use miette::IntoDiagnostic;
use tracing_subscriber::{EnvFilter, fmt, layer::SubscriberExt, util::SubscriberInitExt};

/// Guard that keeps non-blocking writer alive and allows flushing on drop
pub struct TelemetryGuard {
    // Drop to flush writer.
    _guard: Option<tracing_appender::non_blocking::WorkerGuard>,
}

/// Initialize tracing. Console-only for now; OTEL can be wired later.
pub fn init_tracing(_service_name: &str) -> miette::Result<TelemetryGuard> {
    let (nb_writer, guard) = tracing_appender::non_blocking(std::io::stderr());

    let fmt_layer = fmt::layer()
        .with_target(false)
        .with_writer(nb_writer)
        .with_ansi(atty::is(atty::Stream::Stderr));

    let filter = EnvFilter::try_from_default_env()
        .unwrap_or_else(|_| EnvFilter::new("info"));

    tracing_subscriber::registry()
        .with(filter)
        .with(fmt_layer)
        .init();

    Ok(TelemetryGuard { _guard: Some(guard) })
}