/* DictionaryBase.cs
 * part of zaaReloaded2
 * 
 * Copyright 2015-2018 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.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace zaaReloaded2.Thesaurus
{
    /// <summary>
    /// Base class for the <see cref="Parameters"/>
    /// and the <see cref="Units"/>; implements methods
    /// to read configuration files.
    /// </summary>
    public abstract class ThesaurusBase
    {
        #region Public properties

        /// <summary>
        /// Gets a sorted dictionary of records. The records are sorted by the
        /// first field, and each record contains the entire set of fields,
        /// including the first field.
        /// </summary>
        public SortedDictionary<string, string[]> Records { get; protected set; }

        #endregion

        #region Constructor

        /// <summary>
        /// Constructs a new dictionary, loading default data from a built-in
        /// resource, and user data from a custom file.
        /// </summary>
        public ThesaurusBase()
        {
            Records = new SortedDictionary<string, string[]>();
            LoadDefaultValues();
            LoadUserValues();
        }

        #endregion

        #region Public methods

        /// <summary>
        /// Returns true if the dictionary contains a record for
        /// <paramref name="key"/>.
        /// </summary>
        /// <param name="key">Dictionary key to look up.</param>
        /// <returns>True if a record for <paramref name="key"/>
        /// exist, false if not.</returns>
        public bool HasRecord(string key)
        {
            return Records.ContainsKey(key);
        }

        #endregion

        #region Abstract methods

        /// <summary>
        /// Returns a content stream with a default configuration file.
        /// </summary>
        abstract protected Stream GetDefaultStream();

        /// <summary>
        /// Returns the file name of the text file that contains user-defined
        /// values.
        /// </summary>
        /// <returns>File name.</returns>
        abstract protected string GetUserFileName();

        #endregion

        #region Protected methods

        /// <summary>
        /// Reads a text file from a TextReader and fills the dictionary
        /// with the data.
        /// </summary>
        /// <param name="s">TextReader that provides a text file.</param>
        protected void ReadFile(TextReader text)
        {
            LineParser lp = new LineParser();
            string line;
            string key;
            while ((line = text.ReadLine()) != null)
            {
                lp.Line = line;
                if (lp.HasFields)
                {
                    key = lp.Fields[0];
                    if (Records.ContainsKey(key))
                    {
                        Records[key] = lp.Fields;
                    }
                    else
                    {
                        Records.Add(key, lp.Fields);
                    }
                }
            }
        }

        /// <summary>
        /// Reads a text file from a stream and fills the dictionary
        /// with the data.
        /// </summary>
        /// <param name="s">TextReader that provides a text file.</param>
        protected void ReadFile(Stream stream)
        {
            StreamReader sr = new StreamReader(stream);
            ReadFile(sr);
        }

        /// <summary>
        /// Loads default dictionary values from a text file that is built
        /// into the assembly as an embbedded resource.
        /// </summary>
        protected virtual void LoadDefaultValues()
        {
            ReadFile(GetDefaultStream());
        }

        /// <summary>
        /// Attempts to load additional values from a user file whose path
        /// is provided by <see cref="GetUserFileName()"/>.
        /// </summary>
        protected virtual void LoadUserValues()
        {
            try
            {
                FileStream fs = new FileStream(GetUserFileName(), FileMode.Open, FileAccess.Read);
                ReadFile(fs);
            }
            catch { }
        }

