using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Lidgren.Network;
using RageCoop.Core;
using RageCoop.Core.Scripting;
using System.Reflection;
using System.IO;

namespace RageCoop.Server.Scripting
{
    /// <summary>
    /// 
    /// </summary>
    public class ServerEvents
    {
        private readonly Server Server;
        internal ServerEvents(Server server)
        {
            Server = server;
        }
        #region INTERNAL
        internal Dictionary<int, List<Action<CustomEventReceivedArgs>>> CustomEventHandlers = new();
        #endregion
        /// <summary>
        /// Invoked when a chat message is received.
        /// </summary>
        public event EventHandler<ChatEventArgs> OnChatMessage;
        /// <summary>
        /// Will be invoked from main thread before registered handlers
        /// </summary>
        public event EventHandler<OnCommandEventArgs> OnCommandReceived;
        /// <summary>
        /// Will be invoked from main thread when a client is attempting to connect, use <see cref="HandshakeEventArgs.Deny(string)"/> to deny the connection request.
        /// </summary>
        public event EventHandler<HandshakeEventArgs> OnPlayerHandshake;
        /// <summary>
        /// Will be invoked when a player is connected, but this player might not be ready yet(client resources not loaded), using <see cref="OnPlayerReady"/> is recommended.
        /// </summary>
        public event EventHandler<Client> OnPlayerConnected;
        /// <summary>
        /// Will be invoked after the client connected and all resources(if any) have been loaded.
        /// </summary>
        public event EventHandler<Client> OnPlayerReady;
        /// <summary>
        /// Invoked when a player disconnected, all method won't be effective in this scope.
        /// </summary>
        public event EventHandler<Client> OnPlayerDisconnected;
        /// <summary>
        /// Invoked everytime a player's main ped has been updated
        /// </summary>
        public event EventHandler<Client> OnPlayerUpdate;
        internal void ClearHandlers()
        {
            OnChatMessage=null;
            OnPlayerHandshake=null;
            OnPlayerConnected=null;
            OnPlayerReady=null;
            OnPlayerDisconnected=null;
            // OnCustomEventReceived=null;
            OnCommandReceived=null;
            OnPlayerUpdate=null;
        }
        #region INVOKE
        internal void InvokePlayerHandshake(HandshakeEventArgs args)
        { OnPlayerHandshake?.Invoke(this, args); }
        internal void InvokeOnCommandReceived(string cmdName, string[] cmdArgs, Client sender)
        {
            var args = new OnCommandEventArgs()
            {
                Name=cmdName,
                Args=cmdArgs,
                Client=sender
            };
            OnCommandReceived?.Invoke(this, args);
            if (args.Cancel)
            {
                return;
            }
            if (Server.Commands.Any(x => x.Key.Name == cmdName))
            {
                string[] argsWithoutCmd = cmdArgs.Skip(1).ToArray();

                CommandContext ctx = new()
                {
                    Client = sender,
                    Args = argsWithoutCmd
                };

                KeyValuePair<Command, Action<CommandContext>> command = Server.Commands.First(x => x.Key.Name == cmdName);
                command.Value.Invoke(ctx);
            }
            else
            {

                Server.SendChatMessage("Server", "Command not found!", sender);
            }
        }

        internal void InvokeOnChatMessage(string msg, Client sender, string clamiedSender=null)
        {
            OnChatMessage?.Invoke(this, new ChatEventArgs()
            {
                Client=sender,
                Message=msg,
                ClaimedSender=clamiedSender
            });
        }
        internal void InvokePlayerConnected(Client client)
        { OnPlayerConnected?.Invoke(this,client); }
        internal void InvokePlayerReady(Client client)
        { OnPlayerReady?.Invoke(this, client); }
        internal void InvokePlayerDisconnected(Client client)
        { OnPlayerDisconnected?.Invoke(this,client); }

