/*
 * Copyright (c) 2011, 2021 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Oracle - initial API and implementation
//
package org.eclipse.persistence.jpa.jpql.tools.model.query;

import java.io.IOException;
import java.util.List;
import java.util.ListIterator;
import org.eclipse.persistence.jpa.jpql.parser.CollectionMemberDeclaration;
import org.eclipse.persistence.jpa.jpql.tools.spi.IManagedType;
import org.eclipse.persistence.jpa.jpql.tools.utility.iterable.SingleElementListIterable;
import org.eclipse.persistence.jpa.jpql.utility.iterable.ListIterable;
import static org.eclipse.persistence.jpa.jpql.parser.AbstractExpression.*;

/**
 * An identification variable declared by a <code>collection_member_declaration</code> ranges over
 * values of a collection obtained by navigation using a path expression. Such a path expression
 * represents a navigation involving the association-fields of an entity abstract schema type.
 * Because a path expression can be based on another path expression, the navigation can use the
 * association-fields of related entities. An identification variable of a collection member
 * declaration is declared using a special operator, the reserved identifier <code><b>IN</b></code>.
 * The argument to the <code><b>IN</b></code> operator is a collection-valued path expression. The
 * path expression evaluates to a collection type specified as a result of navigation to a
 * collection-valued association-field of an entity abstract schema type. The syntax for declaring a
 * collection member identification variable is as follows:
 *
 * <div><p><b>BNF:</b> <code>collection_member_declaration ::= IN(collection_valued_path_expression) [AS] identification_variable</code></p></div>
 * or
 * <div><p><b>BNF:</b> <code>derived_collection_member_declaration ::= IN superquery_identification_variable.{single_valued_object_field.}*collection_valued_field</code></p></div>
 *
 * @see FromClauseStateObject
 * @see CollectionMemberDeclaration
 *
 * @version 2.5
 * @since 2.4
 * @author Pascal Filion
 */
@SuppressWarnings({"nls", "unused"}) // unused used for the import statement: see bug 330740
public class CollectionMemberDeclarationStateObject extends AbstractStateObject
                                                    implements VariableDeclarationStateObject {

    /**
     * Flag used to determine if the <code><b>AS</b></code> identifier is used or not.
     */
    private boolean as;

    /**
     * The model object representing the collection-valued association-field of an entity abstract
     * schema type.
     */
    private CollectionValuedPathExpressionStateObject collectionValuedPath;

    /**
     * Determines whether this collection member declaration is used as a deriving collection-valued
     * path expression.
     */
    private boolean derived;

    /**
     * The model object representing an identification variable evaluating to a collection-valued
     * association-field of an entity abstract schema type.
     */
    private IdentificationVariableStateObject identificationVariable;

    /**
     * Notifies the visibility of the <code><b>AS</b></code> identifier has changed.
     */
    public static final String AS_PROPERTY = "as";

    /**
     * Creates a new <code>CollectionMemberDeclarationStateObject</code>.
     *
     * @param parent The parent of this state object, which cannot be <code>null</code>
     * @exception NullPointerException The given parent cannot be <code>null</code>
     */
    public CollectionMemberDeclarationStateObject(AbstractFromClauseStateObject parent) {
        super(parent);
    }

    /**
     * Creates a new <code>CollectionMemberDeclarationStateObject</code>.
     *
     * @param parent The parent of this state object, which cannot be <code>null</code>
     * @param paths The segments that represent the collection-valued path
     * @param as Determine whether the <code><b>AS</b></code> identifier is used or not
     * @param identificationVariable The identification variable declaring the collection-valued path
     * @exception NullPointerException The given parent cannot be <code>null</code>
     */
    public CollectionMemberDeclarationStateObject(AbstractFromClauseStateObject parent,
                                                  ListIterator<String> paths,
                                                  boolean as,
                                                  String identificationVariable) {

        super(parent);
        this.as = as;
        getCollectionValuedPath().setPaths(paths);
        setIdentificationVariable(identificationVariable);
    }

