package analytics

import (
	"context"
	"net/http"
)

type contextKey struct{}

var countKeyContextKey contextKey

func WithCountKey(r *http.Request, key string) *http.Request {
	return r.WithContext(context.WithValue(r.Context(), countKeyContextKey, key))
}

func GetCountKey(r *http.Request) (string, bool) {
	key, ok := r.Context().Value(countKeyContextKey).(string)

	return key, ok
}

func CounterMiddleware(counter Counter) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			rw := newStatusCapturingResponseWriter(w)

			next.ServeHTTP(rw, r)

			countKey, ok := GetCountKey(r)
			if !ok {
				if rw.status >= 201 {
					countKey = http.StatusText(rw.status)
				} else {
					countKey = r.URL.Path
				}
			}

			counter.Count(r, countKey)
		})
	}
}

type statusCapturingResponseWriter struct {
	http.ResponseWriter
	status int
}

func newStatusCapturingResponseWriter(w http.ResponseWriter) *statusCapturingResponseWriter {
	return &statusCapturingResponseWriter{w, http.StatusOK}
}

func (w *statusCapturingResponseWriter) WriteHeader(code int) {
	w.status = code
	w.ResponseWriter.WriteHeader(code)
}