<?php
namespace App\Services;
use App\Models\{AuditEvent, DemoOrder, Product, Quote, User};
use Illuminate\Database\QueryException;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;

final class QuoteWorkflow
{
    public function quote(User $actor, array $items, string $key): array {
        usort($items, fn ($a, $b) => strcmp($a['sku'], $b['sku']));
        $hash = hash('sha256', json_encode($items, JSON_THROW_ON_ERROR));
        try {
            return DB::transaction(function () use ($actor, $items, $key, $hash) {
                if ($existing = Quote::where('dealer_id', $actor->dealer_id)->where('request_key', $key)->first()) return [$this->sameRequest($existing, $hash), false];
                $lines = []; $subtotal = 0;
                foreach ($items as $item) {
                    $product = Product::whereKey($item['sku'])->where('active', true)->first();
                    if (!$product || $product->stock < $item['quantity']) throw ValidationException::withMessages(['items' => 'Requested quantity is unavailable.']);
                    $lines[] = ['sku' => $product->sku, 'quantity' => $item['quantity'], 'unit_price_cents' => $product->price_cents];
                    $subtotal += $product->price_cents * $item['quantity'];
                }
                $quote = Quote::create(['dealer_id' => $actor->dealer_id, 'user_id' => $actor->id, 'status' => 'pending', 'subtotal_cents' => $subtotal, 'request_key' => $key, 'request_hash' => $hash, 'expires_at' => now()->addDay()]);
                $quote->lines()->createMany($lines);
                $this->audit($actor, 'quote_requested', $quote->id);
                return [$quote, true];
            }, 3);
        } catch (QueryException $error) {
            // A parallel identical insert may have won the unique key race.
            if (in_array((string) $error->getCode(), ['23000', '23505']) && ($existing = Quote::where('dealer_id', $actor->dealer_id)->where('request_key', $key)->first())) return [$this->sameRequest($existing, $hash), false];
            throw $error;
        }
    }
    private function sameRequest(Quote $quote, string $hash): Quote {
        abort_unless(hash_equals($quote->request_hash, $hash), 409, 'Idempotency key was already used for a different request.');
        return $quote;
    }
    public function approve(User $actor, Quote $quote): Quote {
        return DB::transaction(function () use ($actor, $quote) {
            $locked = Quote::whereKey($quote->id)->lockForUpdate()->firstOrFail();
            abort_if($locked->expires_at->isPast(), 409, 'Quote expired. Request a fresh quote.');
            if ($locked->status === 'approved') return $locked;
            abort_unless($locked->status === 'pending', 409, 'Quote is no longer pending.');
            $locked->update(['status' => 'approved']);
            $this->audit($actor, 'quote_approved', $locked->id);
            return $locked;
        }, 3);
    }
    public function order(User $actor, Quote $quote, string $key): array {
        return DB::transaction(function () use ($actor, $quote, $key) {
            $locked = Quote::whereKey($quote->id)->lockForUpdate()->firstOrFail();
            if ($existing = DemoOrder::where('dealer_id', $actor->dealer_id)->where('request_key', $key)->first()) {
                abort_unless($existing->quote_id === $locked->id, 409, 'Idempotency key was already used for another quote.');
                return [$existing, false];
            }
            abort_unless($locked->status === 'approved', 409, 'An approved quote is required.');
            abort_if($locked->expires_at->isPast(), 409, 'Quote expired. Request a fresh quote.');
            foreach ($locked->lines()->orderBy('sku')->get() as $line) {
                $product = Product::whereKey($line->sku)->lockForUpdate()->firstOrFail();
                abort_unless($product->active && $product->stock >= $line->quantity, 409, 'Stock changed. Request a fresh quote.');
                $product->decrement('stock', $line->quantity);
            }
            $order = DemoOrder::create(['quote_id' => $locked->id, 'dealer_id' => $actor->dealer_id, 'total_cents' => $locked->subtotal_cents, 'request_key' => $key, 'status' => 'synthetic_accepted']);
            $locked->update(['status' => 'converted']);
            $this->audit($actor, 'synthetic_order_accepted', $order->id);
            return [$order, true];
        }, 3);
    }
    private function audit(User $actor, string $event, string $entity): void {
        AuditEvent::create(['dealer_id' => $actor->dealer_id, 'actor_id' => $actor->id, 'event_code' => $event, 'entity_id' => $entity, 'occurred_at' => now()]);
    }
}