using Discord;
using Discord.WebSocket;
using Fleck;
using Newtonsoft.Json;
using System.Diagnostics;
using System.Runtime.Serialization;

namespace MinecraftDiscordBot;

public delegate Task<TResponse> HandleCommandDelegate<TResponse>(SocketUserMessage message, string[] parameters, CancellationToken ct);
public delegate Task HandleCommandDelegate(SocketUserMessage message, string[] parameters, CancellationToken ct);

[AttributeUsage(AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
public sealed class CommandHandlerAttribute : Attribute {
    public CommandHandlerAttribute(string commandName) => CommandName = commandName;
    public string CommandName { get; }
    public string? HelpText { get; init; }
}

public class ConnectedComputer : CommandRouter, ITaskWaitSource {
    protected readonly IWebSocketConnection _socket;
    public override string HelpTextPrefix => "!";
    public ConnectedComputer(IWebSocketConnection socket) : base() {
        socket.OnMessage = OnMessage;
        _socket = socket;
        _rs = new RefinedStorageService(this);
    }

    private void OnMessage(string message) {
        if (JsonConvert.DeserializeObject<ReplyMessage>(message) is not ReplyMessage msg) return;
        IChunkWaiter? waiter;
        lock (_syncRoot) {
            if (!_waits.TryGetValue(msg.AnswerId, out waiter)) {
                Program.LogWarningAsync("Socket", $"Invalid wait id '{msg.AnswerId}'!");
                return;
            }
        }
        if (!msg.Success) waiter.SetUnsuccessful();
        waiter.AddChunk(msg.Chunk, msg.Total, msg.Result);
        if (waiter.Finished || waiter.IsCancellationRequested)
            lock (_syncRoot)
                _waits.Remove(waiter.ID);
    }

    public Task Send(string message) => _socket.Send(message);
    public Task Send(Message message) => Send(JsonConvert.SerializeObject(message));
    private readonly object _syncRoot = new();
    private readonly Dictionary<int, IChunkWaiter> _waits = new();
    private readonly Random _rnd = new();
    public IWebSocketConnectionInfo ConnectionInfo => _socket.ConnectionInfo;

    private int GetFreeId() {
        var attempts = 0;
        while (true) {
            var id = _rnd.Next();
            if (!_waits.ContainsKey(id))
                return id;
            Program.LogWarningAsync(Program.WebSocketSource, $"Could not get a free ID after {++attempts} attempts!");
        }
    }

    public ChunkWaiter<T> GetWaiter<T>(Func<string, T> resultParser, CancellationToken ct) {
        ChunkWaiter<T> waiter;
        lock (_syncRoot) {
            waiter = new ChunkWaiter<T>(GetFreeId(), resultParser, ct);
            _waits.Add(waiter.ID, waiter);
        }
        return waiter;
    }

    private readonly ICommandHandler<ResponseType> _rs;
    [CommandHandler("rs", HelpText = "Provides some commands for interacting with the Refined Storage system.")]
    public Task<ResponseType> RefinedStorageHandler(SocketUserMessage message, string[] parameters, CancellationToken ct)
        => _rs.HandleCommand(message, parameters, ct);

    public static Func<string, T> Deserialize<T>() => msg
             => JsonConvert.DeserializeObject<T>(msg) ?? throw new InvalidProgramException("Empty response!");
    public override Task<ResponseType> RootAnswer(SocketUserMessage message, CancellationToken ct)
        => Task.FromResult(ResponseType.AsString("The Minecraft server is connected!"));
    public override Task<ResponseType> FallbackHandler(SocketUserMessage message, string method, string[] parameters, CancellationToken ct)
        => throw new ReplyException($"What the fuck do you mean by '{method}'?");
}

public interface ITaskWaitSource {
    ChunkWaiter<T> GetWaiter<T>(Func<string, T> resultParser, CancellationToken ct);
    Task Send(Message requestMessage);
}

[Serializable]
public class ReplyException : Exception {
    public ReplyException() { }
    public ReplyException(string message) : base(message) { }
    public ReplyException(string message, Exception inner) : base(message, inner) { }
    protected ReplyException(SerializationInfo info, StreamingContext context) : base(info, context) { }
}

