using System.Text.Json;
using Backend.DatabaseHandler;
using Backend.Interface;

namespace Backend.ServiceHandler;

public sealed class PriceThresholdEvaluator : IAlertEvaluator
{
	public string AlertType => "price_threshold";

	public Task<AlertEvaluation> EvaluateAsync(AlertRecord alert, MarketDataService marketData)
	{
		var parameters = JsonSerializer.Deserialize<PriceThresholdParameters>(alert.Parameters)
			?? throw new InvalidOperationException($"Invalid parameters for alert {alert.Id}");

		var snapshot = marketData.GetLiveQuote(alert.Symbol);

		if (!snapshot.LastPrice.HasValue)
		{
			return Task.FromResult(new AlertEvaluation { Triggered = false });
		}

		double price = snapshot.LastPrice.Value;
		bool triggered = parameters.Direction.ToLowerInvariant() switch
		{
			"above" => price >= parameters.Target,
			"below" => price <= parameters.Target,
			_ => false
		};

		string updatedState = JsonSerializer.Serialize(new { lastPrice = price });

		return Task.FromResult(new AlertEvaluation
		{
			Triggered = triggered,
			UpdatedLastState = updatedState
		});
	}

	private sealed class PriceThresholdParameters
	{
		public string Direction { get; set; } = string.Empty;
		public double Target { get; set; }
	}
}