<?php

namespace App\Services;

use App\Models\Orders\Client;
use App\Models\Tenants\Bill;
use App\Models\Tenants\Deposit;
use App\Models\Tenants\Sale;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;

/**
 * 채권 현황 서비스
 * 거래처별 월별 매출, 입금, 어음, 미수금 현황 조회
 */
class ReceivablesService extends Service
{
    /**
     * 채권 현황 목록 조회
     */
    public function index(array $params): array
    {
        $tenantId = $this->tenantId();
        $year = $params['year'] ?? date('Y');
        $search = $params['search'] ?? null;

        // 거래처 목록 조회
        $clientsQuery = Client::where('tenant_id', $tenantId)
            ->where('is_active', true);

        if ($search) {
            $clientsQuery->where('name', 'like', "%{$search}%");
        }

        $clients = $clientsQuery->orderBy('name')->get();

        $result = [];

        foreach ($clients as $client) {
            // 월별 데이터 수집
            $salesByMonth = $this->getSalesByMonth($tenantId, $client->id, $year);
            $depositsByMonth = $this->getDepositsByMonth($tenantId, $client->id, $year);
            $billsByMonth = $this->getBillsByMonth($tenantId, $client->id, $year);

            // 미수금 계산 (매출 - 입금 - 어음)
            $receivablesByMonth = $this->calculateReceivables($salesByMonth, $depositsByMonth, $billsByMonth);

            // 카테고리별 데이터 생성
            $categories = [
                [
                    'category' => 'sales',
                    'amounts' => $this->formatMonthlyAmounts($salesByMonth),
                ],
                [
                    'category' => 'deposit',
                    'amounts' => $this->formatMonthlyAmounts($depositsByMonth),
                ],
                [
                    'category' => 'bill',
                    'amounts' => $this->formatMonthlyAmounts($billsByMonth),
                ],
                [
                    'category' => 'receivable',
                    'amounts' => $this->formatMonthlyAmounts($receivablesByMonth),
                ],
                [
                    'category' => 'memo',
                    'amounts' => $this->getEmptyMonthlyAmounts(),
                ],
            ];

            // 미수금이 있는 월 확인 (연체 표시용)
            $overdueMonths = [];
            foreach ($receivablesByMonth as $month => $amount) {
                if ($amount > 0) {
                    $overdueMonths[] = $month;
                }
            }

            $result[] = [
                'id' => (string) $client->id,
                'vendor_id' => $client->id,
                'vendor_name' => $client->name,
                'is_overdue' => count($overdueMonths) > 0,
                'overdue_months' => $overdueMonths,
                'categories' => $categories,
            ];
        }

        // 미수금이 있는 거래처만 필터링 (선택적)
        if (! empty($params['has_receivable'])) {
            $result = array_filter($result, function ($item) {
                $receivableCat = collect($item['categories'])->firstWhere('category', 'receivable');

                return $receivableCat && $receivableCat['amounts']['total'] > 0;
            });
            $result = array_values($result);
        }

        return $result;
    }

    /**
     * 요약 통계 조회
     */
    public function summary(array $params): array
    {
        $tenantId = $this->tenantId();
        $year = $params['year'] ?? date('Y');

        $startDate = "{$year}-01-01";
        $endDate = "{$year}-12-31";

        // 총 매출
        $totalSales = Sale::where('tenant_id', $tenantId)
            ->whereNotNull('client_id')
            ->whereBetween('sale_date', [$startDate, $endDate])
            ->sum('total_amount');

        // 총 입금
        $totalDeposits = Deposit::where('tenant_id', $tenantId)
            ->whereNotNull('client_id')
            ->whereBetween('deposit_date', [$startDate, $endDate])
            ->sum('amount');

        // 총 어음
        $totalBills = Bill::where('tenant_id', $tenantId)
            ->whereNotNull('client_id')
            ->where('bill_type', 'received')
            ->whereBetween('issue_date', [$startDate, $endDate])
            ->sum('amount');

        // 총 미수금
        $totalReceivables = $totalSales - $totalDeposits - $totalBills;
        if ($totalReceivables < 0) {
            $totalReceivables = 0;
        }

        // 거래처 수
        $vendorCount = Client::where('tenant_id', $tenantId)
            ->where('is_active', true)
            ->whereHas('orders')
            ->count();

