// Copyright 2022 EMQ Technologies Co., Ltd.
//
// Licensed 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.

//go:build prometheus || !core
// +build prometheus !core

package server

import (
	"context"
	"fmt"
	"github.com/lf-edge/ekuiper/internal/conf"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"net/http"
	"time"
)

func init() {
	servers["prometheus"] = promeComp{}
}

type promeComp struct {
	s *http.Server
}

func (p promeComp) serve() {
	//Start prometheus service
	if conf.Config.Basic.Prometheus {
		portPrometheus := conf.Config.Basic.PrometheusPort
		if portPrometheus <= 0 {
			logger.Fatal("Miss configuration prometheusPort")
		}
		mux := http.NewServeMux()
		mux.Handle("/metrics", promhttp.Handler())
		srvPrometheus := &http.Server{
			Addr:         fmt.Sprintf("0.0.0.0:%d", portPrometheus),
			WriteTimeout: time.Second * 15,
			ReadTimeout:  time.Second * 15,
			IdleTimeout:  time.Second * 60,
			Handler:      mux,
		}
		go func() {
			if err := srvPrometheus.ListenAndServe(); err != nil && err != http.ErrServerClosed {
				logger.Fatal("Listen prometheus error: ", err)
			}
		}()
		p.s = srvPrometheus
		msg := fmt.Sprintf("Serving prometheus metrics on port http://localhost:%d/metrics", portPrometheus)
		logger.Infof(msg)
		fmt.Println(msg)
	}
}

func (p promeComp) close() {
	if p.s != nil {
		if err := p.s.Shutdown(context.TODO()); err != nil {
			logger.Errorf("prometheus server shutdown error: %v", err)
		}
		logger.Info("prometheus server successfully shutdown.")
	}
}