using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using FinlyticCore.Dtos.Assets;
using FinlyticCore.Dtos.TechnicalAnalysis;
using FinlyticCore.Dtos.Trading;
using FinlyticCore.Models.Assets;
using FinlyticCore.Services;
using FinlyticEngine.Services.Mqtt;
using FinlyticEngine.Settings;

namespace FinlyticEngine.Services.Derivatives;

public class KnockOutDerivativeResolver : IKnockOutDerivativeResolver
{
    private readonly IEngineRpcClient _rpcClient;
    private readonly ISettingsService _settingsService;
    private readonly IFinlyticLogger<KnockOutDerivativeResolver> _logger;

    public KnockOutDerivativeResolver(
        IEngineRpcClient rpcClient,
        ISettingsService settingsService,
        IFinlyticLogger<KnockOutDerivativeResolver> logger)
    {
        _rpcClient = rpcClient;
        _settingsService = settingsService;
        _logger = logger;
    }

    public async Task<DerivativeSelectionDto?> ResolveOptimalTurboAsync(
        string underlyingIsin,
        SignalDirection direction,
        decimal chartStopLoss,
        decimal currentPrice,
        CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(underlyingIsin) || chartStopLoss <= 0 || currentPrice <= 0)
        {
            return null;
        }

        var optionType = direction == SignalDirection.Buy ? "long" : "short";
        var minLeverage = await _settingsService.GetSettingAsync(EngineSettingKeys.MinDerivativeLeverage, cancellationToken);
        var targetDefaultLeverage = await _settingsService.GetSettingAsync(EngineSettingKeys.TargetDefaultLeverage, cancellationToken);
        var safetyBufferPercent = await _settingsService.GetSettingAsync(EngineSettingKeys.KnockOutSafetyBufferPercent, cancellationToken);

        try
        {
            var req = new GetDerivativesRequest(
                UnderlyingIsin: underlyingIsin,
                OptionType: optionType,
                TargetLeverage: targetDefaultLeverage,
                After: null,
                Page: 0,
                ForceRefresh: false
            );


            await _logger.LogInfoAsync(EngineSettingKeys.DerivativesChannel,
                "[KnockOutResolver] Requesting derivatives for {Isin} ({OptionType}, target leverage {TargetLev})",
                underlyingIsin, optionType, targetDefaultLeverage);

            var derivatives = await _rpcClient.SendRpcRequestAsync<List<DerivativeDto>, GetDerivativesRequest>(
                "assets_GetDerivatives",
                req,
                TimeSpan.FromSeconds(5)
            );


            if (derivatives == null || derivatives.Count == 0)
            {
                await _logger.LogWarningAsync(EngineSettingKeys.DerivativesChannel,
                    "[KnockOutResolver] No derivatives returned from FinlyticAssets for {Isin}", underlyingIsin);
                return null;
            }

            // Hard Knock-Out Safety Check
            var safeDerivatives = derivatives.Where(d =>
            {
                if (d.Leverage < minLeverage || d.Barrier <= 0) return false;

                if (direction == SignalDirection.Buy)
                {
                    // For Long: Knock-Out Barrier MUST be at or below (StopLoss - Buffer%)
                    decimal maxAllowedBarrier = chartStopLoss * (1.0m - (safetyBufferPercent / 100.0m));
                    return d.Barrier <= maxAllowedBarrier;
                }
                else
                {
                    // For Short: Knock-Out Barrier MUST be at or above (StopLoss + Buffer%)
                    decimal minAllowedBarrier = chartStopLoss * (1.0m + (safetyBufferPercent / 100.0m));
                    return d.Barrier >= minAllowedBarrier;
                }
            }).ToList();

            if (safeDerivatives.Count == 0)
            {
                await _logger.LogWarningAsync(EngineSettingKeys.DerivativesChannel,
                    "[KnockOutResolver] None of the {Count} derivatives passed the hard KO safety buffer ({Buffer}%) for ISIN {Isin} (SL: {SL})",
                    derivatives.Count, safetyBufferPercent, underlyingIsin, chartStopLoss);
                return null;
            }

            // Ranking: 1. Issuer Rank, 2. Closeness to target leverage
            var best = safeDerivatives
                .OrderBy(d => GetIssuerRank(d.Issuer))
                .ThenBy(d => Math.Abs(d.Leverage - targetDefaultLeverage))
                .First();

            decimal calculatedBuffer = direction == SignalDirection.Buy
                ? ((chartStopLoss - best.Barrier) / chartStopLoss) * 100.0m
                : ((best.Barrier - chartStopLoss) / chartStopLoss) * 100.0m;

            // Trade Republic liefert für Derivate keine WKN (nur ISIN, siehe DerivativeDto/
            // TradeRepublicDerivativeItemDto). Die ISIN darf nicht als WKN ausgegeben werden,
            // da beide unterschiedliche Wertpapierkennungen sind (Rules.md §4) - daher null statt Fake-Wert.
            var result = new DerivativeSelectionDto(
                DerivativeIsin: best.Isin,
                DerivativeWkn: null,
                Issuer: best.Issuer ?? "Unknown",
                OptionType: optionType.ToUpperInvariant(),
                Strike: best.Strike,
                Barrier: best.Barrier,
                Leverage: best.Leverage,
                SafetyBufferPercent: Math.Round(calculatedBuffer, 2),
                SpreadPercentage: 0m,
                Size: best.Size ?? 0.1m
            );



            await _logger.LogInfoAsync(EngineSettingKeys.DerivativesChannel,
                "[KnockOutResolver] Selected optimal turbo {DerivIsin} for {Isin}: Lev={Lev}x, Barrier={Barrier}, Buffer={Buffer:F1}%, Issuer={Issuer}",
                result.DerivativeIsin, underlyingIsin, result.Leverage, result.Barrier, result.SafetyBufferPercent, result.Issuer);

            return result;
        }
        catch (Exception ex)
        {
            await _logger.LogErrorAsync(EngineSettingKeys.DerivativesChannel, ex,
                "[KnockOutResolver] Failed to resolve derivative for ISIN {Isin}", underlyingIsin);
            return null;
        }
    }

    private static int GetIssuerRank(string? issuer)
    {
        if (string.IsNullOrWhiteSpace(issuer)) return 5;
        var s = issuer.ToUpperInvariant();
        if (s.Contains("HSBC")) return 1;
        if (s.Contains("SOCIETE") || s.Contains("SG")) return 2;
        if (s.Contains("BNP")) return 3;
        if (s.Contains("UBS") || s.Contains("CITI") || s.Contains("VONTOBEL")) return 4;
        return 5;
    }
}