import java.lang.Class;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.Random;
import java.util.Vector;

/**
 * A class that helps us test unary integer methods.  Written as an
 * example for the take home in CS223.
 *
 * @author Samuel A. Rebelsky
 */
public class UnaryIntegerMethodTester
{

// +--------+------------------------------------------------------------
// | Fields |
// +--------+

	/**
	 * The class that we're testing.
	 */
	Class c;

	/**
	 * The nullary constructor for that class.
	 */
	Constructor cons;

	/**
	 * All the unary methods in that class.
	 */
	Method[] unaries;

	/**
	 * A helpful random-number generator
	 */
	Random rng;

// +--------------+------------------------------------------------------
// | Constructors |
// +--------------+

	/**
	 * Create a new tester for class _c.  Verify that class
	 * _c has a nullary constructor.
	 *
	 * @exception NoNullaryConstructorException
	 *   When there is no nullary constructor.
	 * @exception NoSuchMethodException
	 *   When c lacks a unary integer method.
	 */
	public UnaryIntegerMethodTester(Class _c)
		throws NoNullaryConstructorException, NoSuchMethodException
	{
		this.c = _c;
		// Verify that it has a constructor.  Note that 
		// getConstructor will throw a NoSuchMethodException
		// if it fails.
		try {
			this.cons = this.c.getConstructor(null);
		}
		catch (Exception e) {
			throw new NoNullaryConstructorException();
		}
		// Shove all the unary methods in Vector v;
		Vector v = new Vector();
		Method[] methods = this.c.getMethods();
		for (int i = 0; i < methods.length; i++) {
			Class[] params = methods[i].getParameterTypes();
			if ((params.length == 1) && (params[0].equals(Integer.TYPE)))
				v.add(methods[i]);
		} // for
		// Sanity check: Are there any unary methods?
		if (v.size() == 0)
			throw new NoSuchMethodException("no unary methods");
		// Copy those methods into an array.
		this.unaries = (Method[]) v.toArray(new Method[0]);
		// Get a random number generator;
		this.rng = new Random();
	} // UnaryIntegerMethodTester(Class)


// +---------+-----------------------------------------------------------
// | Methods |
// +---------+

	/**
	 * Print all of the unary methods to standard output.
	 */
	public void printMethods()
	{
		for (int i = 0; i < this.unaries.length; i++)
			System.out.println(this.unaries[i].toString());
	} // printUnaryMethods()

	/**
	 * Conduct n tests with randomly-generated numbers.
	 */
	public boolean randomTest(int n)
	{
		Object base = new Object();
		try {
			base = this.cons.newInstance(null);
		}
		catch (Exception e) {
			// Should never happen.
		}
		boolean passed = true;
		for (int i = 0; i < n; i++) {
			Object[] args= new Object[1];
			args[0] = new Integer(rng.nextInt());
			for (int j = 0; j < this.unaries.length; j++) {
				try {
					this.unaries[j].invoke(base, args);
				}
				catch (Exception e) {
					passed = false;
					System.out.println(e);
					e.printStackTrace(System.out);
				} // catch
			} // for j
		} // for i
		return passed;
	} // randomTest(int)

// +------+--------------------------------------------------------------
// | Main |
// +------+

	/**
	 * Test all the classes specified on the command line.
	 */
	public static void main(String[] args)
	{
		for (int i = 0; i < args.length; i++) {
			System.out.println("*** Testing class " + args[i] + " ***");
			try {
				Class c = Class.forName(args[i]);
				try {
					UnaryIntegerMethodTester tester =
						new UnaryIntegerMethodTester(c);
					// Print the methods
					System.out.println("Methods:");
					tester.printMethods();
					// Try some random tests
					System.out.println("Random tests:");
					if (tester.randomTest(5)) {
						System.out.println("Passed.");
					}
				}
				catch (NoNullaryConstructorException nnme) {
					System.out.println(args[i] + " lacks a nullary constructor");
				}
				catch (NoSuchMethodException nsme) {
					System.out.println(args[i] + " lacks unary integer methods");
				}
			}
			catch (Exception e) {
				System.out.println("No such class: " + e.toString() + ".");
				e.printStackTrace(System.out);
			}
			catch (NoClassDefFoundError nncdfe) {
				System.out.println("No such class: " + nncdfe.toString() + ".");
			}
			System.out.println();
		} // for
	} // main(String[])

} // class UnaryIntegerMethodTester