<?php

namespace App\Services;

use App\Models\Tenants\Purchase;
use Illuminate\Contracts\Pagination\LengthAwarePaginator;
use Illuminate\Support\Facades\DB;

class PurchaseService extends Service
{
    /**
     * 매입 목록 조회
     */
    public function index(array $params): LengthAwarePaginator
    {
        $tenantId = $this->tenantId();

        $query = Purchase::query()
            ->where('tenant_id', $tenantId)
            ->with(['client:id,name']);

        // 검색어 필터
        if (! empty($params['search'])) {
            $search = $params['search'];
            $query->where(function ($q) use ($search) {
                $q->where('purchase_number', 'like', "%{$search}%")
                    ->orWhere('description', 'like', "%{$search}%")
                    ->orWhereHas('client', function ($q) use ($search) {
                        $q->where('name', 'like', "%{$search}%");
                    });
            });
        }

        // 날짜 범위 필터
        if (! empty($params['start_date'])) {
            $query->where('purchase_date', '>=', $params['start_date']);
        }
        if (! empty($params['end_date'])) {
            $query->where('purchase_date', '<=', $params['end_date']);
        }

        // 거래처 필터
        if (! empty($params['client_id'])) {
            $query->where('client_id', $params['client_id']);
        }

        // 상태 필터
        if (! empty($params['status'])) {
            $query->where('status', $params['status']);
        }

        // 정렬
        $sortBy = $params['sort_by'] ?? 'purchase_date';
        $sortDir = $params['sort_dir'] ?? 'desc';
        $query->orderBy($sortBy, $sortDir);

        // 페이지네이션
        $perPage = $params['per_page'] ?? 20;

        return $query->paginate($perPage);
    }

    /**
     * 매입 상세 조회
     */
    public function show(int $id): Purchase
    {
        $tenantId = $this->tenantId();

        return Purchase::query()
            ->where('tenant_id', $tenantId)
            ->with(['client:id,name', 'withdrawal', 'creator:id,name'])
            ->findOrFail($id);
    }

    /**
     * 매입 등록
     */
    public function store(array $data): Purchase
    {
        $tenantId = $this->tenantId();
        $userId = $this->apiUserId();

        return DB::transaction(function () use ($data, $tenantId, $userId) {
            // 매입번호 자동 생성
            $purchaseNumber = $this->generatePurchaseNumber($tenantId, $data['purchase_date']);

            $purchase = new Purchase;
            $purchase->tenant_id = $tenantId;
            $purchase->purchase_number = $purchaseNumber;
            $purchase->purchase_date = $data['purchase_date'];
            $purchase->client_id = $data['client_id'];
            $purchase->supply_amount = $data['supply_amount'];
            $purchase->tax_amount = $data['tax_amount'];
            $purchase->total_amount = $data['total_amount'];
            $purchase->description = $data['description'] ?? null;
            $purchase->status = 'draft';
            $purchase->withdrawal_id = $data['withdrawal_id'] ?? null;
            $purchase->created_by = $userId;
            $purchase->updated_by = $userId;
            $purchase->save();

            return $purchase->load(['client:id,name']);
        });
    }

    /**
     * 매입 수정
     */
    public function update(int $id, array $data): Purchase
    {
        $tenantId = $this->tenantId();
        $userId = $this->apiUserId();

        return DB::transaction(function () use ($id, $data, $tenantId, $userId) {
            $purchase = Purchase::query()
                ->where('tenant_id', $tenantId)
                ->findOrFail($id);

            // 확정 후에는 수정 불가
            if (! $purchase->canEdit()) {
                throw new \Exception(__('error.purchase.cannot_edit'));
            }

            if (isset($data['purchase_date'])) {
                $purchase->purchase_date = $data['purchase_date'];
            }
            if (isset($data['client_id'])) {
                $purchase->client_id = $data['client_id'];
            }
            if (isset($data['supply_amount'])) {
                $purchase->supply_amount = $data['supply_amount'];
            }
            if (isset($data['tax_amount'])) {
                $purchase->tax_amount = $data['tax_amount'];
            }
            if (isset($data['total_amount'])) {
                $purchase->total_amount = $data['total_amount'];
            }
            if (array_key_exists('description', $data)) {
                $purchase->description = $data['description'];
            }
            if (array_key_exists('withdrawal_id', $data)) {
                $purchase->withdrawal_id = $data['withdrawal_id'];
            }