    /**
     * Creates a new <code>CollectionMemberDeclarationStateObject</code>.
     *
     * @param parent The parent of this state object, which cannot be <code>null</code>
     * @param paths The segments that represent the collection-valued path
     * @param identificationVariable The identification variable declaring the collection-valued path
     * @exception NullPointerException The given parent cannot be <code>null</code>
     */
    public CollectionMemberDeclarationStateObject(AbstractFromClauseStateObject parent,
                                                  ListIterator<String> paths,
                                                  String identificationVariable) {

        this(parent, paths, false, identificationVariable);
    }

    /**
     * Creates a new <code>CollectionMemberDeclarationStateObject</code>.
     *
     * @param parent The parent of this state object, which cannot be <code>null</code>
     * @param collectionValuedPath The derived collection-valued path expression
     * @exception NullPointerException The given parent cannot be <code>null</code>
     */
    public CollectionMemberDeclarationStateObject(SimpleFromClauseStateObject parent,
                                                  String collectionValuedPath) {

        super(parent);
        this.derived = true;
        setPath(collectionValuedPath);
    }

    @Override
    public void accept(StateObjectVisitor visitor) {
        visitor.visit(this);
    }

    /**
     * Makes sure the <code><b>AS</b></code> identifier is specified.
     *
     * @return This object
     */
    public CollectionMemberDeclarationStateObject addAs() {
        if (!as) {
            setAs(true);
        }
        return this;
    }

    @Override
    protected void addChildren(List<StateObject> children) {
        super.addChildren(children);
        children.add(collectionValuedPath);
        children.add(identificationVariable);
    }

    /**
     * Returns the model object representing the collection-valued association-field
     * of an entity abstract schema type.
     *
     * @return The collection-valued association-field of an entity abstract
     * schema type
     */
    public CollectionValuedPathExpressionStateObject getCollectionValuedPath() {
        return collectionValuedPath;
    }

    @Override
    public CollectionMemberDeclaration getExpression() {
        return (CollectionMemberDeclaration) super.getExpression();
    }

    /**
     * Returns the model object representing an identification variable
     * evaluating to a collection-valued association-field of an entity abstract
     * schema type.
     *
     * @return The identification variable portion of this declaration
     */
    public IdentificationVariableStateObject getIdentificationVariable() {
        return identificationVariable;
    }

    @Override
    public IManagedType getManagedType(StateObject stateObject) {

        if (identificationVariable.isEquivalent(stateObject)) {
            return collectionValuedPath.getManagedType();
        }

        return null;
    }

    @Override
    public AbstractFromClauseStateObject getParent() {
        return (AbstractFromClauseStateObject) super.getParent();
    }

    /**
     * Determines whether the <code><b>AS</b></code> identifier is used or not.
     *
     * @return <code>true</code> if the <code><b>AS</b></code> identifier is part
     * of the expression; <code>false</code> otherwise
     */
    public boolean hasAs() {
        return as;
    }

    /**
     * Determines whether an identification variable was defined.
     *
     * @return <code>true</code> if an identification variable is defined; <code>false</code> otherwise
     */
    public boolean hasIdentificationVariable() {
        return identificationVariable.hasText();
    }

    @Override
    public ListIterable<IdentificationVariableStateObject> identificationVariables() {
        return new SingleElementListIterable<IdentificationVariableStateObject>(identificationVariable);
    }

    @Override
    protected void initialize() {
        super.initialize();
        collectionValuedPath   = new CollectionValuedPathExpressionStateObject(this);
        identificationVariable = new IdentificationVariableStateObject(this);
    }

    /**
     * Determines whether this collection member declaration is used as a derived collection-valued
     * path expression.
     *
     * @return <code>true</code> if this collection member declaration is used as this form:
     * "<code><b>IN</b> collection_valued_path_expression</code>" in a subquery; <code>false</code>
     * if it's used as this form: <code><b>IN</b>(collection_valued_path_expression)
     * [<b>AS</b>] identification_variable</code>" in a top-level or subquery queries
     */
    public boolean isDerived() {
        return derived;
    }

