#include <nan.h>
#include <node.h>

#include <unicode/ucsdet.h>

NAN_METHOD(DetectCharacterEncoding) {
  Nan::HandleScope scope;

  v8::Local<v8::Object> inputBuffer =
      Nan::To<v8::Object>(info[0]).ToLocalChecked();

  UCharsetDetector *charsetDetector;
  const UCharsetMatch *charsetMatch;
  UErrorCode errorCode = U_ZERO_ERROR;

  charsetDetector = ucsdet_open(&errorCode);

  if (U_FAILURE(errorCode)) {
    Nan::ThrowError("Failed to open ICU charset detector.");
    return;
  }

  ucsdet_setText(charsetDetector, node::Buffer::Data(inputBuffer),
                 node::Buffer::Length(inputBuffer), &errorCode);

  if (U_FAILURE(errorCode)) {
    Nan::ThrowError("Failed to set ICU charset detector’s text.");
    ucsdet_close(charsetDetector);
    return;
  }

  charsetMatch = ucsdet_detect(charsetDetector, &errorCode);

  if (U_FAILURE(errorCode)) {
    Nan::ThrowError("Failed to detect charset.");
    ucsdet_close(charsetDetector);
    return;
  }

  if (charsetMatch == NULL) {
    info.GetReturnValue().Set(Nan::Null());
    ucsdet_close(charsetDetector);
    return;
  }

  const char *charsetName = ucsdet_getName(charsetMatch, &errorCode);

  if (U_FAILURE(errorCode)) {
    Nan::ThrowError("Failed to get name from charset match.");
    ucsdet_close(charsetDetector);
    return;
  }

  int32_t confidence = ucsdet_getConfidence(charsetMatch, &errorCode);

  if (U_FAILURE(errorCode)) {
    Nan::ThrowError("Failed to get confidence from charset match.");
    ucsdet_close(charsetDetector);
    return;
  }

  v8::Local<v8::Object> obj = Nan::New<v8::Object>();
  Nan::Set(obj, Nan::New<v8::String>("encoding").ToLocalChecked(),
           Nan::New<v8::String>(charsetName).ToLocalChecked());
  Nan::Set(obj, Nan::New<v8::String>("confidence").ToLocalChecked(),
           Nan::New<v8::Number>(confidence));

  info.GetReturnValue().Set(obj);
  ucsdet_close(charsetDetector);
}

void Init(v8::Local<v8::Object> exports, v8::Local<v8::Object> module) {
  Nan::SetMethod(module, "exports", DetectCharacterEncoding);
}

NODE_MODULE(icuWrapper, Init);