<?php

namespace App\Http\Controllers;

use App\Models\PurchaseOrder;
use App\Models\Vendor;
use App\Models\Warehouse;
use Illuminate\Http\Request;
use Inertia\Inertia;
use Illuminate\Support\Facades\DB;

class PurchaseOrderController extends Controller
{
    public function index(Request $request)
    {
        $query = PurchaseOrder::with(['vendor', 'warehouse', 'user']);

        // Search
        if ($request->search) {
            $query->where(function($q) use ($request) {
                $q->where('code', 'like', "%{$request->search}%")
                  ->orWhereHas('vendor', function($vq) use ($request) {
                      $vq->where('name', 'like', "%{$request->search}%");
                  });
            });
        }

        // Filters
        if ($request->status && $request->status !== 'all') {
            $query->where('status', $request->status);
        }

        if ($request->warehouse_id && $request->warehouse_id !== 'all') {
            $query->where('warehouse_id', $request->warehouse_id);
        }

        // Sorting
        $sortField = $request->sort_field ?? 'id';
        $sortDirection = $request->sort_direction ?? 'desc';
        $allowedSortFields = ['id', 'code', 'status', 'total_amount', 'created_at', 'expected_delivery_date'];
        
        if (in_array($sortField, $allowedSortFields)) {
            $query->orderBy($sortField, $sortDirection);
        }

        $perPage = $request->input('per_page', 10);
        $orders = $query->paginate($perPage)->withQueryString();

        return Inertia::render('PurchaseOrder/Index', [
            'orders' => $orders,
            'filters' => $request->only(['search', 'status', 'warehouse_id', 'sort_field', 'sort_direction', 'per_page']),
            'warehouses' => Warehouse::all(['id', 'name']),
        ]);
    }

    public function create()
    {
        $vendors = Vendor::with(['products.baseUnit', 'products.largeUnit', 'products.purchaseUnit'])->get()->map(function ($vendor) {
            return [
                'id' => (string) $vendor->id,
                'name' => $vendor->name,
                'commonProducts' => $vendor->products->map(function ($product) {
                    return [
                        'productId' => (string) $product->id,
                        'productName' => $product->name,
                        'base_unit_id' => $product->base_unit_id,
                        'base_unit_name' => $product->baseUnit?->name,
                        'large_unit_id' => $product->large_unit_id,
                        'large_unit_name' => $product->largeUnit?->name,
                        'purchase_unit_id' => $product->purchase_unit_id,
                        'conversion_rate' => (float) $product->conversion_rate,
                        'lastPrice' => (float) ($product->pivot->last_price ?? 0),
                    ];
                })
            ];
        });

        $warehouses = Warehouse::all()->map(function ($w) {
            return [
                'id' => (string) $w->id,
                'name' => $w->name,
            ];
        });

        return Inertia::render('PurchaseOrder/Create', [
            'suppliers' => $vendors,
            'warehouses' => $warehouses,
        ]);
    }

    public function store(Request $request)
    {
        $validated = $request->validate([
            'vendor_id' => 'required|exists:vendors,id',
            'warehouse_id' => 'required|exists:warehouses,id',
            'expected_delivery_date' => 'nullable|date',
            'remark' => 'nullable|string',
            'invoice_number' => ['nullable', 'string', 'max:11', 'regex:/^[A-Z]{2}-\d{8}$/'],
            'invoice_date' => 'nullable|date',
            'invoice_amount' => 'nullable|numeric|min:0',
            'items' => 'required|array|min:1',
            'items.*.productId' => 'required|exists:products,id',
            'items.*.quantity' => 'required|numeric|min:0.01',
            'items.*.subtotal' => 'required|numeric|min:0', // 總金額
            'items.*.unitId' => 'nullable|exists:units,id',
            'tax_amount' => 'nullable|numeric|min:0',
        ]);

        try {
            DB::beginTransaction();

            // 生成單號：YYYYMMDD001
            $today = now()->format('Ymd');
            $lastOrder = PurchaseOrder::where('code', 'like', $today . '%')
                ->lockForUpdate() // 鎖定以避免並發衝突
                ->orderBy('code', 'desc')
                ->first();

            if ($lastOrder) {
                // 取得最後 3 碼序號並加 1
                $lastSequence = intval(substr($lastOrder->code, -3));
                $sequence = str_pad($lastSequence + 1, 3, '0', STR_PAD_LEFT);
            } else {
                $sequence = '001';
            }
            $code = $today . $sequence;

