/*
 Copyright 2013 Red Hat, Inc. and/or its affiliates.

 This file is part of lightblue.

 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, 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 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 com.redhat.lightblue.assoc;

import java.io.Serializable;

import java.util.Map;
import java.util.HashMap;

import com.redhat.lightblue.metadata.CompositeMetadata;

/**
 * Abstract base class for query plan node. The node keeps the composite
 * metadata corresponding to this query plan node, and the query clauses
 * associated with it. The actual tree representation of the node is managed by
 * the implementation, which is an inner class in QueryPlan.
 */
public abstract class QueryPlanNode implements Serializable {

    private static final long serialVersionUID = 1l;

    protected final CompositeMetadata md;
    protected final QueryPlanData data;

    private final Map<String, Object> properties = new HashMap<>();

    /**
     * Creates a query plan node using the given composite metadata, and an
     * empty query clauses list
     */
    public QueryPlanNode(CompositeMetadata md, QueryPlanData data) {
        this.md = md;
        this.data = data;
    }

    /**
     * Copy constructor. A reference to the composite metadata, and a copy of
     * the query clauses is saved.
     */
    public QueryPlanNode(QueryPlanNode source) {
        this.md = source.md;
        this.data = source.data.newInstance();
        this.data.copyFrom(source.data);
        this.properties.putAll(source.properties);
    }

    /**
     * Returns the composite metadata associated with this node
     */
    public CompositeMetadata getMetadata() {
        return md;
    }

    /**
     * Returns the query plan data used by the scorer
     */
    public QueryPlanData getData() {
        return data;
    }

    /**
     * Returns the property with the given property name
     */
    public Object getProperty(String propertyName) {
        return properties.get(propertyName);
    }

    /**
     * Sets the property with the given property name
     */
    public void setProperty(String propertyName, Object value) {
        properties.put(propertyName, value);
    }

    /**
     * Returns the property whose property name is the given class name
     */
    public <T> T getProperty(Class<T> propertyClass) {
        return (T) properties.get(propertyClass.getName());
    }

    /**
     * Sets the property whose property name is the given class name
     */
    public <T> void setProperty(Class<T> propertyClass, T propertyValue) {
        properties.put(propertyClass.getName(), propertyValue);
    }

    /**
     * The implementation returns the unique name for this node. Used to
     * determine uniqueness in resolving field bindings.
     */
    public abstract String getName();

    /**
     * Returns the immediate ancestors of this node. If there are none (i.e.
     * node is a source), returns an array with size 0
     */
    public abstract QueryPlanNode[] getSources();

    /**
     * Returns the immediate descendants of this node. If there are node (i.e.
     * node is a sink), returns an array with size 0
     */
    public abstract QueryPlanNode[] getDestinations();

}