using System;
using System.Collections.Concurrent;

namespace codelanguage
{
    /// <summary>
    /// Manages per-client variables and output routing for the Craft++ runtime.
    /// Mirrors BYOND's client variable store and output channel system.
    /// </summary>
    public static class ClientVariablesService
    {
        private static readonly ConcurrentDictionary<string, CraftValue> _variables = new();

        /// <summary>Callback for sending output to the active client (mob/client << msg).</summary>
        public static Action<string>? OutputCallback { get; set; }

        /// <summary>Callback invoked when a client connects (client.Login equivalent).</summary>
        public static Action<string>? LoginCallback { get; set; }

        /// <summary>Callback invoked when a client disconnects (client.Logout equivalent).</summary>
        public static Action<string>? LogoutCallback { get; set; }

        public static void SetVariable(string key, CraftValue value)
        {
            _variables[key] = value;
        }

        public static CraftValue? GetVariable(string key)
        {
            _variables.TryGetValue(key, out var value);
            return value;
        }

        public static void DeleteVariable(string key)
        {
            _variables.TryRemove(key, out _);
        }

        public static IReadOnlyDictionary<string, CraftValue> GetAllVariables()
        {
            return _variables;
        }

        /// <summary>
        /// Sends output to the active client's output stream.
        /// Routes through OutputCallback if set, otherwise is a no-op.
        /// </summary>
        public static void SendOutput(string message)
        {
            OutputCallback?.Invoke(message);
        }

        /// <summary>
        /// Triggers the Login callback — called when a client attaches to a mob.
        /// Mirrors BYOND's /client/proc/Login().
        /// </summary>
        public static void TriggerLogin(string clientKey)
        {
            LoginCallback?.Invoke(clientKey);
        }

        /// <summary>
        /// Triggers the Logout callback — called when a client disconnects.
        /// Mirrors BYOND's /client/proc/Logout().
        /// </summary>
        public static void TriggerLogout(string clientKey)
        {
            LogoutCallback?.Invoke(clientKey);
        }

        /// <summary>Clears all stored variables (called on world reset).</summary>
        public static void Reset()
        {
            _variables.Clear();
        }
    }
}