# EntityCriteria.java

    package org.codefilarete.stalactite.engine;

    import org.codefilarete.reflection.AccessorChain;
    import org.codefilarete.reflection.Accessors;
    import org.codefilarete.reflection.ValueAccessPoint;
    import org.codefilarete.stalactite.query.model.ConditionalOperator;
    import org.codefilarete.tool.collection.Arrays;
    import org.danekja.java.util.function.serializable.SerializableBiConsumer;
    import org.danekja.java.util.function.serializable.SerializableFunction;

    import java.util.ArrayList;
    import java.util.Collection;
    import java.util.List;

    /**
     * Contract that allows to create some query criteria based on property accessors
     *
     * @param <C> type of object returned by query execution
     */
    public interface EntityCriteria<C, SELF extends EntityCriteria<C, SELF>> {

    	/**
    	 * Adds a criteria to the current instance with an {@code and} condition for the specified property
    	 * and the given operator.
    	 *
    	 * @param getter a method reference to the getter of the property to be evaluated
    	 * @param operator operator of the criteria (will be the condition on the matching column)
    	 * @return this instance for method chaining.
    	 * @param <O> getter return type, also criteria value
    	 * @throws IllegalArgumentException if the column matching the getter is not found.
    	 */
    	<O> SELF and(SerializableFunction<C, O> getter, ConditionalOperator<O, ?> operator);

    	/**
    	 * Adds a criteria to the current instance with an {@code and} condition for the specified property
    	 * and the given operator.
    	 *
    	 * @param setter a method reference to the setter of the property to be evaluated
    	 * @param operator operator of the criteria (will be the condition on the matching column)
    	 * @param <O> getter return type, also criteria value
    	 * @return this
    	 * @throws IllegalArgumentException if the column matching the setter was not found
    	 */
    	<O> SELF and(SerializableBiConsumer<C, O> setter, ConditionalOperator<O, ?> operator);

    	/**
    	 * Particular version of {@link #and(SerializableFunction, ConditionalOperator)} for an embedded or one-to-one bean
    	 * property.
    	 *
    	 * @param getter1 a method reference to the embedded bean
    	 * @param getter2 a method reference to the getter of the embedded property to be evaluated.
    	 * @param operator operator of the criteria (will be the condition on the matching column)
    	 * @param <A> embedded bean type
    	 * @param <B> embedded bean property type, also criteria value
    	 * @return this
    	 * @throws IllegalArgumentException if the column matching the getter was not found
    	 */
    	<A, B> SELF and(SerializableFunction<C, A> getter1, SerializableFunction<A, B> getter2, ConditionalOperator<B, ?> operator);

    	/**
    	 * Particular version of {@link #and(SerializableFunction, ConditionalOperator)} for a collection property to be
    	 * able to target its component type with a {@link ConditionalOperator}. Without it, operators can only apply to
    	 * the collection itself, which is rarely what is needed and not supported by Stalactite.
    	 *
    	 * @param collectionAccessor a method reference to the collection setter of the property to be evaluated
    	 * @param operator operator of the criteria (will be the condition on the matching column)
    	 * @param <O> getter return type, also criteria value
    	 * @return this
    	 * @throws IllegalArgumentException if the column matching the setter was not found
    	 */
    	<S extends Collection<O>, O> SELF and(SerializableCollectionFunction<C, S, O> collectionAccessor, ConditionalOperator<O, ?> operator);

    	/**
    	 * Generic version of {@link #and(SerializableFunction, ConditionalOperator)} with a (long) path to a property
    	 *
    	 * @param propertyPath a path representing access to the property to be evaluated
    	 * @param operator operator of the criteria (will be the condition on the matching column)
    	 * @param <O> getter return type, also criteria value
    	 * @return this
    	 * @throws IllegalArgumentException if the column matching the propertyPath was not found
    	 */
    	<O> SELF and(CriteriaPath<C, O> propertyPath, ConditionalOperator<O, ?> operator);

    	/**
    	 * Adds a criteria to the current instance with an {@code or} condition for the specified property
    	 * and the given operator.
    	 *
    	 * @param getter a method reference to the getter of the property to be evaluated
    	 * @param operator operator of the criteria (will be the condition on the matching column)
    	 * @param <O> getter return type, also criteria value
    	 * @return this
    	 * @throws IllegalArgumentException if the column matching the getter was not found
    	 */
    	<O> SELF or(SerializableFunction<C, O> getter, ConditionalOperator<O, ?> operator);

    	/**
    	 * Adds a criteria to the current instance with an {@code or} condition for the specified property
    	 * and the given operator.
    	 *
    	 * @param setter a method reference to the setter of the property to be evaluated
    	 * @param operator operator of the criteria (will be the condition on the matching column)
    	 * @param <O> getter return type, also criteria value
    	 * @return this
    	 * @throws IllegalArgumentException if the column matching the setter was not found
    	 */
    	<O> SELF or(SerializableBiConsumer<C, O> setter, ConditionalOperator<O, ?> operator);

    	/**
    	 * Particular version of {@link #or(SerializableFunction, ConditionalOperator)} for a collection property to be
    	 * able to target its component type with a {@link ConditionalOperator}. Without it, operators can only apply to
    	 * the collection itself, which is rarely what is needed and not supported by Stalactite.
    	 *
    	 * @param collectionAccessor a method reference to the collection setter of the property to be evaluated
    	 * @param operator operator of the criteria (will be the condition on the matching column)
    	 * @param <O> getter return type, also criteria value
    	 * @return this
    	 * @throws IllegalArgumentException if the column matching the setter was not found
    	 */
    	<S extends Collection<O>, O> SELF or(SerializableCollectionFunction<C, S, O> collectionAccessor, ConditionalOperator<O, ?> operator);

