using System.Text.Json;

namespace Backend.ServiceHander
{
	public sealed class WeatherService
	{
		private static readonly HttpClient Http = new()
		{
			DefaultRequestHeaders = { { "User-Agent", "SoftTrader/1.0" } }
		};

		public async Task<(string City, double Latitude, double Longitude)?> GeocodeAsync(
			string city,
			CancellationToken cancellationToken = default)
		{
			string encoded = Uri.EscapeDataString(city.Trim());
			string url = $"https://geocoding-api.open-meteo.com/v1/search?name={encoded}&count=1&language=en";

			string json = await Http.GetStringAsync(url, cancellationToken);
			using var doc = JsonDocument.Parse(json);

			if (!doc.RootElement.TryGetProperty("results", out var results) ||
				results.GetArrayLength() == 0)
				return null;

			var first = results[0];
			string name = first.GetProperty("name").GetString() ?? city;
			double lat = first.GetProperty("latitude").GetDouble();
			double lng = first.GetProperty("longitude").GetDouble();

			return (name, lat, lng);
		}

		public async Task<WeatherResult?> GetCurrentWeatherAsync(
			double latitude,
			double longitude,
			CancellationToken cancellationToken = default)
		{
			string url =
				$"https://api.open-meteo.com/v1/forecast" +
				$"?latitude={latitude}&longitude={longitude}" +
				$"&current=temperature_2m,relative_humidity_2m,weather_code,wind_speed_10m" +
				$"&temperature_unit=fahrenheit" +
				$"&wind_speed_unit=mph";

			string json = await Http.GetStringAsync(url, cancellationToken);
			using var doc = JsonDocument.Parse(json);

			if (!doc.RootElement.TryGetProperty("current", out var current))
				return null;

			return new WeatherResult
			{
				TemperatureF = current.GetProperty("temperature_2m").GetDouble(),
				HumidityPercent = current.GetProperty("relative_humidity_2m").GetDouble(),
				WeatherCode = current.GetProperty("weather_code").GetInt32(),
				WindSpeedMph = current.GetProperty("wind_speed_10m").GetDouble()
			};
		}
	}

	public sealed class WeatherResult
	{
		public double TemperatureF { get; init; }
		public double HumidityPercent { get; init; }
		public int WeatherCode { get; init; }
		public double WindSpeedMph { get; init; }

		public string Description => WeatherCode switch
		{
			0 => "Clear sky",
			1 => "Mainly clear",
			2 => "Partly cloudy",
			3 => "Overcast",
			45 or 48 => "Foggy",
			51 or 53 or 55 => "Drizzle",
			61 or 63 or 65 => "Rain",
			66 or 67 => "Freezing rain",
			71 or 73 or 75 => "Snowfall",
			77 => "Snow grains",
			80 or 81 or 82 => "Rain showers",
			85 or 86 => "Snow showers",
			95 => "Thunderstorm",
			96 or 99 => "Thunderstorm with hail",
			_ => "Unknown"
		};
	}
}