using System.ComponentModel;
using System.Reflection;

namespace Azaion.Common.Extensions;

/// <summary>Enum extensions</summary>
public static class EnumExtensions
{
    /// <summary>Get all enums with descriptions </summary>
    public static Dictionary<T, string> GetDescriptions<T>() where T : Enum =>
        Enum.GetValues(typeof(T)).Cast<T>()
            .ToDictionary(x => x, x => x.GetEnumAttrib<T, DescriptionAttribute>()?.Description ?? x.ToString());

    /// <summary>
    /// Get the Description from the DescriptionAttribute.
    /// </summary>
    /// <param name="enumValue"></param>
    /// <returns></returns>
    public static string GetDescription(this Enum enumValue)
    {
        return enumValue.GetType()
            .GetMember(enumValue.ToString())
            .First()
            .GetCustomAttribute<DescriptionAttribute>()?
            .Description ?? enumValue.ToString();
    }

    /// <summary> Get attribute for enum's member, usually is used for getting Description attribute </summary>
    private static TAttrib GetEnumAttrib<T, TAttrib>(this T value) where T: Enum
    {
        var field = value.GetType().GetField(value.ToString());
        if (field == null)
            return default!;
            
        return field.GetCustomAttributes(typeof(TAttrib), false)
            .Cast<TAttrib>()
            .FirstOrDefault()!;
    }
        
    /// <summary>
    /// Get default value for enum
    /// </summary>
    /// <typeparam name="TEnum"></typeparam>
    /// <returns></returns>
    public static TEnum GetDefaultValue<TEnum>() where TEnum : struct
    {
        var t = typeof(TEnum);
        var attributes = (DefaultValueAttribute[])t.GetCustomAttributes(typeof(DefaultValueAttribute), false);
        if (attributes is { Length: > 0 })
            return (TEnum)attributes[0].Value!;

        return default;
    }
}