@php
    $skuId = $line['sku_id'] ?? $selected ?? null;
    $resolvedUnitId = $line['unit_id'] ?? null;
    $allowedUnitIds = null;
    if (! empty($skuId)) {
        foreach ($skus ?? [] as $sku) {
            if ((string) $sku->id === (string) $skuId) {
                $baseUnitId = (int) ($sku->variant?->item?->base_unit_id ?? 0);
                $allowedUnitIds = [$baseUnitId];
                if ($sku->relationLoaded('uomConversions')) {
                    foreach ($sku->uomConversions as $conversion) {
                        $allowedUnitIds[] = (int) $conversion->unit_id;
                    }
                }
                $allowedUnitIds = array_values(array_unique(array_filter($allowedUnitIds)));
                if ($resolvedUnitId === null) {
                    $resolvedUnitId = $baseUnitId ?: null;
                }
                break;
            }
        }
    }
@endphp

<select name="lines[{{ $index }}][unit_id]" data-line-unit @if (!empty($required)) required @endif>
    <option value="">— Select —</option>
    @foreach ($units ?? [] as $unit)
        @php
            $isAllowed = $allowedUnitIds === null || in_array((int) $unit->id, $allowedUnitIds, true);
        @endphp
        <option
            value="{{ $unit->id }}"
            @selected((string) $resolvedUnitId === (string) $unit->id)
            @disabled(! $isAllowed)
            @if (! $isAllowed) hidden @endif
        >{{ $unit->name }} ({{ $unit->symbol }})</option>
    @endforeach
</select>