<?php

namespace App\Services;

use App\Models\Audit\AuditLog;
use App\Models\Items\Item;
use Illuminate\Pagination\LengthAwarePaginator;
use Illuminate\Support\Facades\DB;

class ItemManagementService
{
    /**
     * 품목 목록 조회 (검색, 유형 필터, 페이지네이션)
     */
    public function getItemList(array $filters): LengthAwarePaginator
    {
        $tenantId = session('selected_tenant_id');
        $search = $filters['search'] ?? null;
        $itemType = $filters['item_type'] ?? null;
        $perPage = $filters['per_page'] ?? 50;

        return Item::withoutGlobalScopes()
            ->where('tenant_id', $tenantId)
            ->search($search)
            ->active()
            ->when($itemType, function ($query, $types) {
                $typeList = explode(',', $types);
                $query->whereIn('item_type', $typeList);
            })
            ->orderBy('code')
            ->paginate($perPage);
    }

    /**
     * BOM 재귀 트리 조회
     */
    public function getBomTree(int $itemId, int $maxDepth = 10): array
    {
        $item = Item::withoutGlobalScopes()
            ->where('tenant_id', session('selected_tenant_id'))
            ->with('details')
            ->findOrFail($itemId);

        return $this->buildBomNode($item, 0, $maxDepth, []);
    }

    /**
     * 품목 상세 조회 (1depth BOM + 파일 + 절곡정보)
     */
    public function getItemDetail(int $itemId): array
    {
        $tenantId = session('selected_tenant_id');

        $item = Item::withoutGlobalScopes()
            ->where('tenant_id', $tenantId)
            ->with(['details', 'category', 'files'])
            ->findOrFail($itemId);

        // BOM 1depth: 직접 연결된 자식 품목만
        $bomChildren = [];
        $bomData = $item->bom ?? [];
        if (! empty($bomData)) {
            $childIds = array_column($bomData, 'child_item_id');
            $children = Item::withoutGlobalScopes()
                ->where('tenant_id', $tenantId)
                ->whereIn('id', $childIds)
                ->get(['id', 'code', 'name', 'item_type', 'unit'])
                ->keyBy('id');

            foreach ($bomData as $bom) {
                $child = $children->get($bom['child_item_id']);
                if ($child) {
                    $bomChildren[] = [
                        'id' => $child->id,
                        'code' => $child->code,
                        'name' => $child->name,
                        'item_type' => $child->item_type,
                        'unit' => $child->unit,
                        'quantity' => $bom['quantity'] ?? 1,
                    ];
                }
            }
        }

        return [
            'item' => $item,
            'bom_children' => $bomChildren,
        ];
    }

    /**
     * 품목 사용 현황 조회 (삭제 전 참조 체크)
     */
    public function checkItemUsage(int $itemId): array
    {
        $tenantId = session('selected_tenant_id');
        $usage = [];

        // 다른 품목의 BOM에 포함되어 있는지 (JSON 검색)
        $bomParents = Item::withoutGlobalScopes()
            ->where('tenant_id', $tenantId)
            ->whereRaw("JSON_CONTAINS(bom, JSON_OBJECT('child_item_id', ?))", [$itemId])
            ->count();
        if ($bomParents > 0) {
            $usage[] = "다른 품목의 BOM 구성품 ({$bomParents}건)";
        }

        // 주문 항목
        $orderItems = DB::table('order_items')->where('item_id', $itemId)->count();
        if ($orderItems > 0) {
            $usage[] = "수주 항목 ({$orderItems}건)";
        }

        // 견적
        $quotes = DB::table('quotes')->where('item_id', $itemId)->count();
        if ($quotes > 0) {
            $usage[] = "견적 ({$quotes}건)";
        }

        // 자재 입고
        $receipts = DB::table('material_receipts')->where('item_id', $itemId)->count();
        if ($receipts > 0) {
            $usage[] = "자재 입고 ({$receipts}건)";
        }

        // LOT
        $lots = DB::table('lots')->where('item_id', $itemId)->count();
        if ($lots > 0) {
            $usage[] = "LOT ({$lots}건)";
        }