            $totalAmount = 0;
            foreach ($validated['items'] as $item) {
                $totalAmount += $item['subtotal'];
            }

            // Tax calculation
            $taxAmount = isset($validated['tax_amount']) ? $validated['tax_amount'] : round($totalAmount * 0.05, 2);
            $grandTotal = $totalAmount + $taxAmount;

            // 確保有一個有效的使用者 ID
            $userId = auth()->id();
            if (!$userId) {
                $user = \App\Models\User::first();
                if (!$user) {
                    $user = \App\Models\User::create([
                        'name' => '系統管理員',
                        'email' => 'admin@example.com',
                        'password' => bcrypt('password'),
                    ]);
                }
                $userId = $user->id;
            }

            $order = PurchaseOrder::create([
                'code' => $code,
                'vendor_id' => $validated['vendor_id'],
                'warehouse_id' => $validated['warehouse_id'],
                'user_id' => $userId,
                'status' => 'draft',
                'expected_delivery_date' => $validated['expected_delivery_date'],
                'total_amount' => $totalAmount,
                'tax_amount' => $taxAmount,
                'grand_total' => $grandTotal,
                'remark' => $validated['remark'],
                'invoice_number' => $validated['invoice_number'] ?? null,
                'invoice_date' => $validated['invoice_date'] ?? null,
                'invoice_amount' => $validated['invoice_amount'] ?? null,
            ]);

            foreach ($validated['items'] as $item) {
                // 反算單價
                $unitPrice = $item['quantity'] > 0 ? $item['subtotal'] / $item['quantity'] : 0;

                $order->items()->create([
                    'product_id' => $item['productId'],
                    'quantity' => $item['quantity'],
                    'unit_id' => $item['unitId'] ?? null, 
                    'unit_price' => $unitPrice,
                    'subtotal' => $item['subtotal'],
                ]);
            }

            DB::commit();

            return redirect()->route('purchase-orders.index')->with('success', '採購單已成功建立');

        } catch (\Exception $e) {
            DB::rollBack();
            return back()->withErrors(['error' => '建立失敗：' . $e->getMessage()]);
        }
    }

    public function show($id)
    {
        $order = PurchaseOrder::with(['vendor', 'warehouse', 'user', 'items.product.baseUnit', 'items.product.largeUnit'])->findOrFail($id);
        
        $order->items->transform(function ($item) use ($order) {
            $product = $item->product;
            if ($product) {
                // 手動附加所有必要的屬性
                $item->productId = (string) $product->id;
                $item->productName = $product->name;
                $item->base_unit_id = $product->base_unit_id;
                $item->base_unit_name = $product->baseUnit?->name;
                $item->large_unit_id = $product->large_unit_id;
                $item->large_unit_name = $product->largeUnit?->name;
                $item->purchase_unit_id = $product->purchase_unit_id;
                
                $item->conversion_rate = (float) $product->conversion_rate;
                
                // Fetch last price
                $lastPrice = DB::table('product_vendor')
                    ->where('vendor_id', $order->vendor_id)
                    ->where('product_id', $product->id)
                    ->value('last_price');
                $item->previousPrice = (float) ($lastPrice ?? 0);

                // 設定當前選中的單位 ID (from saved item)
                $item->unitId = $item->unit_id; 

                // 決定 selectedUnit (用於 UI 顯示)
                if ($item->unitId && $item->large_unit_id && $item->unitId == $item->large_unit_id) {
                    $item->selectedUnit = 'large';
                } else {
                    $item->selectedUnit = 'base';
                }

                $item->unitPrice = (float) $item->unit_price;
            }
            return $item;
        });

        return Inertia::render('PurchaseOrder/Show', [
            'order' => $order
        ]);
    }

    public function edit($id)
    {
        $order = PurchaseOrder::with(['items.product'])->findOrFail($id);

        $vendors = Vendor::with(['products.baseUnit', 'products.largeUnit', 'products.purchaseUnit'])->get()->map(function ($vendor) {
            return [
                'id' => (string) $vendor->id,
                'name' => $vendor->name,
                'commonProducts' => $vendor->products->map(function ($product) {
                    return [
                        'productId' => (string) $product->id,
                        'productName' => $product->name,
                        'base_unit_id' => $product->base_unit_id,
                        'base_unit_name' => $product->baseUnit?->name,
                        'large_unit_id' => $product->large_unit_id,
                        'large_unit_name' => $product->largeUnit?->name,
                        'purchase_unit_id' => $product->purchase_unit_id,
                        'conversion_rate' => (float) $product->conversion_rate,
                        'lastPrice' => (float) ($product->pivot->last_price ?? 0),
                    ];
                })
            ];
        });

