/*
 * 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 Analyzer = Lucene.Net.Analysis.Analyzer;
using BooleanClause = Lucene.Net.Search.BooleanClause;
using BooleanQuery = Lucene.Net.Search.BooleanQuery;
using MultiPhraseQuery = Lucene.Net.Search.MultiPhraseQuery;
using PhraseQuery = Lucene.Net.Search.PhraseQuery;
using Query = Lucene.Net.Search.Query;

namespace Lucene.Net.QueryParsers
{
	
	/// <summary> A QueryParser which constructs queries to search multiple fields.
	/// 
	/// </summary>
	/// <author>  <a href="mailto:kelvin@relevanz.com">Kelvin Tan</a>, Daniel Naber
	/// </author>
	/// <version>  $Revision: 295117 $
	/// </version>
	public class MultiFieldQueryParser : QueryParser
	{
		
		private System.String[] fields;
		
		/// <summary> Creates a MultiFieldQueryParser.
		/// 
		/// <p>It will, when parse(String query)
		/// is called, construct a query like this (assuming the query consists of
		/// two terms and you specify the two fields <code>title</code> and <code>body</code>):</p>
		/// 
		/// <code>
		/// (title:term1 body:term1) (title:term2 body:term2)
		/// </code>
		/// 
		/// <p>When setDefaultOperator(AND_OPERATOR) is set, the result will be:</p>
		/// 
		/// <code>
		/// +(title:term1 body:term1) +(title:term2 body:term2)
		/// </code>
		/// 
		/// <p>In other words, all the query's terms must appear, but it doesn't matter in
		/// what fields they appear.</p>
		/// </summary>
		public MultiFieldQueryParser(System.String[] fields, Analyzer analyzer) : base(null, analyzer)
		{
			this.fields = fields;
		}
		
		protected internal override Query GetFieldQuery(System.String field, System.String queryText, int slop)
		{
			if (field == null)
			{
				System.Collections.ArrayList clauses = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(10));
				for (int i = 0; i < fields.Length; i++)
				{
					Query q = base.GetFieldQuery(fields[i], queryText);
					if (q != null)
					{
						if (q is PhraseQuery)
						{
							((PhraseQuery) q).SetSlop(slop);
						}
						if (q is MultiPhraseQuery)
						{
							((MultiPhraseQuery) q).SetSlop(slop);
						}
						clauses.Add(new BooleanClause(q, BooleanClause.Occur.SHOULD));
					}
				}
				if (clauses.Count == 0)
				// happens for stopwords
					return null;
				return GetBooleanQuery(clauses, true);
			}
			return base.GetFieldQuery(field, queryText);
		}
		
		
		protected internal override Query GetFieldQuery(System.String field, System.String queryText)
		{
			return GetFieldQuery(field, queryText, 0);
		}
		
		
		protected internal override Query GetFuzzyQuery(System.String field, System.String termStr, float minSimilarity)
		{
			if (field == null)
			{
				System.Collections.ArrayList clauses = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(10));
				for (int i = 0; i < fields.Length; i++)
				{
					clauses.Add(new BooleanClause(base.GetFuzzyQuery(fields[i], termStr, minSimilarity), BooleanClause.Occur.SHOULD));
				}
				return GetBooleanQuery(clauses, true);
			}
			return base.GetFuzzyQuery(field, termStr, minSimilarity);
		}
		
		protected internal override Query GetPrefixQuery(System.String field, System.String termStr)
		{
			if (field == null)
			{
				System.Collections.ArrayList clauses = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(10));
				for (int i = 0; i < fields.Length; i++)
				{
					clauses.Add(new BooleanClause(base.GetPrefixQuery(fields[i], termStr), BooleanClause.Occur.SHOULD));
				}
				return GetBooleanQuery(clauses, true);
			}
			return base.GetPrefixQuery(field, termStr);
		}
		
		protected internal override Query GetWildcardQuery(System.String field, System.String termStr)
		{
			if (field == null)
			{
				System.Collections.ArrayList clauses = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(10));
				for (int i = 0; i < fields.Length; i++)
				{
					clauses.Add(new BooleanClause(base.GetWildcardQuery(fields[i], termStr), BooleanClause.Occur.SHOULD));
				}
				return GetBooleanQuery(clauses, true);
			}
			return base.GetWildcardQuery(field, termStr);
		}
		
		
        protected internal override Query GetRangeQuery(System.String field, System.String part1, System.String part2, bool inclusive)
		{
			if (field == null)
			{
				System.Collections.ArrayList clauses = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(10));
				for (int i = 0; i < fields.Length; i++)
				{
					clauses.Add(new BooleanClause(base.GetRangeQuery(fields[i], part1, part2, inclusive), BooleanClause.Occur.SHOULD));
				}
				return GetBooleanQuery(clauses, true);
			}
			return base.GetRangeQuery(field, part1, part2, inclusive);
		}
		
		
		
