using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace OpenVIII
{
    namespace Movie
    {
        public struct Files : IEnumerable<string>
        {
            #region Fields

            private static readonly string[] Extensions = new string[] { ".avi", ".mkv", ".mp4", ".bik" };
            private static Directories Directories;
            private static List<string> s_files;

            #endregion Fields

            #region Properties

            public static int Count => _Files.Count;
            private static List<string> _Files { get { Init(); return s_files; } set => s_files = value; }

            #endregion Properties

            #region Indexers

            public string this[int i] => At(i);

            #endregion Indexers

            #region Methods

            public static string At(int i) => _Files[i];

            public static bool Exists(int i) => Count > i && i >= 0 && File.Exists(_Files[i]);

            public static void Init()
            {
                if (s_files == null /*|| s_files.Count == 0*/)
                {
                    //Gather all movie files.
                    s_files = (from directory in Directories
                               where Directory.Exists(directory)
                               from file in Directory.GetFiles(directory, "*", SearchOption.AllDirectories)
                               from extension in Extensions
                               where file.EndsWith(extension, StringComparison.OrdinalIgnoreCase)
                               orderby Path.GetFileNameWithoutExtension(file) ascending
                               select file).ToList();
                    //Remove duplicate movies ignoring extension that have same name.
                    (from s1 in _Files.Select((Value, Key) => new { Key, Value })
                     from s2 in _Files.Select((Value, Key) => new { Key, Value })
                     where s1.Key < s2.Key
                     where Path.GetFileNameWithoutExtension(s1.Value).Equals(Path.GetFileNameWithoutExtension(s2.Value), StringComparison.OrdinalIgnoreCase)
                     orderby s2.Key descending
                     select s2.Key).ForEach(Key => s_files.RemoveAt(Key));
                }
            }

            public IEnumerator GetEnumerator() => _Files.GetEnumerator();

            IEnumerator<string> IEnumerable<string>.GetEnumerator() => _Files.GetEnumerator();

            #endregion Methods
        }
    }
}