Formula.java

/*
 * Copyright (C) 2021 INRAE AgroClim
 *
 * This file is part of Indicators.
 *
 * Indicators 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Indicators 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 Indicators. If not, see <http://www.gnu.org/licenses/>.
 */
package fr.inrae.agroclim.indicators.model.indicator;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.function.Function;
import java.util.stream.DoubleStream;

import fr.inrae.agroclim.indicators.exception.IndicatorsException;
import fr.inrae.agroclim.indicators.exception.type.ComputationErrorType;
import fr.inrae.agroclim.indicators.exception.type.ResourceErrorType;
import fr.inrae.agroclim.indicators.model.ExpressionParameter;
import fr.inrae.agroclim.indicators.model.JEXLFormula;
import fr.inrae.agroclim.indicators.model.Knowledge;
import fr.inrae.agroclim.indicators.model.Parameter;
import fr.inrae.agroclim.indicators.model.data.DailyData;
import fr.inrae.agroclim.indicators.model.data.Resource;
import fr.inrae.agroclim.indicators.model.data.Variable;
import fr.inrae.agroclim.indicators.util.Doublet;
import jakarta.xml.bind.annotation.XmlElement;
import jakarta.xml.bind.annotation.XmlType;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.RequiredArgsConstructor;
import lombok.Setter;

/**
 * Compute values using JEXL expressions.
 *
 * Last changed : $Date$
 *
 * @author $Author$
 * @version $Revision$
 */
@XmlType(propOrder = {"aggregation", "expression", "expressionParameters"})
@EqualsAndHashCode(
        callSuper = false,
        of = {"aggregation", "expression", "expressionParameters"}
        )
public final class Formula extends SimpleIndicator implements Detailable {

    /**
     * Aggregation to apply to computed values.
     */
    @RequiredArgsConstructor
    public enum Aggregation {
        /**
         * Average.
         */
        AVERAGE(s -> s.average().orElse(0)),
        /**
         * Count.
         */
        COUNT(s -> Double.valueOf(s.count())),
        /**
         * Get max value.
         */
        MAX(s -> s.max().orElse(0)),
        /**
         * Get min value.
         */
        MIN(s -> Double.valueOf(s.count())),
        /**
         * Get sum of values.
         */
        SUM(s -> s.sum());
        /**
         * Function to compute the aggregated value.
         */
        @Getter
        private final Function<DoubleStream, Double> function;
    }

    /**
     * UUID for Serializable.
     */
    private static final long serialVersionUID = 6030595237342422020L;

    /**
     * Aggregation to apply to computed values.
     */
    @Getter
    @Setter
    private Aggregation aggregation;

    /**
     * JEXL expression.
     */
    @Getter
    @Setter
    private String expression;

    /**
     * Parameters for JEXLFormula.
     */
    @Getter
    @Setter
    @XmlElement(name = "expressionParameter")
    private List<ExpressionParameter> expressionParameters;

    /**
     * org.apache.commons.jexl2.JexlEngine handler.
     */
    private transient JEXLFormula formula = new JEXLFormula();

    /**
     * Values id of parameter ⮕ value of parameter.
     */
    @Setter
    @Getter
    private transient Map<String, Double> parametersValues = new HashMap<>();

    @Override
    public double computeSingleValue(final Resource<? extends DailyData> res) throws IndicatorsException {
        if (aggregation == null) {
            throw new IndicatorsException(ComputationErrorType.FORMULA_AGGREGATION_NULL);
        }
        Objects.requireNonNull(res, "Resource must not be null!");
        if (res.getData() == null) {
            throw new IndicatorsException(ResourceErrorType.CLIMATE_EMPTY);
        }
        final Set<Variable> dataVariables = getVariables();
        final List<Double> computedValues = new ArrayList<>();
        for (final DailyData data : res.getData()) {
            final Map<String, Double> values = new HashMap<>();
            dataVariables.forEach(variable -> values.put(variable.name(), data.getValue(variable)));
            if (parametersValues != null) {
                values.putAll(parametersValues);
            }
            if (expressionParameters != null) {
                expressionParameters.forEach(p -> values.put(p.getName(), p.getValue()));
            }
            computedValues.add(formula.evaluate(values, Double.class));
        }
        final DoubleStream stream = computedValues.stream().mapToDouble(Double::doubleValue);
        return aggregation.getFunction().apply(stream);
    }

    @Override
    public List<Doublet<Parameter, Number>> getParameterDefaults() {
        // no substitution
        return List.of();
    }

    @Override
    public List<Parameter> getParameters() {
        final List<Parameter> params = new ArrayList<>();
        if (super.getParameters() != null) {
            params.addAll(super.getParameters());
        }
        if (parametersValues != null) {
            parametersValues.forEach((paramId, paramValue) -> {
                final Parameter param = new Parameter();
                param.setId(paramId);
                param.setAttribute(paramId);
                params.add(param);
            });
        }
        return params;
    }

    @Override
    public Set<Variable> getVariables() {
        Objects.requireNonNull(expression, "expression must not be null!");
        formula.setExpression(expression);
        return formula.getDataVariables();
    }

    @Override
    public boolean isComputable(final Resource<? extends DailyData> res) {
        if (res == null) {
            throw new IllegalArgumentException("resource must no be null!");
        }
        formula.setExpression(expression);
        return formula.isValid();
    }

    /**
     * Context: Deserialization does not initialize formula.
     *
     * A final field must be initialized either by direct assignment of an initial value or in the constructor. During
     * deserialization, neither of these are invoked, so initial values for transients must be set in the
     * 'readObject()' private method that's invoked during deserialization. And for that to work, the transients must
     * be non-final.
     *
     * @param ois input stream from deserialization
     */
    private void readObject(final ObjectInputStream ois) throws ClassNotFoundException, IOException {
        // perform the default de-serialization first
        ois.defaultReadObject();
        formula = new JEXLFormula();
    }

    @Override
    public void setParametersFromKnowledge(final Knowledge knowledge) {
        final Indicator indicator = knowledge.getIndicator(getId());
        setParameters(indicator.getParameters());
    }

    @Override
    public String toStringTree(final String indent) {
        final StringBuilder sb = new StringBuilder();
        sb.append(toStringTreeBase(indent));
        sb.append(indent).append("  expression: ").append(expression).append("\n");
        return sb.toString();
    }

    @Override
    public void removeParameter(final Parameter param) {
        if (parametersValues != null) {
            parametersValues.remove(param.getId());
        }
    }

}