using System.Text.Json;
using EmbedIO;
using EmbedIO.WebApi;
namespace TorchRemote.Plugin.Utils;

/// <summary>
/// <para>Specifies that a parameter of a controller method will receive
/// an object obtained by deserializing the request body as JSON.</para>
/// <para>The received object will be <see langword="null"/>
/// only if the deserialized object is <c>null</c>.</para>
/// <para>If the request body is not valid JSON,
/// or if it cannot be deserialized to the type of the parameter,
/// a <c>400 Bad Request</c> response will be sent to the client.</para>
/// <para>This class cannot be inherited.</para>
/// </summary>
/// <seealso cref="Attribute" />
/// <seealso cref="IRequestDataAttribute{TController}" />
[AttributeUsage(AttributeTargets.Parameter)]
public class JsonBodyAttribute : Attribute, IRequestDataAttribute<WebApiController>
{
    /// <inheritdoc />
    public async Task<object?> GetRequestDataAsync(WebApiController controller, Type type, string parameterName)
    {
        try
        {
            using var stream = controller.HttpContext.OpenRequestStream();
            return await JsonSerializer.DeserializeAsync(stream, type, Statics.SerializerOptions);
        }
        catch (JsonException)
        {
            throw HttpException.BadRequest($"Expected request body to be deserializable to {type.FullName}.");
        }
    }
}