/* Epidemic Simulator
 * Author: Douglas Jones
 * Status: MP1 solution; it works, but it is full of bugs.
 * Version: 9/16/2020
 */
import java.util.LinkedList;
import java.util.Iterator;
import java.util.Scanner;
import java.util.Random;
import java.io.File;
import java.io.FileNotFoundException;

// Utility classes

/**
 * People occupy places
 * @see Place
 */
class Person {
    // instance variables
    private final Place home;
    public final String name;

    // the collection of all instances
    private static final LinkedList <Person> allPeople =
	new LinkedList <Person> ();

    /** The only constructor
     * the person is constructed with a home
     */
    public Person( Place h ) {
	name = super.toString();
	home = h;
	h.addResident( this );

	allPeople.add( this ); // this is the only place items are added!
    }
    
    /** Primarily for debugging
     * @return textual name and home of this person
     */
    public String toString() {
	return name + " " + home.name;
    }

    /** Allow outsiders to iterate over all people
     * @return an iterator over people
     */
    public static Iterator <Person> iterator() {
	return allPeople.iterator();
    }
}

/**
 * Places are occupied by people
 * @see Person
 */
class Place {
    // instance variables
    public final String name;
    private final LinkedList <Person> residents = new LinkedList <Person> ();

    // the collection of all instances
    private static final LinkedList <Place> allPlaces =
	new LinkedList <Place> ();

    /** The only constructor for Place
     *  Places are constructed with no occupants
     */
    public Place() {
	name = super.toString();
	allPlaces.add( this );
    }

    /** Add a resident to a place
     *  Should only be called from the person constructor
     *  @param r a Person, the new resident
     */
    public void addResident( Person r ) {
	residents.add( r );
	// BUG -- check to see if the person already lives there?
    }

    /** Primarily for debugging
     * @return textual name and residents of the place
     */
    public String toString() {
	String res = name;
	for (Person p: residents) { res = res + " " + p.name; }
	return res;
    }

    /** Allow outsiders to iterate over all places
     * @return an iterator over places
     */
    public static Iterator <Place> iterator() {
	return allPlaces.iterator();
    }
}

/**
 * Main class builds model and will someday simulate it
 * @see Person
 * @see Place
 */
public class Epidemic {

    /** Read the simulation parameters and build a community that they describe
      * Called only from the main method.
      */
    private static void readCommunity( Scanner sc ) {
        // BUG -- is this the right place for the simulation parameters?
	int pop = -1;   /* the target population */
	int house = -1; /* the target household size average */
	int var = -1;   /* the target household size variation */
	// everything has a default value
	// BUG -- these defaults all indicate failure to initialize

	while (sc.hasNext()) {
	    // until the input file is finished
	    String command = sc.next();
	    if ("pop".equals( command )) {
		// BUG -- what if the population was already set?
		// BUG -- what if there is no integer?
		pop = sc.nextInt();
		// BUG -- what if there is no semicolon?
		sc.next( ";" );
	    } else if ("house".equals( command )) {
		// BUG -- what if the size was already set?
		// BUG -- what if there is no integer?
		house = sc.nextInt();
		// BUG -- what if there is no comma?
		sc.next( "," );
		// BUG -- what if there is no integer?
		var = sc.nextInt();
		// BUG -- what if there is no semicolon?
		sc.next( ";" );
	    } else {
		System.out.println( "unknown command: " + command + "\n" );
	    }
	}
	// BUG -- no attempt to abort the following if key values not set!

	// now create the population
	// BUG -- should the following be a separate method, buildCommunity?
	{
	    // must always have a home available as we create people
	    int currentHomeCapacity = 0;
	    Place currentHome = null;

	    // need a source of random numbers // BUG -- does this go here?
	    Random rand = new Random();

	    for (int i = 1; i <= pop; i++) { // create the population
		if (currentHomeCapacity < 1) { // must create a new home
		    currentHome = new Place();
		    currentHomeCapacity
			= rand.nextInt( 2*var + 1 ) + house - var;
		}
		new Person( currentHome );
		currentHomeCapacity = currentHomeCapacity - 1;
	    }
	}
    }

    /** Output the community
      * Called only from the main method.
      * This code exists only for debugging.
      */
    private static void writeCommunity() {

	System.out.println( "People" ); // Note:  Not required in assignment
	for (Iterator<Person> i = Person.iterator(); i.hasNext(); ){
	    System.out.println( i.next().toString() );
	}

	System.out.println( "Places" ); // Note:  Not required in assignment
	for (Iterator<Place> i = Place.iterator(); i.hasNext(); ){
	    System.out.println( i.next().toString() );
	}
    }

    /** The main method
      * This handles the command line arguments.
      * If the args are OK, it calls other methods to build and test a model.
      */
    public static void main( String[] args ) {
	if (args.length < 1) {
	    System.out.println( "Missing file name argument\n" );
	} else try {
	    readCommunity( new Scanner( new File( args[0] ) ) );
	    writeCommunity();  // BUG -- this is just for debugging
	    // BUG -- need to actually add simulation code here
	} catch ( FileNotFoundException e) {
	    System.out.println( "Can't open file: " + args[0] + "\n" );
	}
    }
}