import {EC2Client, DescribeInstancesCommand, TerminateInstancesCommand } from "@aws-sdk/client-ec2";

// CONFIGURATION
const ec2    = new EC2Client({region: 'us-east-1'});
const maxAge = 1000 * 3600 * 3; // Terminate instances older than 3 hours in millis
const tag    = 'jenkins'; // Only terminate instances with this tag
// if not null, send a notification to Slack/Mattermost if any instances are terminated,
// this is an Incoming Webhook URL:
const notifyUrl = null;
    
const thresholdDate = new Date((new Date()).getTime() - maxAge);


async function notifySlack(message) {
  /*global fetch*/
  await fetch(notifyUrl, {
    method: 'POST',
    headers: {
        'Accept': 'application/json',
        'Content-Type': 'application/json'
    },
    body: JSON.stringify({ "text": message })
  })
   .then(response => console.log("Response for notification is: " + JSON.stringify(response)))
   .catch((error) => {
        console.error('error sending notification', error);
    }); 
}

export const handler = async(event) => {
  
  const data = await ec2.send(new DescribeInstancesCommand({
    Filters: [
      { Name: "architecture", Values: ["x86_64"] },
      { Name: "instance-state-name", Values: ["running"] },
      {
        Name: "tag-key",
        Values: [tag],
      },
    ],
  }));
  
  
  var killList = [];
  var message = "I am killing the following AWS instances that have been running longer than " + maxAge + "ms: ";
  
  data.Reservations.forEach(reservation => {
    reservation.Instances.forEach(instance => {
      console.log("Checking instance " + instance.InstanceId + " with launch time " + instance.LaunchTime);
      var instanceLaunchDate = new Date(instance.LaunchTime);
      if (instanceLaunchDate < thresholdDate) {
        console.log("Will kill this instance");
        killList.push(instance.InstanceId);
        //find its name
        var name = "?";
        instance.Tags.forEach(tag => {
          if (tag.Key == 'Name') {
            name = tag.Value;
          }
        });
        message += instance.InstanceId + " (" + name +  "),";
      }
    });
  });
  
  console.log("Final kill list: " + killList);
  
  var killResult = {};
  
  if (killList.length > 0) {
    killResult = await ec2.send(new TerminateInstancesCommand({
      InstanceIds: killList
    }));
  
    console.log("Killed instances (" + message + ") with result: " + JSON.stringify(killResult));
    
    if (notifyUrl != null) {
      await notifySlack(message);
    }
  }
  
  return { 
    killList: killList,
    killResult: killResult
  };
        
};