Add Reverso engine

git-svn-id: file:///srv/svn/repo/mai/trunk@13 e410bdd4-646f-c54f-a7ce-fffcc4f439ae

engines/reverso.go

@@ -0,0 +1,160 @@
+package engines
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+)
+
+// Reverso is an engine that fetches data from https://reverso.net.
+type Reverso struct{}
+
+func (_ *Reverso) InternalName() string { return "reverso" }
+
+func (_ *Reverso) DisplayName() string { return "Reverso" }
+
+var reversoLangs = []Language{
+	{Name: "Arabic", Code: "ara"},
+	{Name: "Chinese (Simplified)", Code: "chi"}, // marketed as just "Chinese"
+	{Name: "Czech", Code: "cze"},
+	{Name: "Danish", Code: "dan"},
+	{Name: "Dutch", Code: "dut"},
+	{Name: "English", Code: "eng"},
+	{Name: "French", Code: "fra"},
+	{Name: "German", Code: "ger"},
+	{Name: "Hebrew", Code: "heb"},
+	{Name: "Hindi", Code: "hin"},
+	{Name: "Hungarian", Code: "hun"},
+	{Name: "Italian", Code: "ita"},
+	{Name: "Japanese", Code: "jpn"},
+	{Name: "Korean", Code: "kor"},
+	{Name: "Persian", Code: "per"},
+	{Name: "Polish", Code: "pol"},
+	{Name: "Portuguese", Code: "por"},
+	{Name: "Romanian", Code: "rum"},
+	{Name: "Russian", Code: "rus"},
+	{Name: "Slovak", Code: "slo"},
+	{Name: "Spanish", Code: "spa"},
+	{Name: "Swedish", Code: "swe"},
+	{Name: "Thai", Code: "tha"},
+	{Name: "Turkish", Code: "tur"},
+	{Name: "Ukrainian", Code: "ukr"},
+}
+
+func (_ *Reverso) SourceLanguages() ([]Language, error) { return reversoLangs, nil }
+
+func (_ *Reverso) TargetLanguages() ([]Language, error) { return reversoLangs, nil }
+
+func (_ *Reverso) SupportsAutodetect() bool { return true }
+
+type reversoAPIResponse struct {
+	LanguageDetection struct {
+		DetectedLanguage string `json:"detectedLanguage"`
+	} `json:"languageDetection"`
+	Translation []string `json:"translation"`
+}
+
+func (e *Reverso) callAPI(text string, from, to Language) (reversoAPIResponse, error) {
+	// `contextResults` must be false for language detection
+	formData := map[string]interface{}{
+		"format": "text",
+		"from":   from.Code,
+		"to":     to.Code,
+		"input":  text,
+		"options": map[string]interface{}{
+			"sentenceSplitter":  false,
+			"origin":            "translation.web",
+			"contextResults":    false,
+			"languageDetection": true,
+		},
+	}
+
+	formDataJSON, err := json.Marshal(formData)
+
+	if err != nil {
+		return reversoAPIResponse{}, err
+	}
+
+	request, err := http.NewRequest("POST", "https://api.reverso.net/translate/v1/translation", bytes.NewBuffer(formDataJSON))
+
+	if err != nil {
+		return reversoAPIResponse{}, err
+	}
+
+	request.Header.Set("Content-Type", "application/json")
+	// Returns 403 with empty or no user agent.
+	request.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 10.0; rv:110.0) Gecko/20100101 Firefox/110.0")
+
+	client := &http.Client{}
+
+	response, err := client.Do(request)
+
+	if err != nil {
+		return reversoAPIResponse{}, err
+	}
+
+	defer response.Body.Close()
+
+	if response.StatusCode != 200 {
+		return reversoAPIResponse{}, fmt.Errorf("got status code %d from Reverso API", response.StatusCode)
+	}
+
+	var result reversoAPIResponse
+
+	if err := json.NewDecoder(response.Body).Decode(&result); err != nil {
+		return reversoAPIResponse{}, err
+	}
+
+	return result, nil
+}
+
+func (e *Reverso) DetectLanguage(text string) (Language, error) {
+	// Any language pair works here, does not affect result
+	r, err := e.callAPI(text, reversoLangs[0], reversoLangs[1])
+
+	if err != nil {
+		return Language{}, err
+	}
+
+	langCode := r.LanguageDetection.DetectedLanguage
+
+	for _, lang := range reversoLangs {
+		if lang.Code == langCode {
+			return lang, nil
+		}
+	}
+
+	return Language{}, fmt.Errorf("language code \"%s\" is not in Reverso's language list", langCode)
+}
+
+func (e *Reverso) Translate(text string, from, to Language) (TranslationResult, error) {
+	if from.Code == "auto" {
+		from_, err := e.DetectLanguage(text)
+
+		if err != nil {
+			return TranslationResult{}, err
+		}
+
+		from = from_
+	}
+
+	var translation string
+
+	if from == to {
+		translation = text
+	} else {
+		r, err := e.callAPI(text, from, to)
+
+		if err != nil {
+			return TranslationResult{}, err
+		}
+
+		translation = r.Translation[0]
+	}
+
+	return TranslationResult{
+		SourceLanguage: from,
+		TranslatedText: translation,
+	}, nil
+}