using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace libxmltv
{
    public static class DateTimeStringConverter
    {
        private const string DEFAULT_DATE_FORMAT = "yyyy/MM/dd hh:mm tt";
        public static string ToDateTimeString(this DateTime dt)
        {
            return dt.ToDateTimeString(DateTimeStringConverter.DEFAULT_DATE_FORMAT);
        }
        public static string ToDateTimeString(this DateTime dt, IFormatProvider provider)
        {
            return dt.ToString(provider);
        }
        public static string ToDateTimeString(this DateTime dt, string format)
        {
            return dt.ToString(format);
        }
        public static string ToDateTimeString(this DateTime dt, string format, IFormatProvider provider)
        {
            return dt.ToString(format, provider);
        }
    }

    public static class extensions
    {
        public static IEnumerable<IEnumerable<T>> Chunk<T>(this IEnumerable<T> source,
            int chunkSize)
        {
            // Validate parameters.
            if (source == null) throw new ArgumentNullException("source");
            if (chunkSize <= 0) throw new ArgumentOutOfRangeException("chunkSize",
                "The chunkSize parameter must be a positive value.");

            // Call the internal implementation.
            return source.ChunkInternal(chunkSize);
        }
        private static IEnumerable<IEnumerable<T>> ChunkInternal<T>(this IEnumerable<T> source, int chunkSize)
        {
            // Validate parameters.
            Debug.Assert(source != null);
            Debug.Assert(chunkSize > 0);

            // Get the enumerator.  Dispose of when done.
            using (IEnumerator<T> enumerator = source.GetEnumerator())
                do
                {
                    // Move to the next element.  If there's nothing left
                    // then get out.
                    if (!enumerator.MoveNext()) yield break;

                    // Return the chunked sequence.
                    yield return ChunkSequence(enumerator, chunkSize);
                } while (true);
        }
        private static IEnumerable<T> ChunkSequence<T>(IEnumerator<T> enumerator, int chunkSize)
        {
            // Validate parameters.
            Debug.Assert(enumerator != null);
            Debug.Assert(chunkSize > 0);

            // The count.
            int count = 0;

            // There is at least one item.  Yield and then continue.
            do
            {
                // Yield the item.
                yield return enumerator.Current;
            } while (++count < chunkSize && enumerator.MoveNext());
        }
    }
}