#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

/* statically allocated mutex initialization */
pthread_mutex_t shared_region = PTHREAD_MUTEX_INITIALIZER;
static int active = 0;

typedef struct __thread_data
{
	pthread_t thread_id;
	int thread_index;
	int thread_pause;
	int thread_exec;
	int thread_wait;
	int thread_run;
}
thread_data;

#include <unistd.h> /* STDIN_FILENO */
#include <termios.h> /* struct termios */
#define MASK_LFLAG (ICANON|ECHO|ECHOE|ISIG)
int getch(void)
{
	struct termios oldt, newt;
	int ch;
	tcgetattr(STDIN_FILENO, &oldt);
	newt = oldt;
	newt.c_lflag &= ~MASK_LFLAG;
	tcsetattr(STDIN_FILENO, TCSANOW, &newt);
	ch = getchar();
	tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
	return ch;
}

void* thread_exec(void* arg)
{
	if(arg)
	{
		thread_data *pdata = (thread_data*) arg;
		pdata->thread_run = 1;
		while(pdata->thread_exec)
		{
			if(pdata->thread_pause)
			{
				if(pdata->thread_run)
				{
					printf("[Thread-%d] Thread Paused!\n",pdata->thread_index);
					pdata->thread_run = 0;
				}
				continue;
			}
			if(!pdata->thread_run)
			{
				printf("[Thread-%d] Thread Resumes\n",pdata->thread_index);
				pdata->thread_run = 1;
			}
			printf("[Thread-%d] Sleeping %d seconds\n",pdata->thread_index,
				pdata->thread_wait);
			sleep(pdata->thread_wait);
			/* something happened while you were sleeping */
			if(!pdata->thread_exec) break;
			pthread_mutex_lock(&shared_region);
			printf("[Thread-%d] Changing active from %d to %d!\n",
				pdata->thread_index,active,pdata->thread_index);
			active = pdata->thread_index;
			pthread_mutex_unlock(&shared_region);
		}
		pthread_exit(0);
	}
	return 0x0;
}

int main(int argc, char *argv[])
{
	thread_data exec1, exec2;
	int not_done = 1, test;
	/* start random number generator */
	srand(time(0x0));
	/** initialize exec1 */
	exec1.thread_index = 1;
	exec1.thread_pause = 1;
	exec1.thread_exec = 1;
	exec1.thread_wait = (rand()%10)+1;
	exec1.thread_run = 0;
	pthread_create(&exec1.thread_id,0x0,&thread_exec,(void*)&exec1);
	/** initialize exec2 */
	exec2.thread_index = 2;
	exec2.thread_pause = 1;
	exec2.thread_exec = 1;
	exec2.thread_wait = (rand()%10)+1;
	exec2.thread_run = 0;
	pthread_create(&exec2.thread_id,0x0,&thread_exec,(void*)&exec2);
	/** main loop for main thread */
	sleep(1);
	printf("[Main] Starting threads execution...\n");
	exec1.thread_pause = 0;
	exec2.thread_pause = 0;
	while(not_done)
	{
		printf("[Main] <ESC> Exit, <SPACE> Pause/Resume, <R>andomize Sleep\n");
		switch(test=getch())
		{
			case 0x1B: /** ASCII ESC */
				not_done = 0;
				break;
			case 0x20: /** ASCII SPACE */
				exec1.thread_pause = !exec1.thread_pause;
				exec2.thread_pause = !exec2.thread_pause;
				break;
			case (int)'R':
				printf("[Main] Pause threads execution...\n");
				exec1.thread_pause = 1;
				exec2.thread_pause = 1;
				printf("[Main] Waiting for threads to pause...\n");
				while(exec1.thread_run||exec2.thread_run);
				printf("[Main] Randomizing Sleep Params...\n");
				exec1.thread_wait = (rand()%10)+1;
				exec2.thread_wait = (rand()%10)+1;
				printf("[Main] Wait1=%d, Wait2=%d\n",exec1.thread_wait,
					exec2.thread_wait);
				printf("[Main] Resume threads execution...\n");
				exec1.thread_pause = 0;
				exec2.thread_pause = 0;
				break;
			default:
				printf("[CHECK]=>'%02X'\n",test);
		}
	}
	/* stop threads */
	printf("[Main] Stopping threads execution...\n");
	exec1.thread_exec = 0;
	exec2.thread_exec = 0;
	/* wait threads to finish */
	printf("[Main] Waiting for threads to finish...\n");
	pthread_join(exec1.thread_id,0x0);
	pthread_join(exec2.thread_id,0x0);
	printf("[Main] Done!\n");
	return 0;
}