package webutility
  
  import (
  	"encoding/json"

  	"errors"

  	"io/ioutil"

  	"net/http"
  	"strings"

  	"sync"

  )

  type Dictionary struct {

  	my            sync.Mutex

  	locales       map[string]map[string]string
  	supported     []string
  	defaultLocale string

  }

  func NewDictionary() *Dictionary {
  	return &Dictionary{

  		locales: map[string]map[string]string{},
  	}
  }

  func (d *Dictionary) AddLocale(loc, filePath string) error {

  	file, err := ioutil.ReadFile(filePath)
  	if err != nil {
  		return err
  	}
  
  	var data interface{}
  	err = json.Unmarshal(file, &data)
  	if err != nil {
  		return err
  	}
  
  	l := map[string]string{}
  	for k, v := range data.(map[string]interface{}) {
  		l[k] = v.(string)
  	}

  
  	mu.Lock()
  	defer mu.Unlock()

  	d.locales[loc] = l

  	d.supported = append(d.supported, loc)

  
  	return nil
  }

  func (d *Dictionary) Translate(loc, key string) string {
  	return d.locales[loc][key]
  }

  func (d *Dictionary) HasLocale(loc string) bool {
  	for _, v := range d.supported {
  		if v == loc {

  			return true
  		}
  	}
  	return false

  }

  
  func (d *Dictionary) SetDefaultLocale(loc string) error {
  	if !d.HasLocale(loc) {
  		return errors.New("dictionary does not contain translations for " + loc)
  	}
  	d.defaultLocale = loc
  	return nil
  }
  
  func (d *Dictionary) GetDefaultLocale() string {
  	return d.defaultLocale
  }

  
  func (d *Dictionary) GetBestMatchLocale(req *http.Request) (best string) {
  	accepted := d.parseAcceptedLanguageHeader(req)
  	best = accepted[0]
  	return
  }
  
  func (d *Dictionary) parseAcceptedLanguageHeader(req *http.Request) (langs []string) {
  	a := req.Header.Get("Accepted-Language")
  	if a == "" {
  		langs = append(langs, d.GetDefaultLocale())
  		return
  	}
  
  	parts := strings.Split(a, ",")
  	for _, p := range parts {
  		langs = append(langs, p)
  	}
  
  	return
  }