            $purchase->updated_by = $userId;
            $purchase->save();

            return $purchase->fresh(['client:id,name']);
        });
    }

    /**
     * 매입 삭제
     */
    public function destroy(int $id): bool
    {
        $tenantId = $this->tenantId();
        $userId = $this->apiUserId();

        return DB::transaction(function () use ($id, $tenantId, $userId) {
            $purchase = Purchase::query()
                ->where('tenant_id', $tenantId)
                ->findOrFail($id);

            // 확정 후에는 삭제 불가
            if (! $purchase->canDelete()) {
                throw new \Exception(__('error.purchase.cannot_delete'));
            }

            $purchase->deleted_by = $userId;
            $purchase->save();
            $purchase->delete();

            return true;
        });
    }

    /**
     * 매입 확정
     */
    public function confirm(int $id): Purchase
    {
        $tenantId = $this->tenantId();
        $userId = $this->apiUserId();

        return DB::transaction(function () use ($id, $tenantId, $userId) {
            $purchase = Purchase::query()
                ->where('tenant_id', $tenantId)
                ->findOrFail($id);

            if (! $purchase->canConfirm()) {
                throw new \Exception(__('error.purchase.cannot_confirm'));
            }

            $purchase->status = 'confirmed';
            $purchase->updated_by = $userId;
            $purchase->save();

            return $purchase->fresh(['client:id,name']);
        });
    }

    /**
     * 매입 요약 (기간별 합계)
     */
    public function summary(array $params): array
    {
        $tenantId = $this->tenantId();

        $query = Purchase::query()
            ->where('tenant_id', $tenantId);

        // 날짜 범위 필터
        if (! empty($params['start_date'])) {
            $query->where('purchase_date', '>=', $params['start_date']);
        }
        if (! empty($params['end_date'])) {
            $query->where('purchase_date', '<=', $params['end_date']);
        }

        // 거래처 필터
        if (! empty($params['client_id'])) {
            $query->where('client_id', $params['client_id']);
        }

        // 상태 필터
        if (! empty($params['status'])) {
            $query->where('status', $params['status']);
        }

        // 전체 합계
        $totalSupply = (clone $query)->sum('supply_amount');
        $totalTax = (clone $query)->sum('tax_amount');
        $totalAmount = (clone $query)->sum('total_amount');
        $count = (clone $query)->count();

        // 상태별 합계
        $byStatus = (clone $query)
            ->select('status', DB::raw('SUM(total_amount) as total'), DB::raw('COUNT(*) as count'))
            ->groupBy('status')
            ->get()
            ->keyBy('status')
            ->toArray();

        return [
            'total_supply_amount' => (float) $totalSupply,
            'total_tax_amount' => (float) $totalTax,
            'total_amount' => (float) $totalAmount,
            'total_count' => $count,
            'by_status' => $byStatus,
        ];
    }

    /**
     * 매입번호 자동 생성
     */
    private function generatePurchaseNumber(int $tenantId, string $purchaseDate): string
    {
        $prefix = 'PU'.date('Ymd', strtotime($purchaseDate));

        $lastPurchase = Purchase::query()
            ->where('tenant_id', $tenantId)
            ->where('purchase_number', 'like', $prefix.'%')
            ->orderBy('purchase_number', 'desc')
            ->first();

        if ($lastPurchase) {
            $lastSeq = (int) substr($lastPurchase->purchase_number, -4);
            $newSeq = $lastSeq + 1;
        } else {
            $newSeq = 1;
        }

        return $prefix.str_pad($newSeq, 4, '0', STR_PAD_LEFT);
    }
}