amesh.js

// Description:
//   東京アメッシュ(http://tokyo-ame.jwa.or.jp/)から雨雲画像を取得して送る
// Commands:
//   amesh - amesh tokyo を実行
//   amesh <region> - 指定された地域の雨雲画像を表示

'use strict';
const fs = require('fs');
const request = require('request').defaults({ encoding: null });
const { WebClient, RTMClient } = require('@slack/client');
const momentTz = require('moment-timezone');
const sharp = require('sharp');

const map = 'image/map100.jpg';
const msk = 'image/msk100.png';
const result = 'image/amesh.png';

const tokyo = { left: 1150, top: 570, width: 1280, height: 768 };
const kanto = { left: 0, top: 0, width: 3080, height: 1920 };
const region = { tokyo, kanto };

const ameshFilename = () => {
  const now = momentTz()
    .tz('Asia/Tokyo')
    .format('YYYYMMDDHHmm');
  return now - (now % 5);
};

const fetchImage = url =>
  new Promise((resolve, reject) => {
    request(url, (err, res, body) => {
      if (err || res.statusCode !== 200) {
        reject(err);
      }

      resolve(body);
    });
  });

module.exports = robot => {
  robot.hear(/amesh(.*)/, async msg => {
    const rtm = new RTMClient(robot.adapter.options.token);
    rtm.start();
    rtm.sendTyping(msg.message.room);

    const targetRegion = region[msg.match[1].trim()] || tokyo;
    const base = await sharp(map).toBuffer();
    const mesh = await fetchImage(
      `http://tokyo-ame.jwa.or.jp/mesh/100/${ameshFilename()}.gif`,
    );
    const amesh = await [mesh, msk].reduce(
      async (input, overlay) =>
        sharp(await input)
          .overlayWith(overlay)
          .toBuffer(),
      base,
    );

    sharp(amesh)
      .extract(targetRegion)
      .toFile(result)
      .then(() => {
        const data = {
          file: fs.createReadStream(result),
          channels: msg.message.room,
        };
        new WebClient(robot.adapter.options.token).files.upload(data);
      });
    rtm.disconnect();
  });
};