/*
 *
 * (c) Copyright Ascensio System Limited 2010-2020
 *
 * This program is freeware. You can redistribute it and/or modify it under the terms of the GNU 
 * General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html). 
 * In accordance with Section 7(a) of the GNU GPL its Section 15 shall be amended to the effect that 
 * Ascensio System SIA expressly excludes the warranty of non-infringement of any third-party rights.
 *
 * THIS PROGRAM IS DISTRIBUTED WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE. For more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
 *
 * You can contact Ascensio System SIA by email at sales@onlyoffice.com
 *
 * The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display 
 * Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
 *
 * Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains 
 * relevant author attributions when distributing the software. If the display of the logo in its graphic 
 * form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE" 
 * in every copy of the program you distribute. 
 * Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
 *
*/

namespace ASC.TelegramService;

[Singletone(Additional = typeof(TelegramHandlerExtension))]
public class TelegramHandler
{
    private readonly Dictionary<int, TenantTgClient> _clients;
    private readonly CommandModule _command;
    private readonly ILog _log;
    private readonly IServiceScopeFactory _scopeFactory;

    public TelegramHandler(CommandModule command, IOptionsMonitor<ILog> option, IServiceScopeFactory scopeFactory)
    {
        _command = command;
        _log = option.CurrentValue;
        _scopeFactory = scopeFactory;
        _clients = new Dictionary<int, TenantTgClient>();
        ServicePointManager.SecurityProtocol |= SecurityProtocolType.Tls12 | SecurityProtocolType.Tls13;
    }

    public Task SendMessage(NotifyMessage msg)
    {
        if (string.IsNullOrEmpty(msg.To)) return Task.CompletedTask;
        if (!_clients.ContainsKey(msg.Tenant)) return Task.CompletedTask;

        return InternalSendMessage(msg);
    }

    private async Task InternalSendMessage(NotifyMessage msg)
    {
        var scope = _scopeFactory.CreateScope();
        var cachedTelegramDao = scope.ServiceProvider.GetService<IOptionsSnapshot<CachedTelegramDao>>().Value;

        var client = _clients[msg.Tenant].Client;

        try
        {
            var tgUser = cachedTelegramDao.GetUser(Guid.Parse(msg.To), msg.Tenant);

            if (tgUser == null)
            {
                _log.DebugFormat("Couldn't find telegramId for user '{0}'", msg.To);
                return;
            }

            var chat = await client.GetChatAsync(tgUser.TelegramUserId);
            await client.SendTextMessageAsync(chat, msg.Content, Telegram.Bot.Types.Enums.ParseMode.Markdown);
        }
        catch (Exception e)
        {
            _log.DebugFormat("Couldn't send message for user '{0}' got an '{1}'", msg.To, e.Message);
        }
    }

    public void DisableClient(int tenantId)
    {
        if (!_clients.ContainsKey(tenantId)) return;

        var client = _clients[tenantId];
        client.Client.StopReceiving();

        _clients.Remove(tenantId);
    }

    public void CreateOrUpdateClientForTenant(int tenantId, string token, int tokenLifespan, string proxy, bool startTelegramService, bool force = false)
    {
        var scope = _scopeFactory.CreateScope();
        var telegramHelper = scope.ServiceProvider.GetService<TelegramHelper>();
        var newClient = telegramHelper.InitClient(token, proxy);

        if (_clients.TryGetValue(tenantId, out var client))
        {
            client.TokenLifeSpan = tokenLifespan;

            if (token != client.Token || proxy != client.Proxy)
            {
                if (startTelegramService)
                {
                    if (!telegramHelper.TestingClient(newClient)) return;
                }

                client.Client.StopReceiving();

                BindClient(newClient, tenantId);

                client.Client = newClient;
                client.Token = token;
                client.Proxy = proxy;
            }
        }
        else
        {
            if (!force && startTelegramService)
            {
                if (!telegramHelper.TestingClient(newClient)) return;
            }

            BindClient(newClient, tenantId);

            _clients.Add(tenantId, new TenantTgClient()
            {
                Token = token,
                Client = newClient,
                Proxy = proxy,
                TenantId = tenantId,
                TokenLifeSpan = tokenLifespan
            });
        }
    }

    public void RegisterUser(string userId, int tenantId, string token)
    {
        if (!_clients.ContainsKey(tenantId)) return;

        var userKey = UserKey(userId, tenantId);
        var dateExpires = DateTimeOffset.Now.AddMinutes(_clients[tenantId].TokenLifeSpan);
        MemoryCache.Default.Set(token, userKey, dateExpires);
    }

    private Task OnMessage(object sender, MessageEventArgs e, TelegramBotClient client, int tenantId)
    {
        if (string.IsNullOrEmpty(e.Message.Text) || e.Message.Text[0] != '/') return Task.CompletedTask;
        return InternalOnMessage(sender, e, client, tenantId);
    }

    private async Task InternalOnMessage(object sender, MessageEventArgs e, TelegramBotClient client, int tenantId)
    {
        await _command.HandleCommand(e.Message, client, tenantId);
    }


    private void BindClient(TelegramBotClient client, int tenantId)
    {
        client.OnMessage += async (sender, e) => { await OnMessage(sender, e, client, tenantId); };
        client.StartReceiving();
    }

    private string UserKey(string userId, int tenantId)
    {
        return string.Format("{0}:{1}", userId, tenantId);
    }
}

public static class TelegramHandlerExtension
{
    public static void Register(DIHelper services)
    {
        services.TryAdd<TelegramHelper>();
    }
}