/*
 * File name: simpsim.cpp
 * Author: Xiannong Meng
 * Date: February 15, 1997
 * Course: CS2330
 * Assignment: classroom demonstration
 * Problem statement:
 * This is a traffic simulation program using random numbers.
 *
 */ 
#include <iostream.h>
#include <stdlib.h>     // rand and srand are in stdlib.h

// define event type
enum Event {Idle, ArrvN, ArrvS, ArrvE, ArrvW};

// user defined constants and functions
// they can be in a separate header file
const int NUMEVNTYPE = 5;       // five different types of events

void Simulation(int);           // main simulation loop
Event EventGen(void);           // event generator

void FromNorth(void);           // five event handlers
void FromSouth(void);
void FromEast(void);
void FromWest(void);
void Wait(void);

void main(void)
{
   int time;                    // simulation time limit
   int seed;                    // random seed

   cout << " type a random seed : ";
   cin >> seed;
   srand(seed);
   cout << " type a time limit : ";
   cin >> time;
   Simulation(time);
}

// Name: Simulation
// Intent: loop until the time expires, generate
//         and process events in between
// Pre-condition: total simulation time specified
// Post-contidion: simulation finished
void Simulation(int timeLimit)
{
    int currentTime = 0;
    Event event;

    while (currentTime < timeLimit)
    {
       event = EventGen();
       switch (event)
       {
	  case Idle  : Wait();
		       break;
	  case ArrvN : FromNorth();
		       break;
	  case ArrvS : FromSouth();
		       break;
	  case ArrvE : FromEast();
		       break;
	  case ArrvW : FromWest();
		       break;
	  default: cout << " error in event type " << endl;
       }
       currentTime += 1;
    }
}

// Name: EventGen
// Inteng: event generator
// Pre-condition: none
// Post-condition: generates one event
Event EventGen()
{
   return (Event)(rand() % NUMEVNTYPE);
}

// Name: FromNorth
// Intent: representing one vehicle from north direction
// Pre-condition: simulation started
// Post-condition: event processed
void FromNorth()
{
   cout << " one vehicle from north \n";
}

// Name: FromSouth
// Intent: representing one vehicle from south direction
// Pre-condition: simulation started
// Post-condition: event processed
void FromSouth()
{
   cout << " one vehicle from south \n";
}

// Name: FromEast
// Intent: representing one vehicle from east direction
// Pre-condition: simulation started
// Post-condition: event processed
void FromEast()
{
   cout << " one vehicle from east \n";
}

// Name: FromWest
// Intent: representing one vehicle from west direction
// Pre-condition: simulation started
// Post-condition: event processed
void FromWest()
{
   cout << " one vehicle from west \n";
}

// Name: Wait
// Intent: traffic is busy, newly arrived vehicle has to wait
// Pre-condition: simulation started, one vehicle is at
//                intersection
// Post-condition: vehicle waits
void Wait()
{
   cout << " traffic busy, wait ... \n";
}