using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using FinlyticCore.Dtos.TechnicalAnalysis;
using FinlyticCore.Services;
using FinlyticTechnicals.Timeframe;
using FinlyticTechnicals.Util;

namespace FinlyticTechnicals.Services;

public interface IMultiTimeframeCandleAggregator
{
    /// <summary>
    /// Initializes historical ring buffers for an ISIN with Yahoo/database candles.
    /// </summary>
    void InitializeHistory(string isin, string timeframe, IEnumerable<CandleDto> candles);

    /// <summary>
    /// Processes an incoming clean tick and updates 1m, 5m, 15m, 1h, and 1d candles.
    /// </summary>
    void ProcessTick(CleanLiveTick tick);

    /// <summary>
    /// Gets a snapshot of the ring buffer for an ISIN and timeframe.
    /// </summary>
    IReadOnlyList<CandleDto> GetCandles(string isin, string timeframe);

    /// <summary>
    /// Gets all multi-timeframe candles (1m, 5m, 15m, 1h, 1d) as a dictionary.
    /// </summary>
    Dictionary<string, IReadOnlyList<CandleDto>> GetAllTimeframes(string isin);

    /// <summary>
    /// Event triggered when a timeframe bar completes.
    /// </summary>
    event Action<string, string, CandleDto>? OnCandleClosed;
}

public class MultiTimeframeCandleAggregator : IMultiTimeframeCandleAggregator
{
    private readonly IFinlyticLogger<MultiTimeframeCandleAggregator> _logger;
    private readonly ConcurrentDictionary<string, ConcurrentDictionary<string, CircularRingBuffer<CandleDto>>> _buffers = new(StringComparer.OrdinalIgnoreCase);
    private readonly ConcurrentDictionary<string, CandleDto> _current1mCandles = new(StringComparer.OrdinalIgnoreCase);
    private readonly object _aggregationLock = new();

    public event Action<string, string, CandleDto>? OnCandleClosed;

    public MultiTimeframeCandleAggregator(IFinlyticLogger<MultiTimeframeCandleAggregator> logger)
    {
        _logger = logger;
    }

    public void InitializeHistory(string isin, string timeframe, IEnumerable<CandleDto> candles)
    {
        if (string.IsNullOrWhiteSpace(isin) || string.IsNullOrWhiteSpace(timeframe)) return;

        var cleanIsin = isin.Trim().ToUpperInvariant();
        var cleanTf = timeframe.Trim().ToLowerInvariant();

        var isinBuffers = _buffers.GetOrAdd(cleanIsin, _ => new ConcurrentDictionary<string, CircularRingBuffer<CandleDto>>(StringComparer.OrdinalIgnoreCase));
        var ringBuffer = isinBuffers.GetOrAdd(cleanTf, _ => new CircularRingBuffer<CandleDto>(500));

        var ordered = candles
            .Where(c => c.Close > 0m)
            .OrderBy(c => c.Timestamp)
            .ToList();

        ringBuffer.LoadBulk(ordered);
    }

    public void ProcessTick(CleanLiveTick tick)
    {
        if (tick == null || string.IsNullOrWhiteSpace(tick.Isin)) return;

        var isin = tick.Isin.Trim().ToUpperInvariant();
        var tickTime = tick.TimestampUtc;
        var minuteBoundary = new DateTime(tickTime.Year, tickTime.Month, tickTime.Day, tickTime.Hour, tickTime.Minute, 0, DateTimeKind.Utc);

        lock (_aggregationLock)
        {
            var isinBuffers = _buffers.GetOrAdd(isin, _ => new ConcurrentDictionary<string, CircularRingBuffer<CandleDto>>(StringComparer.OrdinalIgnoreCase));
            var ringBuffer1m = isinBuffers.GetOrAdd("1m", _ => new CircularRingBuffer<CandleDto>(500));

            if (_current1mCandles.TryGetValue(isin, out var current1m))
            {
                if (current1m.Timestamp == minuteBoundary)
                {
                    // Update current open 1m bar
                    var updated = current1m with
                    {
                        High = Math.Max(current1m.High, tick.MidPrice),
                        Low = Math.Min(current1m.Low, tick.MidPrice),
                        Close = tick.MidPrice,
                        Volume = current1m.Volume + 1,
                        Bid = tick.Bid,
                        Ask = tick.Ask
                    };
                    _current1mCandles[isin] = updated;
                    ringBuffer1m.UpdateLast(updated);
                }
                else if (minuteBoundary > current1m.Timestamp)
                {
                    // 1. Close current 1m bar
                    ringBuffer1m.UpdateLast(current1m);
                    OnCandleClosed?.Invoke(isin, "1m", current1m);

