using IBKRTrader.Core.Budget;
using IBKRTrader.Core.Database;
using IBKRTrader.Core.Logging;

namespace IBKRTrader.Core.Trading;

/// <summary>
/// DB-gestützte Buchführung über offene Positionen (core_position),
/// Trade-Historie (core_trade_history) und Budget (core_budget).
/// </summary>
public sealed class PortfolioService : IPortfolioService
{
    private readonly DatabaseService     _db;
    private readonly TradeHistoryService _history;
    private readonly BudgetService       _budget;
    private readonly LoggingService      _logger;

    public PortfolioService(
        DatabaseService db,
        TradeHistoryService history,
        BudgetService budget,
        LoggingService logger)
    {
        _db      = db;
        _history = history;
        _budget  = budget;
        _logger  = logger;
    }

    private sealed class PosDto
    {
        public int     Quantity { get; set; }
        public decimal AvgPrice { get; set; }
    }

    public async Task<decimal> GetModuleExposureAsync(string module, CancellationToken ct = default)
    {
        var sum = await _db.ExecuteScalarAsync<decimal?>(
            "SELECT SUM(quantity * avg_price) FROM `core_position` WHERE module = @module",
            new { module });
        return sum ?? 0m;
    }

    public async Task<int> GetPositionQuantityAsync(string module, string symbol, CancellationToken ct = default)
    {
        var row = await _db.QueryFirstOrDefaultAsync<PosDto>(
            "SELECT quantity AS Quantity, avg_price AS AvgPrice FROM `core_position` " +
            "WHERE module = @module AND symbol = @symbol",
            new { module, symbol });
        return row?.Quantity ?? 0;
    }

    public async Task<IReadOnlyList<Position>> GetPositionsAsync(string module, CancellationToken ct = default)
    {
        var rows = await _db.QueryAsync<Position>(
            "SELECT module AS Module, symbol AS Symbol, quantity AS Quantity, avg_price AS AvgPrice " +
            "FROM `core_position` WHERE module = @module AND quantity > 0",
            new { module });
        return rows.ToList();
    }

    public async Task RecordFillAsync(
        string module, string symbol, TradeSide side,
        int quantity, decimal price, string? orderId, CancellationToken ct = default)
    {
        if (quantity <= 0) return;

        var action = side == TradeSide.Buy ? "BUY" : "SELL";
        await _history.RecordTradeAsync(module, symbol, action, quantity, price, orderId);

        var current = await _db.QueryFirstOrDefaultAsync<PosDto>(
            "SELECT quantity AS Quantity, avg_price AS AvgPrice FROM `core_position` " +
            "WHERE module = @module AND symbol = @symbol",
            new { module, symbol });

        var oldQty = current?.Quantity ?? 0;
        var oldAvg = current?.AvgPrice ?? 0m;

        if (side == TradeSide.Buy)
        {
            var newQty = oldQty + quantity;
            var newAvg = oldQty > 0 ? (oldQty * oldAvg + quantity * price) / newQty : price;
            await UpsertPositionAsync(module, symbol, newQty, newAvg);
            await _budget.ReserveBudgetAsync(module, quantity * price);
        }
        else
        {
            var newQty = oldQty - quantity;
            if (newQty <= 0)
                await DeletePositionAsync(module, symbol);
            else
                await UpsertPositionAsync(module, symbol, newQty, oldAvg);
            await _budget.ReleaseBudgetAsync(module, quantity * price);
        }

        _logger.Info(module, $"Position gebucht: {action} {quantity}x {symbol} @ {price:F2}");
    }

    private Task UpsertPositionAsync(string module, string symbol, int quantity, decimal avgPrice) =>
        _db.ExecuteAsync(@"
            INSERT INTO `core_position` (module, symbol, quantity, avg_price)
            VALUES (@module, @symbol, @quantity, @avgPrice)
            ON DUPLICATE KEY UPDATE quantity = @quantity, avg_price = @avgPrice",
            new { module, symbol, quantity, avgPrice });

    private Task DeletePositionAsync(string module, string symbol) =>
        _db.ExecuteAsync(
            "DELETE FROM `core_position` WHERE module = @module AND symbol = @symbol",
            new { module, symbol });
}