        internal void InvokeCustomEventReceived(Packets.CustomEvent p, Client sender)
        {
            var args = new CustomEventReceivedArgs() { Hash=p.Hash, Args=p.Args, Client=sender };
            List<Action<CustomEventReceivedArgs>> handlers;
            if (CustomEventHandlers.TryGetValue(p.Hash, out handlers))
            {
                handlers.ForEach((x) => { x.Invoke(args); });
            }
        }
        internal void InvokePlayerUpdate(Client client)
        {
            OnPlayerUpdate?.Invoke(this, client);
        }
        #endregion
    }
    /// <summary>
    /// An class that can be used to interact with RageCoop server.
    /// </summary>
    public class API
    {
        internal readonly Server Server;
        internal readonly Dictionary<string, Func<Stream>> RegisteredFiles=new Dictionary<string, Func<System.IO.Stream>>();
        internal API(Server server)
        {
            Server=server;
            Events=new(server);
            Server.RequestHandlers.Add(PacketType.FileTransferRequest, (data,client) =>
            {
                var p = new Packets.FileTransferRequest();
                p.Unpack(data);
                var id=Server.NewFileID();
                if(RegisteredFiles.TryGetValue(p.Name,out var s))
                {
                    Task.Run(() =>
                    {
                        Server.SendFile(s(), p.Name, client,id);
                    });
                    return new Packets.FileTransferResponse()
                    {
                        ID=id,
                        Response=FileResponse.Loaded
                    };
                }
                return new Packets.FileTransferResponse()
                {
                    ID=id,
                    Response=FileResponse.LoadFailed
                };
            });
        }
        /// <summary>
        /// Server side events
        /// </summary>
        public readonly ServerEvents Events;

        /// <summary>
        /// All synchronized entities on this server.
        /// </summary>
        public ServerEntities Entities { get { return Server.Entities; } }

        #region FUNCTIONS
        /// <summary>
        /// Get a list of all Clients
        /// </summary>
        /// <returns>All clients as a dictionary indexed by NetID</returns>
        public Dictionary<string, Client> GetAllClients()
        {
            return new(Server.ClientsByName);
        }

        /// <summary>
        /// Get the client by its username
        /// </summary>
        /// <param name="username">The username to search for (non case-sensitive)</param>
        /// <returns>The Client from this user or null</returns>
        public Client GetClientByUsername(string username)
        {
            return Server.Clients.Values.FirstOrDefault(x => x.Username.ToLower() == username.ToLower());
        }

        /// <summary>
        /// Send a chat message to all players, use <see cref="Client.SendChatMessage(string, string)"/> to send to an individual client.
        /// </summary>
        /// <param name="targets">The clients to send message, leave it null to send to all clients</param>
        /// <param name="message">The chat message</param>
        /// <param name="username">The username which send this message (default = "Server")</param>
        /// <param name="raiseEvent">Weather to raise the <see cref="ServerEvents.OnChatMessage"/> event defined in <see cref="API.Events"/></param>
        /// <remarks>When <paramref name="raiseEvent"/> is unspecified and <paramref name="targets"/> is null or unspecified, <paramref name="raiseEvent"/> will be set to true</remarks>
        public void SendChatMessage(string message, List<Client> targets = null, string username = "Server",bool? raiseEvent=null)
        {
            raiseEvent ??= targets==null;
            try
            {
                if (Server.MainNetServer.ConnectionsCount == 0)
                {
                    return;
                }
                targets ??= new(Server.Clients.Values);
                foreach(Client client in targets)
                {
                    Server.SendChatMessage(username, message, client);
                }
            }
            catch (Exception e)
            {
                Server.Logger?.Error($">> {e.Message} <<>> {e.Source ?? string.Empty} <<>> {e.StackTrace ?? string.Empty} <<");
            }
            if (raiseEvent.Value)
            {
                Events.InvokeOnChatMessage(message, null, username);
            }
        }

        /// <summary>
        /// Register a file to be shared with clients
        /// </summary>
        /// <param name="name">name of this file</param>
        /// <param name="path">path to this file</param>
        public void RegisterSharedFile(string name,string path)
        {
            RegisteredFiles.Add(name, () => { return File.OpenRead(path); });
        }

