<?php
/*
 * worker.php
 * 
 *  This file is part of the VE.Direct notify service
 *  https://git.schauaus.at/VE-Tools/VE.Direct-notify
 *  It is licensed under the GPL3.0 or later.             
 *  You should have received a copy of the license with this software
 */

// read configuration
$config = readConfig();
if( !isset($config) )
    exit("Error reading configuration! Exit!\r\n");

// check whether test message shall be delivered to notification service
if( $argc >= 3 && $argv[1] == "test" && isset($argv[2]) ) {
    sendMessage($argv[2] . ": Testmessage");
    exit();
}

queryMonitors();

function checkCondition($value, $condition) {
    switch($condition[0]) {
        case "e": // equal
            if($value == $condition[1])
                return ' equals ' . $condition[1];
            break;
        case "gt": // greater than
            if( floatval($value) > floatval($condition[1]) )
                return ' = ' . $value  . ' and greater than ' . $condition[1];
            break;
        case "gte": // greater than or equal
            if( floatval($value) >= floatval($condition[1]) )
                return ' = ' . $value . ' and greater than or equal ' . $condition[1];
            break;
        case "lt": // lower than
            if( floatval($value) < floatval($condition[1]) )
                return ' = ' . $value . ' and lower than ' . $condition[1];
            break;
        case "lte": // lower than or equal
            if( floatval($value) <= floatval($condition[1]) )
                return ' = ' . $value . ' and lower than or equal ' . $condition[1];
            break;
        case "ne": // not equal
            if($value != $condition[1])
                return ' = ' . $value . ' and not equal to ' . $condition[1];
            break;
    }
    return false;
}

function queryMonitors() {
    global $config;

    // establish database connection
    $dbPath = (str_starts_with($config->database, '/')) ? $config->database : dirname(__FILE__) . '/' . $config->database;
    try {
    	$db = new SQLite3($dbPath, SQLITE3_OPEN_READONLY);
    }
    catch (Exception $e) {
	print ('error detected: ' . $e->getMessage() . "\r\n");
    	return false;
    }

    // query devices from database
    $sql = "SELECT name FROM sqlite_schema WHERE name NOT LIKE 'sqlite_%' AND name <> 'meta' ORDER BY name ASC;";
    $data = $db->query($sql);

    // process every device found on database
    while( $device = $data->fetchArray(SQLITE3_ASSOC) ) {
        // query device data from database
        $sql = "SELECT * FROM '" . $device['name'] . "' ORDER BY date DESC, time DESC LIMIT 1;";
        $res = $db->query($sql)->fetchArray(SQLITE3_NUM);
        $dataset = json_decode($res[2]);

        // read last status of warnings and errors for comparison to avoid double sending of notifications
        $statusFile = __DIR__ . '/status/' . $device['name'];
        $lastStatus = [];
        if( is_file($statusFile) )
            $lastStatus = json_decode( file_get_contents( $statusFile ), true );
        $checksum = hash( 'sha256', json_encode($lastStatus) );

        // process configured monitors
        foreach($config->monitors as $monitor) {
            if( !empty($monitor->warning) ) {
                if( !isset( $lastStatus[$monitor->parameter]['warning'] ) )
                    $lastStatus[$monitor->parameter]['warning'] = 0;

                $status = checkCondition($dataset->{$monitor->parameter}, $monitor->warning);
                if( $status && $lastStatus[$monitor->parameter]['warning'] == 0  ) { // new warning
                    sendMessage('Warning from ' . $device['name'] . ': ' . $monitor->parameter . $status);
                    $lastStatus[$monitor->parameter]['warning'] = 1;
                }
                else if( !$status && $lastStatus[$monitor->parameter]['warning'] == 1) { // warning cleared
                    sendMessage( 'Warning cleared on ' . $device['name'] . '. ' . $monitor->parameter . ' = ' . $dataset->{$monitor->parameter} . ' and back to normal.');
                    $lastStatus[$monitor->parameter]['warning'] = 0;
                }
            }
            if( !empty($monitor->error) ) {
                if( !isset( $lastStatus[$monitor->parameter]['error'] ) )
                    $lastStatus[$monitor->parameter]['error'] = 0;

                $status = checkCondition($dataset->{$monitor->parameter}, $monitor->error);
                if( $status && $lastStatus[$monitor->parameter]['error'] == 0 ) { // new error!
                    sendMessage('Error from ' . $device['name'] . ': ' . $monitor->parameter . $status);
                    $lastStatus[$monitor->parameter]['error'] = 1;
                }
                else if( !$status && $lastStatus[$monitor->parameter]['error'] == 1 ) { // error cleared
                    sendMessage('Error cleared on ' . $device['name'] . '. ' . $monitor->parameter . ' = ' . $dataset->{$monitor->parameter} . ' and out of critical range.');
                    $lastStatus[$monitor->parameter]['error'] = 0;
                }
           }
        }
        if( hash( 'sha256', json_encode($lastStatus) ) !== $checksum)
            file_put_contents( $statusFile, json_encode($lastStatus) );
    }
}

function readConfig() {
    return json_decode( file_get_contents(__DIR__ . '/config.json') );
}

function sendMessage($message) {
    global $config;
    $authorization = "Authorization: ";

    if( !empty($config->service->username) && !empty($config->service->password) )
        $authorization .= 'Basic ' . base64_encode($config->service->username . ':' . $config->service->password);
    elseif( !empty($config->service->auth_token) )
        $authorization .= 'Bearer ' . $config->service->auth_token;
    else
        $authorization = '';

    $result = file_get_contents( $config->service->url . '/' . $config->service->topic, false, stream_context_create([
        'http' => [
            'method' => 'POST',
            'header' =>
                "Content-Type: text/plain\r\n" .
                $authorization,
            'content' => $message
        ]
    ]));

    return true;
}

?>