package pkg

import (
	"context"
	"net/http"

	"github.com/leonelquinteros/gotext"
	"golang.org/x/text/language"
)

const contextLocaleKey = "numerus-locale"

func Locale(next http.Handler) http.Handler {
	supportedLanguages := []language.Tag{
		language.Catalan,
		language.Spanish,
	}
	var matcher = language.NewMatcher(supportedLanguages)

	locales := map[language.Tag]*gotext.Locale{}
	for _, lang := range supportedLanguages {
		locale := gotext.NewLocale("locales", lang.String())
		locale.AddDomain("numerus")
		locales[lang] = locale
	}
	defaultLocale := locales[language.Catalan]

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var locale *gotext.Locale
		t, _, err := language.ParseAcceptLanguage(r.Header.Get("Accept-Language"))
		if err == nil {
			tag, _, _ := matcher.Match(t...)
			var ok bool
			locale, ok = locales[tag]
			for !ok && !tag.IsRoot() {
				tag = tag.Parent()
				locale, ok = locales[tag]
			}
		}
		if locale == nil {
			locale = defaultLocale
		}
		ctx := context.WithValue(r.Context(), contextLocaleKey, locale)
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}

func getLocale(r *http.Request) *gotext.Locale {
	return r.Context().Value(contextLocaleKey).(*gotext.Locale)
}