        // 작업지시
        $workOrders = DB::table('work_order_items')->where('item_id', $itemId)->count();
        if ($workOrders > 0) {
            $usage[] = "작업지시 ({$workOrders}건)";
        }

        return $usage;
    }

    /**
     * 품목 삭제 (Soft Delete)
     */
    public function deleteItem(int $itemId): array
    {
        $tenantId = session('selected_tenant_id');

        $item = Item::withoutGlobalScopes()
            ->where('tenant_id', $tenantId)
            ->findOrFail($itemId);

        // 사용 현황 체크
        $usage = $this->checkItemUsage($itemId);
        if (! empty($usage)) {
            return [
                'success' => false,
                'error' => '사용 중인 품목은 삭제할 수 없습니다.',
                'usage' => $usage,
            ];
        }

        $item->deleted_by = auth()->id();
        $item->save();
        $item->delete();

        return ['success' => true, 'message' => "품목 '{$item->name}'이(가) 삭제되었습니다."];
    }

    /**
     * 품목 이력 조회 (audit_logs + 생성/수정 정보)
     */
    public function getItemHistory(int $itemId): array
    {
        $tenantId = session('selected_tenant_id');

        $item = Item::withoutGlobalScopes()
            ->where('tenant_id', $tenantId)
            ->findOrFail($itemId);

        // audit_logs에서 해당 품목 이력
        $auditLogs = AuditLog::where('tenant_id', $tenantId)
            ->where('target_type', 'item')
            ->where('target_id', $itemId)
            ->orderByDesc('created_at')
            ->limit(50)
            ->get();

        // 사용자 ID → 이름 매핑
        $actorIds = $auditLogs->pluck('actor_id')->filter()->unique()->values();
        $actors = [];
        if ($actorIds->isNotEmpty()) {
            $actors = DB::table('users')
                ->whereIn('id', $actorIds)
                ->pluck('name', 'id')
                ->toArray();
        }

        $logs = $auditLogs->map(function ($log) use ($actors) {
            return [
                'id' => $log->id,
                'action' => $log->action,
                'action_label' => $this->getActionLabel($log->action),
                'actor' => $actors[$log->actor_id] ?? '시스템',
                'created_at' => $log->created_at->format('Y-m-d H:i:s'),
                'before' => $log->before,
                'after' => $log->after,
            ];
        });

        return [
            'item' => [
                'id' => $item->id,
                'code' => $item->code,
                'name' => $item->name,
                'created_at' => $item->created_at?->format('Y-m-d H:i:s'),
                'updated_at' => $item->updated_at?->format('Y-m-d H:i:s'),
            ],
            'logs' => $logs,
        ];
    }

    private function getActionLabel(string $action): string
    {
        return match ($action) {
            'created' => '생성',
            'updated' => '수정',
            'deleted' => '삭제',
            'restored' => '복원',
            'bom_updated' => 'BOM 변경',
            'stock_increase' => '재고 증가',
            'stock_decrease' => '재고 차감',
            default => $action,
        };
    }

    // ── Private ──

    private function buildBomNode(Item $item, int $depth, int $maxDepth, array $visited): array
    {
        // 순환 참조 방지: visited 배열 + maxDepth 이중 안전장치
        if (in_array($item->id, $visited) || $depth >= $maxDepth) {
            return $this->formatNode($item, $depth, []);
        }

        $visited[] = $item->id;
        $children = [];

        $bomData = $item->bom ?? [];
        if (! empty($bomData)) {
            $childIds = array_column($bomData, 'child_item_id');
            $childItems = Item::withoutGlobalScopes()
                ->where('tenant_id', session('selected_tenant_id'))
                ->whereIn('id', $childIds)
                ->get()
                ->keyBy('id');

            foreach ($bomData as $bom) {
                $childItem = $childItems->get($bom['child_item_id']);
                if ($childItem) {
                    $childNode = $this->buildBomNode($childItem, $depth + 1, $maxDepth, $visited);
                    $childNode['quantity'] = $bom['quantity'] ?? 1;
                    $children[] = $childNode;
                }
            }
        }

        return $this->formatNode($item, $depth, $children);
    }

    private function formatNode(Item $item, int $depth, array $children): array
    {
        return [
            'id' => $item->id,
            'code' => $item->code,
            'name' => $item->name,
            'item_type' => $item->item_type,
            'unit' => $item->unit,
            'depth' => $depth,
            'has_children' => count($children) > 0,
            'children' => $children,
        ];
    }
}