import java.util.HashSet;
import java.util.Random;
import java.util.Set;

public class Test {
    static Random randgen = new Random(686585037);

    static int nopdone = 0;
    static int lastnopdone = -1;
    static int noperation = 0;
    static StringBuilder log = new StringBuilder();

    static void showException(Exception e, StringBuilder log) {
        System.out.println("The operation on the last line of the following code causes an exception:\n");
        System.out.print(log.toString());
        System.out.println("\nThe exception is: " + e.toString());
        System.exit(1);
    }

    static void runTest(Class<IntSet> intSetClass, int noperation, int interval) {
        log = new StringBuilder();

        log.append("IntSet set = new " + intSetClass.getName() + "();\n");
        IntSet set = null;
        try {
            set = intSetClass.getDeclaredConstructor().newInstance();
        } catch (ReflectiveOperationException e) {
            System.out.println("Could not instantiate specified class, " + intSetClass.getName() + ".");
            System.out.println("Exception: " + e.toString());
            System.exit(1);
        }
        Set<Integer> refset = new HashSet<Integer>();
        for (int j = 0; j < noperation; j++) {
            int whichop = randgen.nextInt(3);
            switch (whichop) {
                case 0: {  // add
                    int element = randgen.nextInt(interval);
                    log.append("set.add(" + element + ");\n");
                    try {
                        set.add(element);
                    } catch (Exception e) {
                        showException(e, log);
                    }
                    refset.add(element);
                }
                break;
                case 1: {  // member
                    int element = randgen.nextInt(interval);
                    log.append("set.contains(" + element + ");");
                    boolean res = false;
                    try {
                        res = set.contains(element);
                    } catch (Exception e) {
                        showException(e, log);
                    }
                    log.append("  // result: " + res + "\n");
                    boolean refres = refset.contains(element);
                    if (res != refres) {
                        System.out.println("The result on the last line of the following code is incorrect:\n");
                        System.out.print(log.toString());
                        System.out.println(" \nThe set should add this point contain the following elements:");
                        System.out.println(refset.toString());
                        System.exit(1);
                    }
                }
                break;
                case 2: {  // remove
                    int element = randgen.nextInt(interval);
                    log.append("set.remove(" + element + ");\n");
                    try {
                        set.remove(element);
                    } catch (Exception e) {
                        showException(e, log);
                    }
                    refset.remove(element);
                }
                break;
            }
            nopdone++;
        }

    }

    private static class Monitor implements Runnable {
        final int nsec;

        Monitor(int nsec) {
            this.nsec = nsec;
        }

        @Override
        public void run() {
            for (int secs = 0; secs < nsec; secs++) {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    return;
                }
                if (nopdone == lastnopdone) {
                    System.out.println("No new operation completed during the last second.");
                    System.out.println("Your program seems to loop (or be very slow) at the operation on the last line of the following code:\n");
                    System.out.print(log.toString());
                    System.exit(1);
                }
                lastnopdone = nopdone;
                System.out.println(nopdone + " operations executed. (No bugs found so far.)");
            }
            System.out.println("No bugs found in " + nsec + " seconds.");
            System.exit(0);
        }

    }


    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        if (args.length == 0 || args.length > 2) {
            System.out.println("The program accepts one or two arguments.");
            System.out.println("The first argument is the name of the class implementing IntSet that should be tested.");
            System.out.println("If there is a second argument this should be a positive number specifying the number of seconds to run the test.");
            System.exit(1);
        }

        Class<IntSet> intSetClass = null;
        try {
            intSetClass = (Class<IntSet>) Class.forName(args[0]);
        } catch (ClassNotFoundException e) {
            System.out.println("The specified class, " + args[0] + ", cannot be found.");
            System.exit(1);
        }

        int nrepetition = 5;

        int nsec = 5;
        if (args.length == 2) {
            try {
                nsec = Integer.parseInt(args[1]);
            } catch (NumberFormatException e) {
                System.out.println("The given argument is not a valid number.");
                System.exit(1);
            }
        }

        if (args.length == 1) {
            System.out.println("The test will run for " + nsec + " seconds or until a bug is found. (The number of seconds can be specified as an argument to the program.)");
        }

        new Thread(new Monitor(nsec)).start();

        for (int iter = 1; ; iter++) {
            nrepetition *= 2;
            noperation = iter;
            int interval = iter;
            for (int i = 0; i < nrepetition; i++) {
                runTest(intSetClass, noperation, interval);
            }
        }

    }
}