    	/**
    	 * Generic version of {@link #or(SerializableFunction, ConditionalOperator)} with a (long) path to a property
    	 *
    	 * @param propertyPath a path representing access to the property to be evaluated
    	 * @param operator operator of the criteria (will be the condition on the matching column)
    	 * @param <O> getter return type, also criteria value
    	 * @return this
    	 * @throws IllegalArgumentException if the column matching the propertyPath was not found
    	 */
    	<O> SELF or(CriteriaPath<C, O> propertyPath, ConditionalOperator<O, ?> operator);

    	/**
    	 * Starts a nested condition and returns it. At SQL rendering time, it should be embedded between parenthesis.
    	 * Result must be used to fill the nested condition, not the current instance.
    	 * After filling it, it must be closed by {@link #endNested()}
    	 *
    	 * @return a nested condition to be filled
    	 */
    	EntityCriteria<C, SELF> beginNested();

    	/**
    	 * Ends a nested condition started with {@link #beginNested()}. It returns the enclosing instance (the one on which {@link #beginNested()}
    	 * was called).
    	 *
    	 * @return the enclosing condition
    	 */
    	EntityCriteria<C, SELF> endNested();

    	default <O> SELF and(ValueAccessPoint<C> accessor, ConditionalOperator<O, ?> operator) {
    		if (accessor instanceof AccessorChain) {
    			return and(((AccessorChain<?, ?>) accessor).getAccessors(), operator);
    		} else {
    			return and(Arrays.asList(accessor), operator);
    		}
    	}

    	default <O> SELF or(ValueAccessPoint<C> accessor, ConditionalOperator<O, ?> operator) {
    		if (accessor instanceof AccessorChain) {
    			return or(((AccessorChain<?, ?>) accessor).getAccessors(), operator);
    		} else {
    			return or(Arrays.asList(accessor), operator);
    		}
    	}

    	<O> SELF and(List<? extends ValueAccessPoint<?>> accessors, ConditionalOperator<O, ?> operator);

    	<O> SELF or(List<? extends ValueAccessPoint<?>> accessors, ConditionalOperator<O, ?> operator);

    	interface OrderByChain<C, SELF extends OrderByChain<C, SELF>> {

    		default SELF orderBy(SerializableFunction<C, ?> getter) {
    			return orderBy(getter, Order.ASC);
    		}

    		default SELF orderBy(SerializableBiConsumer<C, ?> setter) {
    			return orderBy(setter, Order.ASC);
    		}

    		default SELF orderBy(AccessorChain<C, ?> getter) {
    			return orderBy(getter, Order.ASC);
    		}

    		SELF orderBy(SerializableFunction<C, ?> getter, Order order);

    		SELF orderBy(SerializableBiConsumer<C, ?> setter, Order order);

    		SELF orderBy(AccessorChain<C, ?> getter, Order order);

    		SELF orderBy(AccessorChain<C, ?> getter, Order order, boolean ignoreCase);

    		enum Order {
    			ASC,
    			DESC
    		}
    	}

    	interface LimitAware<R> {

    		R limit(int value);

    		R limit(int value, Integer offset);
    	}

    	interface FluentOrderByClause<C, SELF extends FluentOrderByClause<C, SELF>> extends OrderByChain<C, SELF>, LimitAware<SELF> {

    	}

    	/**
    	 * Represents a path of property to be given as a criteria.
    	 *
    	 * @param <IN> the input type, representing the source object type
    	 * @param <OUT> the output type, representing the target property type
    	 */
    	class CriteriaPath<IN, OUT> {

    		private final List<ValueAccessPoint<?>> accessors = new ArrayList<>();

    		public CriteriaPath(SerializableFunction<IN, OUT> accessor) {
    			this.accessors.add(Accessors.accessorByMethodReference(accessor));
    		}

    		public <S extends Collection<O>, O> CriteriaPath(SerializableCollectionFunction<IN, S, O> collectionAccessor, SerializableFunction<O, OUT> elementPropertyAccessor) {
    			this.accessors.add(Accessors.accessorByMethodReference(collectionAccessor));
    			this.accessors.add(Accessors.accessorByMethodReference(elementPropertyAccessor));
    		}

    		public List<ValueAccessPoint<?>> getAccessors() {
    			return accessors;
    		}

    		public <NEXT> CriteriaPath<IN, NEXT> add(SerializableFunction<OUT, NEXT> accessor) {
    			this.accessors.add(Accessors.accessorByMethodReference(accessor));
    			return (CriteriaPath<IN, NEXT>) this;
    		}

    		public <NEXT, S extends Collection<NEXT>> CriteriaPath<IN, NEXT> add(SerializableCollectionFunction<OUT, S, NEXT> accessor) {
    			this.accessors.add(Accessors.accessorByMethodReference(accessor));
    			return (CriteriaPath<IN, NEXT>) this;
    		}
    	}

    	/**
    	 * Specialized version of {@link SerializableFunction} for collection accessors: the output type is the collection
    	 * element type, which makes this not really a {@link SerializableFunction} but useful in the context of {@link CriteriaPath}
    	 *
    	 * @param <T> the input type
    	 * @param <S> the collection type
    	 * @param <O> the collection element type
    	 * @author Guillaume Mary
    	 */
    	@FunctionalInterface
    	interface SerializableCollectionFunction<T, S extends Collection<O>, O> extends SerializableFunction<T, S> {

    	}
    }