import {
  createVideoClipper,
  YouTube,
  VideoType,
  ClipVideoParams,
} from '@modal/webvideo-clip-core';
import { constants } from 'http2';
import { RouteHandlerMethod } from 'fastify';

export type ClipArgs = {
  url?: unknown,
  start?: string | number,
  end?: string | number,
}

const DURATION_STRING_REGEXP = /^\d\d:[0-5]\d:[0-5]\d(\.\d+)?$/;

const validateRequestBody = (body: ClipArgs) => {
  const messages = [] as string[];
  const { url, start, end } = body;
  if (typeof url !== 'string') {
    messages.push('URL is required.');
  }

  const typeofStart = typeof start;
  if (typeofStart !== 'undefined') {
    if (
      !['string', 'number'].includes(typeofStart)
      || (typeofStart === 'string' && !DURATION_STRING_REGEXP.test(start as string))
    ) {
      messages.push('Invalid start value.');
    }
  }

  const typeofEnd = typeof end;
  if (typeofEnd !== 'undefined') {
    if (
      !['string', 'number'].includes(typeofEnd)
      || (typeofEnd === 'string' && !DURATION_STRING_REGEXP.test(end as string))
    ) {
      messages.push('Invalid end value.');
    }
  }

  return messages;
};

const getVideoType = (url: string) => {
  if (url.startsWith('https://www.youtube.com')) {
    return YouTube.VIDEO_TYPE as VideoType;
  }

  return null;
};

export const clip: RouteHandlerMethod = async (request, reply) => {
  const validationMessages = validateRequestBody(request.body as ClipArgs);
  if (validationMessages.length > 0) {
    reply
      .status(constants.HTTP_STATUS_BAD_REQUEST)
      .send({
        errors: validationMessages,
      });
    return;
  }
  const videoType = getVideoType((request.body as ClipArgs).url as string);
  if (videoType === null) {
    reply
      .status(constants.HTTP_STATUS_UNPROCESSABLE_ENTITY)
      .send({
        errors: ['Unsupported URL.'],
      });
  }

  const clipper = createVideoClipper({
    type: videoType as VideoType,
    downloaderExecutablePath: process.env.YOUTUBE_DOWNLOADER_EXECUTABLE_PATH as string,
  });

  const { url, start, end } = request.body as ClipVideoParams;
  const clipResult = await clipper({
    url,
    start,
    end,
  });

  reply
    .header('Content-Type', clipResult.contentType)
    .send(clipResult.content);
};