#include "main.h"

//======================================================================
/*
$ ps aux # a:all users, u:detailled, x:daemons // look at bash  PID

Unidirectional pipe : you have to choose the direction
PARENT					   CHILD
		  1 >> PtC >> 0 
		X 0 << PtC << 1 X
		
		  0 << CtP << 1 
		X 1 >> CtP >> 0 X

*/
//======================================================================
int main(int argc, char **argv)
{
	int ok;
	int value=100;
	char *msg;
	char buffer[0x100];
	
	bool usePause=false;
	
	// Parse Args
	for(int i=1;i<argc;++i)
	{
		  if(!strcmp(argv[i],"pause")) usePause=true;
	}
	
	int childToParent[2]; // Declare pipe, then create
	ok = pipe(childToParent);
						if( ok == -1 ) { perror("pipe"); exit(1); }
	int parentToChild[2];
	ok = pipe(parentToChild); 
						if( ok == -1 ) { perror("pipe"); exit(1); }
	
	pid_t child=fork(); //>>>>>>>> CREATE CHILD >>>>>>>>>>>>>>>>>>>>>>>>
  
	switch(child)
	{
		case -1: perror("fork"); return EXIT_FAILURE; break;
		
		//############ CHILD CODE ######################################
		case 0 : 
				close(childToParent[0]); // child will not read from this pipe
				close(parentToChild[1]); // child will not write to this pipe
				
				msg="first message from child to parent\n";
				write(childToParent[1],msg,strlen(msg)); 
				if(usePause) { sleep(1); }
				msg="second message from child to parent\n";
				write(childToParent[1],msg,strlen(msg));
				close(childToParent[1]); // done with writing
			  
			  for(;;)
				{
				int r=read(parentToChild[0],buffer,0xFF);
							if(r==0) break; // end of file
							if(r==-1) { perror("read"); exit(1); }
				buffer[r]='\0';
				printf("child received [%s]\n",buffer);
				}
			  close(parentToChild[0]); // done with reading	

			break;		
		
		//############ PARENT CODE #####################################
		default : 
				close(parentToChild[0]); // parent will not read from this pipe
				close(childToParent[1]); // parent will not write to this pipe

			  for(;;)
				{
				int r=read(childToParent[0],buffer,0xFF);
							if(r==0) break; // end of file
							if(r==-1) { perror("read"); exit(1); }
				buffer[r]='\0';
				printf("parent received [%s]\n",buffer);
				}
				
			  close(childToParent[0]); // done with reading
			  msg="first message from parent to child\n";
			  write(parentToChild[1],msg,strlen(msg)); 
			  if(usePause) { sleep(1); }
			  msg="second message from parent to child\n";
			  write(parentToChild[1],msg,strlen(msg));
			  close(parentToChild[1]); // done with writing

			int status;
		    pid_t p=waitpid(child,&status,0);	// PARENT MUST WAIT FOR HIS CHILD
								if(p==-1) { perror("waitpid");  return EXIT_FAILURE; }
			break;
	}	
			
return EXIT_SUCCESS;
}
//^^^^^^^^^^^^^^^^^^^^^^^^^^ EOF ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^