package main

import (
	"context"

	"github.com/prometheus/client_golang/prometheus/promhttp"
	"go.opentelemetry.io/otel/exporters/prometheus"
	"go.opentelemetry.io/otel/sdk/metric"

	"github.com/gogf/gf/contrib/metric/otelmetric/v2"
	"github.com/gogf/gf/v2/frame/g"
	"github.com/gogf/gf/v2/net/ghttp"
	"github.com/gogf/gf/v2/os/gctx"
	"github.com/gogf/gf/v2/os/gmetric"
)

var (
	meter = gmetric.GetGlobalProvider().Meter(gmetric.MeterOption{
		Instrument:        "github.com/gogf/gf/example/metric/basic",
		InstrumentVersion: "v1.0",
	})
	observableCounter = meter.MustObservableCounter(
		"goframe.metric.demo.observable_counter",
		gmetric.MetricOption{
			Help: "This is a simple demo for ObservableCounter usage",
			Unit: "%",
		},
	)
	observableUpDownCounter = meter.MustObservableUpDownCounter(
		"goframe.metric.demo.observable_updown_counter",
		gmetric.MetricOption{
			Help: "This is a simple demo for ObservableUpDownCounter usage",
			Unit: "%",
		},
	)
	observableGauge = meter.MustObservableGauge(
		"goframe.metric.demo.observable_gauge",
		gmetric.MetricOption{
			Help: "This is a simple demo for ObservableGauge usage",
			Unit: "%",
		},
	)
)

func main() {
	var ctx = gctx.New()

	// Callback for observable metrics.
	meter.MustRegisterCallback(func(ctx context.Context, obs gmetric.Observer) error {
		obs.Observe(observableCounter, 10)
		obs.Observe(observableUpDownCounter, 20)
		obs.Observe(observableGauge, 30)
		return nil
	}, observableCounter, observableUpDownCounter, observableGauge)

	// Prometheus exporter to export metrics as Prometheus format.
	exporter, err := prometheus.New(
		prometheus.WithoutCounterSuffixes(),
		prometheus.WithoutUnits(),
	)
	if err != nil {
		g.Log().Fatal(ctx, err)
	}

	// OpenTelemetry provider.
	provider := otelmetric.MustProvider(metricotelmetric.WithReader(exporter))
	provider.SetAsGlobal()
	defer provider.Shutdown(ctx)

	// HTTP Server for metrics exporting.
	s := g.Server()
	s.BindHandler(otelmetric.StartPrometheusMetricsServer(8000, "/metrics", ghttp.WrapH(promhttp.Handler()))
	s.SetPort(8000)
	s.Run()
}

observableCounter = meter.MustObservableCounter(
	"goframe.metric.demo.observable_counter",
	gmetric.MetricOption{
		Help: "This is a simple demo for ObservableCounter usage",
		Unit: "%",
		Callback: func(ctx context.Context, obs gmetric.MetricObserver) error {
			obs.Observe(10)
			return nil
		},
	},
)

sotelmetric.BindHandlerStartPrometheusMetricsServer(8000, "/metrics", ghttp.WrapH(promhttp.Handler()))