/* LineParser.cs
 * part of zaaReloaded2
 * 
 * Copyright 2015-2017 Daniel Kraus
 * 
 * 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.
 */
using System;
using System.Linq;
using System.Text.RegularExpressions;

namespace zaaReloaded2.Thesaurus
{
    /// <summary>
    /// Simple parser that separates a line from a text file into
    /// space-separated fields; field values that contain spaces must
    /// be enclosed by double quotation marks.
    /// </summary>
    /// <remarks>
    /// Everything after a hash (#) will be ignored.
    /// </remarks>
    public class LineParser
    {
        #region Public properties

        /// <summary>
        /// Gets or sets the line being parsed.
        /// </summary>
        public string Line
        {
            get
            {
                return _line;
            }
            set
            {
                _line = value;
                ParseLine();
            }
        }

        /// <summary>
        /// Gets an array of fields in the line.
        /// </summary>
        public string[] Fields { get; private set; }

        /// <summary>
        /// Indicates whether the parsed <see cref="Line"/>
        /// contains fields.
        /// </summary>
        public bool HasFields
        {
            get
            {
                return Fields.Length > 0;
            }
        }

        #endregion

        #region Constructors

        /// <summary>
        /// Constructs a LineParser object without a line.
        /// </summary>
        public LineParser() { }

        /// <summary>
        /// Constructs a LineParser object with an initial <paramref name="line"/>.
        /// </summary>
        /// <param name="line">Initial line to parse.</param>
        public LineParser(string line)
            : this()
        {
            Line = line;
        }

        #endregion

        #region Private methods

        void ParseLine()
        {
            string s = Line.Split('#')[0];
            Fields = _parser
                .Matches(s)
                .Cast<Match>()
                .Select(m => m.Groups["match"].Value)
                .ToArray<string>();
        }

        #endregion

        #region Fields

        // Regex modified after http://stackoverflow.com/a/554068/270712
        static readonly Regex _parser = new Regex(@"(?<match>[^\s""]+)|\""(?<match>[^""]*)""");
        string _line;

        #endregion
    }
}