CalculatorInput.java

/*******************************************************************************
 * Copyright (c) 2010 Denis Solonenko.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Public License v2.0
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 *
 * Contributors:
 *     Denis Solonenko - initial API and implementation
 ******************************************************************************/
package ru.orangesoftware.financisto2.widget;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Vibrator;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.widget.Button;
import android.widget.TextView;
import ru.orangesoftware.financisto2.R;
import ru.orangesoftware.financisto2.utils.Utils;

import java.math.BigDecimal;
import java.util.Stack;

public class CalculatorInput extends Activity implements OnClickListener {

    public static final int[] buttons = {R.id.b0, R.id.b1, R.id.b2, R.id.b3,
            R.id.b4, R.id.b5, R.id.b6, R.id.b7, R.id.b8, R.id.b9, R.id.bAdd,
            R.id.bSubtract, R.id.bDivide, R.id.bMultiply, R.id.bPercent,
            R.id.bPlusMinus, R.id.bDot, R.id.bResult, R.id.bClear, R.id.bDelete};

    private TextView tvResult;
    private TextView tvOp;

    private Vibrator vibrator;

    private final Stack<String> stack = new Stack<String>();
    private String result = "0";
    private boolean isRestart = true;
    private boolean isInEquals = false;
    private char lastOp = '\0';

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.calculator);

        vibrator = (Vibrator) getSystemService(VIBRATOR_SERVICE);

        for (int id : buttons) {
            Button b = (Button) findViewById(id);
            b.setOnClickListener(this);
        }

        tvResult = (TextView) findViewById(R.id.result);
        tvOp = (TextView) findViewById(R.id.op);

        Button b = (Button) findViewById(R.id.bOK);
        b.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View arg0) {
                if (!isInEquals) {
                    doEqualsChar();
                }
                close();
            }
        });
        b = (Button) findViewById(R.id.bCancel);
        b.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View arg0) {
                setResult(RESULT_CANCELED);
                finish();
            }
        });

        Intent intent = getIntent();
        if (intent != null) {
            String amount = intent.getStringExtra(AmountInput.EXTRA_AMOUNT);
            if (amount != null) {
                setDisplay(amount);
            }
        }

    }

    @Override
    public void onClick(View v) {
        Button b = (Button) v;
        char c = b.getText().charAt(0);
        onButtonClick(c);
    }

    private void setDisplay(String s) {
        if (Utils.isNotEmpty(s)) {
            s = s.replaceAll(",", ".");
            result = s;
            tvResult.setText(s);
        }
    }

    private void onButtonClick(char c) {
        if (vibrator != null) {
            vibrator.vibrate(20);
        }
        switch (c) {
            case 'C':
                resetAll();
                break;
            case '<':
                doBackspace();
                break;
            default:
                doButton(c);
                break;
        }
    }

    private void resetAll() {
        setDisplay("0");
        tvOp.setText("");
        lastOp = '\0';
        isRestart = true;
        stack.clear();
    }

    private void doBackspace() {
        String s = tvResult.getText().toString();
        if ("0".equals(s) || isRestart) {
            return;
        }
        String newDisplay = s.length() > 1 ? s.substring(0, s.length() - 1) : "0";
        if ("-".equals(newDisplay)) {
            newDisplay = "0";
        }
        setDisplay(newDisplay);
    }

    private void doButton(char c) {
        if (Character.isDigit(c) || c == '.') {
            addChar(c);
        } else {
            switch (c) {
                case '+':
                case '-':
                case '/':
                case '*':
                    doOpChar(c);
                    break;
                case '%':
                    doPercentChar();
                    break;
                case '=':
                case '\r':
                    doEqualsChar();
                    break;
                case '\u00B1':
                    setDisplay(new BigDecimal(result).negate().toPlainString());
                    break;
            }
        }
    }

    private void addChar(char c) {
        String s = tvResult.getText().toString();
        if (c == '.' && s.indexOf('.') != -1 && !isRestart) {
            return;
        }
        if ("0".equals(s)) {
            s = String.valueOf(c);
        } else {
            s += c;
        }
        setDisplay(s);
        if (isRestart) {
            setDisplay(String.valueOf(c));
            isRestart = false;
        }
    }

    private void doOpChar(char op) {
        if (isInEquals) {
            stack.clear();
            isInEquals = false;
        }
        stack.push(result);
        doLastOp();
        lastOp = op;
        tvOp.setText(String.valueOf(lastOp));
    }

    private void doLastOp() {
        isRestart = true;
        if (lastOp == '\0' || stack.size() == 1) {
            return;
        }

        String valTwo = stack.pop();
        String valOne = stack.pop();
        switch (lastOp) {
            case '+':
                stack.push(new BigDecimal(valOne).add(new BigDecimal(valTwo)).toPlainString());
                break;
            case '-':
                stack.push(new BigDecimal(valOne).subtract(new BigDecimal(valTwo)).toPlainString());
                break;
            case '*':
                stack.push(new BigDecimal(valOne).multiply(new BigDecimal(valTwo)).toPlainString());
                break;
            case '/':
                BigDecimal d2 = new BigDecimal(valTwo);
                if (d2.intValue() == 0) {
                    stack.push("0.0");
                } else {
                    stack.push(new BigDecimal(valOne).divide(d2, 2, BigDecimal.ROUND_HALF_UP).toPlainString());
                }
                break;
            default:
                break;
        }
        setDisplay(stack.peek());
        if (isInEquals) {
            stack.push(valTwo);
        }
    }

    private void doPercentChar() {
        if (stack.size() == 0)
            return;
        setDisplay(new BigDecimal(result).divide(Utils.HUNDRED).multiply(new BigDecimal(stack.peek())).toPlainString());
        tvOp.setText("");
    }

    private void doEqualsChar() {
        if (lastOp == '\0') {
            return;
        }
        if (!isInEquals) {
            isInEquals = true;
            stack.push(result);
        }
        doLastOp();
        tvOp.setText("");
    }

    private void close() {
        Intent data = new Intent();
        data.putExtra(AmountInput.EXTRA_AMOUNT, result);
        setResult(RESULT_OK, data);
        finish();
    }

}