package com.vaadin.addon.spreadsheet;

/*
 * #%L
 * Vaadin Spreadsheet
 * %%
 * Copyright (C) 2013 - 2015 Vaadin Ltd
 * %%
 * This program is available under Commercial Vaadin Add-On License 3.0
 * (CVALv3).
 * 
 * See the file license.html distributed with this software for more
 * information about licensing.
 * 
 * You should have received a copy of the CVALv3 along with this program.
 * If not, see <http://vaadin.com/license/cval-3>.
 * #L%
 */

import java.io.Serializable;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.util.Arrays;

/**
 * Utility class for formatting cell values
 */
public class CellValueFormatter implements Serializable {

    private DecimalFormatSymbols localeDecimalSymbols = DecimalFormatSymbols
            .getInstance();

    public String getScientificNotationStringForNumericCell(
            double numericValue, String formattedValue, float cellWidthRatio,
            int width) {
        BigDecimal ratio = new BigDecimal(cellWidthRatio);
        BigDecimal columnWidth = new BigDecimal(width);
        int numberOfDigits = columnWidth.divide(ratio, RoundingMode.DOWN)
                .intValue();
        if (numberOfDigits < 2) {
            return "#";
        } else {
            int integerPartLength = formattedValue.indexOf(localeDecimalSymbols
                    .getDecimalSeparator());
            if (integerPartLength == -1) {
                integerPartLength = formattedValue.length();
            }
            StringBuilder format = new StringBuilder("0");

            if (integerPartLength == formattedValue.length()
                    && numberOfDigits <= 4
                    && integerPartLength > numberOfDigits) {
                return createFillString(numberOfDigits);
            }

            // Needs scientific if integer part doesn't fit or if it's only
            // decimals and all decimal don't fit
            boolean needsScientific = integerPartLength > numberOfDigits
                    || (Math.abs(numericValue) < 1
                            && formattedValue.length() > numberOfDigits && numberOfDigits > 4);
            int numberOfDecimals = 0;
            if (needsScientific) {
                // 0.#E10
                numberOfDecimals = numberOfDigits - 5;
            } else {
                numberOfDecimals = numberOfDigits - (integerPartLength + 1);
            }

            if (numberOfDecimals > 0) {
                format.append('.');
                for (int i = 0; i < numberOfDecimals; i++) {
                    format.append('#');
                }
            }
            if (needsScientific) {
                format.append("E0");
            }

            if (format.length() > numberOfDigits) {
                return createFillString(numberOfDigits);
            }

            return new DecimalFormat(format.toString(), localeDecimalSymbols)
                    .format(numericValue);
        }
    }

    private String createFillString(int numberOfDigits) {
        char[] filling = new char[numberOfDigits];
        Arrays.fill(filling, '#');
        return new String(filling);
    }

    public void setLocaleDecimalSymbols(
            DecimalFormatSymbols localeDecimalSymbols) {
        this.localeDecimalSymbols = localeDecimalSymbols;
    }
}