<?php

declare(strict_types=1);

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\BalanceTransaction;
use App\Models\Tenant;
use App\Models\User;
use App\Services\Billing\BillingTopupService;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;

/**
 * Биллинг тенанта — кошелёк, транзакции, счета, пополнение (audit E1/E3).
 *
 * Все эндпоинты под middleware [auth:sanctum, tenant] (RLS-контекст).
 * Отдельно от TenantChargesController (lead_charges ledger) и
 * AdminBillingController (SaaS-уровневые агрегаты).
 *
 * E1: POST /api/billing/topup — MVP-stub пополнения (без платёжного шлюза).
 * E3: GET wallet/transactions/invoices — данные для BillingView Overview.
 */
class BillingController extends Controller
{
    public function __construct(
        private readonly BillingTopupService $topupService,
    ) {}

    /**
     * POST /api/billing/topup — пополнить рублёвый баланс.
     *
     * MVP-stub: кредитует баланс немедленно (без ЮKassa — реальная оплата
     * post-Б-1). Записывает append-only строку balance_transactions(topup).
     */
    public function topup(Request $request): JsonResponse
    {
        $validated = $request->validate([
            'amount_rub' => ['required', 'numeric', 'min:100', 'max:1000000', 'decimal:0,2'],
        ]);

        /** @var User $user */
        $user = $request->user();

        // Нормализуем в DECIMAL-строку scale 2 для bcmath (НЕ float).
        $amountRub = bcadd((string) $validated['amount_rub'], '0', 2);

        $tx = $this->topupService->topup((int) $user->tenant_id, $amountRub, (int) $user->id);

        return response()->json([
            'transaction' => [
                'id' => $tx->id,
                'type' => $tx->type,
                'amount_rub' => $tx->amount_rub,
                'balance_rub_after' => $tx->balance_rub_after,
                'created_at' => $tx->created_at,
            ],
            'balance_rub' => $tx->balance_rub_after,
        ], 201);
    }

    /**
     * GET /api/billing/wallet — балансы тенанта + текущий тариф + runway.
     */
    public function wallet(Request $request): JsonResponse
    {
        /** @var User $user */
        $user = $request->user();
        /** @var Tenant $tenant */
        $tenant = Tenant::query()->with('tariff')->findOrFail((int) $user->tenant_id);

        return response()->json([
            'balance_rub' => $tenant->balance_rub,
            'balance_leads' => $tenant->balance_leads,
            'runway_days' => $this->runwayDays($tenant),
            'tariff' => $tenant->tariff === null ? null : [
                'code' => $tenant->tariff->code,
                'name' => $tenant->tariff->name,
                'price_monthly' => $tenant->tariff->price_monthly,
                'billing_model' => $tenant->tariff->billing_model,
                'features' => $tenant->tariff->features ?? [],
            ],
        ]);
    }

    /**
     * GET /api/billing/transactions?type=topup|lead_charge|refund&page=N
     * — пагинированная история balance_transactions тенанта (20/страница).
     */
    public function transactions(Request $request): JsonResponse
    {
        /** @var User $user */
        $user = $request->user();
        $tenantId = (int) $user->tenant_id;

        // Явный tenant_id фильтр — defense-in-depth поверх RLS (тесты идут
        // под superuser BYPASSRLS; паттерн TenantChargesController).
        $query = BalanceTransaction::query()
            ->where('tenant_id', $tenantId)
            ->orderBy('created_at', 'desc')
            ->orderBy('id', 'desc');

        $type = $request->query('type');
        if (is_string($type) && in_array($type, ['topup', 'lead_charge', 'refund'], true)) {
            $query->where('type', $type);
        }

        $page = $query->paginate(20);

        return response()->json([
            'data' => array_map(static fn (BalanceTransaction $tx): array => [
                'id' => $tx->id,
                'code' => 'TX-'.$tx->id,
                'type' => $tx->type,
                'description' => $tx->description,
                'amount_rub' => $tx->amount_rub,
                'amount_leads' => $tx->amount_leads,
                'balance_rub_after' => $tx->balance_rub_after,
                'created_at' => $tx->created_at,
            ], $page->items()),
            'meta' => [
                'current_page' => $page->currentPage(),
                'last_page' => $page->lastPage(),
                'total' => $page->total(),
                'per_page' => $page->perPage(),
            ],
        ]);
    }

    /**
     * GET /api/billing/invoices — счета тенанта (saas_invoices).
     *
     * Real-but-empty на MVP: saas_invoices.legal_entity_id NOT NULL требует
     * зарегистрированного юр-лица (блокируется Б-1). Read-only выборка через
     * DB::table — без Eloquent-модели (паттерн AdminBillingController).
     */
    public function invoices(Request $request): JsonResponse
    {
        /** @var User $user */
        $user = $request->user();
        $tenantId = (int) $user->tenant_id;

        $rows = DB::table('saas_invoices')
            ->where('tenant_id', $tenantId)
            ->orderBy('issued_at', 'desc')
            ->get(['id', 'invoice_number', 'amount_total', 'status', 'issued_at', 'pdf_path']);

        return response()->json([
            'data' => $rows->map(static fn (\stdClass $r): array => [
                'id' => $r->id,
                'invoice_number' => $r->invoice_number,
                'amount_total' => $r->amount_total,
                'status' => $r->status,
                'issued_at' => $r->issued_at,
                'has_pdf' => $r->pdf_path !== null,
            ])->all(),
        ]);
    }

    /**
     * Прогноз «на сколько дней хватит баланса» — оценочный UX-показатель.
     *
     * = balance_rub / (рублёвые списания за 30 дней / 30). NULL, если списаний
     * не было. Float здесь допустим: грубая оценка для шапки, НЕ мутация
     * баланса (мутации баланса — строго bcmath, см. BillingTopupService).
     * Отрицательный баланс → 0 (тенант уже в минусе, runway не может быть < 0).
     */
    private function runwayDays(Tenant $tenant): ?int
    {
        $spent = abs((float) DB::table('balance_transactions')
            ->where('tenant_id', $tenant->id)
            ->where('type', BalanceTransaction::TYPE_LEAD_CHARGE)
            ->where('created_at', '>=', now()->subDays(30))
            ->sum('amount_rub'));

        if ($spent <= 0.0) {
            return null;
        }

        $perDay = $spent / 30.0;

        return max(0, (int) floor((float) $tenant->balance_rub / $perDay));
    }
}