using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Telegram.Bot.Types;
using TelegramBotBase.Args;
using TelegramBotBase.Attributes;
using TelegramBotBase.Base;
using TelegramBotBase.Enums;

namespace TelegramBotBase.Form
{
    /// <summary>
    /// A form which cleans up old messages sent within
    /// </summary>
    public class AutoCleanForm : FormBase
    {
        [SaveState]
        public List<int> OldMessages { get; set; }

        [SaveState]
        public eDeleteMode DeleteMode { get; set; }

        [SaveState]
        public eDeleteSide DeleteSide { get; set; }



        public AutoCleanForm()
        {
            this.OldMessages = new List<int>();
            this.DeleteMode = eDeleteMode.OnEveryCall;
            this.DeleteSide = eDeleteSide.BotOnly;

            this.Init += AutoCleanForm_Init;

            this.Closed += AutoCleanForm_Closed;

        }

        private async Task AutoCleanForm_Init(object sender, InitEventArgs e)
        {
            if (this.Device == null)
                return;

            this.Device.MessageSent += Device_MessageSent;

            this.Device.MessageReceived += Device_MessageReceived;
        }


        private void Device_MessageReceived(object sender, MessageReceivedEventArgs e)
        {
            if (this.DeleteSide == eDeleteSide.BotOnly)
                return;

            this.OldMessages.Add(e.Message.MessageId);
        }

        private void Device_MessageSent(object sender, MessageSentEventArgs e)
        {
            if (this.DeleteSide == eDeleteSide.UserOnly)
                return;

            this.OldMessages.Add(e.Message.MessageId);
        }

        public override async Task PreLoad(MessageResult message)
        {
            if (this.DeleteMode != eDeleteMode.OnEveryCall)
                return;

            await MessageCleanup();
        }

        /// <summary>
        /// Adds a message to this of removable ones
        /// </summary>
        /// <param name="Id"></param>
        public void AddMessage(Message m)
        {
            this.OldMessages.Add(m.MessageId);
        }


        /// <summary>
        /// Adds a message to this of removable ones
        /// </summary>
        /// <param name="Id"></param>
        public void AddMessage(int messageId)
        {
            this.OldMessages.Add(messageId);
        }

        /// <summary>
        /// Keeps the message by removing it from the list
        /// </summary>
        /// <param name="Id"></param>
        public void LeaveMessage(int Id)
        {
            this.OldMessages.Remove(Id);
        }

        /// <summary>
        /// Keeps the last sent message
        /// </summary>
        public void LeaveLastMessage()
        {
            if (this.OldMessages.Count == 0)
                return;

            this.OldMessages.RemoveAt(this.OldMessages.Count - 1);
        }

        private async Task AutoCleanForm_Closed(object sender, EventArgs e)
        {
            if (this.DeleteMode != eDeleteMode.OnLeavingForm)
                return;

            MessageCleanup().Wait();
        }

        /// <summary>
        /// Cleans up all remembered messages.
        /// </summary>
        /// <returns></returns>
        public async Task MessageCleanup()
        {
            while (this.OldMessages.Count > 0)
            {
                var tasks = new List<Task>();
                var msgs = this.OldMessages.Take(Constants.Telegram.MessageDeletionsPerSecond);

                foreach (var msg in msgs)
                {
                    tasks.Add(this.Device.DeleteMessage(msg));
                }

                await Task.WhenAll(tasks);

                foreach(var m in msgs)
                {
                    Device.OnMessageDeleted(new MessageDeletedEventArgs(m));
                    this.OldMessages.Remove(m);
                }
            }            
        }
    }
}