//OPT: -lpthread
#include<thread>
#include<sstream>
#include<iostream>
#include<vector>
#include<chrono>

using namespace std;
using namespace std::chrono;

class bankaccount {
public:
	bankaccount() {
		bal = 0;
		numchecks = 0;
	}

	void deposit(int amt) {
		lock_guard<mutex> L(m);
			// only operation on lock_guard is constructor (and destructor)
		int currbal = bal;
		this_thread::sleep_for(milliseconds(1));
		bal = currbal + amt;
	}

	void withdraw(int amt) {
		lock_guard<mutex> L(m);
		int currbal = bal;
		this_thread::sleep_for(milliseconds(1));
		bal = currbal - amt;
	}

	void writecheck(int amt) {
		unique_lock<mutex> Lamt(m,defer_lock);
		unique_lock<mutex> Lchk(m2,defer_lock);
		// Lamt.lock(); Lchk.lock(); -- bad -- could be ordering problem
		std::lock(Lamt,Lchk);
		bal -= amt;
		numchecks--;
	}

	void printchecks() {
		unique_lock<mutex> Lamt(m,defer_lock);
		unique_lock<mutex> Lchk(m2,defer_lock);
		std::lock(Lamt,Lchk);
		numchecks += 50;	
		bal -= 1000; // 50 checks cost ten dollars
	}

	int balance() { return bal; }
	int nchecks() { return numchecks; }

private:
	mutex m;
	int bal; // in cents
	mutex m2;
	int numchecks;
};

void earner(bankaccount &a) {
	a.deposit(1000); // add ten dollars
	a.deposit(1000); // add ten dollars
	a.printchecks();
	a.deposit(1000); // add ten dollars
	a.deposit(1000); // add ten dollars
}

void spender(bankaccount &a) {
	a.withdraw(800); // spend eight dollars
	a.writecheck(200); // write check for 2 dollars
	a.withdraw(800); // spend eight dollars
	a.withdraw(800); // spend eight dollars
}

int main(int argc, char **argv) {
	bankaccount acct;
	thread t1(earner,ref(acct));
	thread t2(spender,ref(acct));
	t1.join();
	t2.join();
	cout << "balance = " << acct.balance() << endl;
	cout << "numchecks = " << acct.nchecks() << endl;
}