buckets/app/Actions/CreateBucketAction.php

<?php

namespace App\Actions;

use App\Enums\BucketAllocationTypeEnum;
use App\Enums\BucketTypeEnum;
use App\Models\Bucket;
use App\Models\Scenario;
use Illuminate\Support\Facades\DB;
use InvalidArgumentException;

class CreateBucketAction
{
    public function execute(
        Scenario $scenario,
        string $name,
        BucketAllocationTypeEnum $allocationType,
        BucketTypeEnum $type = BucketTypeEnum::NEED,
        ?float $allocationValue = null,
        ?int $priority = null,
    ): Bucket {
        // Validate type + allocation type constraints
        $this->validateTypeConstraints($type, $allocationType);

        // Enforce one overflow bucket per scenario
        if ($type === BucketTypeEnum::OVERFLOW && $scenario->buckets()->where('type', BucketTypeEnum::OVERFLOW->value)->exists()) {
            throw new InvalidArgumentException('A scenario can only have one overflow bucket');
        }

        // Validate allocation value based on type
        $this->validateAllocationValue($allocationType, $allocationValue);

        // Set allocation_value to null for unlimited buckets
        if ($allocationType === BucketAllocationTypeEnum::UNLIMITED) {
            $allocationValue = null;
        }

        return DB::transaction(function () use ($scenario, $name, $allocationType, $allocationValue, $priority, $type) {
            // Determine priority (append to end if not specified)
            if ($priority === null) {
                $maxPriority = $scenario->buckets()->max('priority') ?? 0;
                $priority = $maxPriority + 1;
            } else {
                // Validate priority is positive
                if ($priority < 1) {
                    throw new InvalidArgumentException('Priority must be at least 1');
                }

                // Check if priority already exists and shift others if needed
                $existingBucket = $scenario->buckets()->where('priority', $priority)->first();
                if ($existingBucket) {
                    // Shift priorities in reverse order to avoid unique constraint violations
                    // (SQLite checks constraints per-row during bulk updates)
                    $scenario->buckets()
                        ->where('priority', '>=', $priority)
                        ->orderByDesc('priority')
                        ->each(function ($bucket) {
                            $bucket->increment('priority');
                        });
                }
            }

            // Create the bucket
            return $scenario->buckets()->create([
                'name' => $name,
                'type' => $type,
                'priority' => $priority,
                'sort_order' => $priority, // Start with sort_order matching priority
                'allocation_type' => $allocationType,
                'allocation_value' => $allocationValue,
            ]);
        });
    }

    /**
     * Validate that bucket type and allocation type are compatible.
     */
    private function validateTypeConstraints(BucketTypeEnum $type, BucketAllocationTypeEnum $allocationType): void
    {
        $allowedTypes = $type->getAllowedAllocationTypes();
        if (! in_array($allocationType, $allowedTypes, true)) {
            $allowed = implode(', ', array_map(fn ($t) => $t->value, $allowedTypes));
            throw new InvalidArgumentException("Invalid allocation type for {$type->value} bucket. Allowed: {$allowed}");
        }
    }

    /**
     * Validate allocation value based on allocation type.
     */
    private function validateAllocationValue(BucketAllocationTypeEnum $allocationType, ?float $allocationValue): void
    {
        switch ($allocationType) {
            case BucketAllocationTypeEnum::FIXED_LIMIT:
                if ($allocationValue === null) {
                    throw new InvalidArgumentException('Fixed limit buckets require an allocation value');
                }
                if ($allocationValue < 0) {
                    throw new InvalidArgumentException('Fixed limit allocation value must be non-negative');
                }
                break;

            case BucketAllocationTypeEnum::PERCENTAGE:
                if ($allocationValue === null) {
                    throw new InvalidArgumentException('Percentage buckets require an allocation value');
                }
                if ($allocationValue < 0.01 || $allocationValue > 100) {
                    throw new InvalidArgumentException('Percentage allocation value must be between 0.01 and 100');
                }
                break;

            case BucketAllocationTypeEnum::UNLIMITED:
                // Unlimited buckets should not have an allocation value
                // We'll set it to null in the main method regardless
                break;
        }
    }

    /**
     * Create default buckets for a scenario.
     */
    public function createDefaultBuckets(Scenario $scenario): array
    {
        $buckets = [];

        // Monthly Expenses - Need, fixed limit, priority 1
        $buckets[] = $this->execute(
            $scenario,
            'Monthly Expenses',
            BucketAllocationTypeEnum::FIXED_LIMIT,
            BucketTypeEnum::NEED,
            0,
            1
        );

        // Emergency Fund - Need, fixed limit, priority 2
        $buckets[] = $this->execute(
            $scenario,
            'Emergency Fund',
            BucketAllocationTypeEnum::FIXED_LIMIT,
            BucketTypeEnum::NEED,
            0,
            2
        );

        // Overflow - Overflow, unlimited, priority 3
        $buckets[] = $this->execute(
            $scenario,
            'Overflow',
            BucketAllocationTypeEnum::UNLIMITED,
            BucketTypeEnum::OVERFLOW,
            null,
            3
        );

        return $buckets;
    }
}