PossibleUnitConversionsImpl.java

/**
 * ***************************************************************************
 * Copyright (c) 2010 Qcadoo Limited
 * Project: Qcadoo Framework
 * Version: 1.4
 *
 * This file is part of Qcadoo.
 *
 * Qcadoo is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published
 * by the Free Software Foundation; either version 3 of the License,
 * or (at your option) any later version.
 *
 * 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 * ***************************************************************************
 */
package com.qcadoo.model.internal.units;

import java.math.BigDecimal;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.qcadoo.model.api.DataDefinition;
import com.qcadoo.model.api.Entity;
import com.qcadoo.model.api.NumberService;
import com.qcadoo.model.api.units.UnitConversion;
import com.qcadoo.model.api.units.UnsupportedUnitConversionException;
import com.qcadoo.model.constants.UnitConversionItemFields;

public final class PossibleUnitConversionsImpl implements InternalPossibleUnitConversions {

    private final Map<String, BigDecimal> targetUnitToFactor;

    private final String unitFrom;

    private final NumberService numberService;

    private final DataDefinition unitConversionItemDD;

    public PossibleUnitConversionsImpl(final String unitFrom, final NumberService numberService,
            final DataDefinition unitConversionItemDD) {
        Preconditions.checkNotNull(unitFrom);
        Preconditions.checkNotNull(numberService);
        Preconditions.checkNotNull(unitConversionItemDD);

        this.unitFrom = unitFrom;
        this.numberService = numberService;
        this.unitConversionItemDD = unitConversionItemDD;
        this.targetUnitToFactor = Maps.newHashMap();
    }

    @Override
    public void addConversion(final UnitConversion unitConversion) {
        Preconditions.checkArgument(unitFrom.equals(unitConversion.getUnitFrom()), "Wrong source unit!");
        final String unit = unitConversion.getUnitTo();
        if (!isDefinedFor(unit)) {
            targetUnitToFactor.put(unitConversion.getUnitTo(), unitConversion.getRatio());
        }
    }

    @Override
    public boolean isEmpty() {
        return targetUnitToFactor.isEmpty();
    }

    @Override
    public boolean isDefinedFor(final String unit) {
        return targetUnitToFactor.containsKey(unit);
    }

    @Override
    public Set<String> getSupportedUnits() {
        return Collections.unmodifiableSet(targetUnitToFactor.keySet());
    }

    @Override
    public BigDecimal convertTo(final BigDecimal quantityFrom, final String unitTo) {
        final BigDecimal ratio = targetUnitToFactor.get(unitTo);
        if (ratio == null) {
            throw new UnsupportedUnitConversionException(unitFrom, unitTo);
        }
        return numberService.setScale(quantityFrom.multiply(ratio));
    }

    @Override
    public String getUnitFrom() {
        return unitFrom;
    }

    @Override
    public Map<String, BigDecimal> asUnitToConversionMap() {
        return Collections.unmodifiableMap(targetUnitToFactor);
    }

    @Override
    public List<Entity> asEntities(final String ownerFieldName, final Entity ownerEntity) {
        final List<Entity> entities = Lists.newArrayList();
        for (final Map.Entry<String, BigDecimal> unitToFactorMapEntry : targetUnitToFactor.entrySet()) {
            final Entity entity = buildUnitConversionItem(unitToFactorMapEntry.getKey(), unitToFactorMapEntry.getValue(),
                    ownerEntity);
            entity.setField(ownerFieldName, ownerEntity);
            entities.add(entity);
        }
        return entities;
    }

    private Entity buildUnitConversionItem(final String unitTo, final BigDecimal ratio, final Entity ownerEntity) {
        final Entity unitConversionItem = unitConversionItemDD.create();
        unitConversionItem.setField(UnitConversionItemFields.UNIT_FROM, unitFrom);
        unitConversionItem.setField(UnitConversionItemFields.UNIT_TO, unitTo);
        unitConversionItem.setField(UnitConversionItemFields.QUANTITY_FROM, numberService.setScale(BigDecimal.ONE));
        unitConversionItem.setField(UnitConversionItemFields.QUANTITY_TO,
                calculateQuantityTo(unitFrom, unitTo, ratio, ownerEntity));
        return unitConversionItem;
    }

    private BigDecimal calculateQuantityTo(final String unitFrom, final String unitTo, final BigDecimal ratio,
            final Entity ownerEntity) {
        return numberService.setScale(BigDecimal.ONE.multiply(ratio));
    }
}