinder : public QObject
{
    Q_OBJECT

private:
    PrimeApp * primeApp;
    QThread * worker;
    QList<long> primes;

    /**
     * This variable emulates Java's isInterrupted() functionality.
     * To guarantee that any writes are detected immediately,
     * the variable is atomic. (This variable is just like
     * a variable declared private volatile int isInterrupted)
     *
     * It is treated as a boolean value.
     */
    QAtomicInt isInterrupted;

public:
    PrimeFinder(PrimeApp * primeApp);

public slots:
    void findPrimes();
    void interrupt();

signals:
    void newPrimeText(const QString &text);

private:
    /**
     * Slow O((2^b)) or worse algorithm (where b is the number of bits in candidate)
     *
     * TODO: Implement Miller-Rabin Primality test to get O(n^12) or better performance.
     * http://en.wikipedia.org/wiki/Miller%E2%80%93Rabin_primality_test
     * (Why nine characters for one dash?
     *   Unicode character  Oct     Dec	    Hex	    HTML
     *            en dash   020023	8211	0x2013	&ndash;   )
     *
     * @param candidate candidate to test
     * @return true if candidate is prime.
     */
    bool isPrime(long candidate);
};

#endif