package api

import (
	"errors"
	"fmt"
	"net/http"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/prometheus/client_golang/prometheus/push"
	"qoobing.com/gomod/log"
)

var (
	MetricExporterPusher                         = func() error { return nil }
	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 dumpMetricExporterPusher() error {
	return errors.New("not initilized, forgot call 'SetupMetricsExporterPusher'?")
}

func InitMetrics() {
	instance := getInstanceIpAddress()
	log.Infof("self instance ip: [%s]", instance)
	metricApiCounter = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Name:        "api_requests_total",
			Help:        "How many HTTP requests processed",
			ConstLabels: prometheus.Labels{"instance": instance},
		},
		[]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},
			ConstLabels: prometheus.Labels{"instance": instance},
		},
		[]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() error {
		RecordMetrics("push_metrics_to_prometheus", "0", "selfmonitoring", 1.0)
		return pusher.Push()
	}
}