use anyhow::Context;
use opentelemetry::trace::TracerProvider;
use opentelemetry_otlp::{SpanExporter, WithExportConfig};
use opentelemetry_sdk::trace as sdktrace;
use tracing_opentelemetry::layer;
use tracing_subscriber::prelude::*;

pub struct OtelGuard {
    provider: sdktrace::SdkTracerProvider,
}

impl OtelGuard {
    pub async fn shutdown(self) {
        if let Err(e) = self.provider.shutdown() {
            tracing::warn!(error = %e, "OTLP shutdown error");
        }
    }
}

pub fn init_otel(endpoint: &str, service_name: &str) -> anyhow::Result<OtelGuard> {
    let exporter = SpanExporter::builder()
        .with_http()
        .with_endpoint(endpoint)
        .build()
        .context("build OTLP exporter")?;

    let tracer_provider = sdktrace::SdkTracerProvider::builder()
        .with_batch_exporter(exporter)
        .build();

    let tracer = tracer_provider.tracer(service_name.to_string());
    let otel_layer = layer().with_tracer(tracer);

    tracing_subscriber::registry()
        .with(otel_layer)
        .try_init()
        .context("install OTLP tracing subscriber")?;

    Ok(OtelGuard {
        provider: tracer_provider,
    })
}