using Humanizer;
using OneOf;
using Remora.Discord.API.Abstractions.Objects;
using Remora.Discord.API.Abstractions.Rest;
using Remora.Discord.API.Objects;
using Remora.Discord.Commands.Contexts;
using Remora.Discord.Commands.Extensions;
using Remora.Discord.Commands.Services;
using Remora.Rest.Core;
using Remora.Results;

namespace Catalogger.Backend.Extensions;

public static class DiscordExtensions
{
    public static string Tag(this IPartialUser user)
    {
        var discriminator = user.Discriminator.OrDefault();
        return discriminator == 0 ? user.Username.Value : $"{user.Username.Value}#{discriminator:0000}";
    }

    public static string AvatarUrl(this IUser user, int size = 256)
    {
        if (user.Avatar != null)
        {
            var ext = user.Avatar.HasGif ? ".gif" : ".webp";
            return $"https://cdn.discordapp.com/avatars/{user.ID}/{user.Avatar.Value}{ext}?size={size}";
        }

        var avatarIndex = user.Discriminator == 0 ? (int)((user.ID.Value >> 22) % 6) : user.Discriminator % 5;
        return $"https://cdn.discordapp.com/embed/avatars/{avatarIndex}.png?size={size}";
    }

    public static string? IconUrl(this IGuild guild, int size = 256)
    {
        if (guild.Icon == null) return null;

        var ext = guild.Icon.HasGif ? ".gif" : ".webp";

        return $"https://cdn.discordapp.com/icons/{guild.ID}/{guild.Icon.Value}{ext}?size={size}";
    }

    public static ulong ToUlong(this Snowflake snowflake) => snowflake.Value;

    public static ulong ToUlong(this Optional<Snowflake> snowflake)
    {
        if (!snowflake.IsDefined()) throw new Exception("ToUlong called on an undefined Snowflake");
        return snowflake.Value.Value;
    }

    public static bool Is(this Optional<Snowflake> s1, Snowflake s2) => s1.IsDefined(out var value) && value == s2;
    public static bool Is(this Optional<Snowflake> s1, ulong s2) => s1.IsDefined(out var value) && value == s2;

    public static T GetOrThrow<T>(this Result<T> result)
    {
        if (result.Error != null) throw new DiscordRestException(result.Error.Message);
        return result.Entity;
    }

    public static T GetOrThrow<T>(this Optional<T> optional) =>
        optional.OrThrow(() => new CataloggerError("Optional<T> was unset"));

    public static async Task<T> GetOrThrow<T>(this Task<Result<T>> result) => (await result).GetOrThrow();

    public static async Task<Result> UpdateMessageAsync(this IDiscordRestInteractionAPI interactionApi,
        IInteraction interaction, InteractionMessageCallbackData data) =>
        await interactionApi.CreateInteractionResponseAsync(interaction.ID,
            interaction.Token,
            new InteractionResponse(InteractionCallbackType.UpdateMessage,
                new Optional<OneOf<IInteractionMessageCallbackData, IInteractionAutocompleteCallbackData,
                    IInteractionModalCallbackData>>(data)));

    public static string ToPrettyString(this IDiscordPermissionSet permissionSet) =>
        string.Join(", ", permissionSet.GetPermissions().Select(p => p.Humanize(LetterCasing.Title)));

    public static (Snowflake, Snowflake) GetUserAndGuild(this ContextInjectionService contextInjectionService)
    {
        if (contextInjectionService.Context is not IInteractionCommandContext ctx)
            throw new CataloggerError("No context");
        if (!ctx.TryGetUserID(out var userId)) throw new CataloggerError("No user ID in context");
        if (!ctx.TryGetGuildID(out var guildId)) throw new CataloggerError("No guild ID in context");
        return (userId, guildId);
    }
    
    /// <summary>
    /// Sorts a list of roles by their position in the Discord interface.
    /// </summary>
    /// <param name="roles">The list of guild roles to filter.</param>
    /// <param name="filterByIds">An optional list of role IDs to return, from a member object or similar.
    /// If null, the entire list is returned.</param>
    /// <returns></returns>
    public static IEnumerable<IRole> Sorted(this IEnumerable<IRole> roles,
        IEnumerable<Snowflake>? filterByIds = null)
    {
        var sorted = roles.OrderByDescending(r => r.Position);
        return filterByIds != null ? sorted.Where(r => filterByIds.Contains(r.ID)) : sorted;
    }

    public class DiscordRestException(string message) : Exception(message);
}