using DiscordRPC;
using Ryujinx.Common;
using Ryujinx.UI.Common.Configuration;
using System.Text;

namespace Ryujinx.UI.Common
{
    public static class DiscordIntegrationModule
    {
        private const string Description = "A simple, experimental Nintendo Switch emulator.";
        private const string ApplicationId = "1216775165866807456";

        private const int ApplicationByteLimit = 128;
        private const string Ellipsis = "…";

        private static DiscordRpcClient _discordClient;
        private static RichPresence _discordPresenceMain;

        public static void Initialize()
        {
            _discordPresenceMain = new RichPresence
            {
                Assets = new Assets
                {
                    LargeImageKey = "ryujinx",
                    LargeImageText = Description,
                },
                Details = "Main Menu",
                State = "Idling",
                Timestamps = Timestamps.Now,
                Buttons =
                [
                    new Button
                    {
                        Label = "Website",
                        Url = "https://ryujinx.org/",
                    },
                ],
            };

            ConfigurationState.Instance.EnableDiscordIntegration.Event += Update;
        }

        private static void Update(object sender, ReactiveEventArgs<bool> evnt)
        {
            if (evnt.OldValue != evnt.NewValue)
            {
                // If the integration was active, disable it and unload everything
                if (evnt.OldValue)
                {
                    _discordClient?.Dispose();

                    _discordClient = null;
                }

                // If we need to activate it and the client isn't active, initialize it
                if (evnt.NewValue && _discordClient == null)
                {
                    _discordClient = new DiscordRpcClient(ApplicationId);

                    _discordClient.Initialize();
                    _discordClient.SetPresence(_discordPresenceMain);
                }
            }
        }

        public static void SwitchToPlayingState(string titleId, string applicationName)
        {
            _discordClient?.SetPresence(new RichPresence
            {
                Assets = new Assets
                {
                    LargeImageKey = "game",
                    LargeImageText = TruncateToByteLength(applicationName, ApplicationByteLimit),
                    SmallImageKey = "ryujinx",
                    SmallImageText = Description,
                },
                Details = TruncateToByteLength($"Playing {applicationName}", ApplicationByteLimit),
                State = (titleId == "0000000000000000") ? "Homebrew" : titleId.ToUpper(),
                Timestamps = Timestamps.Now,
                Buttons =
                [
                    new Button
                    {
                        Label = "Website",
                        Url = "https://ryujinx.org/",
                    },
                ],
            });
        }

        public static void SwitchToMainMenu()
        {
            _discordClient?.SetPresence(_discordPresenceMain);
        }

        private static string TruncateToByteLength(string input, int byteLimit)
        {
            if (Encoding.UTF8.GetByteCount(input) <= byteLimit)
            {
                return input;
            }

            // Find the length to trim the string to guarantee we have space for the trailing ellipsis.
            int trimLimit = byteLimit - Encoding.UTF8.GetByteCount(Ellipsis);

            // Basic trim to best case scenario of 1 byte characters.
            input = input[..trimLimit];

            while (Encoding.UTF8.GetByteCount(input) > trimLimit)
            {
                // Remove one character from the end of the string at a time.
                input = input[..^1];
            }

            return input.TrimEnd() + Ellipsis;
        }

        public static void Exit()
        {
            _discordClient?.Dispose();
        }
    }
}
