core/src/Shipping/Extensions/ShippingMethodResourceExtension.php

<?php

namespace Modules\Core\Shipping\Extensions;

use Filament\Forms\Components\Component;
use Filament\Forms\Components\Concerns\HasChildComponents;
use Filament\Forms\Components\Select;
use Filament\Forms\Form;
use Filament\Forms\Get;
use Filament\Tables\Columns\TextColumn;
use Filament\Tables\Table;
use Lunar\Admin\Support\Extending\ResourceExtension;
use Lunar\Shipping\Facades\Shipping;
use Modules\Core\Shipping\Contracts\SupportsLivePricing;

class ShippingMethodResourceExtension extends ResourceExtension
{
    public function extendForm(Form $form): Form
    {
        return $form->schema(
            $this->replaceChargeByField(
                $this->replaceDriverField($form->getComponents())
            )
        );
    }

    /**
     * Extend the vendor's cart_total/weight charge_by Select with a third
     * "live" option — only offered when the currently selected driver
     * supports live pricing (see SupportsLivePricing). Picking it is what
     * tells the driver to call its carrier API instead of resolving a
     * price break.
     */
    private function replaceChargeByField(array $components): array
    {
        return array_map(function (Component $component) {
            if (method_exists($component, 'getName') && $component->getName() === 'charge_by') {
                return $this->chargeBySelect();
            }

            if (in_array(HasChildComponents::class, class_uses_recursive($component), true)) {
                $component->schema(
                    $this->replaceChargeByField($component->getChildComponents())
                );
            }

            return $component;
        }, $components);
    }

    private function chargeBySelect(): Select
    {
        return Select::make('charge_by')
            ->label('Charge by')
            ->options(function (Get $get) {
                $options = [
                    'cart_total' => 'Cart Total',
                    'weight' => 'Weight',
                ];

                // "charge_by" is nested inside a Group with
                // ->statePath('data'), while "driver" sits one level up, at
                // the form root. Note: an *absolute* path here would need to
                // additionally account for the page's own form wrapper
                // (EditRecord::getFormStatePath() === 'data'), which relative
                // paths never cross — so "../driver" (relative) is the
                // correct, page-independent way to reach it, not an
                // absolute 'driver' string.
                if ($this->driverSupportsLivePricing($get('../driver'))) {
                    $options['live'] = 'Live API pricing';
                }

                return $options;
            })
            ->live();
    }

    private function driverSupportsLivePricing(?string $driver): bool
    {
        if (! $driver) {
            return false;
        }

        try {
            return Shipping::driver($driver) instanceof SupportsLivePricing;
        } catch (\InvalidArgumentException) {
            return false;
        }
    }

    public function extendTable(Table $table): Table
    {
        return $table->columns(
            array_map(function ($column) {
                if (method_exists($column, 'getName') && $column->getName() === 'driver') {
                    return $this->driverColumn();
                }

                return $column;
            }, $table->getColumns())
        );
    }

    private function driverColumn(): TextColumn
    {
        return TextColumn::make('driver')
            ->label('Type')
            ->formatStateUsing(fn ($state) => $this->driverLabel($state));
    }

    private function driverLabel(string $key): string
    {
        $driver = collect(Shipping::getSupportedDrivers())->get($key);

        return $driver?->name() ?? $key;
    }

    /**
     * Recursively walk the form tree and replace the hardcoded driver
     * Select (nested inside Section > Group) with one listing every
     * registered driver, built-in or custom.
     *
     * @param  array<Component>  $components
     * @return array<Component>
     */
    private function replaceDriverField(array $components): array
    {
        return array_map(function (Component $component) {
            if (method_exists($component, 'getName') && $component->getName() === 'driver') {
                return $this->driverSelect();
            }

            if (in_array(HasChildComponents::class, class_uses_recursive($component), true)) {
                $component->schema(
                    $this->replaceDriverField($component->getChildComponents())
                );
            }

            return $component;
        }, $components);
    }

    private function driverSelect(): Select
    {
        return Select::make('driver')
            ->label('Type')
            ->options(fn () => collect(Shipping::getSupportedDrivers())
                ->mapWithKeys(fn ($driver, $key) => [$key => $driver->name()]))
            ->default('flat-rate')
            ->live();
    }
}