#include "stdafx.h"


#include <Windows.h>
#include <process.h>
#include <ctime>
#include <conio.h>
#include <iostream>
#include <iomanip>
#include <fstream>
#include <sstream>
#include <queue>

int MAXSLOTS = 50;                      // max available slots
int NUM_CONSUMERS = 10;
int NUM_PRODUCERS = 10;
CRITICAL_SECTION logCritSection;        // critical section for log purpose
HANDLE mutex, empty, full;

// container shared between consumers
std::queue<int> queue;
bool running = true;

// thread functions
void produce(void*);
void consume(void*);

// logging function
void log(const std::string& message);
// get current date & time
std::string getTimestamp();

// generate new item
int genRand();
// fibonacci recursive generator
int fibo(int x);

int main(int argc, char** argv)
{
    // redefining MAXSLOTS variable with input from prompt
    if (argc > 3)
    {
        MAXSLOTS      = atoi(argv[1]);
        NUM_PRODUCERS = atoi(argv[2]);
        NUM_CONSUMERS = atoi(argv[3]);
    }

    // initialize semaphores
    mutex = CreateSemaphore(NULL, 1, 1, NULL);
    empty = CreateSemaphore(NULL, MAXSLOTS, MAXSLOTS, NULL);
    full = CreateSemaphore(NULL, 0, 1, NULL);

    std::srand(time(0));
    remove("log.txt");
    InitializeCriticalSection(&logCritSection);

    std::cout << "App started" << std::endl;
    log("App started");
    log("Operation\tAgent\t\tSize");

    // create producer threads
    for (int id = 0; id < NUM_PRODUCERS; ++id)
        if (_beginthread(produce, 1024, reinterpret_cast<void*>(id)) == -1)
        {
            std::cout << "Error: can't launch producer thread." << std::endl;
            running = false;
        }

    // create consumer threads
    for (int id = 0; id < NUM_CONSUMERS; ++id)
    {
        if (_beginthread(consume, 1024, reinterpret_cast<void*>(id)) == -1)
        {
            std::cout << "Error: can't launch consumer threads." << std::endl;
            running = false;
        }
    }

    _getch();
    running = false;

    std::cout << "App terminated successfully. Check log file" << std::endl;
    system("pause");
    log("App finished");

    DeleteCriticalSection(&logCritSection);

    return 0;
}

void produce(void* producerID)
{
    int ID = (int)producerID;
    log("Init\t\tProducer " + std::to_string(ID));
    int item, size;
    while (running)
    {
        item = genRand();
        WaitForSingleObject(empty, INFINITE);
        WaitForSingleObject(mutex, INFINITE);
        queue.push(item);
        size = queue.size();
        ReleaseSemaphore(mutex, 1, NULL);
        ReleaseSemaphore(full, 1, NULL);

        // logging produce
        std::stringstream msg;
        msg << "Write\t" << "Producer " << ID << "\t" << size;
        log(msg.str());
    }

    log("Exit\t\tProducer " + std::to_string(ID));
    _endthread();
}

void consume(void* consumerID)
{
    int ID = (int)consumerID;
    log("Init\t\tConsumer " + std::to_string(ID));
    int item, size;
    while (running)
    {
        WaitForSingleObject(full, INFINITE);
        WaitForSingleObject(mutex, INFINITE);
        item = queue.back();                    // accessing item from queue
        queue.pop();                        // and removing it
        size = queue.size();
        fibo(item);                     // calculate fibonacci to slow down
        ReleaseSemaphore(mutex, 1, NULL);
        ReleaseSemaphore(empty, 1, NULL);

        // logging consume
        std::stringstream msg;
        msg << "Read \t" << "Consumer " << ID << "\t" << size;
        log(msg.str());
    }

    log("Exit\t\tConsumer " + std::to_string(ID));
    _endthread();
}

int genRand()
{
    return rand() % 40;
}

std::string getTimestamp() {
    std::time_t t = std::time(NULL);
    std::tm tm;
    localtime_s(&tm, &t);
    std::stringstream res;
    res << std::put_time(&tm, "[%H:%M:%S]");
    return res.str();
}

void log(const std::string& msg)
{
    EnterCriticalSection(&logCritSection);
    std::fstream file("log.txt", std::ios::app);
    if (file.good())
    {
        file << getTimestamp() << " " << msg << std::endl;
        file.close();
    }
    LeaveCriticalSection(&logCritSection);
}

int fibo(int x)
{
    if (x == 0)
    {
        return 0;
    }

    if (x == 1)
    {
        return 1;
    }

    return fibo(x - 1) + fibo(x - 2);
}