greenhouse-api.php

<?php
ini_set( 'memory_limit', '4G' );

define( 'GREENHOUSE_USER_ID', getenv( 'GREENHOUSE_USER_ID' ) );
define( 'GREENHOUSE_TOKEN', getenv( 'GREENHOUSE_TOKEN' ) );

function create_curl_handle( $page, $params = array() ) {
	$ch = curl_init();

	$url = sprintf( 'https://harvest.greenhouse.io/v1/candidates?per_page=500&page=%d', $page );

	curl_setopt( $ch, CURLOPT_URL, $url );
	curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
	curl_setopt( $ch, CURLOPT_CONNECTTIMEOUT, 30 );
	curl_setopt( $ch, CURLOPT_TIMEOUT, 30 );
	curl_setopt( $ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1 );

	$params[ CURLOPT_HTTPHEADER ][] = 'Authorization: Basic ' . base64_encode( GREENHOUSE_TOKEN . ':' );
	$params[ CURLOPT_HTTPHEADER ][] = 'On-Behalf-Of: ' . GREENHOUSE_USER_ID;

	foreach ( $params as $key => $value ) {
		curl_setopt( $ch, $key, $value );
	}

	return $ch;
}

function gh_request( $offset, $parallel_requests ) {
	$mh = curl_multi_init();
	$handles = [];

	foreach ( range( $offset * $parallel_requests + 1, $offset * $parallel_requests + 1 + $parallel_requests ) as $page ) {
		$handles[ $page ] = create_curl_handle( $page );
	}

	foreach ( $handles as $handle ) {
		curl_multi_add_handle( $mh, $handle );
	}

	$running = null;
	do {
		curl_multi_exec( $mh, $running );
	} while ( $running );

	foreach ( $handles as $handle ) {
		curl_multi_remove_handle( $mh, $handle );
	}

	curl_multi_close( $mh );

	return $handles;
}

function has_active_application( $entry ) {
	foreach ( $entry['applications'] as $application ) {
		if ( 'active' === $application['status'] ) {
			return true;
		}
	}
	return false;
}

function process_map( $handles ) {
	return array_map( function( $handle, $page ) {
		$response = curl_multi_getcontent( $handle );
		$result = json_decode( $response, true );

		if ( JSON_ERROR_NONE !== json_last_error() ) {
			var_dump( "Failed to fetch " . $page );
			return array();
//			throw new Exception( 'Failed to parse returning JSON from the API' );
		}

		return $result;
	}, $handles, array_keys( $handles )  );
}

function process_reducer( $results ) {
	return call_user_func_array( 'array_merge', $results );
}

$entries = [];

for ( $i = 0; ; $i++ ) {
	printf( "Processing offset %d...\n", $i );

	$results = gh_request( $i, 50 );
	$results = process_map( $results );
	$results = process_reducer( $results );

	if ( empty( $results ) ) {
		break;
	}

	// Only select those candidates that have a GitHub username assigned
	$results = array_filter( $results, function( $entry ) {
		return ! empty( $entry['keyed_custom_fields']['git_hub_username']['value'] );
	} );

	// Only retrieve the necessary fields
	$results = array_map( function( $entry ) {
		return [
			'id'     => $entry['id'],
			'github' => $entry['keyed_custom_fields']['git_hub_username']['value'],
			'active' => has_active_application( $entry ),
		];
	}, $results );

	// Only select those candidates that have no active applications
	$results = array_filter( $results, function( $entry ) {
		return ! $entry['active'];
	} );

	$results = array_map( function( $entry ) {
		unset( $entry['active'] ); // no need to display that
		return implode( ',', $entry );
	}, $results );

	$entries = array_merge( $entries, $results );
	break;
}

var_dump( $entries );