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

using Swan.Collections;

namespace Swan {
  /// <summary>
  /// Provide Enumerations helpers with internal cache.
  /// </summary>
  public class EnumHelper
        : SingletonBase<CollectionCacheRepository<Tuple<String, Object>>> {
    /// <summary>
    /// Gets all the names and enumerators from a specific Enum type.
    /// </summary>
    /// <typeparam name="T">The type of the attribute to be retrieved.</typeparam>
    /// <returns>A tuple of enumerator names and their value stored for the specified type.</returns>
    public static IEnumerable<Tuple<String, Object>> Retrieve<T>() where T : struct, IConvertible => Instance.Retrieve(typeof(T), t => Enum.GetValues(t).Cast<Object>().Select(item => Tuple.Create(Enum.GetName(t, item), item)));

    /// <summary>
    /// Gets the cached items with the enum item value.
    /// </summary>
    /// <typeparam name="T">The type of enumeration.</typeparam>
    /// <param name="humanize">if set to <c>true</c> [humanize].</param>
    /// <returns>
    /// A collection of Type/Tuple pairs 
    /// that represents items with the enum item value.
    /// </returns>
    public static IEnumerable<Tuple<Int32, String>> GetItemsWithValue<T>(Boolean humanize = true) where T : struct, IConvertible => Retrieve<T>().Select(x => Tuple.Create((Int32)x.Item2, humanize ? x.Item1.Humanize() : x.Item1));

    /// <summary>
    /// Gets the flag values.
    /// </summary>
    /// <typeparam name="TEnum">The type of the enum.</typeparam>
    /// <param name="value">The value.</param>
    /// <param name="ignoreZero">if set to <c>true</c> [ignore zero].</param>
    /// <returns>
    /// A list of values in the flag.
    /// </returns>
    public static IEnumerable<Int32> GetFlagValues<TEnum>(Int32 value, Boolean ignoreZero = false) where TEnum : struct, IConvertible => Retrieve<TEnum>().Select(x => (Int32)x.Item2).When(() => ignoreZero, q => q.Where(f => f != 0)).Where(x => (x & value) == x);

    /// <summary>
    /// Gets the flag values.
    /// </summary>
    /// <typeparam name="TEnum">The type of the enum.</typeparam>
    /// <param name="value">The value.</param>
    /// <param name="ignoreZero">if set to <c>true</c> [ignore zero].</param>
    /// <returns>
    /// A list of values in the flag.
    /// </returns>
    public static IEnumerable<Int64> GetFlagValues<TEnum>(Int64 value, Boolean ignoreZero = false) where TEnum : struct, IConvertible => Retrieve<TEnum>().Select(x => (Int64)x.Item2).When(() => ignoreZero, q => q.Where(f => f != 0)).Where(x => (x & value) == x);

    /// <summary>
    /// Gets the flag values.
    /// </summary>
    /// <typeparam name="TEnum">The type of the enum.</typeparam>
    /// <param name="value">The value.</param>
    /// <param name="ignoreZero">if set to <c>true</c> [ignore zero].</param>
    /// <returns>
    /// A list of values in the flag.
    /// </returns>
    public static IEnumerable<Byte> GetFlagValues<TEnum>(Byte value, Boolean ignoreZero = false) where TEnum : struct, IConvertible => Retrieve<TEnum>().Select(x => (Byte)x.Item2).When(() => ignoreZero, q => q.Where(f => f != 0)).Where(x => (x & value) == x);

    /// <summary>
    /// Gets the flag names.
    /// </summary>
    /// <typeparam name="TEnum">The type of the enum.</typeparam>
    /// <param name="value">the value.</param>
    /// <param name="ignoreZero">if set to <c>true</c> [ignore zero].</param>
    /// <param name="humanize">if set to <c>true</c> [humanize].</param>
    /// <returns>
    /// A list of flag names.
    /// </returns>
    public static IEnumerable<String> GetFlagNames<TEnum>(Int32 value, Boolean ignoreZero = false, Boolean humanize = true) where TEnum : struct, IConvertible => Retrieve<TEnum>().When(() => ignoreZero, q => q.Where(f => (Int32)f.Item2 != 0)).Where(x => ((Int32)x.Item2 & value) == (Int32)x.Item2).Select(x => humanize ? x.Item1.Humanize() : x.Item1);

    /// <summary>
    /// Gets the flag names.
    /// </summary>
    /// <typeparam name="TEnum">The type of the enum.</typeparam>
    /// <param name="value">The value.</param>
    /// <param name="ignoreZero">if set to <c>true</c> [ignore zero].</param>
    /// <param name="humanize">if set to <c>true</c> [humanize].</param>
    /// <returns>
    /// A list of flag names.
    /// </returns>
    public static IEnumerable<String> GetFlagNames<TEnum>(Int64 value, Boolean ignoreZero = false, Boolean humanize = true) where TEnum : struct, IConvertible => Retrieve<TEnum>().When(() => ignoreZero, q => q.Where(f => (Int64)f.Item2 != 0)).Where(x => ((Int64)x.Item2 & value) == (Int64)x.Item2).Select(x => humanize ? x.Item1.Humanize() : x.Item1);

    /// <summary>
    /// Gets the flag names.
    /// </summary>
    /// <typeparam name="TEnum">The type of the enum.</typeparam>
    /// <param name="value">The value.</param>
    /// <param name="ignoreZero">if set to <c>true</c> [ignore zero].</param>
    /// <param name="humanize">if set to <c>true</c> [humanize].</param>
    /// <returns>
    /// A list of flag names.
    /// </returns>
    public static IEnumerable<String> GetFlagNames<TEnum>(Byte value, Boolean ignoreZero = false, Boolean humanize = true) where TEnum : struct, IConvertible => Retrieve<TEnum>().When(() => ignoreZero, q => q.Where(f => (Byte)f.Item2 != 0)).Where(x => ((Byte)x.Item2 & value) == (Byte)x.Item2).Select(x => humanize ? x.Item1.Humanize() : x.Item1);

    /// <summary>
    /// Gets the cached items with the enum item index.
    /// </summary>
    /// <typeparam name="T">The type of enumeration.</typeparam>
    /// <param name="humanize">if set to <c>true</c> [humanize].</param>
    /// <returns>
    /// A collection of Type/Tuple pairs that represents items with the enum item value.
    /// </returns>
    public static IEnumerable<Tuple<Int32, String>> GetItemsWithIndex<T>(Boolean humanize = true) where T : struct, IConvertible {
      Int32 i = 0;

      return Retrieve<T>().Select(x => Tuple.Create(i++, humanize ? x.Item1.Humanize() : x.Item1));
    }
  }
}