        // 연체 거래처 수 (미수금이 있는 거래처)
        $overdueVendorCount = DB::table('sales')
            ->where('tenant_id', $tenantId)
            ->whereNotNull('client_id')
            ->whereBetween('sale_date', [$startDate, $endDate])
            ->select('client_id')
            ->groupBy('client_id')
            ->havingRaw('SUM(total_amount) > (
                SELECT COALESCE(SUM(d.amount), 0) FROM deposits d
                WHERE d.tenant_id = ? AND d.client_id = sales.client_id
                AND d.deposit_date BETWEEN ? AND ?
            ) + (
                SELECT COALESCE(SUM(b.amount), 0) FROM bills b
                WHERE b.tenant_id = ? AND b.client_id = sales.client_id
                AND b.bill_type = "received"
                AND b.issue_date BETWEEN ? AND ?
            )', [$tenantId, $startDate, $endDate, $tenantId, $startDate, $endDate])
            ->count();

        return [
            'total_sales' => (float) $totalSales,
            'total_deposits' => (float) $totalDeposits,
            'total_bills' => (float) $totalBills,
            'total_receivables' => (float) $totalReceivables,
            'vendor_count' => $vendorCount,
            'overdue_vendor_count' => $overdueVendorCount,
        ];
    }

    /**
     * 월별 매출 조회
     */
    private function getSalesByMonth(int $tenantId, int $clientId, string $year): array
    {
        $result = [];

        $sales = Sale::where('tenant_id', $tenantId)
            ->where('client_id', $clientId)
            ->whereYear('sale_date', $year)
            ->select(
                DB::raw('MONTH(sale_date) as month'),
                DB::raw('SUM(total_amount) as total')
            )
            ->groupBy(DB::raw('MONTH(sale_date)'))
            ->get();

        foreach ($sales as $sale) {
            $result[(int) $sale->month] = (float) $sale->total;
        }

        return $result;
    }

    /**
     * 월별 입금 조회
     */
    private function getDepositsByMonth(int $tenantId, int $clientId, string $year): array
    {
        $result = [];

        $deposits = Deposit::where('tenant_id', $tenantId)
            ->where('client_id', $clientId)
            ->whereYear('deposit_date', $year)
            ->select(
                DB::raw('MONTH(deposit_date) as month'),
                DB::raw('SUM(amount) as total')
            )
            ->groupBy(DB::raw('MONTH(deposit_date)'))
            ->get();

        foreach ($deposits as $deposit) {
            $result[(int) $deposit->month] = (float) $deposit->total;
        }

        return $result;
    }

    /**
     * 월별 어음 조회
     */
    private function getBillsByMonth(int $tenantId, int $clientId, string $year): array
    {
        $result = [];

        $bills = Bill::where('tenant_id', $tenantId)
            ->where('client_id', $clientId)
            ->where('bill_type', 'received')
            ->whereYear('issue_date', $year)
            ->select(
                DB::raw('MONTH(issue_date) as month'),
                DB::raw('SUM(amount) as total')
            )
            ->groupBy(DB::raw('MONTH(issue_date)'))
            ->get();

        foreach ($bills as $bill) {
            $result[(int) $bill->month] = (float) $bill->total;
        }

        return $result;
    }

    /**
     * 미수금 계산
     */
    private function calculateReceivables(array $sales, array $deposits, array $bills): array
    {
        $result = [];

        for ($month = 1; $month <= 12; $month++) {
            $salesAmount = $sales[$month] ?? 0;
            $depositAmount = $deposits[$month] ?? 0;
            $billAmount = $bills[$month] ?? 0;

            $receivable = $salesAmount - $depositAmount - $billAmount;
            $result[$month] = max(0, $receivable);
        }

        return $result;
    }

    /**
     * 월별 금액을 프론트엔드 형식으로 변환
     */
    private function formatMonthlyAmounts(array $monthlyData): array
    {
        $amounts = [];
        $total = 0;

        for ($month = 1; $month <= 12; $month++) {
            $key = "month{$month}";
            $amount = $monthlyData[$month] ?? 0;
            $amounts[$key] = $amount;
            $total += $amount;
        }

        $amounts['total'] = $total;

        return $amounts;
    }

    /**
     * 빈 월별 금액 데이터
     */
    private function getEmptyMonthlyAmounts(): array
    {
        $amounts = [];

        for ($month = 1; $month <= 12; $month++) {
            $amounts["month{$month}"] = 0;
        }

        $amounts['total'] = 0;

        return $amounts;
    }
}