#include <iostream>
#include <unistd.h>   // fork
#include <sys/types.h>  // wait
#include <sys/wait.h>  // wait
#include <stdio.h>     // perror
#include <stdlib.h>    // exit


#include <vector>
#include <algorithm>

#include <string>

using namespace std;

const string PROMPT = "? ";

void ReportStatus(int pid, int status) {
    cout << "\tStatus Report for pid " << pid << endl;
    cout << "\t\t" << pid << " used exit(" 
         << WEXITSTATUS(status) << ")" << endl;

    return;
}

void CleanUp(int pid, int status, vector<pid_t> & children) {
       vector<pid_t>::iterator j;

       cout <<"\t" << "Process " << pid << " just exited with status "
            << status << endl;
       ReportStatus(pid, status);
       j = find(children.begin(), children.end(),pid);
       children.erase(j);
  
       return;
}

void ReportChildren(vector<pid_t> children){
   int i=0;

   cout << "Still to Exit: ";
   if (children.size() > 0) {
       for(i = 0; i < children.size()-1; i++) {
          cout << children[i] << ", ";
       }

       if (i < children.size()) {
           cout << children[i] << endl;
       }
   } else {
       cout << "none " << endl;
   }
   
   return;
}

void  BeAChild() {

       int sleepTime;
       int status;

       srand(getpid());

       sleepTime = rand() % 10 + 5;
       cout <<"\t" << getpid() << " going to sleep for " << sleepTime << endl;
       sleep(sleepTime);
       cout <<"\t" << getpid() << " Is back." << endl;
       status = rand() % 5;
       cout <<"\t" << getpid() << " is exiting with status " << status << endl;
       cout << endl;
       exit(status);

       return;
}


void ForkOne(vector<pid_t> & children) {
   pid_t pid = fork();
   if (pid) {
       children.push_back(pid);
   } else {
       BeAChild();
   }

   return;
}


int main() {
   vector<pid_t> children;
   pid_t pid;
   int status;
   string cmd;

   do {
       cout << PROMPT ;
       getline(cin, cmd);
       if (cmd == "FORK") {
          ForkOne(children); 
       } else if (cmd == "STATUS") {
          ReportChildren(children);
       }

       pid = waitpid(-1, &status, WNOHANG);
       while (pid != 0 and children.size() > 0) {
           CleanUp(pid, status, children);
           pid = waitpid(-1, &status, WNOHANG);
       }

   } while (cmd != "EXIT");


   return 0;
}