import java.util.InputMismatchException;
import java.util.Scanner;

/**
 *
 * @author AChapin
 */
public class ExceptionExamples {

    // just explicitly throw an Exception
    public static void thrower() throws BadThingHappened {
        throw new BadThingHappened();
    }

    // return string based on number for day of the week
    // throw a tantrum if you get bad parameters
    public static String dayOfWeek(int n) {
        if (n < 0 || n > 6) {
            throw new IllegalArgumentException("Invalid day of week: " + n);
        }
        return (new String[]{"MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY", "SATURDAY", "SUNDAY"})[n];
    }

    // force a null pointer exception
    public static void badPointer() {
        System.out.println("in badPointer");
        String bad = null;
        bad.equals("bad");
    }

    // Force an out of bounds exception
    public static void badArray() {
        System.out.println("in badArray");
        int list[] = new int[5];
        list[27] = 4;
    }

    // get stack information from exception and control output
    public static void exceptionOutput(Exception ex) {
        
        // exceptions can print stack themselves
        // print to System.err may result in
        // different format, different location, or not show up at all...
        System.err.println("Normal Stack Trace");
        ex.printStackTrace();
        
        // get array of lines in the stack
        StackTraceElement[] stack = ex.getStackTrace();

        // build up string of stack trace lines
        String out = "\t";
        for (int i = stack.length - 1; i >= 0; i--) {
            // after first line
            if (i < stack.length - 1) {
                out += "called\t";
            }
            // each line of stack
            out += " line " + stack[i].getLineNumber() + "\t"
                    + stack[i].getMethodName()
                    + " (in " + stack[i].getFileName() + ")";
            // last line
            if (i == 0) {
                out += " <-- error!!";
            }
            out += "\n";
        }
        // print the stack trace
        System.err.println("My Stack Trace");
        System.err.print(out);
    }

    // -----------------------------------------------------
    // exceptions with Scanner
    public static void readInExceptions() {
        Scanner scan = new Scanner(System.in);
        Bunny b1, b2;

        System.out.println("Let's make some Bunnys");

        System.out.println("I will read string and a number");
        System.out.println("pls enter name");
        String name = scan.next();
        int count;
        System.out.println("pls enter carrotcount");
        try {
            count = scan.nextInt(); // could cause exception
            b2 = new Bunny(name, count);
            System.out.println("you have successfully made a bunny");
            System.out.println(b2);
        } catch (InputMismatchException e) {
            System.out.println("Can you even type?");
            // if scanner fails to nextInt, nextDouble, etc
            // everything up to the end of the line is still there
            // in its buffer and this will mess up later input
            // so tell Scanner to do a nextline to clear it out
            String leftovers = scan.nextLine();
                // Scanner what are you doing?
                // Scanner go home you're drunk.
                // System.out.println("scanner was caught eating " + leftovers + " out of the buffer's garbage");
                // Scanner STAHP
        } catch (IllegalArgumentException e) {
            System.out.println(e);
        }

        System.out.println("pls enter name and carrotcount");
        System.out.println("I will read two strings and convert to a number");
        System.out.println("pls enter name");
        name = scan.next();
        System.out.println("pls enter carrotcount");
        String scount = scan.next();
        try {
            count = Integer.parseInt(scount); // could cause exception
            b1 = new Bunny(name, count);
            System.out.println("you have successfully made a bunny");
            System.out.println(b1);
        } catch (NumberFormatException e) {
            System.out.println("Can you even type?");
        } catch (IllegalArgumentException e) {
            System.out.println(e);
        }

    }

	//------------------------------------------------------
    // Demonstrate try-catch to deal with exceptions
    public static void main(String[] args) {

        readInExceptions();

        // exception may occur, but program continues anyway
        try {
            System.out.println(dayOfWeek(0));
            System.out.println(dayOfWeek(5));
            // this throws exception
            System.out.println(dayOfWeek(88));
        } catch (IllegalArgumentException e) {
            System.out.println("Error was: " + e);
        }

        // exception may occur, but program continues anyway
        try {
            // random chance for null pointer OR array OR no exception
            int ch = (int) (Math.random() * 4);
            switch (ch) {
                case 0:
                    badPointer();
                    break;
                case 1:
                    badArray();
                    break;
                case 2:
                    thrower();
                    break;
                default:
                    // only happens if no exceptions
                    System.out.println("Nothing bad happened");
            }
            // if null pointer exception
        } catch (NullPointerException e) {
            System.out.println("Null Pointer");
            exceptionOutput(e);
            // if array exception
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Array out of bounds!");
            exceptionOutput(e);
            // if BadThing exception
        } catch (BadThingHappened e) {
            System.out.println("Apparently something bad happened.");
            exceptionOutput(e);
            // no matter what happens
        } finally {
            System.out.println("Let's continue, shall we?");
        }

        System.out.println("End of program");

    }

}