package main

import (
	"crypto/subtle"
	"log"
	"net/http"
	"runtime/debug"
	"time"
)

func chain(h http.Handler, mws ...func(http.Handler) http.Handler) http.Handler {
	for i := len(mws) - 1; i >= 0; i-- {
		h = mws[i](h)
	}
	return h
}

func recoverMW(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer func() {
			if rec := recover(); rec != nil {
				log.Printf("panic %s %s: %v\n%s", r.Method, r.URL.Path, rec, debug.Stack())
				http.Error(w, "internal error", http.StatusInternalServerError)
			}
		}()
		next.ServeHTTP(w, r)
	})
}

type statusRecorder struct {
	http.ResponseWriter
	status int
}

func (sr *statusRecorder) WriteHeader(code int) {
	sr.status = code
	sr.ResponseWriter.WriteHeader(code)
}

func accessLogMW(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		sr := &statusRecorder{ResponseWriter: w, status: http.StatusOK}
		next.ServeHTTP(sr, r)
		log.Printf("%s %s %d %s", r.Method, r.URL.Path, sr.status, time.Since(start))
	})
}

func verifyTelegramSecret(provided, expected string) bool {
	if expected == "" {
		return false
	}
	return subtle.ConstantTimeCompare([]byte(provided), []byte(expected)) == 1
}