// Usage:
// $ babel-node keepalive.js > keepalive-code.js && \
//   zip keepalive-code.zip keepalive-code.js && \
//   aws lambda update-function-code \
//     --function-name DawsonKeepAliveProd \
//     --zip-file fileb://./keepalive-code.zip && \
//   rm keepalive-code*

import execa from 'execa';
import assert from 'assert';

const DAWSON_STAGE = process.env.DAWSON_STAGE;
assert(DAWSON_STAGE, 'DAWSON_STAGE env is required');

const SNS_FAILURE_TOPIC_ARN = 'arn:aws:sns:eu-west-1:XXX:GePodKeepAliveFailed';

const createInvokeCode = name => {
  return `
    lambda.invoke({
      FunctionName: '${name}',
      InvocationType: 'RequestResponse',
      LogType: 'None',
      Payload: JSON.stringify({ __ping: true })
    }).promise()`;
};

const createFunctionCode = functionNames => {
  return `
module.exports.handler = function (event, context, callback) {
  const AWS = require('aws-sdk');
  const lambda = new AWS.Lambda({});

  Promise.all([
    ${functionNames.map(name => {
      return createInvokeCode(name);
    }).join(',\n')}
  ])
  .then(res => {
    console.error(res.length, 'invocations completed');
    console.error('Lambda status codes:', res.map(r => r.StatusCode));
  })
  .catch(err => {
    console.error('One invocation failed (aborting whole execution)', err);
    sns.publish({
      TopicArn: '${SNS_FAILURE_TOPIC_ARN}',
      Message: 'One or more keepalive invocations failed: \\n' + JSON.stringify(err, null, 2)
    }).promise()
    .then(() => callback(err.message))
    .catch(snsError => callback(snsError.message));
  })
};
  `;
};

execa.shell(`cd .. && dawson describe --shell | grep -i '\\-lambda'`)
.then(result => {
  assert(result.code === 0);
  const functionNames = result.stdout.split('\n').map(v => v.split('=')[1]);
  const functionCode = createFunctionCode(functionNames);
  process.stdout.write(functionCode);
});