using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using Microsoft.Xna.Framework;

namespace CarFire
{
    /// <summary>
    /// Class with handy static methods taking strings and returning objects
    /// parsed from those strings.  For all of these functions, white space is
    /// generally ignored, but superfluous characters are not allowed.
    /// </summary>
    public class Parse
    {
        /// <summary>
        /// Parses a section header of an INI file.
        /// </summary>
        /// <param name="line">Text.</param>
        /// <returns>The section header, or null if parsing failed.</returns>
        public static string IniSectionHeader(string line)
        {
            Match match = Regex.Match(line, @"^\s*\[(\w+)\]\s*$");
            if (match.Success) return match.Groups[1].Value;
            return null;
        }

        /// <summary>
        /// Parses a comment of an INI file.
        /// </summary>
        /// <param name="line">Text.</param>
        /// <returns>The comment, or null if parsing failed.</returns>
        public static string IniComment(string line)
        {
            Match match = Regex.Match(line, @"^;\s*(.*)\s*$");
            if (match.Success) return match.Groups[1].Value;
            return null;
        }

        /// <summary>
        /// Parses a key-value pair.
        /// </summary>
        /// <param name="line">Text.</param>
        /// <returns>An array of two strings containg the key and value,
        /// in that order, or null if parsing failed.</returns>
        public static string[] KeyValuePair(string line)
        {
            Match match = Regex.Match(line, @"^\s*(\w+)\s*=\s*(.+)\s*$");
            if (match.Success)
            {
                string[] pair = { match.Groups[1].Value, match.Groups[2].Value };
                return pair;
            }
            return null;
        }

        /// <summary>
        /// Parses a pair of coordinates.
        /// </summary>
        /// <param name="atom">Text.</param>
        /// <returns>The coordinates, or null if parsing failed.</returns>
        public static Point? Coordinates(string atom)
        {
            Match match = Regex.Match(atom, @"^\s*\[(\S+?)\s*,\s*(\S+?)\]\s*$");
            if (match.Success)
            {
                int? x = Integer(match.Groups[1].Value);
                int? y = Integer(match.Groups[2].Value);
                if (x != null && y != null)
                {
                    return new Point(x.Value, y.Value);
                }
            }
            return null;
        }

        /// <summary>
        /// Parses a range of integers.
        /// </summary>
        /// <param name="atom">Text.</param>
        /// <returns>An array of two integers containing the min and max,
        /// in that order, or null if parsing failed.</returns>
        public static int[] Range(string atom)
        {
            Match match = Regex.Match(atom, @"^\s*<(\S+?)\s*,\s*(\S+?)>\s*$");
            if (match.Success)
            {
                int? min = Integer(match.Groups[1].Value);
                int? max = Integer(match.Groups[2].Value);
                if (min != null && max != null)
                {
                    int[] range = { min.Value, max.Value };
                    return range;
                }
            }
            return null;
        }

        /// <summary>
        /// Parses a string.
        /// </summary>
        /// <param name="atom">Text.</param>
        /// <returns>The string, or null if parsing failed.</returns>
        public static string String(string atom)
        {
            Match match = Regex.Match(atom, @"^\s*(""?)(.*)\1\s*$");
            if (match.Success) return match.Groups[2].Value;
            return null;
        }

        /// <summary>
        /// Parses a single character.
        /// </summary>
        /// <param name="atom">Text.</param>
        /// <returns>The character, or null if parsing failed.</returns>
        public static char? Char(string atom)
        {
            string str = String(atom);
            if (str != null && str.Length == 1) return str[0];
            return null;
        }

        /// <summary>
        /// Parses a constant from an enum.
        /// </summary>
        /// <typeparam name="T">An enumeration.</typeparam>
        /// <param name="atom">Text.</param>
        /// <returns>The constant, or null if parsing failed.</returns>
        public static T? Constant<T>(string atom) where T : struct
        {
            try
            {
                return (T)System.Enum.Parse(typeof(T), String(atom));
            }
#pragma warning disable 0168
            catch (System.Exception ex)
#pragma warning restore 0168
            {
                return null;
            }
        }

        /// <summary>
        /// Parses an integer.
        /// </summary>
        /// <param name="atom">Text.</param>
        /// <returns>The integer, or null if parsing failed.</returns>
        public static int? Integer(string atom)
        {
            try
            {
                int integer = Convert.ToInt32(atom.Trim());
                return integer;
            }
#pragma warning disable 0168
            catch (System.Exception ex)
#pragma warning restore 0168
            {
                return null;
            }
        }

        /// <summary>
        /// Parses a boolean value.
        /// </summary>
        /// <param name="atom">Text.</param>
        /// <returns>True or false, or null if parsing failed.</returns>
        public static bool? Boolean(string atom)
        {
            Match match = Regex.Match(atom, @"^\s*(true|false)\s*$", RegexOptions.IgnoreCase);
            if (match.Success)
            {
                if (match.Groups[1].Value[0] == 't' || match.Groups[1].Value[0] == 'T') return true;
                else return false;
            }
            return null;
        }

        /// <summary>
        /// Parses a function.
        /// </summary>
        /// <param name="atom">Text.</param>
        /// <returns>An array with two strings containing the function name and
        /// parameter-list, in that order, or null if parsing failed.</returns>
        public static string[] Function(string atom)
        {
            Match match = Regex.Match(atom, @"^\s*(\w+)\((.*)\)\s*$");
            if (match.Success)
            {
                string[] pair = { match.Groups[1].Value, match.Groups[2].Value };
                return pair;
            }
            return null;
        }

        /// <summary>
        /// Parses a whitespace-separated list of atoms.
        /// </summary>
        /// <param name="text">Text.</param>
        /// <returns>An array of atoms, or null if parsing failed.</returns>
        public static string[] List(string text)
        {
            List<string> list = new List<string>();

            MatchCollection matches = Regex.Matches(text, @"\s*("".*?"")|(\w+\(.*?\))|(\[.*?\])|(<.*?>)|(\S+)(?:\s+|$)");
            // FIXME: This may barf all over itself if there are nested parentheses, doublequotes, brackets, etc.
            foreach (Match match in matches)
            {
                list.Add(match.Value);
            }

            return list.ToArray();
        }
    }
}