/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package pixiu

import (
	"net/http"
	"strconv"
)

import (
	"go.opentelemetry.io/otel/exporters/prometheus"

	"go.opentelemetry.io/otel/metric/global"

	export "go.opentelemetry.io/otel/sdk/export/metric"
	"go.opentelemetry.io/otel/sdk/metric/aggregator/histogram"
	controller "go.opentelemetry.io/otel/sdk/metric/controller/basic"
	processor "go.opentelemetry.io/otel/sdk/metric/processor/basic"
	selector "go.opentelemetry.io/otel/sdk/metric/selector/simple"
	"go.opentelemetry.io/otel/sdk/resource"

	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
)

import (
	"github.com/apache/dubbo-go-pixiu/pkg/logger"
	"github.com/apache/dubbo-go-pixiu/pkg/model"
)

func registerOtelMetricMeter(conf model.Metric) {
	if conf.Enable {
		config := prometheus.Config{}
		resources := resource.NewWithAttributes(
			semconv.SchemaURL,
		)
		c := controller.New(
			processor.New(
				selector.NewWithHistogramDistribution(
					histogram.WithExplicitBoundaries(config.DefaultHistogramBoundaries),
				),
				export.CumulativeExportKindSelector(),
				processor.WithMemory(true),
			),
			controller.WithResource(resources),
		)
		exporter, err := prometheus.New(config, c)
		if err != nil {
			logger.Error("failed to initialize prometheus exporter %v", err)
		}
		global.SetMeterProvider(exporter.MeterProvider())

		http.HandleFunc("/", exporter.ServeHTTP)
		addr := ":" + strconv.Itoa(conf.PrometheusPort)
		go func() {
			_ = http.ListenAndServe(addr, nil)
		}()

		logger.Info("Prometheus server running on " + addr)
	}
}