sentinel.js

'use strict';

const moment = require('moment');
const AWS = require('aws-sdk');

const generate_year_range = (start, end) => {
  const years = [];
  for(var year = start; year <= end; year++){
    years.push(year);
  }
  return years;
};

const aws_list_directory = (bucket, prefix, s3) => {
  const params = {
    Bucket: bucket,
    Delimiter: '/',
    Prefix: prefix};

  return s3.listObjectsV2(params).promise()
    .then(data => {
      return data.CommonPrefixes.map(e => {
        return e.Prefix;
      });
    })
    .catch(() => {
      return [];
    });
};

const get_s2_info = (bucket, key, s3) => {
  const params = {
    Bucket: bucket,
    Key: key};

  return s3.getObject(params).promise()
    .then(data => {
      data = JSON.parse(data.Body.toString());
      return {
        cloud_coverage: data.cloudyPixelPercentage,
        coverage: data.dataCoveragePercentage,
        geometry : data.tileGeometry,
        sat: data.productName.slice(0,3)};
    })
    .catch(() => {
      return {};
    });
};

//Bucket: sentinel-s2-l1c 
//Key: tiles/38/S/NG/2017/10/9/1/
const get_sentinel = (utm, lat, grid, full=false) => {
  const s3 = new AWS.S3({region: 'eu-central-1'});
  const sentinel_bucket = 'sentinel-s2-l1c';
  const img_year = utils.generate_year_range(2015, moment().year());

  // get list of month
  return Promise.all(img_year.map(e => {
    let prefix = `tiles/${utm}/${lat}/${grid}/${e}/`;
    return utils.aws_list_directory(sentinel_bucket, prefix, s3);
  }))
    .then(dirs => {
      // get list of day
      dirs = [].concat.apply([], dirs);
      return Promise.all(dirs.map(e => {
        return utils.aws_list_directory(sentinel_bucket, e, s3);
      }));
    })
    .then(dirs => {
      // get list of version
      dirs = [].concat.apply([], dirs);
      return Promise.all(dirs.map(e => {
        return utils.aws_list_directory(sentinel_bucket, e, s3);
      }));
    })
    .then(data => {
      //create list of image
      data = [].concat.apply([], data);
      return Promise.all(data.map(e => {
        let s2path = e.replace(/\/$/, '');
        let yeah = s2path.split('/')[4];
        let month = utils.zeroPad(s2path.split('/')[5], 2);
        let day = utils.zeroPad(s2path.split('/')[6], 2);

        let info = {
          path: s2path,
          utm_zone: s2path.split('/')[1],
          latitude_band: s2path.split('/')[2],
          grid_square: s2path.split('/')[3],
          num: s2path.split('/')[7],
          acquisition_date: `${yeah}${month}${day}`,
          browseURL: `https://sentinel-s2-l1c.s3.amazonaws.com/${s2path}/preview.jpg`};

        info.scene_id = `S2A_tile_${info.date}_${info.utm_zone}${info.latitude_band}${info.grid_square}_${info.num}`;

        if (full) {
          let json_path = `${e}tileInfo.json`;
          return utils.get_s2_info(sentinel_bucket, json_path, s3)
            .then(data => {
              info = Object.assign({}, info, data);
              info.scene_id = `${info.sat}_tile_${info.acquisition_date}_${info.utm_zone}${info.latitude_band}${info.grid_square}_${info.num}`;
              return info;
            });
        } else {
          return info;
        }
      }));
    });
};