        /// <summary>
        /// Looks up a dictionary key and returns an integer value from the requested field,
        /// or a default value if the field is empty or contains only dashes.
        /// </summary>
        /// <param name="key">Key to look up.</param>
        /// <param name="fieldNum">Zero-based index of the field to look up
        /// (note that field 0 is the key itself).</param>
        /// <param name="defaultValue">Default value that will be returned
        /// if the field is empty or contains only dashes.</param>
        /// <returns>Value of the requested field, or <paramref name="defaultValue"/>
        /// if the field is empty or contains only dashes.</returns>
        /// <exception cref="System.IndexOutOfRangeException">if fieldNum is negative.</exception>
        protected int LookUpValue(string key, int fieldNum, int defaultValue)
        {
            string[] record;
            if (Records.TryGetValue(key, out record))
            {
                if (fieldNum >= record.Length) return defaultValue;
                string value = record[fieldNum];
                if (string.IsNullOrWhiteSpace(value) || _dashes.IsMatch(value))
                {
                    return defaultValue;
                }
                else
                {
                    int intval;
                    if (int.TryParse(value, out intval))
                    {
                        return intval;
                    }
                    else
                    {
                        return defaultValue;
                    }
                }
            }
            else
            {
                return defaultValue;
            }
        }

        /// <summary>
        /// Looks up a dictionary key and returns the value from the requested field,
        /// or a default value if the field is empty or contains only dashes.
        /// </summary>
        /// <param name="key">Key to look up.</param>
        /// <param name="fieldNum">Zero-based index of the field to look up
        /// (note that field 0 is the key itself).</param>
        /// <param name="defaultValue">Default value that will be returned
        /// if the field is empty or contains only dashes.</param>
        /// <returns>Value of the requested field, or <paramref name="defaultValue"/>
        /// if the field is empty or contains only dashes.</returns>
        /// <exception cref="System.IndexOutOfRangeException">if fieldNum is negative.</exception>
        protected string LookUpValue(string key, int fieldNum, string defaultValue)
        {
            string[] record;
            if (Records.TryGetValue(key, out record))
            {
                if (fieldNum >= record.Length) return defaultValue;
                string value = record[fieldNum];
                if (string.IsNullOrWhiteSpace(value) || _dashes.IsMatch(value))
                {
                    return defaultValue;
                }
                else
                {
                    return value;
                }
            }
            else
            {
                return defaultValue;
            }
        }

        /// <summary>
        /// Looks up a dictionary key and returns the value from the requested field,
        /// or an empty string if the field is empty or contains only dashes.
        /// </summary>
        /// <param name="key">Key to look up.</param>
        /// <param name="fieldNum">Zero-based index of the field to look up
        /// (note that field 0 is the key itself).</param>
        /// <returns>Value of the requested field, or <see cref="String.Empty"/>
        /// if the field is empty or contains only dashes.</returns>
        /// <exception cref="System.IndexOutOfRangeException">if fieldNum is negative.</exception>
        protected string LookUpValue(string key, int fieldNum)
        {
            return LookUpValue(key, fieldNum, String.Empty);
        }

        /// <summary>
        /// Looks up a dictionary key and returns a boolean value from the requested field,
        /// or a default value if the field is empty or contains only dashes.
        /// </summary>
        /// <remarks>
        /// The following case-insensitive text values are evaluated as "true": X, Y, J, +,
        /// 1, JA, TRUE, WAHR.
        /// </remarks>
        /// <param name="key">Key to look up.</param>
        /// <param name="fieldNum">Zero-based index of the field to look up
        /// (note that field 0 is the key itself).</param>
        /// <param name="defaultValue">Default value that will be returned
        /// if the field is empty or contains only dashes.</param>
        /// <returns>Value of the requested field, or <paramref name="defaultValue"/>
        /// if the field is empty or contains only dashes.</returns>
        /// <exception cref="System.IndexOutOfRangeException">if fieldNum is negative.</exception>
        protected bool LookUpValue(string key, int fieldNum, bool defaultValue)
        {
            string textValue = LookUpValue(key, fieldNum, String.Empty);
            switch (textValue.ToUpper())
            {
                case "X":
                case "Y":
                case "J":
                case "+":
                case "1":
                case "JA":
                case "YES":
                case "TRUE":
                case "WAHR":
                    return true;
                default:
                    return defaultValue;
            }
        }

        #endregion

        #region Fields

        private static readonly Regex _dashes = new Regex("^-+$");

        #endregion
    }
}