		
        /// <summary> Parses a query which searches on the fields specified.
		/// <p>
		/// If x fields are specified, this effectively constructs:
		/// <pre>
		/// <code>
		/// (field1:query1) (field2:query2) (field3:query3)...(fieldx:queryx)
		/// </code>
		/// </pre>
		/// </summary>
		/// <param name="queries">Queries strings to parse
		/// </param>
		/// <param name="fields">Fields to search on
		/// </param>
		/// <param name="analyzer">Analyzer to use
		/// </param>
		/// <throws>  ParseException if query parsing fails </throws>
		/// <throws>  IllegalArgumentException if the length of the queries array differs </throws>
		/// <summary>  from the length of the fields array
		/// </summary>
		public static Query Parse(System.String[] queries, System.String[] fields, Analyzer analyzer)
		{
			if (queries.Length != fields.Length)
				throw new System.ArgumentException("queries.length != fields.length");
			BooleanQuery bQuery = new BooleanQuery();
			for (int i = 0; i < fields.Length; i++)
			{
				QueryParser qp = new QueryParser(fields[i], analyzer);
				Query q = qp.Parse(queries[i]);
				bQuery.Add(q, BooleanClause.Occur.SHOULD);
			}
			return bQuery;
		}
		
		
		/// <summary> Parses a query, searching on the fields specified.
		/// Use this if you need to specify certain fields as required,
		/// and others as prohibited.
		/// <p><pre>
		/// Usage:
		/// <code>
		/// String[] fields = {"filename", "contents", "description"};
		/// BooleanClause.Occur[] flags = {BooleanClause.Occur.SHOULD,
		/// BooleanClause.Occur.MUST,
		/// BooleanClause.Occur.MUST_NOT};
		/// MultiFieldQueryParser.parse("query", fields, flags, analyzer);
		/// </code>
		/// </pre>
		/// <p>
		/// The code above would construct a query:
		/// <pre>
		/// <code>
		/// (filename:query) +(contents:query) -(description:query)
		/// </code>
		/// </pre>
		/// 
		/// </summary>
		/// <param name="query">Query string to parse
		/// </param>
		/// <param name="fields">Fields to search on
		/// </param>
		/// <param name="flags">Flags describing the fields
		/// </param>
		/// <param name="analyzer">Analyzer to use
		/// </param>
		/// <throws>  ParseException if query parsing fails </throws>
		/// <throws>  IllegalArgumentException if the length of the fields array differs </throws>
		/// <summary>  from the length of the flags array
		/// </summary>
		public static Query Parse(System.String query, System.String[] fields, BooleanClause.Occur[] flags, Analyzer analyzer)
		{
			if (fields.Length != flags.Length)
				throw new System.ArgumentException("fields.length != flags.length");
			BooleanQuery bQuery = new BooleanQuery();
			for (int i = 0; i < fields.Length; i++)
			{
				QueryParser qp = new QueryParser(fields[i], analyzer);
				Query q = qp.Parse(query);
				bQuery.Add(q, flags[i]);
			}
			return bQuery;
		}
		
		
        /// <summary> Parses a query, searching on the fields specified.
		/// Use this if you need to specify certain fields as required,
		/// and others as prohibited.
		/// <p><pre>
		/// Usage:
		/// <code>
		/// String[] query = {"query1", "query2", "query3"};
		/// String[] fields = {"filename", "contents", "description"};
		/// BooleanClause.Occur[] flags = {BooleanClause.Occur.SHOULD,
		/// BooleanClause.Occur.MUST,
		/// BooleanClause.Occur.MUST_NOT};
		/// MultiFieldQueryParser.parse(query, fields, flags, analyzer);
		/// </code>
		/// </pre>
		/// <p>
		/// The code above would construct a query:
		/// <pre>
		/// <code>
		/// (filename:query1) +(contents:query2) -(description:query3)
		/// </code>
		/// </pre>
		/// 
		/// </summary>
		/// <param name="queries">Queries string to parse
		/// </param>
		/// <param name="fields">Fields to search on
		/// </param>
		/// <param name="flags">Flags describing the fields
		/// </param>
		/// <param name="analyzer">Analyzer to use
		/// </param>
		/// <throws>  ParseException if query parsing fails </throws>
		/// <throws>  IllegalArgumentException if the length of the queries, fields, </throws>
		/// <summary>  and flags array differ
		/// </summary>
		public static Query Parse(System.String[] queries, System.String[] fields, BooleanClause.Occur[] flags, Analyzer analyzer)
		{
			if (!(queries.Length == fields.Length && queries.Length == flags.Length))
				throw new System.ArgumentException("queries, fields, and flags array have have different length");
			BooleanQuery bQuery = new BooleanQuery();
			for (int i = 0; i < fields.Length; i++)
			{
				QueryParser qp = new QueryParser(fields[i], analyzer);
				Query q = qp.Parse(queries[i]);
				bQuery.Add(q, flags[i]);
			}
			return bQuery;
		}
	}
}