<?php

namespace App\Actions;

use App\Models\Bucket;
use App\Models\Scenario;
use App\Services\Projection\PipelineAllocationService;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;

class ApplyDistributionAction
{
    public function __construct(
        private readonly PipelineAllocationService $pipelineAllocationService,
    ) {}

    /**
     * Apply an income distribution to bucket balances.
     *
     * Re-runs the allocation algorithm server-side and updates each bucket's
     * starting_amount by adding the allocated amount.
     *
     * @return array{allocations: Collection<int, array{bucket_id: string, bucket_name: string, bucket_type: string, allocated_amount: int}>, total_allocated: int, unallocated: int}
     */
    public function execute(Scenario $scenario, int $amount): array
    {
        $draws = $this->pipelineAllocationService->allocateInflow($scenario, $amount);

        /** @var array<int, Bucket> $bucketLookup */
        $bucketLookup = $scenario->buckets->keyBy('id')->all();

        DB::transaction(function () use ($draws, $bucketLookup) {
            foreach ($draws as $draw) {
                $bucket = $bucketLookup[$draw->bucket_id];
                $bucket->increment('starting_amount', (int) $draw->amount);
            }
        });

        $allocations = $draws->map(function ($draw) use ($bucketLookup) {
            $bucket = $bucketLookup[$draw->bucket_id];

            return [
                'bucket_id' => $bucket->uuid,
                'bucket_name' => $bucket->name,
                'bucket_type' => $bucket->type->value,
                'allocated_amount' => (int) $draw->amount,
            ];
        })->values();

        /** @var int $totalAllocated */
        $totalAllocated = $draws->sum('amount');

        return [
            'allocations' => $allocations,
            'total_allocated' => $totalAllocated,
            'unallocated' => $amount - $totalAllocated,
        ];
    }
}