using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Alpaca.Markets;
using FinlyticBot.Database;
using FinlyticBot.Entities;
using FinlyticBot.Util;
using FinlyticCore.Models.Trades;
using FinlyticCore.Services;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;

namespace FinlyticBot.Services;

public interface IBotOrderExecutionService
{
    Task ProcessTradeProposalAsync(TradeProposalDto proposal, CancellationToken ct = default);
}

public class BotOrderExecutionService : IBotOrderExecutionService
{
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly IAlpacaBrokerService _brokerService;
    private readonly IBotRiskSizingService _sizingService;
    private readonly ISettingsService _settingsService;
    private readonly IFinlyticLogger<BotOrderExecutionService> _finlyticLogger;

    public BotOrderExecutionService(
        IServiceScopeFactory scopeFactory,
        IAlpacaBrokerService brokerService,
        IBotRiskSizingService sizingService,
        ISettingsService settingsService,
        IFinlyticLogger<BotOrderExecutionService> finlyticLogger)
    {
        _scopeFactory = scopeFactory;
        _brokerService = brokerService;
        _sizingService = sizingService;
        _settingsService = settingsService;
        _finlyticLogger = finlyticLogger;
    }

    public async Task ProcessTradeProposalAsync(TradeProposalDto proposal, CancellationToken ct = default)
    {
        ArgumentNullException.ThrowIfNull(proposal);

        if (string.IsNullOrWhiteSpace(proposal.Symbol))
        {
            await _finlyticLogger.LogWarningAsync(SettingKeys.BotChannel,
                "[BotExecution] Trade proposal has no valid Symbol. Skipping.");
            return;
        }

        using var scope = _scopeFactory.CreateScope();
        var dbContext = scope.ServiceProvider.GetRequiredService<BotDbContext>();

        // 1. Check if trade was already processed
        bool alreadyExists = await dbContext.ExecutedPaperTrades
            .AnyAsync(t => t.TradeId == proposal.TradeId, ct);
        if (alreadyExists)
        {
            await _finlyticLogger.LogInfoAsync(SettingKeys.BotChannel,
                "[BotExecution] Trade proposal {TradeId} ({Symbol}) already processed. Skipping duplicate.",
                proposal.TradeId, proposal.Symbol);
            return;
        }

        // 2. Validate asset on Alpaca
        var asset = await _brokerService.GetAssetAsync(proposal.Symbol, ct);
        if (asset == null || !asset.IsTradable)
        {
            string reason = $"Asset '{proposal.Symbol}' is not tradeable on Alpaca.";
            await _finlyticLogger.LogWarningAsync(SettingKeys.BotChannel,
                "[BotExecution] Trade {TradeId} ({Symbol}) rejected: {Reason}", proposal.TradeId, proposal.Symbol, reason);

            await RecordAuditLogAsync(dbContext, proposal, "Rejected", false, reason, 0, 0, ct);
            return;
        }

        // 3. Query Account Equity from Alpaca
        var account = await _brokerService.GetAccountInfoAsync(ct);
        if (account == null)
        {
            string reason = "Failed to query account information from Alpaca API.";
            await RecordAuditLogAsync(dbContext, proposal, "Rejected", false, reason, 0, 0, ct);
            return;
        }

        if (account.IsBlocked)
        {
            string reason = "Alpaca trading account is currently blocked.";
            await RecordAuditLogAsync(dbContext, proposal, "Rejected", false, reason, 0, account.Equity, ct);
            return;
        }

        // 4. Calculate stats (current open trades and today's loss)
        int openTradesCount = await dbContext.ExecutedPaperTrades
            .CountAsync(t => t.Status == "Submitted" || t.Status == "Filled" || t.Status == "PartiallyFilled", ct);

        var todayUtc = DateTime.UtcNow.Date;
        var todayClosedTrades = await dbContext.ExecutedPaperTrades
            .Where(t => t.ClosedAt >= todayUtc && t.Status == "Closed")
            .ToListAsync(ct);

        decimal todayRealizedLoss = todayClosedTrades.Where(t => t.RealizedPnl < 0).Sum(t => Math.Abs(t.RealizedPnl));
        decimal todayLossPercent = account.Equity > 0 ? (todayRealizedLoss / account.Equity) * 100m : 0m;

