LoraIncomingEntryController.php

<?php

namespace App\Http\Controllers;

use App\Model\LoraEntryIncoming;
use Illuminate\Http\Response;

/**
 * Controller of the LUMEN-Framework for handling incoming Lora-Entries.
 * 
 * - This works with the V2 of TTN
 * - It saves the incoming data into a database
 */
class LoraIncomingEntryController extends Controller
{

    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        //
    }

    /**
     * Add a new entry to the internal lora database.
     *
     * @return Response
     */
    public function apiLoraAdd()
    {
        $content = $this->addEntry();

        return (new Response(json_encode($content), 200))
            ->header('Content-Type', 'json');
    }

    private function addEntry()
    {
        $entry = [
            'payload' => false,
            'app_id' => false,
            'counter' => false,
            'dev_id' => false,
            'hardware_serial' => false,
            'payload_raw' => false,
            'downlink_url' => false,
            'port' => false,
            'content_raw' => false,
            'timestamp' => time(),
        ];

        $postdata_raw = file_get_contents('php://input');
        $postdata = json_decode($postdata_raw);

        foreach ($entry as $key => &$item) {
            if (property_exists($postdata, $key)) {
                $item = $postdata->$key;
            }
        }

        // entry payload
        $entry['payload'] = base64_decode($postdata->payload_raw);

        // metadata entries
        if (property_exists($postdata, 'metadata')) {
            $metakeys = [
                'time',
                'frequency',
                'modulation',
                'coding_rate',
                'data_rate',
            ];

            foreach ($metakeys as $key) {
                if (property_exists($postdata->metadata, $key)) {
                    $entry['meta_' . $key] = $postdata->metadata->$key;
                }
            }

            if (property_exists($postdata->metadata, 'gateways')) {
                $gatewaykeys = [
                    'gtw_id',
                    'latitude',
                    'longitude',
                    'altitude',
                    'channel',
                    'rssi',
                    'snr',
                    'rf_chain',
                ];
                $gateway = $postdata->metadata->gateways[0];
                foreach ($gatewaykeys as $key) {
                    $entry['gw_' . $key] = $gateway->$key;
                }
            }
        }

        $entry['content_raw'] = $postdata_raw;

        // save entry
        LoraEntryIncoming::create($entry);

        $this->checkLastEntry($entry);

        return $entry;
    }

    /**
     * Check last incoming Lora Entry. If it was "sync", send a call back via the Lorawan.
     * Think at your limits: 10 downlinks a day in the TTN V2.
     */
    private function checkLastEntry(array $entry)
    {
        $payload = $entry['payload'];

        if ($payload === 'sync') {
            $url = $entry['downlink_url'];
            $payload_string = 'fc:' . $entry['counter'];
            $payload_base64 = base64_encode($payload_string);

            $content = [
                'dev_id' => $entry['dev_id'],
                'port' => 1,
                'confirmed' => false,
                'payload_raw' => $payload_base64,
            ];

            $content_json = json_encode($content);

            $this->callTTNDownlink($url, $content_json);
        }
    }

    /**
     * Make the call to the TTN, send a downlink.
     */
    private function callTTNDownlink($url, $json) {
        $ch = curl_init();

        curl_setopt($ch, CURLOPT_URL,$url);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $json);
        $result = curl_exec ($ch);
        $info = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    }

}