using System.Collections.Concurrent;
using System.Reflection;
using System.Text.Json;

namespace NotPogo.Core.Rooms
{
    public static class RoomManager
    {
        static readonly ConcurrentDictionary<string, Room> Rooms = new();

        static readonly Dictionary<string, Func<string, IGameRoom>> Factories = BuildFactories();

        public sealed record RoomDef(string Key, string Name, string Rule, int Capacity = 50);

        public static void LoadFromFile(string path)
        {
            var opts = new JsonSerializerOptions { PropertyNameCaseInsensitive = true, ReadCommentHandling = JsonCommentHandling.Skip, AllowTrailingCommas = true };
            var games = JsonSerializer.Deserialize<Dictionary<string, RoomDef[]>>(File.ReadAllText(path), opts)!;

            foreach (var (gameCode, rooms) in games)
                foreach (var r in rooms)
                    Define(r.Key, r.Name, gameCode, r.Rule, true, r.Capacity);
        }

        static Dictionary<string, Func<string, IGameRoom>> BuildFactories()
        {
            var map = new Dictionary<string, Func<string, IGameRoom>>(StringComparer.OrdinalIgnoreCase);

            foreach (var type in typeof(IGameRoom).Assembly.GetTypes()
                         .Where(t => typeof(IGameRoom).IsAssignableFrom(t) && !t.IsAbstract))
            {
                foreach (var attr in type.GetCustomAttributes<GameRoomAttribute>())
                {
                    // constructor convention: (string ruleId) if the game has modes, otherwise parameterless
                    Func<string, IGameRoom> factory =
                        type.GetConstructor([typeof(string)]) is not null ? rule => (IGameRoom)Activator.CreateInstance(type, rule)!
                      : type.GetConstructor(Type.EmptyTypes) is not null ? _ => (IGameRoom)Activator.CreateInstance(type)!
                      : throw new InvalidOperationException($"{type.Name} needs a (string ruleId) or parameterless constructor");

                    if (!map.TryAdd(attr.GameCode, factory))
                        throw new InvalidOperationException($"Game code '{attr.GameCode}' is claimed by more than one room class");
                }
            }
            return map;
        }

        static IGameRoom CreateGame(string gameCode, string ruleId) =>
            Factories.TryGetValue(gameCode, out var create) ? create(ruleId) : new ChatOnlyRoom();

        public static Room Define(string key, string humanName, string gameCode, string ruleId, bool isLive, int softCapacity = 50, int tabId = 1) =>
            Rooms.GetOrAdd(key, _ => new Room(key, humanName, gameCode, ruleId, softCapacity, tabId, isLive, CreateGame(gameCode, ruleId)));

        public static Room GetOrCreate(string key, string gameCode, string ruleId = "") =>
            Rooms.GetOrAdd(key, _ => new Room(key, key, gameCode, ruleId, 50, 1, false, CreateGame(gameCode, ruleId)));

        public static Room? Find(string key) => Rooms.TryGetValue(key, out var r) ? r : null;
        public static IEnumerable<Room> ForGame(string gameCode) => Rooms.Values.Where(r => r.GameCode == gameCode);
    }
}