package webutility
  
  import (
  	"encoding/json"

  	"fmt"

  	"io/ioutil"

  	"net/http"

  	"path"

  	"strconv"

  	"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) AddTranslations(directory string) error {
  	files, err := ioutil.ReadDir(directory)

  	if err != nil {
  		return err
  	}

  	for _, fileInfo := range files {
  		fName := fileInfo.Name()

  		path := directory + "/" + fName

  		file, err := ioutil.ReadFile(path)
  		if err != nil {
  			return err
  		}

  		loc := stripFileExtension(fName)

  		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)
  	}

  	if d.defaultLocale == "" && len(d.supported) > 0 {
  		d.defaultLocale = d.supported[0]

  	}

  	return nil
  }

  func (d *Dictionary) GetBestMatchLocale(req *http.Request) (best string) {
  	accepted := d.parseAcceptedLanguages(req.Header.Get("Accept-Language"))

  
  	for i, _ := range accepted {

  		if accepted[i].Code == "*" {
  			return d.defaultLocale
  		}

  		for j, _ := range d.supported {
  			if accepted[i].Code == d.supported[j] {
  				return d.supported[j]
  			}
  		}
  	}
  
  	return d.defaultLocale

  }

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

  func (d *Dictionary) SetDefaultLocale(loc string) error {
  	if !d.contains(loc) {
  		return fmt.Errorf("locale file not loaded: %s", loc)
  	}
  
  	d.defaultLocale = loc
  
  	return nil
  }
  
  func (d *Dictionary) contains(loc string) bool {

  	for _, v := range d.supported {
  		if v == loc {

  			return true
  		}
  	}
  	return false

  }

  type LangWeight struct {
  	Code   string
  	Weight float64

  }

  func (d *Dictionary) parseAcceptedLanguages(accepted string) (langs []LangWeight) {
  	if accepted == "" {
  		langs = append(langs, LangWeight{Code: d.defaultLocale, Weight: 1.0})
  		return langs

  	}

  	parts := strings.Split(accepted, ",")
  	for i, _ := range parts {

  		parts[i] = strings.Trim(parts[i], " ")

  
  		var code string = ""
  		var weight float64 = 0.0
  
  		cw := strings.Split(parts[i], ";")
  		paramCount := len(cw)
  
  		if paramCount == 1 {
  			// default weight of 1
  			code = cw[0]
  			weight = 1.0
  		} else if paramCount == 2 {
  			// parse weight
  			code = cw[0]

  			weight, _ = strconv.ParseFloat(cw[1][2:], 64)

  
  		}

  		langs = append(langs, LangWeight{Code: code, Weight: weight})

  	}

  	// TODO(marko): sort langs by weights?

  
  	return langs

  }

  
  func stripFileExtension(full string) (stripped string) {

  	extension := path.Ext(full)
  	stripped = strings.TrimSuffix(full, extension)
  	return stripped

  }