        /// <summary>
        /// Register a file to be shared with clients
        /// </summary>
        /// <param name="name">name of this file</param>
        /// <param name="file"></param>
        public void RegisterSharedFile(string name, ResourceFile file)
        {
            RegisteredFiles.Add(name, file.GetStream);
        }

        /// <summary>
        /// Register a new command chat command (Example: "/test")
        /// </summary>
        /// <param name="name">The name of the command (Example: "test" for "/test")</param>
        /// <param name="usage">How to use this message (argsLength required!)</param>
        /// <param name="argsLength">The length of args (Example: "/message USERNAME MESSAGE" = 2) (usage required!)</param>
        /// <param name="callback">A callback to invoke when the command received.</param>
        public void RegisterCommand(string name, string usage, short argsLength, Action<CommandContext> callback)
        {
            Server.RegisterCommand(name, usage, argsLength, callback);
        }
        /// <summary>
        /// Register a new command chat command (Example: "/test")
        /// </summary>
        /// <param name="name">The name of the command (Example: "test" for "/test")</param>
        /// <param name="callback">A callback to invoke when the command received.</param>
        public void RegisterCommand(string name, Action<CommandContext> callback)
        {
            Server.RegisterCommand(name, callback);
        }

        /// <summary>
        /// Register all commands in a static class
        /// </summary>
        /// <typeparam name="T">Your static class with commands</typeparam>
        public void RegisterCommands<T>()
        {
            Server.RegisterCommands<T>();
        }

        /// <summary>
        /// Register all commands inside an class instance
        /// </summary>
        /// <param name="obj">The instance of type containing the commands</param>
        public void RegisterCommands(object obj)
        {
            IEnumerable<MethodInfo> commands = obj.GetType().GetMethods().Where(method => method.GetCustomAttributes(typeof(Command), false).Any());

            foreach (MethodInfo method in commands)
            {
                Command attribute = method.GetCustomAttribute<Command>(true);
                RegisterCommand(attribute.Name, attribute.Usage, attribute.ArgsLength,
                    (ctx) => { method.Invoke(obj, new object[] { ctx }); });
            }
        }

        /// <summary>
        /// Send native call specified clients.
        /// </summary>
        /// <param name="hash"></param>
        /// <param name="args"></param>
        /// /// <param name="clients">Clients to send, null for all clients</param>
        public void SendNativeCall(List<Client> clients , GTA.Native.Hash hash, params object[] args)
        {
            var argsList = new List<object>(args);
            argsList.InsertRange(0, new object[] { (byte)TypeCode.Empty, (ulong)hash });
            SendCustomEventQueued(clients, CustomEvents.NativeCall, argsList.ToArray());
        }


        /// <summary>
        /// Send an event and data to the specified clients. Use <see cref="Client.SendCustomEvent(int,object[])"/> if you want to send event to individual client.
        /// </summary>
        /// <param name="eventHash">An unique identifier of the event, you can use <see cref="CustomEvents.Hash(string)"/> to get it from a string</param>
        /// <param name="args">The objects conataing your data, see <see cref="Scripting.CustomEventReceivedArgs.Args"/> for supported types.</param>
        /// <param name="targets">The target clients to send. Leave it null to send to all clients</param>
        public void SendCustomEvent(List<Client> targets, int eventHash,  params object[] args)
        {

            targets ??= new(Server.Clients.Values);
            var p = new Packets.CustomEvent()
            {
                Args=args,
                Hash=eventHash
            };
            foreach (var c in targets)
            {
                Server.Send(p, c, ConnectionChannel.Event, NetDeliveryMethod.ReliableOrdered);
            }
        }

