Serve newest camera jpg snapshot

cam2.php

<?php

define('MIN_HOUR', 6);
define('MAX_HOUR', 18);
define('SNAPSHOT_DIR', 'cam');
define('SNAPSHOT_PATTERN', '/camera[0-9]*_([0-9]+)\.jpg/');
define('SECONDS_TO_CACHE', 660); // 11 minutes
define('PLACEHOLDER_TEXT', 'Stream is over for today. We will be back at 6:00am.');

$now = time();
$currentYear = date('Y', $now);
$currentMonth = date('m', $now);
$currentDay = date('d', $now);
$currentHour = date('G', $now);
$currentMinute = intval(date('i', $now));

if ($currentHour >= MAX_HOUR || $currentHour < MIN_HOUR) {
    $lastModifiedTime = mktime(MAX_HOUR, 0, 0, date('n', $now), date('j', $now), date('Y', $now));
    $expireTime = mktime(MIN_HOUR, 0, 0, date('n', $now), date('j', $now), date('Y', $now));
    if ($currentHour >= MAX_HOUR) {
        $expireTime = strtotime('+1 day', $expireTime);
    }
    if ($currentHour < MIN_HOUR) {
        $lastModifiedTime = strtotime('-1 day', $lastModifiedTime);
    }
    header('Last-Modified: ' . gmdate('D, d M Y H:i:s', $lastModifiedTime) . ' GMT');
    header('Expires: ' . gmdate('D, d M Y H:i:s', $expireTime) . ' GMT');
    header('X-Stream-Status: offline');

    show_placeholder(PLACEHOLDER_TEXT);
    exit;
}

$dir = realpath(__DIR__) . DIRECTORY_SEPARATOR . SNAPSHOT_DIR
    . DIRECTORY_SEPARATOR . $currentYear 
    . DIRECTORY_SEPARATOR . $currentMonth 
    . DIRECTORY_SEPARATOR . $currentDay;

// get array of files within $dir, alphabetically sorted descending (newest first)
$files = @scandir($dir, 1);
if ($files === false) {
    show_placeholder(PLACEHOLDER_TEXT);
    exit(1);
}

// get most recent uploaded image
$image = get_latest_image($files, 60, $now);
if ($image === false) {
    show_placeholder(PLACEHOLDER_TEXT);
    exit(1);
}

list($file, $fileTimestamp) = $image;
$filePath = $dir . DIRECTORY_SEPARATOR . $file;
$lastModified = gmdate('D, d M Y H:i:s', $fileTimestamp) . ' GMT';
$expire = gmdate('D, d M Y H:i:s', $fileTimestamp + SECONDS_TO_CACHE) . ' GMT';

header('Content-type: image/jpeg');
header('Content-Length: ' . filesize($filePath));
header('Last-Modified: ' . $lastModified);
header('Expires: ' . $expire);
header('Pragma: cache');

readfile($filePath);

function get_latest_image($files, $minAge, $now) {
    foreach ($files as $file) {
        if (preg_match(SNAPSHOT_PATTERN, $file, $matches) === 1) {
            $fileDate = date_create_from_format('YmdHis', $matches[1]);
            $fileTimestamp = date_timestamp_get($fileDate);
            // make sure file is older than $minAge to prevent serving not fully uploaded images
            if (($now - $fileTimestamp) >= $minAge) {
                return array($file, $fileTimestamp);
            }
        }
    }
    return false;
} 

function show_placeholder($text) {
    /**
     * Dynamic Dummy Image Generator — as seen on DummyImage.com
     *
     * This script enables you to create placeholder images in a breeze.
     * Please refer to the README on how to use it.
     *
     * (Original idea by Russel Heimlich. When I first published this script,
     * DummyImage.com was not Open Source, so I had to write a small script to
     * replace the function on my own server.)
     *
     * @author  Fabian Beiner <fb@fabianbeiner.de>
     * @license MIT
     * @link    https://github.com/FabianBeiner/PHP-Dummy-Image-Generator/
     * @version 0.3.0 <2017-12-26>
     */

    /**
     * Handle the “size” parameter.
     */
    $size = '640x480';
    list($imgWidth, $imgHeight) = explode('x', $size . 'x');
    if ($imgHeight === '') {
        $imgHeight = $imgWidth;
    }
    $filterOptions = array(
        'options' => array(
            'min_range' => 0,
            'max_range' => 9999
        )
    );
    if (filter_var($imgWidth, FILTER_VALIDATE_INT, $filterOptions) === false) {
        $imgWidth = '640';
    }
    if (filter_var($imgHeight, FILTER_VALIDATE_INT, $filterOptions) === false) {
        $imgHeight = '480';
    }

    /**
     * Handle the “type” parameter.
     */
    $type = 'png';

    /**
     * Handle the “text” parameter.
     */
    $encoding = mb_detect_encoding($text, 'UTF-8, ISO-8859-1');
    if ($encoding !== 'UTF-8') {
        $text = mb_convert_encoding($text, 'UTF-8', $encoding);
    }
    $text = mb_encode_numericentity($text,
                                    array(0x0, 0xffff, 0, 0xffff),
                                    'UTF-8');

    /**
     * Handle the “bg” parameter.
     */
    $bg = '000000';
    list($bgRed, $bgGreen, $bgBlue) = sscanf($bg, '%02x%02x%02x');

    /**
     * Handle the “color” parameter.
     */
    $color = 'FFFFFF';
    list($colorRed, $colorGreen, $colorBlue) = sscanf($color, '%02x%02x%02x');

    /**
     * Define the typeface settings.
     */
    $fontFile = realpath(__DIR__) . DIRECTORY_SEPARATOR . 'RobotoMono-Regular.ttf';
    if ( ! is_readable($fontFile)) {
        $fontFile = 'arial';
    }

    $fontSize = round(($imgWidth - 50) / 8);
    if ($fontSize <= 9) {
        $fontSize = 9;
    }

    /**
     * Generate the image.
     */
    $image     = imagecreatetruecolor($imgWidth, $imgHeight);
    $colorFill = imagecolorallocate($image, $colorRed, $colorGreen, $colorBlue);
    $bgFill    = imagecolorallocate($image, $bgRed, $bgGreen, $bgBlue);
    imagefill($image, 0, 0, $bgFill);
    $textBox = imagettfbbox($fontSize, 0, $fontFile, $text);

    while ($textBox[4] >= $imgWidth) {
        $fontSize -= round($fontSize / 2);
        $textBox  = imagettfbbox($fontSize, 0, $fontFile, $text);
        if ($fontSize <= 9) {
            $fontSize = 9;
            break;
        }
    }
    $textWidth  = abs($textBox[4] - $textBox[0]);
    $textHeight = abs($textBox[5] - $textBox[1]);
    $textX      = ($imgWidth - $textWidth) / 2;
    $textY      = ($imgHeight + $textHeight) / 2;
    imagettftext($image, $fontSize, 0, $textX, $textY, $colorFill, $fontFile, $text);

    /**
     * Return the image and destroy it afterwards.
     */
    switch ($type) {
        case 'png':
            header('Content-Type: image/png');
            imagepng($image, null, 9);
            break;
        case 'gif':
            header('Content-Type: image/gif');
            imagegif($image);
            break;
        case 'jpg':
        case 'jpeg':
            header('Content-Type: image/jpeg');
            imagejpeg($image);
            break;
    }
    imagedestroy($image);
}