import {
  reader,
  readerTaskEither as rte,
  readonlyArray,
  taskEither,
} from "fp-ts";
import { flow, pipe } from "fp-ts/lib/function.js";

// parseJsonCont :: string -> string -> TaskEither string string
const parseJsonCont = (attr) => (source) => {
  try {
    const data = JSON.parse(source)[attr];
    if (!data) throw new Error(`Key '${attr}' doesn't exist`);
    return taskEither.right(data);
  } catch (e) {
    return taskEither.left(`Invalid json data: ${e}`);
  }
};

const YANDEX_GPT_API_URL = "https://300.ya.ru/api/sharing-url";

// getYandexGptSharedUrl ::
//     string ->
//     ReaderTaskEither {yandexGptApiToken} string string
const getYandexGptSharedUrl = (articleUrl) =>
  pipe(
    reader.ask(),
    reader.map(({ yandexGptApiToken }) =>
      pipe(
        taskEither.tryCatch(
          () =>
            fetch(YANDEX_GPT_API_URL, {
              method: "POST",
              headers: new Headers({
                "Content-Type": "application/json",
                "Authorization": `OAuth ${yandexGptApiToken}`,
              }),
              body: JSON.stringify({ article_url: articleUrl }),
            }),
          String,
        ),
        /* TODO: fix to many requests error
        {
          ok: false,
          error_code: 429,
          description: 'Too Many Requests: retry after 5',
          parameters: { retry_after: 5 }
        }
        */
        taskEither.flatMap((res) =>
          taskEither.tryCatch(() => res.json(), String)
        ),
        taskEither.flatMap((data) =>
          data.status === "success" && data.sharing_url
            ? taskEither.right(data.sharing_url)
            : taskEither.left(`Invalid response: ${JSON.stringify(data)}`)
        ),
      )
    ),
  );

// getYandexGptTesisesFromSharedUrl :: string -> TaskEither string[] string
const getYandexGptTesisesFromSharedUrl = (sharingUrl) =>
  pipe(
    taskEither.tryCatch(() => fetch(sharingUrl), String),
    taskEither.flatMap((res) => taskEither.tryCatch(() => res.text(), String)),
    taskEither.flatMap((html) =>
      taskEither.fromNullable("Cannot find data in the shared url")(
        /<script.+?type="application\/json".*?>([\s\S]+?)<\/script>/.exec(
          html,
        )[1],
      )
    ),
    taskEither.flatMap(parseJsonCont("body")),
    taskEither.flatMap(parseJsonCont("thesis")),
    taskEither.map(readonlyArray.map((t) => t.content)),
  );

// describeArticle ::
//     string ->
//     ReaderTaskEither {yandexGptApiToken} string string
export const describeArticle = flow(
  getYandexGptSharedUrl,
  rte.flatMapTaskEither(getYandexGptTesisesFromSharedUrl),
);