Conditional code for different days of a week

gistfile1.php

<?php

$dates = array("Sunday",
               "Monday",
               "Tuesday",
               "Wednesday",
               "Thursday",
               "Friday",
               "Saturday"
              );

// This echos today's date
// echo $dates[date("w")];

if ( $dates[date("w")] == "Saturday" || $dates[date("w")] == "Sunday" ) {
	echo 'Yes, It is weekend!';
}
else {
	echo 'Oh no, back to work';
}

gistfile2.php

<?php

$dates = array("Sunday",
               "Monday",
               "Tuesday",
               "Wednesday",
               "Thursday",
               "Friday",
               "Saturday"
              );

$day = $dates[date("w")];

switch ($day) {
    case "Sunday":
        $image_of_day = '<img src="' . get_stylesheet_directory_uri() . '/images/offer-box/weekend.jpg" />';
        break;
    case "Monday":
        $image_of_day = '<img src="' . get_stylesheet_directory_uri() . '/images/offer-box/monday.jpg" />';
        break;
    case "Tuesday":
        $image_of_day = '<img src="' . get_stylesheet_directory_uri() . '/images/offer-box/tuesday.jpg" />';
        break;
    case "Wednesday":
    	$image_of_day = '<img src="' . get_stylesheet_directory_uri() . '/images/offer-box/wednesday.jpg" />';
    	break;
	case "Thursday":
    	$image_of_day = '<img src="' . get_stylesheet_directory_uri() . '/images/offer-box/thursday.jpg" />';
    	break;
	case "Friday":
    	$image_of_day = '<img src="' . get_stylesheet_directory_uri() . '/images/offer-box/friday.jpg" />';
    	break;
    case "Saturday":
    	$image_of_day = '<img src="' . get_stylesheet_directory_uri() . '/images/offer-box/weekend.jpg" />';
    	break;
}

echo $image_of_day;

gistfile3.php

<?php

$image_of_day_file = in_array( date( 'l' ), ['Saturday', 'Sunday'] ) ? 'weekend' : strtolower( date( 'l' ) );

$image_url = get_stylesheet_directory_uri() . '/images/offer-box/' . $image_of_day_file . '.jpg';

echo '<img src="' . esc_url( $image_url ) . '" alt="" />';