#include<iostream>
#include<vector>
#include<cstdlib>
#include<ctime>
#include<list>
#include<pthread.h>
#include<cstring>
using namespace std;

static int round;
#define checkResults(string, val){	\
   if(val){	\
       printf("failed with %d at %s", val, string);	\
       exit(1);	\
   }	\
}	\

#define _NODES 8

typedef struct{      // thread parameter
  int id;
  int rcvd_from;
  string msg;
}thread_param_t;

struct node          // node structure 
{
   pthread_mutex_t f_lock;
   thread_param_t  packet;
   vector<int> edges;
   bool msg_received;
} nodes[_NODES];

pthread_t callThd[_NODES];    //keeps track of all thread IDs
pthread_mutex_t list_lock;    //locks the array nodes[], which stores node structures
pthread_mutex_t path_mutex;   //locks the path array--we don't need it as we always read the path
pthread_cond_t  next_round_ready = PTHREAD_COND_INITIALIZER;  //statically initializing a condition variable-- it assures the message is sent
// to all other sender's neighbours before one of the neighbours tries to find it's surrounding neighbours


bool msg_sent_to_all(int , int );  // it looks whether the message is sent to all sender's surrounding neighbours

//---------------
int path[_NODES][_NODES] = {
      { 0, 1, 1, 1, 0, 0, 0, 0 },
      { 1, 0, 0, 1, 1, 0, 0, 0 },
      { 1, 0, 0, 1, 0, 1, 0, 0 },
      { 1, 1, 1, 0, 1, 0, 0, 0 },
      { 0, 1, 0, 1, 0, 1, 0, 1 },
      { 0, 0, 1, 0, 1, 0, 1, 1 },
      { 0, 0, 0, 0, 0, 1, 0, 1 },
      { 0, 0, 0, 0, 1, 1, 1, 0 }
                                 }; // keeps the sparse graph
//---------------

void *funcThd(void *arg)   //Thread function, the argument is the structure defined above (thread_param..)
{
   cout << "void *funcThd(void *arg)\n";

   pthread_attr_t attr;
   string message;
   int index, rc, received_from, neighbours_size;
   pthread_t tid;

  rc = pthread_attr_init(&attr);
 	 checkResults("pthread_attr_init()\n", rc);
  rc = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); // setting detached as our thread attributes, this way none of the calling threads
//expect the caller thread to wait for them-- so, no need for pthread_join(..)
  	checkResults("pthread_attr_setdetachstate()\n", rc);

   thread_param_t *p = (thread_param_t *) arg;  //store the message properties temporarily
               index = p -> id;	
             message = p -> msg;
       received_from = p -> rcvd_from;

   printf("Thread %d Activated by %d\n", index, received_from);
  //pthread_mutex_lock(&path_mutex); we don need to lock the path as we always read it

  pthread_mutex_lock(&list_lock);           //lock the list of nodes
  pthread_mutex_lock(&nodes[index].f_lock); //lock the particular node in which the message has been sent to, this lock exists in every node structure
  
  nodes[index].msg_received = true;      //node got the message
  nodes[index].packet.id    = index;     //index of the node
  nodes[index].packet.msg   = message;   //message content
  neighbours_size = nodes[received_from].edges.size();   //number of neighbours staying adjacent to the node 

  printf("Message Delivered to %d from %d : ", index, received_from); 
  cout << message << endl;

 //for optimality, for each round the calling threads are not gonna start finding their neighbouring nodes BEFORE the message is sent to all
//the neighbours of the calling threads, for example is message is sent from 0 to 1, 1 is not gonna send the message to its neighbours 1, 3, 4
 // before 0 sends the message to all its neighbours first 1, 3, 5 -- so, we wouldn't have redundant threads

  while(msg_sent_to_all(received_from, neighbours_size) == false && received_from != 0)
	pthread_cond_wait(&next_round_ready, &list_lock);   
//the condition variable is locked by the node list mutex, it will then automaticly get unlocked whenever the condition satisfies
// that is when the message is sent to all the neighbours     


     for(int i = 0; i < _NODES; i++)
     {
        printf("loop %d\n", i);

         if(path[index][i])
         {
             nodes[index].edges.push_back(i);  //finding neighbours from path matrix and push them back to the nodes edge property

                if(nodes[i].msg_received == false)  // if the msg is not sent to the node, then try sending it
                {
                   p -> id = i; 
                   p -> msg = message;
                   p -> rcvd_from = index;
                   
                   printf("Sending Message to %d from %d \n", i, index);                 
                   pthread_create(&callThd[i], &attr, funcThd, (void *) p); // calling the thread
                   cout << "\n\n";
                }
         }
     }//end of for
     
  pthread_mutex_unlock(&nodes[index].f_lock);  //unlocking, node structure lock
  pthread_mutex_unlock(&list_lock);            //unlocking node list lock
  //pthread_mutex_unlock(&path_mutex);
  
  pthread_exit(NULL);

}
//-----------------
bool msg_sent_to_all(int index, int neighbours_size)  
{
   int temp;

   cout << "msg_send_to_all()..\n";   
   //pthread_mutex_lock(&list_lock);
   //pthread_mutex_lock(&nodes[index].f_lock);   
   printf("Node ID : %d  No. of neighbours : %d\n", index, neighbours_size);    

     for(int i = 0; i < neighbours_size; i++)
     {
           temp = nodes[index].edges[i];   cout << "temp =  " << temp;
           	if(nodes[temp].msg_received == false)      cout << "--> " << nodes[temp].msg_received << endl;
                cout << "returning false..\n";
              	return false; 
     }
   //pthread_mutex_unlock(&list_lock);
   //pthread_mutex_unlock(&nodes[index].f_lock);
   cout << "returning true..\n";
   return true;
}
//-----------------

int main(int argc, char **argv)
{
  thread_param_t	param;
  pthread_attr_t	attr;
  pthread_t		thread;  
  int 			rc = 0, detachstate;

  //START-->initializing mutexs
   if(!pthread_mutex_init(&list_lock, NULL))
        	cout << "mutex_nodes initialized..\n";

   if(!pthread_mutex_init(&path_mutex, NULL))
		cout << "path_mutex initialized..\n";

   	for(int index = 0; index < _NODES; index++)
       		if(!pthread_mutex_init(&nodes[index].f_lock, NULL))
                	printf("nodes[%d].f_lock initialized..\n", index);
  //END-->initializing mutex

  //START-->setting thread attributes

  // create a default thread attributes object
   rc = pthread_attr_init(&attr);
   checkResults("pthread_attr_init()\n", rc);
   //set the detach state thread attribute
   rc = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
   checkResults("pthread_attr_setdetachstate()\n", rc);
          
   //END-->setting thread attributes
  
  //Initializing the source node -- node 0

    param.id = 0;
    param.rcvd_from = -1;
    param.msg = "Purple";
    
    nodes[0].msg_received = true;
    pthread_create(&callThd[0], &attr, funcThd, (void *) &param); // starting the first round ;-)
    sleep(10);

    /*    
	for(int i = 0; i < _NODES; i++)
	{
    		cout << nodes[i].msg_received << " " << nodes[i].packet.id << " " << nodes[i].packet.msg << endl;
    		int cap = nodes[i].edges.size();
    				for(int j = 0;  j < cap; j++)
    				{
        				cout << nodes[0].edges[j] << "  ";
    				}
  		cout << "\n";
	}
*/	
   cout << "Exiting Main()..\n"; 
   pthread_exit(NULL);

  return 0;
}

//-------------------

sample code