                    // 2. Reconnect-Lückenbehandlung (Gap Handling)
                    // If multiple minutes passed without ticks (e.g. disconnect), fill gaps flatly with Volume = 0
                    var gapStart = current1m.Timestamp.AddMinutes(1);
                    var lastClose = current1m.Close;
                    while (gapStart < minuteBoundary)
                    {
                        var flatBar = new CandleDto(
                            Timestamp: gapStart,
                            Open: lastClose,
                            High: lastClose,
                            Low: lastClose,
                            Close: lastClose,
                            Volume: 0,
                            Bid: tick.Bid,
                            Ask: tick.Ask
                        );
                        ringBuffer1m.Add(flatBar);
                        OnCandleClosed?.Invoke(isin, "1m", flatBar);
                        gapStart = gapStart.AddMinutes(1);
                    }

                    // 3. Start new 1m bar
                    var new1m = new CandleDto(
                        Timestamp: minuteBoundary,
                        Open: tick.MidPrice,
                        High: tick.MidPrice,
                        Low: tick.MidPrice,
                        Close: tick.MidPrice,
                        Volume: 1,
                        Bid: tick.Bid,
                        Ask: tick.Ask
                    );
                    _current1mCandles[isin] = new1m;
                    ringBuffer1m.Add(new1m);

                    // 4. Update higher timeframes (5m, 15m, 1h, 1d)
                    RebuildHigherTimeframes(isin, isinBuffers, ringBuffer1m);
                }
            }
            else
            {
                // First tick for this ISIN
                var new1m = new CandleDto(
                    Timestamp: minuteBoundary,
                    Open: tick.MidPrice,
                    High: tick.MidPrice,
                    Low: tick.MidPrice,
                    Close: tick.MidPrice,
                    Volume: 1,
                    Bid: tick.Bid,
                    Ask: tick.Ask
                );
                _current1mCandles[isin] = new1m;
                ringBuffer1m.Add(new1m);
            }
        }
    }

    private void RebuildHigherTimeframes(string isin, ConcurrentDictionary<string, CircularRingBuffer<CandleDto>> isinBuffers, CircularRingBuffer<CandleDto> ringBuffer1m)
    {
        var snapshot1m = ringBuffer1m.ToArray();
        if (snapshot1m.Length == 0) return;

        // Build 5m candles
        AggregatePeriod(isin, isinBuffers, snapshot1m, "5m", 5);

        // Build 15m candles
        AggregatePeriod(isin, isinBuffers, snapshot1m, "15m", 15);

        // Build 1h candles
        AggregatePeriod(isin, isinBuffers, snapshot1m, "1h", 60);

        // Build 1d candles
        AggregateDaily(isin, isinBuffers, snapshot1m);
    }

    private void AggregatePeriod(string isin, ConcurrentDictionary<string, CircularRingBuffer<CandleDto>> isinBuffers, CandleDto[] candles1m, string tfName, int minutes)
    {
        var targetBuffer = isinBuffers.GetOrAdd(tfName, _ => new CircularRingBuffer<CandleDto>(500));
        targetBuffer.LoadBulk(FinlyticTechnicals.Indicators.CandleResampler.Resample(candles1m, minutes));
    }

    private void AggregateDaily(string isin, ConcurrentDictionary<string, CircularRingBuffer<CandleDto>> isinBuffers, CandleDto[] candles1m)
    {
        var targetBuffer = isinBuffers.GetOrAdd("1d", _ => new CircularRingBuffer<CandleDto>(500));
        var aggregated = FinlyticTechnicals.Indicators.CandleResampler.Resample(candles1m, 1440);

        // If daily buffer already has deep Yahoo history, stitch today's aggregated bar onto the end
        if (targetBuffer.Count > 0 && aggregated.Count > 0)
        {
            var today = aggregated.Last();
            var lastHistory = targetBuffer.GetLast();
            if (lastHistory != null && lastHistory.Timestamp.Date == today.Timestamp.Date)
            {
                targetBuffer.UpdateLast(today);
            }
            else
            {
                targetBuffer.Add(today);
            }
        }
        else if (aggregated.Count > 0)
        {
            targetBuffer.LoadBulk(aggregated);
        }
    }

    public IReadOnlyList<CandleDto> GetCandles(string isin, string timeframe)
    {
        if (string.IsNullOrWhiteSpace(isin)) return [];
        var cleanIsin = isin.Trim().ToUpperInvariant();
        var cleanTf = (timeframe ?? "15m").Trim().ToLowerInvariant();

        if (_buffers.TryGetValue(cleanIsin, out var isinBuffers) &&
            isinBuffers.TryGetValue(cleanTf, out var ringBuffer))
        {
            return ringBuffer.ToArray();
        }
        return [];
    }

    public Dictionary<string, IReadOnlyList<CandleDto>> GetAllTimeframes(string isin)
    {
        var result = new Dictionary<string, IReadOnlyList<CandleDto>>(StringComparer.OrdinalIgnoreCase);
        if (string.IsNullOrWhiteSpace(isin)) return result;

        var cleanIsin = isin.Trim().ToUpperInvariant();
        if (_buffers.TryGetValue(cleanIsin, out var isinBuffers))
        {
            foreach (var kvp in isinBuffers)
            {
                result[kvp.Key] = kvp.Value.ToArray();
            }
        }
        return result;
    }
}