#!/usr/bin/env node

/**
 * This script reads the AWS region data from GitHub (the AWS SDK project) and
 * checks the regions against the amazon.js file.
 *
 * It will update this file with the latest regions if there are changes (regions added or removed)
 *
 */

const fs = require('fs');
const path = require('path');

console.log('Updating EC2 and EKS region lists');
console.log('=================================');
console.log('');

const SCRIPT = process.argv[1];
const DIR = path.resolve(SCRIPT, '../../..');
const PARTITIONS = ['aws', 'aws-us-gov', 'aws-cn'];
const ENDPOINTS_URL = 'https://raw.githubusercontent.com/boto/botocore/develop/botocore/data/endpoints.json';
const JS_FILE = path.resolve(DIR, 'lib/shared/addon/utils/amazon.js');

const request = require('request');

function cleanArrayItem(item) {
  item = item.trim();

  if (item.startsWith('\'')) {
    item = item.substr(1);
  }
  if (item.endsWith(',')) {
    item = item.slice(0, -1);
  }
  if (item.endsWith('\'')) {
    item = item.slice(0, -1);
  }
  return item;
}

function readExisting(name) {
  const data = fs.readFileSync(JS_FILE).toString();

  const items = [];

  let processing = false;
  let done = false;

  data.split(/\r?\n/).forEach(line =>  {
    if (!done) {
      if (!processing) {
        if (line.includes(`export const ${ name } = [`)) {
          processing = true;
        }
      } else {
        if (line === '];') {
          processing = false;
          done = true;
        } else {
          items.push(cleanArrayItem(line.trim()));
        }
      }
    }
  });

  return items;
}

function patchRegions(key, latest) {
  const data = fs.readFileSync(JS_FILE).toString();

  const items = [];
  const out = [];

  let processing = false;
  let done = false;

  data.split(/\r?\n/).forEach(line =>  {
    if (!done) {
      if (!processing) {
        if (line.includes(`export const ${ key } = [`)) {
          processing = true;
        }
        out.push(line);
      } else {
        if (line === '];') {
          processing = false;
          done = true;

          // We've skipped the existing list - now write the new list
          latest.forEach((r) => {
            out.push(`  '${ r }',`);
          });

          out.push(line);
        } else {
          items.push(cleanArrayItem(line.trim()));
        }
      }
    } else {
      out.push(line);
    }
  });

  // Write the file back out;
  fs.writeFileSync(JS_FILE, out.join('\n'));
}

// List regions in a partition
function listRegions(endpoints, partition, svc) {
  const p = endpoints.partitions.find((p => p.partition === partition));

  if (!p) {
    console.error(`Can not find partition ${ partition }`);
    return;
  }

  const regions = [];

  Object.keys(p.services?.[svc]?.endpoints || {}).forEach((r) => {
    const v = p.services[svc].endpoints[r];

    if (!v.deprecated) {
      regions.push(r);
      // console.log(`    ${ r }`);
    }
  });

  regions.sort();

  return regions;
}

function checkService(endpoints, svc, key) {
  const latest = [];

  console.log(`Checking regions for ${ svc }`);

  PARTITIONS.forEach((p) => latest.push(...listRegions(endpoints, p, svc)));

  const existing = readExisting(key);

  const latestMap = {};
  const existingMap = {};

  latest.forEach((r) => latestMap[r] = true);
  existing.forEach((r) => existingMap[r] = true);

  let changes = false;

  latest.forEach((r) => {
    if (!existingMap[r]) {
      console.log('  + new region ' + r);
      changes = true;
    }
  });

  existing.forEach((r) => {
    if (!latestMap[r]) {
      console.log('  - removed region ' + r);
      changes = true;
    }
  });

  // Patch the changes

  if (changes) {
    patchRegions(key, latest);
  } else {
    console.log('  No region changes');
  }

  console.log('');

  return changes;
}

request(ENDPOINTS_URL, function (error, res, body) {
  if (error) {
    console.error('Could not fetch endpoints data');

    process.exit(1);
  }

  if (res.statusCode !== 200) {
    console.error(`Could not fetch endpoints data - status ${ res.statusCode } ${ res.statusMessage }`);

    process.exit(2);
  }

  try {
    const endpoints = JSON.parse(body);

    checkService(endpoints, 'eks', 'EKS_REGIONS');
    checkService(endpoints, 'ec2', 'REGIONS');
  } catch (e) {
    console.error('Error parsing and processing data');
    console.error(e);

    process.exit(3);
  }
});