using System;
using System.Collections.Generic;
using System.Linq;
using Unosquare.Swan.Abstractions;

namespace Unosquare.Swan.Components {
  /// <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));
    }
  }
}