using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using FinlyticCore.Dtos.Bot;
using FinlyticCore.Dtos.TechnicalAnalysis;
using FinlyticCore.Dtos.Trading;
using FinlyticCore.Services;
using FinlyticBot.Database;
using FinlyticBot.Database.Entities;
using FinlyticBot.Settings;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;

namespace FinlyticBot.Services.Ledger;

public class SyntheticPaperBroker : ISyntheticPaperBroker
{
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly ISettingsService _settingsService;
    private readonly IFinlyticLogger<SyntheticPaperBroker> _logger;

    public SyntheticPaperBroker(
        IServiceScopeFactory scopeFactory,
        ISettingsService settingsService,
        IFinlyticLogger<SyntheticPaperBroker> logger)
    {
        _scopeFactory = scopeFactory;
        _settingsService = settingsService;
        _logger = logger;
    }

    public async Task<BotPositionEntity> OpenPositionAsync(
        TradeProposalDto proposal,
        decimal quantity,
        CancellationToken cancellationToken = default)
    {
        using var scope = _scopeFactory.CreateScope();
        var db = scope.ServiceProvider.GetRequiredService<BotDbContext>();

        decimal entryPrice = proposal.EntryPrice;
        decimal takeProfit1 = proposal.ExitPlan.TakeProfitStages.Count > 0
            ? proposal.ExitPlan.TakeProfitStages[0].TargetPrice
            : (proposal.Direction == SignalDirection.Buy ? entryPrice * 1.05m : entryPrice * 0.95m);

        decimal takeProfit2 = proposal.ExitPlan.TakeProfitStages.Count > 1
            ? proposal.ExitPlan.TakeProfitStages[1].TargetPrice
            : (proposal.Direction == SignalDirection.Buy ? entryPrice * 1.10m : entryPrice * 0.90m);

        var position = new BotPositionEntity
        {
            Id = Guid.NewGuid(),
            ProposalId = proposal.ProposalId,
            Isin = proposal.UnderlyingIsin,
            Symbol = proposal.Symbol,
            Venue = BotExecutionVenue.SyntheticPaperBroker,
            ClientOrderId = $"SYN_{Guid.NewGuid():N}",
            Direction = proposal.Direction,
            Quantity = quantity,
            EntryPrice = entryPrice,
            AverageBuyIn = entryPrice,
            InitialStopLoss = proposal.InvalidationPrice,
            CurrentStopLoss = proposal.InvalidationPrice,
            CurrentPrice = entryPrice,
            TakeProfit1 = takeProfit1,
            TakeProfit2 = takeProfit2,
            TotalFeesEur = 1.00m,
            RealizedPnlEur = 0m,
            Status = BotPositionStatus.Active,
            ExitPlan = proposal.ExitPlan,
            OpenedAtUtc = DateTime.UtcNow,
            LastSyncAtUtc = DateTime.UtcNow
        };

        db.Positions.Add(position);
        await db.SaveChangesAsync(cancellationToken);

        await _logger.LogInfoAsync(BotSettingKeys.LedgerChannel,
            "[SyntheticBroker] Opened position {Id} for {Isin} ({Symbol}) at {Entry:F2} € (Qty: {Qty}, SL: {SL:F2}, TP1: {TP1:F2})",
            position.Id, position.Isin, position.Symbol, position.EntryPrice, position.Quantity, position.CurrentStopLoss, position.TakeProfit1);

        return position;
    }

    public async Task<BotPositionEntity> ClosePositionAsync(
        Guid positionId,
        decimal exitPrice,
        BotPositionStatus exitStatus,
        CancellationToken cancellationToken = default)
    {
        using var scope = _scopeFactory.CreateScope();
        var db = scope.ServiceProvider.GetRequiredService<BotDbContext>();

        var pos = await db.Positions.FirstOrDefaultAsync(p => p.Id == positionId, cancellationToken);
        if (pos == null) throw new InvalidOperationException($"Position {positionId} not found.");

        pos.Status = exitStatus;
        pos.ClosedAtUtc = DateTime.UtcNow;
        pos.CurrentPrice = exitPrice;
        pos.LastSyncAtUtc = DateTime.UtcNow;
        pos.TotalFeesEur += 1.00m; // Exit fee

        if (exitStatus == BotPositionStatus.KnockedOut)
        {
            pos.RealizedPnlEur = -((pos.AverageBuyIn * pos.Quantity) + pos.TotalFeesEur);
        }
        else
        {
            decimal pnl = pos.Direction == SignalDirection.Buy
                ? ((exitPrice - pos.AverageBuyIn) * pos.Quantity) - pos.TotalFeesEur
                : ((pos.AverageBuyIn - exitPrice) * pos.Quantity) - pos.TotalFeesEur;

            pos.RealizedPnlEur = Math.Round(pnl, 2);
        }

        await db.SaveChangesAsync(cancellationToken);

        await _logger.LogInfoAsync(BotSettingKeys.LedgerChannel,
            "[SyntheticBroker] Closed position {Id} at {Exit:F2} € with status {Status} (PnL: {PnL:F2} €)",
            pos.Id, exitPrice, exitStatus, pos.RealizedPnlEur);

        return pos;
    }

    public async Task<AccountSummaryDto> GetSummaryAsync(CancellationToken cancellationToken = default)
    {
        using var scope = _scopeFactory.CreateScope();
        var db = scope.ServiceProvider.GetRequiredService<BotDbContext>();

        decimal baseCapital = await _settingsService.GetSettingAsync(BotSettingKeys.SyntheticBaseCapitalEur, cancellationToken);
        var positions = await db.Positions.AsNoTracking().ToListAsync(cancellationToken);

        decimal totalRealized = positions.Sum(p => p.RealizedPnlEur);
        decimal totalFees = positions.Sum(p => p.TotalFeesEur);

        var openPositions = positions
            .Where(p => p.Status == BotPositionStatus.Active || p.Status == BotPositionStatus.BreakEvenTriggered)
            .ToList();

        // Unrealized P&L of still-open positions (direction-aware: a short position gains when
        // CurrentPrice drops below AverageBuyIn). CurrentPrice is kept fresh by
        // BotTradeLifecycleBackgroundService, which re-fetches the latest candle close for every open
        // position on each monitoring tick. Without this term, equity only ever moved when a position
        // closed, even though open positions were already sitting on real gains/losses.
        decimal unrealizedPnl = openPositions.Sum(p => p.Direction == SignalDirection.Buy
            ? (p.CurrentPrice - p.AverageBuyIn) * p.Quantity
            : (p.AverageBuyIn - p.CurrentPrice) * p.Quantity);

        decimal currentEquity = baseCapital + totalRealized + unrealizedPnl;
        decimal invested = openPositions.Sum(p => p.AverageBuyIn * p.Quantity);

        // Cash is equity minus the capital tied up in open positions at cost (AverageBuyIn), i.e. the
        // portion of the ledger not currently committed to a position - unrealized gains/losses on open
        // positions are reflected in `currentEquity` above but not in `cash` until the position closes.
        decimal cash = Math.Max(0m, currentEquity - invested);

        // BuyingPower = cash * 2.0 is a deliberate simplification (flat 2x leverage assumption for this
        // internal synthetic paper broker), not a real margin/buying-power calculation from a broker API.
        return new AccountSummaryDto(
            Equity: Math.Round(currentEquity, 2),
            Cash: Math.Round(cash, 2),
            BuyingPower: Math.Round(cash * 2.0m, 2),
            Currency: "EUR",
            Status: "Active"
        );
    }
}