#include <condition_variable>
#include <iostream>
#include <mutex>
#include <string>
#include <thread>

using namespace std ;

mutex mutexObject ;
condition_variable cv;




bool ready1 = false ;
bool ready2 = false ;
bool readyMain  = false ;

void worker_thread1()
{
	cout << "worker_thread1() ...entering.\n";
	ready1 = false ;
    unique_lock lk( mutexObject );
    cv.wait(lk, []{ return ready1; });
	cout << "worker_thread1() doing some work.\n";
	this_thread::sleep_for(chrono::seconds(10));
	readyMain = true ;
	cv.notify_one() ;

    cout << "worker_thread1() exiting.\n";
}

void worker_thread2()
{
	cout << "worker_thread2() ...entering.\n";
	ready2 = false ;
    unique_lock lk( mutexObject );
    cout << "worker_thread2() grabbed the lock\n";
    cv.wait(lk, []{ return ready2; });
	cout << "worker_thread2() doing some work.\n" ;
	this_thread::sleep_for(chrono::seconds(1)) ;
    cout << "worker_thread2() exiting.\n" ;
}


int main()
{
	thread worker1(worker_thread1);
	thread worker2(worker_thread2);
	cout << "main thread() waiting for 5 seconds.\n" ;
    this_thread::sleep_for(chrono::seconds(5)) ;
    cout << "main thread() sending signal to worker thread 1.\n" ;
    ready1 = true ;
    cv.notify_one() ;

    cout << "main thread() before unique_lock.\n" ;
    unique_lock lk( mutexObject );
    cout << "main thread() waiting for worker thread 1.\n" ;
    cv.wait(lk, []{ return readyMain; });
    cout << "main thread() after waiting for worker thread 1.\n" ;

	cout << "main thread() waiting for 5 seconds.\n" ;
    this_thread::sleep_for(chrono::seconds(5)) ;
    cout << "main thread() sending signal to worker thread 2.\n" ;
    ready2 = true ;
    cv.notify_one() ;

    worker1.join();
    worker2.join();


}