using Backend.Interface;
using Npgsql;

namespace Backend.DatabaseHandler
{
	public sealed class PostgresUserLocationStore : IUserLocationStore
	{
		private readonly string _connectionString;

		public PostgresUserLocationStore(IConfiguration configuration)
		{
			_connectionString = configuration.GetConnectionString("MarketDataDb")
				?? throw new InvalidOperationException("Missing connection string: MarketDataDb");
		}

		public async Task<UserLocationRecord?> GetAsync(
			string user,
			CancellationToken cancellationToken = default)
		{
			await using var conn = new NpgsqlConnection(_connectionString);
			await conn.OpenAsync(cancellationToken);

			const string sql = """
				SELECT username, city, latitude, longitude
				FROM user_location
				WHERE username = @user;
				""";

			await using var cmd = new NpgsqlCommand(sql, conn);
			cmd.Parameters.AddWithValue("user", user.Trim());

			await using var reader = await cmd.ExecuteReaderAsync(cancellationToken);
			if (!await reader.ReadAsync(cancellationToken))
				return null;

			return new UserLocationRecord
			{
				Username = reader.GetString(0),
				City = reader.GetString(1),
				Latitude = reader.GetDouble(2),
				Longitude = reader.GetDouble(3)
			};
		}

		public async Task UpsertAsync(
			UserLocationRecord record,
			CancellationToken cancellationToken = default)
		{
			await using var conn = new NpgsqlConnection(_connectionString);
			await conn.OpenAsync(cancellationToken);

			const string sql = """
				INSERT INTO user_location (username, city, latitude, longitude)
				VALUES (@user, @city, @lat, @lng)
				ON CONFLICT (username)
				DO UPDATE SET city = @city, latitude = @lat, longitude = @lng;
				""";

			await using var cmd = new NpgsqlCommand(sql, conn);
			cmd.Parameters.AddWithValue("user", record.Username);
			cmd.Parameters.AddWithValue("city", record.City);
			cmd.Parameters.AddWithValue("lat", record.Latitude);
			cmd.Parameters.AddWithValue("lng", record.Longitude);

			await cmd.ExecuteNonQueryAsync(cancellationToken);
		}
	}
}