        /// <summary>
        /// Send a CustomEvent that'll be queued at client side and invoked from script thread
        /// </summary>
        /// <param name="targets"></param>
        /// <param name="eventHash"></param>
        /// <param name="args"></param>
        public void SendCustomEventQueued(List<Client> targets, int eventHash, params object[] args)
        {

            targets ??= new(Server.Clients.Values);
            var p = new Packets.CustomEvent(null,true)
            {
                Args=args,
                Hash=eventHash
            };
            foreach (var c in targets)
            {
                Server.Send(p, c, ConnectionChannel.Event, NetDeliveryMethod.ReliableOrdered);
            }
        }
        /// <summary>
        /// Register an handler to the specifed event hash, one event can have multiple handlers.
        /// </summary>
        /// <param name="hash">An unique identifier of the event, you can hash your event name with <see cref="CustomEvents.Hash(string)"/></param>
        /// <param name="handler">An handler to be invoked when the event is received from the server.</param>
        public void RegisterCustomEventHandler(int hash,Action<CustomEventReceivedArgs> handler)
        {
            List<Action<CustomEventReceivedArgs>> handlers;
            lock (Events.CustomEventHandlers)
            {
                if (!Events.CustomEventHandlers.TryGetValue(hash,out handlers))
                {
                    Events.CustomEventHandlers.Add(hash, handlers = new List<Action<CustomEventReceivedArgs>>());
                }
                handlers.Add(handler);
            }
        }
        /// <summary>
        /// Register an event handler for specified event name.
        /// </summary>
        /// <param name="name">This value will be hashed to an int to reduce overhead</param>
        /// <param name="handler">The handler to be invoked when the event is received</param>
        public void RegisterCustomEventHandler(string name, Action<CustomEventReceivedArgs> handler)
        {
            RegisterCustomEventHandler(CustomEvents.Hash(name), handler);
        }


        /// <summary>
        /// Find a script matching the specified type
        /// </summary>
        /// <param name="scriptFullName">The full name of the script's type, e.g. RageCoop.Resources.Discord.Main</param>
        /// <param name="resourceName">Which resource to search for this script. Will search in all loaded resources if unspecified </param>
        /// <returns>A <see langword="dynamic"/> object reprensenting the script, or <see langword="null"/> if not found.</returns>
        /// <remarks>Explicitly casting the return value to orginal type will case a exception to be thrown due to the dependency isolation mechanism in resource system. 
        /// You shouldn't reference the target resource assemblies either, since it causes the referenced assembly to be loaded and started in your resource.</remarks>
        public dynamic FindScript(string scriptFullName,string resourceName=null)
        {
            if (resourceName==null)
            {
                foreach(var res in LoadedResources.Values)
                {
                    if (res.Scripts.TryGetValue(scriptFullName, out var script))
                    {
                        return script;
                    }
                }
            }
            else if (LoadedResources.TryGetValue(resourceName, out var res))
            {
                if(res.Scripts.TryGetValue(scriptFullName, out var script))
                {
                    return script;
                }    
            }
            return null;
        }

        #endregion


        #region PROPERTIES

        /// <summary>
        /// Get a <see cref="Core.Logger"/> that the server is currently using, you should use <see cref="ServerResource.Logger"/> to display resource-specific information.
        /// </summary>
        public Logger Logger { get { return Server.Logger; } }


        /// <summary>
        /// Gets or sets the client that is resposible for synchronizing time and weather
        /// </summary>
        public Client Host
        {
            get { return Server._hostClient; }
            set { 
                if (Server._hostClient != value) 
                {
                    Server._hostClient?.SendCustomEvent(CustomEvents.IsHost, false);
                    value.SendCustomEvent(CustomEvents.IsHost, true);
                    Server._hostClient = value; 
                } 
            }
        }

        /// <summary>
        /// Get all currently loaded <see cref="ServerResource"/> as a dictionary indexed by their names
        /// </summary>
        /// <remarks>Accessing this property from script constructor is stronly discouraged since other scripts and resources might have yet been loaded.
        /// Accessing from <see cref="ServerScript.OnStart"/> is not recommended either. Although all script assemblies will have been loaded to memory and instantiated, <see cref="ServerScript.OnStart"/> invocation of other scripts are not guaranteed.
        /// </remarks>
        public Dictionary<string,ServerResource> LoadedResources
        {
            get
            {
                if (!Server.Resources.IsLoaded)
                {
                    Logger?.Warning("Attempting to get resources before all scripts are loaded");
                    Logger.Trace(new System.Diagnostics.StackTrace().ToString());
                }
                return Server.Resources.LoadedResources;
            }
        }
        #endregion
    }
}