Laravel Helpers

AppServiceProvider.php

<?php // Pop these in App\Providers\AppServiceProvider::boot()

// Exception Handling
Blade::directive('try', fn ($x) => '<?php try { ?>');
Blade::directive('catch', fn ($x) => "<?php } catch ($x) { ?>");
Blade::directive('finally', fn ($x) => '<?php } finally { ?>');
Blade::directive('endtry', fn ($x) => '<?php } ?>');

// JSON Encode
Blade::directive('json', fn ($x) => "<?php echo \Illuminate\Support\Js::encode($x); ?>");

// Quick ifs
Blade::if('isempty', fn (?iterable $value = []) => count($value) === 0);
Blade::if('hide', fn () => false);

// Carbon Macros
Carbon::macro('toUserTimezone', fn () => $this->setTimezone(user()->timezone ?? 'Europe/London'));

// Generate a unique token for a form, and store it in the cache or session
// On form submission, we can check the cache for existance of the token;
// If we've seen the token before, the form has already been submitted at least once.
Blade::directive('onlyonce', function () {
    return <<<'PHP'
        <?php echo '<input type="hidden" name="_only_once" value="'.Str::random(6).'">' ?>
        PHP;
});

helpers.php

<?php declare(strict_types=1);

function user(): App\Models\User|Illuminate\Contracts\Auth\Authenticatable|null
{
    return auth()->user();
}

/**
 * Toggle a boolean variable.
 */
function toggle(bool &$var): void
{
    $var = ! $var;
}

/**
 * Get the contrast color for a given hex colour.
 * Taken from https://stackoverflow.com/a/42921358
 */
function get_contrast_color($hexColor)
{
    // hexColor RGB
    $R1 = hexdec(substr($hexColor, 1, 2));
    $G1 = hexdec(substr($hexColor, 3, 2));
    $B1 = hexdec(substr($hexColor, 5, 2));

    // Black RGB
    $blackColor = '#000000';
    $R2BlackColor = hexdec(substr($blackColor, 1, 2));
    $G2BlackColor = hexdec(substr($blackColor, 3, 2));
    $B2BlackColor = hexdec(substr($blackColor, 5, 2));

    // Calc contrast ratio
    $L1 = 0.2126 * pow($R1 / 255, 2.2) +
        0.7152 * pow($G1 / 255, 2.2) +
        0.0722 * pow($B1 / 255, 2.2);

    $L2 = 0.2126 * pow($R2BlackColor / 255, 2.2) +
        0.7152 * pow($G2BlackColor / 255, 2.2) +
        0.0722 * pow($B2BlackColor / 255, 2.2);

    $contrastRatio = 0;
    if ($L1 > $L2) {
        $contrastRatio = (int) (($L1 + 0.05) / ($L2 + 0.05));
    } else {
        $contrastRatio = (int) (($L2 + 0.05) / ($L1 + 0.05));
    }

    // If contrast is more than 5, return black color
    if ($contrastRatio > 5) {
        return '#000000';
    } else {
        // if not, return white color.
        return '#FFFFFF';
    }
}

PreventDoubleSubmits.php

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Session;
use Symfony\Component\HttpFoundation\Response;

class PreventDoubleSubmits
{
    /**
     * Prevent double-submits of forms.
     * Every form has a unique token which is generated when the form is rendered.
     * Once the form is submitted, the token is saved to the user's session.
     * On any subsequent requests, if the token is found in the user's session, we know that this form has already been submitted once before.
     * Doing this check stops use from doing the same action twice, which could cause problems such as duplicate records in the database or sending the same email twice.
     *
     * @param  \Closure(\Illuminate\Http\Request): (\Symfony\Component\HttpFoundation\Response)  $next
     */
    public function handle(Request $request, Closure $next): Response
    {
        // If the request is a "read-only" operation, then we don't need to check for double-submits, as no data is being modified.
        if ($request->isMethodSafe()) {
            return $next($request);
        }

        // If this is a Livewire update, then we don't want to check for double-submits
        if ($request->route()?->getName() === 'livewire.message') {
            return $next($request);
        }

        // Get the unique token from the submitted form data.
        $token = $request->post('_only_once');

        // If the token is missing, then we can't check for double-submits. Abort the request to prevent potential double-submits.
        abort_if($token === null, 400, 'Missing _only_once token in form. Add @onlyonce inside the <form> tags.');

        // Build up the session key by setting the prefix and the token.
        $session_key = "only_once_tokens.{$token}";

        // If the token is found in the user's session, then we know that this form has already been submitted once before.
        // Abort the request so we don't
        abort_if(Session::pull($session_key, false), 429, 'Form submitted more than once.');

        // If the token is not found in the user's session, then we know that this is the first time the form has been submitted.
        // Store the token in the user's session so that we can check for double-submits of this form on any subsequent requests.
        Session::put($session_key, now()->timestamp);

        return $next($request);
    }
}