#include <iostream>
#include <sstream>
#include <cstdlib>
#include <ctime>

#include <windows.h>

using namespace std;

static int s2i(string const& str) {
    int ret = 0;
    stringstream s(str);
    s >> ret;
    return ret;
}

struct thread_data {
    int num;
    int seed;
};

static int *values;
int thrdCount=0;
int thrdNum;
bool done=false;
CRITICAL_SECTION CritSection;
CONDITION_VARIABLE ConditionVar;

 

static DWORD WINAPI thread_proc(LPVOID data)
{
    thread_data* i = (thread_data*)data;
    srand(i->seed);
    rand();
    values[i->num] = (rand() % 200) - 100;

    
    EnterCriticalSection(&CritSection);
	cout << "values[" << i->num << "] = " << values[i->num] << endl;
    thrdCount++;
	if (thrdCount==thrdNum){
	   done=true;
       WakeAllConditionVariable(&ConditionVar);
   // Wait until the predicate is TRUE
	}
	else
       while(!done)
       {
         SleepConditionVariableCS(&ConditionVar, &CritSection, INFINITE);
        }
/*
Condition variables are subject to spurious wakeups (those not associated with an explicit wake) 
and stolen wakeups (another thread manages to run before the woken thread). Therefore, you 
should recheck a predicate (typically in a while loop) after a sleep operation returns.
*/ 
    LeaveCriticalSection(&CritSection);
	int sum=0;
    for(int j=0;j<thrdNum;j++) sum+=values[j];
	cout << "thread "<< i->num << ": randon value = " << values[i->num]<<" , sum = "<< sum << "\n";
    return 0;
	}

int main(int argc, char *argv[])
{
    if(argc < 2) {
        cout << "You must specify the number of threads to create" << endl;
        return -1;
    }
    InitializeCriticalSection(&CritSection);
    InitializeConditionVariable (&ConditionVar);
    thrdNum = s2i(argv[1]);

    if(thrdNum <= 0) {
        cout << "You must specify a number that is > 0" << endl;
        return -1;
    }

    values = new int[thrdNum];
    HANDLE *handles = new HANDLE[thrdNum];
    thread_data *data = new thread_data[thrdNum];
    
    for(int i = 0; i < thrdNum; ++i) {
        data[i].num = i;
        data[i].seed = rand();//could use rand_s
        handles[i] = CreateThread(NULL, 0, &thread_proc, data+i, 0, NULL);
        if(!handles[i]) {
            cerr << "Failed to create thread " << i << endl;
            return -1;
        }
    }

    WaitForMultipleObjects(thrdNum, handles, TRUE, INFINITE);

    int sum = 0;
    for(int j = 0; j < thrdNum; ++j) {
        CloseHandle(handles[j]);
    }

    

    delete [] handles;
    delete [] values;
    delete [] data;

    return 0;
}