using Predictalytics.Domain.Entities;
using Predictalytics.Domain.Interfaces;
using Predictalytics.Infrastructure.Providers.Polymarket;
using Predictalytics.Application.Interfaces;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace Predictalytics.Worker.Services;

/// <summary>
/// Retroactively enriches trades of top/watchlisted traders with high-resolution 
/// 1-minute price contexts immediately before and after execution.
/// Avoids burdening the live PollingWorker.
/// </summary>
public class TradeContextEnrichmentWorker : BackgroundService
{
    private readonly IServiceProvider _services;
    private readonly ILogger<TradeContextEnrichmentWorker> _logger;

    public TradeContextEnrichmentWorker(IServiceProvider services, ILogger<TradeContextEnrichmentWorker> logger)
    {
        _services = services;
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("🧠 TradeContextEnrichmentWorker started");
        await Task.Delay(10000, stoppingToken); // Wait for app startup

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                using var scope = _services.CreateScope();
                var tradeRepo = scope.ServiceProvider.GetRequiredService<ITradeRepository>();
                var polymarketClient = scope.ServiceProvider.GetRequiredService<PolymarketApiClient>();
                var rateLimiter = scope.ServiceProvider.GetRequiredService<IRateLimiter>();

                var estimator = scope.ServiceProvider.GetRequiredService<ICopytradingEstimator>();

                // Fetch a batch of unenriched trades
                var unenrichedTrades = await tradeRepo.GetTradesForContextEnrichmentAsync(50, stoppingToken);
                
                if (unenrichedTrades.Count == 0)
                {
                    // No work to do, sleep longer
                    await Task.Delay(TimeSpan.FromMinutes(5), stoppingToken);
                    continue;
                }

                // Group by AssetId to minimize API calls for the history endpoint (if we still use it)
                var tradesByAsset = unenrichedTrades.GroupBy(t => t.AssetId).ToList();
                _logger.LogInformation("Enriching {TradeCount} trades across {AssetCount} assets...", unenrichedTrades.Count, tradesByAsset.Count);

                int updatedCount = 0;

                foreach (var group in tradesByAsset)
                {
                    if (stoppingToken.IsCancellationRequested) break;
                    var assetId = group.Key;

                    try
                    {
                        // Wait for rate limiter to respect global limits
                        await rateLimiter.WaitAsync(Predictalytics.Domain.Enums.PlatformType.Polymarket, stoppingToken);

                        // We still fetch history for PriceBefore1m
                        var history = await polymarketClient.GetPricesHistoryAsync(assetId, "max", stoppingToken);
                        var orderedHistory = history?.OrderBy(h => h.Timestamp).ToList() ?? new List<PriceHistoryEntry>();

                        foreach (var trade in group)
                        {
                            var tradeTimeUnix = ((DateTimeOffset)trade.ExecutedAt).ToUnixTimeSeconds();

                            // Find the closest point BEFORE the trade (approx 1 min before)
                            var prePoint = orderedHistory
                                .LastOrDefault(h => h.Timestamp < tradeTimeUnix);
                            
                            // Find the closest point AFTER the trade (approx 1 min after) - old logic
                            var postPoint = orderedHistory
                                .FirstOrDefault(h => h.Timestamp > tradeTimeUnix);

                            var prePrice = prePoint != null ? (decimal?)prePoint.Price : null;
                            trade.PreTradePrice1m = prePrice;
                            trade.PostTradePrice1m = postPoint != null ? (decimal?)postPoint.Price : null;
                            trade.IsContextEnriched = true;

                            // NEW: Calculate exact follower fill prices from Trade Tape
                            var followerFill10s = await estimator.EstimateFollowerFillPriceAsync(trade, 10, stoppingToken);
                            var followerFill60s = await estimator.EstimateFollowerFillPriceAsync(trade, 60, stoppingToken);

                            // Populate new high-res TradeContext
                            trade.Context = new TradeContext
                            {
                                TradeId = trade.Id,
                                PriceBefore1m = prePrice,
                                PriceAfter1m = trade.PostTradePrice1m,
                                FollowerFillPrice10s = followerFill10s,
                                FollowerFillPrice60s = followerFill60s,
                                EstimatedSlippage = prePrice.HasValue ? Math.Abs(trade.Price - prePrice.Value) : null,
                                EstimatedOrderType = DetermineOrderType(trade, prePrice)
                            };

                            await tradeRepo.UpdateAsync(trade, stoppingToken);
                            updatedCount++;
                        }
                    }
                    catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
                    {
                        _logger.LogInformation("Cancellation requested during enrichment, stopping batch.");
                        break;
                    }
                    catch (Exception ex)
                    {
                        _logger.LogError(ex, "Failed to enrich asset {AssetId}", assetId);
                        // Do NOT mark as enriched on failure, try again later
                    }
                }

                _logger.LogInformation("✅ Enriched {UpdatedCount} trades in this cycle.", updatedCount);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error in TradeContextEnrichmentWorker loop");
            }

            // Sleep briefly before next batch
            await Task.Delay(TimeSpan.FromSeconds(30), stoppingToken);
        }

        _logger.LogInformation("🧠 TradeContextEnrichmentWorker stopped");
    }

    private static Predictalytics.Domain.Enums.OrderType DetermineOrderType(Trade trade, decimal? priceBefore)
    {
        if (priceBefore == null) return Predictalytics.Domain.Enums.OrderType.Unknown;
        
        if (trade.Side == Predictalytics.Domain.Enums.TradeSide.Buy)
        {
            return trade.Price <= priceBefore.Value ? Predictalytics.Domain.Enums.OrderType.Maker : Predictalytics.Domain.Enums.OrderType.Taker;
        }
        else if (trade.Side == Predictalytics.Domain.Enums.TradeSide.Sell)
        {
            return trade.Price >= priceBefore.Value ? Predictalytics.Domain.Enums.OrderType.Maker : Predictalytics.Domain.Enums.OrderType.Taker;
        }

        return Predictalytics.Domain.Enums.OrderType.Unknown;
    }
}