/**
 * Calculator
 * Copyright (c) http://www.javamaniac.com. All Rights Reserved.
 * Commercial use is subject to license terms.
 * FREE for non-commercial use.
 *
 * @author gertsho@yahoo.com
 */

package javamaniac;

import java.awt.*;

class Calculator extends MainPanel
{
    private double buffer;
    private double firstN;
    private int operation;
    private boolean firstReady;
    private boolean hasDot;
    private int p;
    private int counter;

	public Calculator()
    {
        operation = -1;
        firstReady = false;
        hasDot = false;
    }

    private void addToStringBuffer(String s)
    {
        if(firstReady)
        {
            buffer = 0.0D;
            showToDisplay();
            firstReady = false;
            hasDot = false;
            counter = 0;
        }
        if(hasDot)
        {
            if(display.getText().indexOf('.') != -1)
                buffer = Double.valueOf(display.getText() + s).doubleValue();
            else
                buffer = Double.valueOf(display.getText() + "." + s).doubleValue();
            if(s.equals("0"))
                counter++;
            else
                counter = 0;
        }
		else
        {
            buffer = buffer * 10D + (double)Integer.parseInt(s);
        }
        showToDisplay();
    }

    private void showToDisplay()
    {
        if((double)Math.round(buffer) == buffer && !hasDot)
        {
            display.setText("" + (int)buffer);
            return;
        }
        String s = "" + buffer;
        if(s.endsWith(".0"))
            s = s.substring(0, s.lastIndexOf(".0") + 1);
        else
        if(s.endsWith("0"))
            s = s.substring(0, s.lastIndexOf("0"));
        String s1 = "" + buffer;
        if(s1.indexOf(".") == -1)
        {
            display.setText("" + buffer + "." + addZero());
            return;
        }
		else
        {
            display.setText("" + s + addZero());
            return;
        }
    }

    private String addZero()
    {
        String s = "";
        for(int i = 0; i < counter; i++)
            s += "0";

        return s;
    }

    private void calculate()
    {
        firstReady = true;
        switch(operation)
        {
        case 0: // '\0'
            buffer = firstN + buffer;
            break;

        case 1: // '\001'
            buffer = firstN - buffer;
            break;

        case 2: // '\002'
            buffer = firstN * buffer;
            break;

        case 3: // '\003'
            buffer = firstN / buffer;
            break;

        case 4: // '\004'
            buffer = firstN / buffer;
            break;
        }
        showToDisplay();
    }

    public boolean handleEvent(Event event)
    {
        switch(event.id)
        {
        default:
            break;

        case 1001: // Event.ACTION_EVENT
            if(!(event.target instanceof Button))
                break;
            Button button = (Button)event.target;
            String s = button.getActionCommand();
            if(s.equals("number"))
                addToStringBuffer("" + button.getLabel());
            else
            if(s.equals("+/-"))
            {
                buffer = -buffer;
                showToDisplay();
            } else
            if(s.equals("."))
                hasDot = true;
            else
            if(s.equals("="))
                calculate();
            else
            if(s.equals("%"))
                calculate();
            else
            if(s.equals("+"))
            {
                operation = 0;
                firstN = buffer;
                firstReady = true;
            } else
            if(s.equals("-"))
            {
                operation = 1;
                firstN = buffer;
                firstReady = true;
            } else
            {
                if(s.equals("*"))
                {
                    operation = 2;
                    firstN = buffer;
                    firstReady = true;
                    break;
                }
                if(s.equals("/"))
                {
                    operation = 3;
                    firstN = buffer;
                    firstReady = true;
                } else
                if(s.equals("C"))
                {
                    buffer = 0.0D;
                    firstN = 0.0D;
                    counter = 0;
                    hasDot = false;
                    showToDisplay();
                } else
                {
                    if(!s.equals("CE"))
                        break;
                    buffer = 0.0D;
                    counter = 0;
                    hasDot = false;
                    showToDisplay();
                }
            }

        case 401: // Event.KEY_PRESS
            String s1 = "" + (char)event.key;
            try
            {
                Integer.parseInt(s1);
                addToStringBuffer(s1);
                return true;
            }
            catch(Exception _ex) { }
            if(event.key == 46 || event.key == 44)
            {
                hasDot = true;
                counter = 0;
            } else
            if(event.key == 43)
            {
                operation = 0;
                firstN = buffer;
                firstReady = true;
            } else
            if(event.key == 45)
            {
                operation = 1;
                firstN = buffer;
                firstReady = true;
            } else
            if(event.key == 42)
            {
                operation = 2;
                firstN = buffer;
                firstReady = true;
            } else
            if(event.key == 47)
            {
                operation = 3;
                firstN = buffer;
                firstReady = true;
            } else
            if(event.key == 10)
                calculate();
            else
            if(event.key == 8 || event.key == 127)
            {
                buffer = 0.0D;
                firstN = 0.0D;
                counter = 0;
                hasDot = false;
                showToDisplay();
            }
            break;
        }
        return super.handleEvent(event);
    }
}