using Sony.Filtr.AdminAPI.Modules.AnalyzePlaylist.ViewModels;
using Sony.Filtr.Playlists.Spotify.Model.History;
using System;
using System.Collections.Generic;
using System.Linq;

namespace Sony.Filtr.AdminAPI.Extensions
{
    public static class TrackPositionExtensions
    {
        public static void CalculateTrendAndIsEntry(this IEnumerable<HistoricTrackPosition> trendHistory, IEnumerable<SonyTrackViewModel> trackIsrcGroup)
        {
            if (trendHistory == null || !trendHistory.Any()) { return; }

            SonyTrackViewModel topPositionTrack = trackIsrcGroup.OrderBy(g => g.Position).First();

            Tuple<int, DateTime> trend = trendHistory.CalculateTrend(topPositionTrack.Position);

            if (trend != null)
            {
                topPositionTrack.PositionChange = trend.Item1;
                topPositionTrack.PositionChangeDate = (trend.Item2 > DateTime.Now.Date ? DateTime.Now.Date : trend.Item2);
            }

            topPositionTrack.IsEntry = trendHistory.IsEntry(topPositionTrack.Position, topPositionTrack.AddedDate.HasValue ? topPositionTrack.AddedDate.Value : DateTime.Now);
        }

        public static Tuple<int, DateTime> CalculateTrend(this IEnumerable<HistoricTrackPosition> trendHistory, int currentTrackPosition)
        {
            if (trendHistory == null || !trendHistory.Any()) { return null; }

            HistoricTrackPosition previousPosition = trendHistory.GetPreviousPosition(currentTrackPosition);

            return previousPosition == null ? 
                null : 
                new Tuple<int, DateTime>(currentTrackPosition - previousPosition.Position, previousPosition.Date.AddDays(1));
        }

        public static bool IsEntry(this IEnumerable<HistoricTrackPosition> trendHistory, int currentTrackPosition, DateTime currentDate)
        {
            if(trendHistory == null) { return false; }

            HistoricTrackPosition previousPosition = trendHistory.GetPreviousPosition(currentTrackPosition);

            return previousPosition == null ?
                true :
                previousPosition.Position == currentTrackPosition && previousPosition.Date.Date == currentDate.Date;
        }

        private static HistoricTrackPosition GetPreviousPosition(this IEnumerable<HistoricTrackPosition> trendHistory, int currentTrackPosition)
        {
            return trendHistory
                .GroupBy(th => th.Date)
                .OrderByDescending(g => g.Key)
                .Select(g => g.Aggregate((HistoricTrackPosition)null, (min, current) => (min == null || min.Position > current.Position) ? current : min))
                .FirstOrDefault(dateMin => dateMin.Position != currentTrackPosition);
        }
    }
}