/**
 * SQL-DK
 * Copyright © 2015 František Kučera (frantovo.cz)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 3 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package info.globalcode.sql.dk.formatting;

import info.globalcode.sql.dk.Functions;
import info.globalcode.sql.dk.configuration.PropertyDeclaration;
import info.globalcode.sql.dk.logging.LoggerProducer;
import java.math.BigDecimal;
import java.math.MathContext;
import java.math.RoundingMode;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * TODO: min/max values – range for case that no value is 100 %
 *
 * TODO: multiple barcharts in same table (last column is still default) + multiple resultsets
 *
 * TODO: negative values - bar starting from the middle, not always from the left
 *
 * @author Ing. František Kučera (frantovo.cz)
 */
@PropertyDeclaration(name = BarChartFormatter.PROPERTY_PRECISION, type = Integer.class, defaultValue = BarChartFormatter.PROPERTY_PRECISION_DEFAULT, description = "number of characters representing 100 % in the bar chart")
public class BarChartFormatter extends TabularPrefetchingFormatter {

	public static final String NAME = "barchart"; // bash-completion:formatter
	public static final String PROPERTY_PRECISION = "precision";
	protected static final String PROPERTY_PRECISION_DEFAULT = "100";
	private static final MathContext mathContext = MathContext.DECIMAL128;
	public static final Logger log = LoggerProducer.getLogger();
	private final BigDecimal chartPrecision;
	private final char chartFull;
	private final char chartEmpty;

	public BarChartFormatter(FormatterContext formatterContext) {
		super(formatterContext);
		chartPrecision = BigDecimal.valueOf(formatterContext.getProperties().getInteger(PROPERTY_PRECISION, Integer.parseInt(PROPERTY_PRECISION_DEFAULT)));
		chartFull = isAsciiNostalgia() ? '#' : '█';
		chartEmpty = isAsciiNostalgia() ? '~' : '░';
		// TODO: consider using partial blocks for more precision: https://en.wikipedia.org/wiki/Block_Elements
	}

	@Override
	protected void postprocessPrefetchedResultSet(ColumnsHeader currentHeader, List<Object[]> currentResultSet) {
		super.postprocessPrefetchedResultSet(currentHeader, currentResultSet);

		updateColumnWidth(currentHeader.getColumnCount(), chartPrecision.intValue());

		BigDecimal maximum = BigDecimal.ZERO;
		BigDecimal minimum = BigDecimal.ZERO;
		int lastIndex = currentHeader.getColumnCount() - 1;

		Object valueObject = null;
		try {
			for (Object[] row : currentResultSet) {
				valueObject = row[lastIndex];
				if (valueObject != null) {
					BigDecimal value = new BigDecimal(valueObject.toString());
					maximum = maximum.max(value);
					minimum = minimum.min(value);
				}
			}

			BigDecimal range = maximum.subtract(minimum);

			for (Object[] row : currentResultSet) {
				valueObject = row[lastIndex];
				if (valueObject == null) {
					row[lastIndex] = "";
				} else {
					BigDecimal value = new BigDecimal(valueObject.toString());
					BigDecimal valueFromMinimum = value.subtract(minimum);

					BigDecimal points = chartPrecision.divide(range, mathContext).multiply(valueFromMinimum, mathContext);
					int pointsRounded = points.setScale(0, RoundingMode.HALF_UP).intValue();
					row[lastIndex] = Functions.repeat(chartFull, pointsRounded) + Functions.repeat(chartEmpty, chartPrecision.intValue() - pointsRounded);
				}
			}

		} catch (NumberFormatException e) {
			// https://en.wiktionary.org/wiki/parsable
			log.log(Level.SEVERE, "Last column must be number or an object with toString() value parsable to a number. But was „{0}“", valueObject);
			// FIXME: throw FormatterException
			throw e;
		}
	}

}