//This is a demonstration of a simple simulation.
//Error handling has been omitted for clarity.
//
//It should be noted that due to the omission of code for clarity's sake,
//the very first customer will be lost. In actuality, you would want to
//implement a special case for the first customer.

#include<iostream>
#include<queue>
#include"generator.h"
using namespace std;

struct customer {
	int transactions;
	int entrytime;
};


int main() {
	const int SimDuration=10; //Number of units of time to run simulation for.
	const int MeanCustomerArrivalRate=5; //mean arrival customers/unit of time.
	const int MeanTransactionRate=2;	//mean # of transaction/customer
	const int TellerProcessingRate=8;	//Number of transactions/unit time that a teller can perform.
	
	queue<customer> line;
	generator entrance(MeanCustomerArrivalRate);
	generator transactions(MeanTransactionRate);
	
	int CurrentTime=0;
	int NewCustomers, TotalCustomersServiced=-1;
	int AvailTellerTransactions, TotalTransactions=0;
	customer c, CurrentCustomer={0,0};
	
	//start the simulation loop:
	while(CurrentTime<SimDuration || !line.empty()) {
		cout << "------- " << CurrentTime << " units of time passed." << " -------" << endl;
		
		//Generate new customers for this time unit:
		if(CurrentTime<SimDuration) {
			NewCustomers=entrance.GetNumberOfEvents();
			cout << NewCustomers << " customers walk in the door:" << endl;
			while(NewCustomers>0) {
				//generate an individual customer:
				c.entrytime=CurrentTime;
				c.transactions=transactions.GetNumberOfEvents();
				cout << "Customer entering with " << c.transactions << " transactions" << endl;
				line.push(c);
				NewCustomers--;
			};
		}

		//service transactions:
		AvailTellerTransactions=TellerProcessingRate; //amount of trans avail for this time interval.
		while(AvailTellerTransactions>0 && !line.empty()) {
			//perform the transactions that we can:
			if(CurrentCustomer.transactions>0) {
				if(CurrentCustomer.transactions > AvailTellerTransactions) {
					//this customer will exhaust all avail teller transactions:
					TotalTransactions+=AvailTellerTransactions;
					CurrentCustomer.transactions-=AvailTellerTransactions;
					AvailTellerTransactions=0;
				}
				else {
					//this customer can be handled in this time slot:
					TotalTransactions+=CurrentCustomer.transactions;
					AvailTellerTransactions-=CurrentCustomer.transactions;
					CurrentCustomer.transactions=0;
				}
			}
			//Remove the customer and check to see if we need to get a new customer:
			if(0==CurrentCustomer.transactions) {
				cout << "Customer leaving, time spent="<< CurrentTime-line.front().entrytime << endl;
				line.pop();	//actually, we loose the very first customer.
				TotalCustomersServiced++;
				if(!line.empty()) {
					//Get the next customer:
					CurrentCustomer.transactions=(line.front()).transactions;
					CurrentCustomer.entrytime=(line.front()).entrytime;
				}
			}
		}
		
		//update the time:
		CurrentTime++;
	}
	
	//Print a few rudimentary stats:
	cout << TotalCustomersServiced << " customers, " << TotalTransactions << " transactions, "
		 << CurrentTime << " units of time." << endl;
	return(0);
}