        // 5. Evaluate through Risk & Sizing Engine
        var sizing = await _sizingService.EvaluateAndSizeTradeAsync(
            proposal,
            account.Equity,
            openTradesCount,
            todayLossPercent,
            ct
        );

        if (!sizing.IsApproved)
        {
            await RecordAuditLogAsync(dbContext, proposal, "Rejected", false, sizing.RejectReason, 0, account.Equity, ct);
            return;
        }

        // 6. Submit Order to Alpaca
        string orderType = await _settingsService.GetSettingAsync(SettingKeys.ExecutionOrderType, ct);
        var placedOrder = await _brokerService.PlaceBracketOrderAsync(proposal, sizing.Quantity, orderType, ct);

        if (placedOrder == null)
        {
            string reason = "Alpaca API rejected bracket order placement.";
            await RecordAuditLogAsync(dbContext, proposal, "OrderFailed", false, reason, sizing.Quantity, account.Equity, ct);
            return;
        }

        // 7. Persist Executed Paper Trade
        var executedTrade = new ExecutedPaperTradeEntity
        {
            TradeId = proposal.TradeId,
            Symbol = proposal.Symbol,
            Isin = proposal.Isin,
            CompanyName = proposal.CompanyName,
            AlpacaOrderId = placedOrder.OrderId,
            Side = string.Equals(proposal.SignalType, "SELL", StringComparison.OrdinalIgnoreCase) ? "SELL" : "BUY",
            Quantity = sizing.Quantity,
            SignalEntryPrice = proposal.EntryPrice,
            StopLossPrice = proposal.StopLoss,
            TakeProfitPrice1 = proposal.TakeProfit,
            TakeProfitPrice2 = proposal.TakeProfitTargets != null && proposal.TakeProfitTargets.Count > 1 ? proposal.TakeProfitTargets[1] : null,
            CalculatedCrv = sizing.CalculatedCrv,
            WinRate = proposal.WinRate,
            Status = placedOrder.OrderStatus == OrderStatus.Filled ? "Filled" : "Submitted",
            PlacedAt = DateTime.UtcNow,
            FilledAt = placedOrder.OrderStatus == OrderStatus.Filled ? DateTime.UtcNow : null,
            ActualFillPrice = placedOrder.AverageFillPrice ?? (placedOrder.OrderStatus == OrderStatus.Filled ? proposal.EntryPrice : null)
        };

        dbContext.ExecutedPaperTrades.Add(executedTrade);
        await RecordAuditLogAsync(dbContext, proposal, "OrderPlaced", true, $"Bracket Order placed with Alpaca. OrderId: {placedOrder.OrderId}", sizing.Quantity, account.Equity, ct);

        await dbContext.SaveChangesAsync(ct);

        await _finlyticLogger.LogInfoAsync(SettingKeys.BotChannel,
            "[BotExecution] Trade {Symbol} successfully recorded in database with Alpaca OrderId {OrderId}.",
            proposal.Symbol, placedOrder.OrderId);
    }

    private static async Task RecordAuditLogAsync(
        BotDbContext dbContext,
        TradeProposalDto proposal,
        string action,
        bool isAccepted,
        string? reason,
        decimal calculatedSize,
        decimal accountEquity,
        CancellationToken ct)
    {
        var audit = new BotAuditLogEntity
        {
            TradeId = proposal.TradeId,
            Symbol = proposal.Symbol,
            Action = action,
            IsAccepted = isAccepted,
            Reason = reason,
            CalculatedSize = calculatedSize,
            AccountEquity = accountEquity,
            Timestamp = DateTime.UtcNow
        };

        dbContext.BotAuditLogs.Add(audit);
        await dbContext.SaveChangesAsync(ct);
    }
}