package api

import (
	"fmt"
	"net/http"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/prometheus/client_golang/prometheus/push"
)

var (
	MetricExporterPusher                         = func() {}
	MetricExporterHandler Handler                = nil
	metricRegistry        *prometheus.Registry   = nil
	metricApiCounter      *prometheus.CounterVec = nil
	metricApiSummary      *prometheus.SummaryVec = nil
)

type metricExporterHandler struct {
	name            string
	promhttpHandler http.Handler
}

func (m *metricExporterHandler) ApiName() string {
	return m.name
}

func (m *metricExporterHandler) HandlerFunc() HandlerFunc {
	return func(c *Context) (err error) {
		m.promhttpHandler.ServeHTTP(c.Writer, c.Request)
		return nil
	}
}

func InitMetrics() {
	metricApiCounter = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Name: "api_requests_total",
			Help: "How many HTTP requests processed",
		},
		[]string{"api", "errcode", "appid"},
	)
	metricApiSummary = prometheus.NewSummaryVec(
		prometheus.SummaryOpts{
			Name:       "api_requests_summary",
			Help:       "The api request summary of cost.",
			Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
		},
		[]string{"api", "errcode", "appid"},
	)
	metricRegistry = prometheus.NewRegistry()
	metricRegistry.MustRegister(metricApiCounter)
	metricRegistry.MustRegister(metricApiSummary)
}

func SetupMetricsExporterHandler(apiname string) {
	if apiname == "" {
		apiname = "premetheus_metrics_exporter"
	}

	opt := promhttp.HandlerOpts{Registry: metricRegistry}
	MetricExporterHandler = &metricExporterHandler{
		name:            apiname,
		promhttpHandler: promhttp.HandlerFor(metricRegistry, opt),
	}
}

func SetupMetricsExporterPusher(pushgateway string, jobname string) {
	if jobname == "" {
		jobname = fmt.Sprintf("api-metrics-job-%s", getExeFilename())
	}

	var pusher = push.New(pushgateway, jobname).Gatherer(metricRegistry)
	MetricExporterPusher = func() {
		pusher.Push()
	}
}