/* 
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

using System;

using IndexReader = Lucene.Net.Index.IndexReader;
using FieldCache = Lucene.Net.Search.FieldCache;

namespace Lucene.Net.Search.Function
{
    
    /// <summary> Expert: obtains short field values from the 
    /// <see cref="Lucene.Net.Search.FieldCache">FieldCache</see>
    /// using <c>getShorts()</c> and makes those values 
    /// available as other numeric types, casting as needed.
    /// 
    /// <p/><font color="#FF0000">
    /// WARNING: The status of the <b>Search.Function</b> package is experimental. 
    /// The APIs introduced here might change in the future and will not be 
    /// supported anymore in such a case.</font>
    /// 
    /// </summary>
    /// <seealso cref="Lucene.Net.Search.Function.FieldCacheSource"> for requirements
    /// on the field.
    /// 
    /// <p/><b>NOTE</b>: with the switch in 2.9 to segment-based
    /// searching, if <see cref="FieldCacheSource.GetValues" /> is invoked with a
    /// composite (multi-segment) reader, this can easily cause
    /// double RAM usage for the values in the FieldCache.  It's
    /// best to switch your application to pass only atomic
    /// (single segment) readers to this API.<p/>
    /// </seealso>
    [Serializable]
    public class ShortFieldSource:FieldCacheSource
    {
        private class AnonymousClassDocValues:DocValues
        {
            public AnonymousClassDocValues(short[] arr, ShortFieldSource enclosingInstance)
            {
                InitBlock(arr, enclosingInstance);
            }
            private void  InitBlock(short[] arr, ShortFieldSource enclosingInstance)
            {
                this.arr = arr;
                this.enclosingInstance = enclosingInstance;
            }
            private short[] arr;
            private ShortFieldSource enclosingInstance;
            public ShortFieldSource Enclosing_Instance
            {
                get
                {
                    return enclosingInstance;
                }
                
            }
            /*(non-Javadoc) <see cref="Lucene.Net.Search.Function.DocValues.floatVal(int) */
            public override float FloatVal(int doc)
            {
                return (float) arr[doc];
            }
            /*(non-Javadoc) <see cref="Lucene.Net.Search.Function.DocValues.intVal(int) */
            public override int IntVal(int doc)
            {
                return arr[doc];
            }
            /*(non-Javadoc) <see cref="Lucene.Net.Search.Function.DocValues.toString(int) */
            public override System.String ToString(int doc)
            {
                return Enclosing_Instance.Description() + '=' + IntVal(doc);
            }
            /*(non-Javadoc) <see cref="Lucene.Net.Search.Function.DocValues.getInnerArray() */

            protected internal override object InnerArray
            {
                get { return arr; }
            }
        }
        private Lucene.Net.Search.ShortParser parser;
        
        /// <summary> Create a cached short field source with default string-to-short parser. </summary>
        public ShortFieldSource(System.String field):this(field, null)
        {
        }
        
        /// <summary> Create a cached short field source with a specific string-to-short parser. </summary>
        public ShortFieldSource(System.String field, Lucene.Net.Search.ShortParser parser):base(field)
        {
            this.parser = parser;
        }
        
        /*(non-Javadoc) <see cref="Lucene.Net.Search.Function.ValueSource.description() */
        public override System.String Description()
        {
            return "short(" + base.Description() + ')';
        }
        
        /*(non-Javadoc) <see cref="Lucene.Net.Search.Function.FieldCacheSource.getCachedValues(Lucene.Net.Search.FieldCache, java.lang.String, Lucene.Net.Index.IndexReader) */
        public override DocValues GetCachedFieldValues(FieldCache cache, System.String field, IndexReader reader)
        {
            short[] arr = cache.GetShorts(reader, field, parser);
            return new AnonymousClassDocValues(arr, this);
        }
        
        /*(non-Javadoc) <see cref="Lucene.Net.Search.Function.FieldCacheSource.cachedFieldSourceEquals(Lucene.Net.Search.Function.FieldCacheSource) */
        public override bool CachedFieldSourceEquals(FieldCacheSource o)
        {
            if (o.GetType() != typeof(ShortFieldSource))
            {
                return false;
            }
            ShortFieldSource other = (ShortFieldSource) o;
            return this.parser == null?other.parser == null:this.parser.GetType() == other.parser.GetType();
        }
        
        /*(non-Javadoc) <see cref="Lucene.Net.Search.Function.FieldCacheSource.cachedFieldSourceHashCode() */
        public override int CachedFieldSourceHashCode()
        {
            return parser == null?typeof(System.Int16).GetHashCode():parser.GetType().GetHashCode();
        }
    }
}