use console_subscriber::ConsoleLayer;
use lemmy_utils::error::LemmyError;
use opentelemetry::{
  sdk::{propagation::TraceContextPropagator, Resource},
  KeyValue,
};
use opentelemetry_otlp::WithExportConfig;
use tracing::{subscriber::set_global_default, Subscriber};
use tracing_subscriber::{filter::Targets, layer::SubscriberExt, registry::LookupSpan, Layer};

pub fn init_tracing<S>(
  opentelemetry_url: &str,
  subscriber: S,
  targets: Targets,
) -> Result<(), LemmyError>
where
  S: Subscriber + for<'a> LookupSpan<'a> + Send + Sync + 'static,
{
  opentelemetry::global::set_text_map_propagator(TraceContextPropagator::new());

  let console_layer = ConsoleLayer::builder()
    .with_default_env()
    .server_addr(([0, 0, 0, 0], 6669))
    .event_buffer_capacity(1024 * 1024)
    .spawn();

  let subscriber = subscriber.with(console_layer);

  let tracer = opentelemetry_otlp::new_pipeline()
    .tracing()
    .with_trace_config(
      opentelemetry::sdk::trace::config()
        .with_resource(Resource::new(vec![KeyValue::new("service.name", "lemmy")])),
    )
    .with_exporter(
      opentelemetry_otlp::new_exporter()
        .tonic()
        .with_endpoint(opentelemetry_url),
    )
    .install_batch(opentelemetry::runtime::Tokio)?;

  let otel_layer = tracing_opentelemetry::layer()
    .with_tracer(tracer)
    .with_filter(targets);

  let subscriber = subscriber.with(otel_layer);

  set_global_default(subscriber)?;

  Ok(())
}