/*
 * Copyright 1999-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* $Id$ */

package org.apache.fop.fo.properties;

import org.apache.fop.apps.FOPException;
import org.apache.fop.datatypes.Length;
import org.apache.fop.datatypes.Numeric;
import org.apache.fop.fo.FObj;
import org.apache.fop.fo.PropertyList;

/**
 * Superclass for properties wrapping a Length value.
 */
abstract public class LengthProperty extends Property 
    implements Length, Numeric
{
    /**
     * Inner class for making instances of LengthProperty
     */
    public static class Maker extends PropertyMaker {
        private boolean autoOk = false;

        /**
         * @param name name of property for which Maker should be created
         */
        public Maker(int propId) {
            super(propId);
        }

        /**
         * protected Property checkPropertyKeywords(String value) {
         * if (isAutoLengthAllowed() && value.equals("auto")) {
         * return new LengthProperty(Length.AUTO);
         * }
         * return null;
         * }
         */

        /**
         * @return false (auto-length is not allowed for Length values)
         */
        protected boolean isAutoLengthAllowed() {
            return autoOk;
        }

        /**
         * Set the auto length flag.
         * @param inherited
         */
        public void setAutoOk(boolean autoOk) {
            this.autoOk = autoOk;
        }

        /**
         * @see PropertyMaker#convertProperty
         */
        public Property convertProperty(Property p,
                                        PropertyList propertyList,
                                        FObj fo) throws FOPException {
            Property prop = super.convertProperty(p, propertyList, fo);
            if (prop != null) {
                return prop;
            }
            if (isAutoLengthAllowed()) {
                String pval = p.getString();
                if (pval != null && pval.equals("auto")) {
                    return new AutoLength();
                }
            }
            if (p instanceof LengthProperty) {
                return p;
            }
            Length val = p.getLength();
            if (val != null) {
                return (Property) val;
            }
            return convertPropertyDatatype(p, propertyList, fo);
        }

    }

    /**
     * Indicates if the length has the "auto" value.
     * @return True if the length is set to "auto"
     */
    public boolean isAuto() {
        return false;
    }

    /**
     * Return the number of table units which are included in this
     * length specification.
     * This will always be 0 unless the property specification used
     * the proportional-column-width() function (only only table
     * column FOs).
     * <p>If this value is not 0, the actual value of the Length cannot
     * be known without looking at all of the columns in the table to
     * determine the value of a "table-unit".
     * @return The number of table units which are included in this
     * length specification.
     */
    public double getTableUnits() {
        return 0.0;
    }

    /**
     * Return the numeric dimension. Length always a dimension of 1.
     */
    public int getDimension() {
        return 1;
    }

    /**
     * @return this.length cast as a Numeric
     */
    public Numeric getNumeric() {
        return this;
    }

    /**
     * @return this.length
     */
    public Length getLength() {
        return this;
    }

    /**
     * @return this.length cast as an Object
     */
    public Object getObject() {
        return this;
    }

}