/**
 * Class to test simulation of page replacement.
 *
 * <pre>
 * Command-line argument gives number of page frames (and, optionally,
 *   debug to produce extra output -- need not implement this).
 *
 * Input (from standard input) is a line giving number of pages, followed 
 *   by more lines, each giving:
 *
 *   R/W (read/write reference, single character)
 *   Page number (integer)
 *
 * Output is, for each page replacement algorithm implemented, the following 
 *   information:
 *   
 *   Total number of page references
 *   Number of page references that changed the page ('W')
 *   Number of page faults
 *   Number of times a page had to be written out
 *
 * Assume that all page references are valid -- if the page is not in
 *   memory, it's on disk.
 * </pre>
 */
import java.util.List;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;

public class PageReplacerTest {

    /**
     * Main method.
     * @param args see description of class
     */
    public static void main(String[] args) {

        int numPages = 0;
        int numFrames = 0;

        // process arguments 

        String usageMsg = "Need argument:  numFrames [debug]";

        if (args.length < 1) {
            System.err.println(usageMsg);
            System.exit(1);
        }
        try {
            numFrames = Integer.parseInt(args[0]);
        }
        catch (NumberFormatException e) {
            System.err.println(usageMsg);
            System.exit(1);
        }
        if (numFrames <= 0) {
            System.err.println(usageMsg);
            System.exit(1);
        }

        boolean dbg = (args.length > 1) && (args[1].equals("debug"));

        // read input

        List<PageReference> refs = null;
        Scanner input = new Scanner(System.in);
        try {
            numPages = input.nextInt();
            if (numPages <= 0)
                throw new InputMismatchException("invalid number of pages");
            refs = buildList(input, numPages);
        }
        catch (InputMismatchException e) {
            if (e.getMessage() == null) {
                System.err.println("Error in input");
            }
            else {
                System.err.println("Error in input:  " + e.getMessage());
            }
            System.exit(1);
        }
        catch (NoSuchElementException e) {
            if (e.getMessage() == null) {
                System.err.println("Error in input");
            }
            else {
                System.err.println("Error in input:  " + e.getMessage());
            }
            System.exit(1);
        }

        new PageReplacerFIFO(numPages, numFrames).simulate(refs, dbg).print();

        // TODO:  add more
    }

    /**
     * Read input and build list of page references.
     */
    private static List<PageReference> buildList(Scanner input, int numPages) 
            throws InputMismatchException {

        List<PageReference> refs = new ArrayList<PageReference>();

        while (input.hasNext()) {
            String rw = input.next();
            boolean writeRef = false;
            if (rw.equals("W")) {
                writeRef = true;
            }
            else if (!rw.equals("R")) {
                throw new InputMismatchException("R/W expected");
            }
            int pageNum = input.nextInt();
            if ((pageNum < 0) || (pageNum >= numPages)) {
                throw new InputMismatchException("invalid page number");
            }
            refs.add(new PageReference(pageNum, writeRef));
        }
        return refs;
     }
}