source: code/trunk/google_translate_engine.go@ 2

package simplytranslate_engines

import (
        "fmt"
        "net/http"
        "net/url"

        "github.com/PuerkitoBio/goquery"
)

type GoogleTranslateEngine struct{}

func (_ *GoogleTranslateEngine) InternalName() string { return "google" }

func (_ *GoogleTranslateEngine) DisplayName() string { return "Google" }

func (_ *GoogleTranslateEngine) getLangs(type_ string) ([]Language, error) {
        var langsType string
        switch type_ {
        case "source":
                langsType = "sl"

        case "target":
                langsType = "tl"

        default:
                panic(fmt.Errorf("getLangs was passed an invalid language type: %s", langsType))
        }

        requestURL, err := url.Parse("https://translate.google.com/m")

        if err != nil {
                // The URL is constant, so it should never fail.
                panic(err)
        }

        query := url.Values{}
        query.Add("mui", langsType)
        query.Add("hl", "en-US")
        requestURL.RawQuery = query.Encode()

        response, err := http.Get(requestURL.String())

        if err != nil {
                return nil, err
        }

        defer response.Body.Close()

        doc, err := goquery.NewDocumentFromReader(response.Body)

        if err != nil {
                return nil, err
        }

        var langs []Language

        doc.Find(".language-item").Each(func(_ int, s *goquery.Selection) {
                a := s.Find("a").First()

                href, exists := a.Attr("href")

                // Shouldn't happen, but here goes.
                if !exists {
                        return
                }

                langURL, err := url.Parse(href)

                if err != nil {
                        return
                }

                langCode := langURL.Query()[langsType][0]

                if langCode == "auto" {
                        return
                }

                langs = append(langs, Language{Name: a.Text(), Code: langCode})
        })

        return langs, nil
}

func (engine *GoogleTranslateEngine) SourceLanguages() ([]Language, error) {
        return engine.getLangs("source")
}

func (engine *GoogleTranslateEngine) TargetLanguages() ([]Language, error) {
        return engine.getLangs("target")
}

func (_ *GoogleTranslateEngine) SupportsAutodetect() bool { return true }

func (_ *GoogleTranslateEngine) DetectLanguage(text string) (Language, error) { return Language{}, nil }

func (_ *GoogleTranslateEngine) Translate(text string, from Language, to Language) (TranslationResult, error) {
        requestURL, err := url.Parse("https://translate.google.com/m")

        if err != nil {
                // The URL is constant, so it should never fail.
                panic(err)
        }

        query := url.Values{}
        query.Add("sl", from.Code)
        query.Add("tl", to.Code)
        query.Add("hl", to.Code)
        query.Add("q", text)
        requestURL.RawQuery = query.Encode()

        response, err := http.Get(requestURL.String())

        if err != nil {
                return TranslationResult{}, err
        }

        defer response.Body.Close()

        doc, err := goquery.NewDocumentFromReader(response.Body)

        if err != nil {
                return TranslationResult{}, err
        }

        return TranslationResult{
                SourceLanguage: from,
                TranslatedText: doc.Find(".result-container").Text(),
        }, nil
}