/covid19 Slack Slash command in PHP using Johns Hopkins data

covid19.php

<?php

/**
 * Create a new slack command such as /covid19.  Put this script in a web accessible location
 * and point your slash command at it.  Update the $slack_token below with the token for your
 * command.  Accepts a none or one arguments - with no arguments provides US data; one argument
 * can be the name of a state to get data for.  Not much in the way of error checking, was quick
 * and dirty.
 */

$slack_token = '<token>'; // Put your slash command token here

if (filter_input(INPUT_POST, 'token') !== $slack_token) {
    http_response_code(400);
    die('bad bad bad');
}

$user_name = filter_input(INPUT_POST, 'user_name');
$state = filter_input(INPUT_POST, 'text');

if (empty($state = trim($state))) {
    $state = null;
}

$today = date_create(null, new DateTimeZone('America/Los_Angeles'))->format('m-d-Y');
$yesterday = date_create('yesterday', new DateTimeZone('America/Los_Angeles'))->format('m-d-Y');

$files = [
    'county_report_yesterday' => "https://raw.githubusercontent.com/CSSEGISandData/COVID-19/master/csse_covid_19_data/csse_covid_19_daily_reports/$yesterday.csv",
    'county_report_today' => "https://raw.githubusercontent.com/CSSEGISandData/COVID-19/master/csse_covid_19_data/csse_covid_19_daily_reports/$today.csv",
];

$temp = sys_get_temp_dir();

foreach ($files as $file => $url) {
    $filePath = $temp . DIRECTORY_SEPARATOR . $file . '.csv';

    if (!file_exists($filePath) || filemtime($filePath) < time() - 3600) {
        file_put_contents($filePath, file_get_contents($url), LOCK_EX);
    }

    $$file = new SplFileObject($filePath);
    $$file->setFlags(SplFileObject::READ_CSV);
}

function get_stats(SplFileObject $file, ?string $state) {
    $state_confirmed = 0;
    $state_deaths = 0;
    $state_recovered = 0;
    $us_confirmed = 0;
    $us_deaths = 0;
    $us_recovered = 0;

    foreach ($file as $line) {
        if (count($line) < 5) {
            continue;
        }

        if ($state !== null && strcasecmp($state, $line[2]) === 0) {
            $state_confirmed += $line[7];
            $state_deaths += $line[8];
            $state_recovered += $line[9];
        }

        if (strcasecmp('US', $line[3]) === 0) {
            $us_confirmed += $line[7];
            $us_deaths += $line[8];
            $us_recovered += $line[9];
        }
    }

    return compact('state_confirmed', 'state_deaths', 'state_recovered', 'us_confirmed', 'us_deaths', 'us_recovered');
}

$template = 'According to data from <https://coronavirus.jhu.edu/map.html|Johns Hopkins>, I have infected $infected people (a $infected_increase% increase over yesterday).  $recovered people have recovered and sadly $deaths people have died.';

$today_stats = get_stats($county_report_today, $state);
$yesterday_stats = get_stats($county_report_yesterday, $state);

$text = "<@$user_name> asked for my stats";

if ($state !== null) {
    $text .= ' for ' . ucwords($state) . ': ';
    $text .= strtr($template, [
        '$infected' => $today_stats['state_confirmed'],
        '$infected_increase' => round(($today_stats['state_confirmed'] * 100 / $yesterday_stats['state_confirmed']) - 100, 2),
        '$recovered' => $today_stats['state_recovered'],
        '$deaths' => $today_stats['state_deaths']
    ]);
} else {
    $text .= ' for the United States: ';
    $text .= strtr($template, [
        '$infected' => $today_stats['us_confirmed'],
        '$infected_increase' => round(($today_stats['us_confirmed'] * 100 / $yesterday_stats['us_confirmed']) - 100, 2),
        '$recovered' => $today_stats['us_recovered'],
        '$deaths' => $today_stats['us_deaths']
    ]);
}

$response = [
    'response_type' => 'in_channel',
    'text' => $text,
    'unfurl_links' => false,
    'unfurl_media' => false,
];

header('Content-Type: application/json');
echo json_encode($response);