query.ts

import {
  RequestParams,
  RawResponseParams,
  ResponseParams,
  Config,
} from './types';
import { API_URL, REQUEST_ALTERNATIVES } from './const';

function buildRequestParams(sourceLang = 'auto', targetLang = 'en') {
  return {
    jsonrpc: '2.0',
    method: 'LMT_handle_texts',
    id: Math.floor(Math.random() * 100000 + 100000) * 1000,
    params: {
      texts: [{ text: '', requestAlternatives: REQUEST_ALTERNATIVES }],
      timestamp: 0,
      splitting: 'newlines',
      lang: {
        source_lang_user_selected: sourceLang?.toUpperCase(),
        target_lang: targetLang?.toUpperCase(),
      },
    },
  };
}

function countLetterI(translateText: string) {
  return (translateText || '').split('i').length - 1;
}

function getTimestamp(letterCount: number) {
  const timestamp = new Date().getTime();
  return letterCount !== 0
    ? timestamp - (timestamp % (letterCount + 1)) + (letterCount + 1)
    : timestamp;
}

function buildRequestBody(data: RequestParams) {
  const requestData = buildRequestParams(data.source_lang, data.target_lang);
  requestData.params.texts = [
    { text: data.text, requestAlternatives: REQUEST_ALTERNATIVES },
  ];
  requestData.params.timestamp = getTimestamp(countLetterI(data.text));

  let requestString = JSON.stringify(requestData);
  if (
    [0, 3].includes((requestData['id'] + 5) % 29) ||
    (requestData['id'] + 3) % 13 === 0
  ) {
    requestString = requestString.replace('"method":"', '"method" : "');
  } else {
    requestString = requestString.replace('"method":"', '"method": "');
  }

  return requestString;
}

async function query(
  params: RequestParams,
  config?: Config
): Promise<ResponseParams> {
  if (!params?.text) {
    return {
      code: 404,
      message: 'No Translate Text Found',
      data: null,
    };
  }

  const response = await fetch(config?.proxyEndpoint ?? API_URL, {
    headers: {
      'Content-Type': 'application/json; charset=utf-8',
      ...config?.customHeader,
    },
    method: 'POST',
    body: buildRequestBody(params),
  });

  if (response.ok) {
    const { result } = (await response.json()) as RawResponseParams;
    return {
      code: 200,
      message: 'success',
      data: result?.texts?.[0]?.text,
      source_lang: params?.source_lang || result?.lang || 'auto',
      target_lang: params?.target_lang || 'en',
      alternatives: result.texts?.[0]?.alternatives?.map?.(item => item.text),
    };
  } else {
    return {
      code: response.status,
      data: null,
      message:
        response.status === 429
          ? 'Too many requests, please try again later.'
          : 'Unknown error.',
    };
  }
}

export { query };