/*
DESCRIPTION:
Persist HTTP request data to a real-time data store with
an API to query event counts, event data, and reset to 
delete data in the store.

GETTING STARTED:
Copy this workflow into your account to run it for free.

HOW IT WORKS:

- Event details for any HTTP requests to the endpoint URL 
  for this workflow will be saved to $checkpoint (e.g.,
  (headers, body, query data, etc).

- To query the number of events that were made/saved in 
  $checkpoint, make a request to the workflow endpoint
  with the path `/api/events/count`

- To retrieve the contents for any requests made to this
  workflow, make a request to the worfklow endpoint URL 
  with the path `/api/events/`

- To reset $checkpoint, make a request to the workflow 
  endpoint URL with the path `/api/events/reset`

- To customize this works workflow, just edit the Node.js 
  code below in `steps.process_event_data`  

SAVING DATA TO PIPEDREAM'S SQL SERVICE:

- Enable `steps.sql` at the end of this workflow.

- Add a table name -- Pipedream will automagically create
  a table and schema to match your data.

- Navigate to the SQL tab above to query your data. Data will
  automatically be deleted after 30 days.

You can delete this step at any time (or just move it down 
using the arrovs at the top right of the step). 
*/

// customize the max number of events to save in $checkpoint
const event_cache_size = 1000

if (!Array.isArray($checkpoint)) {
  // if $checkpoint is not an array, instantiate it
  $checkpoint = []
}

const eventCount = $checkpoint.length

if (event.url.indexOf('/api/events/count') !== -1) {
  // if the request URL contains /api/events/count, 
  // return the count of events in $checkpoint
  $respond({
    status: 200,
    headers: {
      'content-type': 'application/json'
    },
    body: JSON.stringify({ eventCount } )
  })
  console.log(`Returned count of events: ${eventCount}`)
} else if (event.url.indexOf('/api/events/reset') !== -1) {
  // if the request URL contains /api/events/reset, set 
  // $checkpoint to an empty array.
  $checkpoint = []
  $respond({
    status: 200,
    headers: {
      'content-type': 'application/json'
    },
    body: JSON.stringify({ 'reset': true })
  })
  console.log('Reset $checkpoint')
} else if (event.url.indexOf('/api/events') !== -1) {
  // if the request URL contains /api/events, return the 
  // event contents.
  $respond({
    status: 200,
    headers: {
      'content-type': 'application/json'
    },
    body: JSON.stringify($checkpoint)
  })
  console.log(`Returned ${eventCount} events.`)
} else { 
  // in all other cases, save the event data to $checkpoint.
  // if the number of events is >= event_cache_size, remove 
  // older items first.
  const overage = eventCount + 1 - event_cache_size
  let eventsRemoved = 0
  if (overage > 0) {
    for (let i = 0; i < overage; i++) {
      $checkpoint.shift(overage)  
    }
    eventsRemoved = overage
  }

  // then add the event to $checkpoint and respond to the client.
  $checkpoint.push(event)
  $respond({
    status: 200,
    headers: {
      'content-type': 'application/json'
    },
    body: JSON.stringify({ 
      'success': true, 
      'eventCount': $checkpoint.length, 
      'oldEventsRemoved': eventsRemoved 
    })
  })
  console.log(`Added event to $checkpoint.`)
}