using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

using BirdsiteLive.DAL.Contracts;
using BirdsiteLive.DAL.Models;
using BirdsiteLive.Pipeline.Contracts;
using BirdsiteLive.Pipeline.Models;
using BirdsiteLive.Twitter;
using BirdsiteLive.Twitter.Models;

using Microsoft.Extensions.Logging;

using Tweetinvi.Models;

namespace BirdsiteLive.Pipeline.Processors
{
    public class RetrieveTweetsProcessor : IRetrieveTweetsProcessor
    {
        private readonly ITwitterTweetsService _twitterTweetsService;
        private readonly ICachedTwitterUserService _twitterUserService;
        private readonly ITwitterUserDal _twitterUserDal;
        private readonly ILogger<RetrieveTweetsProcessor> _logger;

        #region Ctor
        public RetrieveTweetsProcessor(
            ITwitterTweetsService twitterTweetsService,
            ITwitterUserDal twitterUserDal,
            ICachedTwitterUserService twitterUserService,
            ILogger<RetrieveTweetsProcessor> logger
        )
        {
            _twitterTweetsService = twitterTweetsService;
            _twitterUserDal = twitterUserDal;
            _twitterUserService = twitterUserService;
            _logger = logger;
        }
        #endregion

        public async Task<UserWithDataToSync[]> ProcessAsync(
            UserWithDataToSync[] syncTwitterUsers,
            CancellationToken ct
        )
        {
            var usersWtTweets = new List<UserWithDataToSync>();

            //TODO multithread this
            foreach (var userWtData in syncTwitterUsers)
            {
                var user = userWtData.User;
                var tweets = RetrieveNewTweets(user);
                if (tweets.Length > 0 && user.LastTweetPostedId != -1)
                {
                    userWtData.Tweets = tweets;
                    usersWtTweets.Add(userWtData);
                }
                else if (tweets.Length > 0 && user.LastTweetPostedId == -1)
                {
                    var tweetId = tweets.Last().Id;
                    var now = DateTime.UtcNow;
                    await _twitterUserDal.UpdateTwitterUserAsync(
                        user.Id,
                        tweetId,
                        tweetId,
                        user.FetchingErrorCount,
                        now
                    );
                }
                else
                {
                    var now = DateTime.UtcNow;
                    await _twitterUserDal.UpdateTwitterUserAsync(
                        user.Id,
                        user.LastTweetPostedId,
                        user.LastTweetSynchronizedForAllFollowersId,
                        user.FetchingErrorCount,
                        now
                    );
                }
            }

            return usersWtTweets.ToArray();
        }

        private ExtractedTweet[] RetrieveNewTweets(SyncTwitterUser user)
        {
            var tweets = Array.Empty<ExtractedTweet>();

            try
            {
                if (user.LastTweetPostedId == -1)
                    tweets = _twitterTweetsService.GetTimeline(user.Acct, 1);
                else
                    tweets = _twitterTweetsService.GetTimeline(
                        user.Acct,
                        200,
                        user.LastTweetSynchronizedForAllFollowersId
                    );
            }
            catch (Exception e)
            {
                _logger.LogError(
                    e,
                    "Error retrieving TL of {Username} from {LastTweetPostedId}, purging user from cache",
                    user.Acct,
                    user.LastTweetPostedId
                );
                _twitterUserService.PurgeUser(user.Acct);
            }

            return tweets;
        }
    }
}