package middleware

import (
	"net/http"
	"strconv"
	"time"

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

var (
	httpRequestsTotal = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Name: "http_requests_total",
			Help: "Total number of HTTP requests",
		},
		[]string{"method", "path", "status"},
	)

	httpRequestDuration = prometheus.NewHistogramVec(
		prometheus.HistogramOpts{
			Name:    "http_request_duration_seconds",
			Help:    "Duration of HTTP requests",
			Buckets: prometheus.DefBuckets,
		},
		[]string{"method", "path", "status"},
	)
)

func init() {
	prometheus.MustRegister(httpRequestsTotal, httpRequestDuration)
}

func PrometheusMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		rr := &responseRecorder{ResponseWriter: w, statusCode: 200}
		next.ServeHTTP(rr, r)
		duration := time.Since(start)

		method := r.Method
		path := r.URL.Path
		status := strconv.Itoa(rr.statusCode)

		httpRequestsTotal.WithLabelValues(method, path, status).Inc()
		httpRequestDuration.WithLabelValues(method, path, status).Observe(duration.Seconds())
	})
}

type responseRecorder struct {
	http.ResponseWriter
	statusCode int
}

func (rr *responseRecorder) WriteHeader(code int) {
	rr.statusCode = code
	rr.ResponseWriter.WriteHeader(code)
}