use futures::stream::Stream;
use futures::StreamExt;
use opentelemetry::global::shutdown_tracer_provider;
use opentelemetry::sdk::metrics::{selectors, PushController};
use opentelemetry::trace::TraceError;
use opentelemetry::{
    baggage::BaggageExt,
    metrics::{self, ObserverResult},
    trace::{TraceContextExt, Tracer},
    Context, Key, KeyValue,
};
use opentelemetry::{global, sdk::trace as sdktrace};
use opentelemetry_otlp::{ExportConfig, WithExportConfig};
use std::error::Error;
use std::time::Duration;

fn init_tracer() -> Result<sdktrace::Tracer, TraceError> {
    opentelemetry_otlp::new_pipeline()
        .tracing()
        .with_exporter(
            opentelemetry_otlp::new_exporter()
                .tonic()
                .with_endpoint("http://localhost:4317"),
        )
        .install_batch(opentelemetry::runtime::Tokio)
}

// Skip first immediate tick from tokio, not needed for async_std.
fn delayed_interval(duration: Duration) -> impl Stream<Item = tokio::time::Instant> {
    opentelemetry::util::tokio_interval_stream(duration).skip(1)
}

fn init_meter() -> metrics::Result<PushController> {
    let export_config = ExportConfig {
        endpoint: "http://localhost:4317".to_string(),
        ..ExportConfig::default()
    };
    opentelemetry_otlp::new_pipeline()
        .metrics(tokio::spawn, delayed_interval)
        .with_exporter(
            opentelemetry_otlp::new_exporter()
                .tonic()
                .with_export_config(export_config),
        )
        .with_aggregator_selector(selectors::simple::Selector::Exact)
        .build()
}

const FOO_KEY: Key = Key::from_static_str("ex.com/foo");
const BAR_KEY: Key = Key::from_static_str("ex.com/bar");
const LEMONS_KEY: Key = Key::from_static_str("lemons");
const ANOTHER_KEY: Key = Key::from_static_str("ex.com/another");

lazy_static::lazy_static! {
    static ref COMMON_ATTRIBUTES: [KeyValue; 4] = [
        LEMONS_KEY.i64(10),
        KeyValue::new("A", "1"),
        KeyValue::new("B", "2"),
        KeyValue::new("C", "3"),
    ];
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error + Send + Sync + 'static>> {
    let _ = init_tracer()?;
    let _started = init_meter()?;

    let tracer = global::tracer("ex.com/basic");
    let meter = global::meter("ex.com/basic");

    let one_metric_callback =
        |res: ObserverResult<f64>| res.observe(1.0, COMMON_ATTRIBUTES.as_ref());
    let _ = meter
        .f64_value_observer("ex.com.one", one_metric_callback)
        .with_description("A ValueObserver set to 1.0")
        .init();

    let value_recorder_two = meter.f64_value_recorder("ex.com.two").init();

    let another_recorder = meter.f64_value_recorder("ex.com.two").init();
    another_recorder.record(5.5, COMMON_ATTRIBUTES.as_ref());

    let _baggage =
        Context::current_with_baggage(vec![FOO_KEY.string("foo1"), BAR_KEY.string("bar1")])
            .attach();

    let value_recorder = value_recorder_two.bind(COMMON_ATTRIBUTES.as_ref());

    tracer.in_span("operation", |cx| {
        let span = cx.span();
        span.add_event(
            "Nice operation!".to_string(),
            vec![Key::new("bogons").i64(100)],
        );
        span.set_attribute(ANOTHER_KEY.string("yes"));

        meter.record_batch_with_context(
            // Note: call-site variables added as context Entries:
            &Context::current_with_baggage(vec![ANOTHER_KEY.string("xyz")]),
            COMMON_ATTRIBUTES.as_ref(),
            vec![value_recorder_two.measurement(2.0)],
        );

        tracer.in_span("Sub operation...", |cx| {
            let span = cx.span();
            span.set_attribute(LEMONS_KEY.string("five"));

            span.add_event("Sub span event".to_string(), vec![]);

            value_recorder.record(1.3);
        });
    });

    // wait for 1 minutes so that we could see metrics being pushed via OTLP every 10 seconds.
    tokio::time::sleep(Duration::from_secs(60)).await;

    shutdown_tracer_provider();

    Ok(())
}
