package utils

import (
	"encoding/json"
	"github.com/muety/wakapi/config"
	"net/http"
	"regexp"
	"strconv"
	"strings"
	"time"
)

const (
	cacheMaxAgePattern = `max-age=(\d+)`
)

var (
	cacheMaxAgeRe *regexp.Regexp
)

func init() {
	cacheMaxAgeRe = regexp.MustCompile(cacheMaxAgePattern)
}

func RespondJSON(w http.ResponseWriter, r *http.Request, status int, object interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	if err := json.NewEncoder(w).Encode(object); err != nil {
		config.Log().Request(r).Error("error while writing json response: %v", err)
	}
}

func IsNoCache(r *http.Request, cacheTtl time.Duration) bool {
	cacheControl := r.Header.Get("cache-control")
	if strings.Contains(cacheControl, "no-cache") {
		return true
	}
	if match := cacheMaxAgeRe.FindStringSubmatch(cacheControl); match != nil && len(match) > 1 {
		if maxAge, _ := strconv.Atoi(match[1]); time.Duration(maxAge)*time.Second <= cacheTtl {
			return true
		}
	}
	return false
}