using Lucene.Net.Support;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;

namespace Lucene.Net.Analysis.Ja.Util
{
    /*
     * 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.
     */

    public class ConnectionCostsBuilder
    {
        private static readonly Regex whiteSpaceRegex = new Regex("\\s+", RegexOptions.Compiled);

        private ConnectionCostsBuilder()
        {
        }

        public static ConnectionCostsWriter Build(string filename)
        {
            using (Stream inputStream = new FileStream(filename, FileMode.Open, FileAccess.Read))
            {
                StreamReader streamReader = new StreamReader(inputStream, Encoding.ASCII);

                string line = streamReader.ReadLine();
                string[] dimensions = whiteSpaceRegex.Split(line).TrimEnd();

                Debug.Assert(dimensions.Length == 2);

                int forwardSize = int.Parse(dimensions[0], CultureInfo.InvariantCulture);
                int backwardSize = int.Parse(dimensions[1], CultureInfo.InvariantCulture);

                Debug.Assert(forwardSize > 0 && backwardSize > 0);

                ConnectionCostsWriter costs = new ConnectionCostsWriter(forwardSize, backwardSize);

                while ((line = streamReader.ReadLine()) != null)
                {
                    string[] fields = whiteSpaceRegex.Split(line).TrimEnd();

                    Debug.Assert(fields.Length == 3);

                    int forwardId = int.Parse(fields[0], CultureInfo.InvariantCulture);
                    int backwardId = int.Parse(fields[1], CultureInfo.InvariantCulture);
                    int cost = int.Parse(fields[2], CultureInfo.InvariantCulture);

                    costs.Add(forwardId, backwardId, cost);
                }
                return costs;
            }
        }
    }
}