[JsonObject(MemberSerialization.OptIn, Description = "Describes an item in a Refined Storage system.", MissingMemberHandling = MissingMemberHandling.Ignore)]
[DebuggerDisplay($"{{{nameof(ToString)}(),nq}}")]
public class Item : Fluid {
    [JsonProperty("fingerprint", Required = Required.Always)]
    public Md5Hash Fingerprint { get; set; } = default!;
    [JsonProperty("nbt", Required = Required.DisallowNull)]
    public dynamic? NBT { get; set; }
    public override string ToString() => $"{Amount:n0}x {DisplayName}";
}

[JsonObject(MemberSerialization.OptIn, Description = "Describes a fluid in a Refined Storage system.", MissingMemberHandling = MissingMemberHandling.Ignore)]
[DebuggerDisplay($"{{{nameof(ToString)}(),nq}}")]
public class Fluid {
    [JsonProperty("amount", Required = Required.Always)]
    public int Amount { get; set; }
    [JsonProperty("displayName", Required = Required.Always)]
    public string DisplayName { get; set; } = default!;
    [JsonProperty("tags", Required = Required.DisallowNull)]
    public string[]? Tags { get; set; } = default;
    [JsonProperty("name", Required = Required.Always)]
    public ModItemId ItemId { get; set; } = default!;
    public override string ToString() => Amount > 10000
        ? $"{Amount / 1000.0f:n2} B of {DisplayName}"
        : $"{Amount:n0} mB of {DisplayName}";
    [JsonIgnore]
    public string CleanDisplayName => DisplayName[1..^2];
}

[JsonConverter(typeof(ModItemIdJsonConverter))]
[DebuggerDisplay($"{{{nameof(ToString)}(),nq}}")]
public class ModItemId {
    public ModItemId(string name) {
        var colon = name.IndexOf(':');
        if (colon < 0) throw new ArgumentException("Invalid mod item id!", nameof(name));
        ModName = name[..colon];
        ModItem = name[(colon + 1)..];
        if (ToString() != name) throw new InvalidProgramException("Bad Parsing!");
    }
    public override string ToString() => $"{ModName}:{ModItem}";
    public string ModName { get; }
    public string ModItem { get; }

    public class ModItemIdJsonConverter : JsonConverter<ModItemId> {
        public override ModItemId? ReadJson(JsonReader reader, Type objectType, ModItemId? existingValue, bool hasExistingValue, JsonSerializer serializer)
            => reader.Value is string value
                ? new(value)
                : throw new JsonException($"Could not parse mod name with token '{reader.Value}'");
        public override void WriteJson(JsonWriter writer, ModItemId? value, JsonSerializer serializer) {
            if (value is null) writer.WriteNull();
            else writer.WriteValue(value.ToString());
        }
    }
}

[JsonConverter(typeof(Md5JsonConverter))]
[DebuggerDisplay($"{{{nameof(ToString)}(),nq}}")]
public class Md5Hash : IEquatable<Md5Hash?> {
    private readonly byte[] _hash;
    public Md5Hash(string hash) : this(Convert.FromHexString(hash)) { }
    public Md5Hash(byte[] hash) {
        if (hash is not { Length: 16 }) throw new ArgumentException("Invalid digest size!", nameof(hash));
        _hash = hash;
    }
    public override bool Equals(object? obj) => Equals(obj as Md5Hash);
    public bool Equals(Md5Hash? other) => other != null && _hash.SequenceEqual(other._hash);
    public override int GetHashCode() {
        var hashCode = new HashCode();
        hashCode.AddBytes(_hash);
        return hashCode.ToHashCode();
    }
    public override string ToString() => Convert.ToHexString(_hash);

    public class Md5JsonConverter : JsonConverter<Md5Hash> {
        public override Md5Hash? ReadJson(JsonReader reader, Type objectType, Md5Hash? existingValue, bool hasExistingValue, JsonSerializer serializer)
            => reader.Value is string { Length: 32 } value
                ? new(value)
                : throw new JsonException($"Could not parse MD5 hash with token '{reader.Value}'");
        public override void WriteJson(JsonWriter writer, Md5Hash? value, JsonSerializer serializer) {
            if (value is null) writer.WriteNull();
            else writer.WriteValue(value.ToString());
        }
    }
}