    @Override
    public boolean isEquivalent(StateObject stateObject) {

        if (super.isEquivalent(stateObject)) {
            CollectionMemberDeclarationStateObject declaration = (CollectionMemberDeclarationStateObject) stateObject;

            return as      == declaration.as      &&
                   derived == declaration.derived &&
                   identificationVariable.isEquivalent(declaration.identificationVariable) &&
                   collectionValuedPath  .isEquivalent(declaration.collectionValuedPath);
        }

        return false;
    }

    /**
     * Makes sure the <code><b>AS</b></code> identifier is not specified.
     */
    public void removeAs() {
        if (as) {
            setAs(false);
        }
    }

    /**
     * Sets whether the <code><b>AS</b></code> identifier is used or not.
     *
     * @param as <code>true</code> if the <code><b>AS</b></code> identifier is part of the expression;
     * <code>false</code> otherwise
     */
    public void setAs(boolean as) {
        boolean oldAs = this.as;
        this.as = as;
        firePropertyChanged(AS_PROPERTY, oldAs, as);
    }

    /**
     * Sets whether this collection member declaration is used as a derived collection-valued path
     * expression.
     *
     * @param derived <code>true</code> if this collection member declaration is used as this form:
     * "<code><b>IN</b> collection_valued_path_expression</code>" in a subquery; <code>false</code>
     * if it's used as this form: <code><b>IN</b>(collection_valued_path_expression)
     * [<b>AS</b>] identification_variable</code>" in a top-level or subquery queries
     */
    public void setDerived(boolean derived) {
        this.derived = derived;
    }

    /**
     * Keeps a reference of the {@link CollectionMemberDeclaration parsed object} object, which
     * should only be done when this object is instantiated during the conversion of a parsed JPQL
     * query into {@link StateObject StateObjects}.
     *
     * @param expression The {@link CollectionMemberDeclaration parsed object} representing an <code><b>IN</b></code>
     * expression
     */
    public void setExpression(CollectionMemberDeclaration expression) {
        super.setExpression(expression);
    }

    /**
     * Sets the new identification variable that will range over the collection-valued path.
     *
     * @param identificationVariable The new identification variable
     */
    public void setIdentificationVariable(String identificationVariable) {
        this.identificationVariable.setText(identificationVariable);
    }

    /**
     * Changes the path expression with the list of segments, the identification variable will also
     * be updated with the first segment.
     *
     * @param path The new path expression
     */
    public void setPath(String path) {
        collectionValuedPath.setPath(path);
    }

    /**
     * Changes the path expression with the list of segments, the identification variable will also
     * be updated with the first segment.
     *
     * @param paths The new path expression
     */
    public void setPaths(List<String> paths) {
        collectionValuedPath.setPaths(paths);
    }

    /**
     * Changes the path expression with the list of segments, the identification variable will also
     * be updated with the first segment.
     *
     * @param paths The new path expression
     */
    public void setPaths(ListIterator<String> paths) {
        collectionValuedPath.setPaths(paths);
    }

    /**
     * Changes the path expression with the list of segments, the identification variable will also
     * be updated with the first segment.
     *
     * @param paths The new path expression
     */
    public void setPaths(String... paths) {
        collectionValuedPath.setPaths(paths);
    }

    /**
     * Toggles the usage of the <code><b>AS</b></code> identifier.
     */
    public void toggleAs() {
        setAs(!as);
    }

    @Override
    protected void toTextInternal(Appendable writer) throws IOException {

        writer.append(IN);

        if (!derived) {
            writer.append(LEFT_PARENTHESIS);
        }
        else {
            writer.append(SPACE);
        }

        collectionValuedPath.toString(writer);

        if (!derived) {
            writer.append(RIGHT_PARENTHESIS);
        }

        if (!derived) {
            writer.append(SPACE);

            if (as) {
                writer.append(AS);
                writer.append(SPACE);
            }

            identificationVariable.toString(writer);
        }
    }
}