        $warehouses = Warehouse::all()->map(function ($w) {
            return [
                'id' => (string) $w->id,
                'name' => $w->name,
            ];
        });

        // Transform items for frontend form
        // Transform items for frontend form
        $vendorId = $order->vendor_id;
        $order->items->transform(function ($item) use ($vendorId) {
            $product = $item->product;
            if ($product) {
                // 手動附加所有必要的屬性
                $item->productId = (string) $product->id;
                $item->productName = $product->name;
                $item->base_unit_id = $product->base_unit_id;
                $item->base_unit_name = $product->baseUnit?->name;
                $item->large_unit_id = $product->large_unit_id;
                $item->large_unit_name = $product->largeUnit?->name;
                
                $item->conversion_rate = (float) $product->conversion_rate;
                
                // Fetch last price
                $lastPrice = DB::table('product_vendor')
                    ->where('vendor_id', $vendorId)
                    ->where('product_id', $product->id)
                    ->value('last_price');
                $item->previousPrice = (float) ($lastPrice ?? 0);
                
                // 設定當前選中的單位 ID
                $item->unitId = $item->unit_id; // 資料庫中的 unit_id

                // 決定 selectedUnit (用於 UI 狀態)
                if ($item->unitId && $item->large_unit_id && $item->unitId == $item->large_unit_id) {
                    $item->selectedUnit = 'large';
                } else {
                    $item->selectedUnit = 'base';
                }

                $item->unitPrice = (float) $item->unit_price;
            }
            return $item;
        });

        return Inertia::render('PurchaseOrder/Create', [
            'order' => $order,
            'suppliers' => $vendors,
            'warehouses' => $warehouses,
        ]);
    }

    public function update(Request $request, $id)
    {
        $order = PurchaseOrder::findOrFail($id);

        $validated = $request->validate([
            'vendor_id' => 'required|exists:vendors,id',
            'warehouse_id' => 'required|exists:warehouses,id',
            'expected_delivery_date' => 'nullable|date',
            'remark' => 'nullable|string',
            'status' => 'required|string|in:draft,pending,processing,shipping,confirming,completed,cancelled',
            'invoice_number' => ['nullable', 'string', 'max:11', 'regex:/^[A-Z]{2}-\d{8}$/'],
            'invoice_date' => 'nullable|date',
            'invoice_amount' => 'nullable|numeric|min:0',
            'items' => 'required|array|min:1',
            'items.*.productId' => 'required|exists:products,id',
            'items.*.quantity' => 'required|numeric|min:0.01',
            'items.*.subtotal' => 'required|numeric|min:0', // 總金額
            'items.*.unitId' => 'nullable|exists:units,id',
            // Allow both tax_amount and taxAmount for compatibility
            'tax_amount' => 'nullable|numeric|min:0', 
            'taxAmount' => 'nullable|numeric|min:0',
        ]);

        try {
            DB::beginTransaction();

            $totalAmount = 0;
            foreach ($validated['items'] as $item) {
                $totalAmount += $item['subtotal'];
            }

            // Tax calculation (handle both keys)
            $inputTax = $validated['tax_amount'] ?? $validated['taxAmount'] ?? null;
            $taxAmount = !is_null($inputTax) ? $inputTax : round($totalAmount * 0.05, 2);
            $grandTotal = $totalAmount + $taxAmount;

            // 1. Fill attributes but don't save yet to capture changes
            $order->fill([
                'vendor_id' => $validated['vendor_id'],
                'warehouse_id' => $validated['warehouse_id'],
                'expected_delivery_date' => $validated['expected_delivery_date'],
                'total_amount' => $totalAmount,
                'tax_amount' => $taxAmount,
                'grand_total' => $grandTotal,
                'remark' => $validated['remark'],
                'status' => $validated['status'],
                'invoice_number' => $validated['invoice_number'] ?? null,
                'invoice_date' => $validated['invoice_date'] ?? null,
                'invoice_amount' => $validated['invoice_amount'] ?? null,
            ]);

            // Capture attribute changes for manual logging
            $dirty = $order->getDirty();
            $oldAttributes = [];
            $newAttributes = [];

            foreach ($dirty as $key => $value) {
                $oldAttributes[$key] = $order->getOriginal($key);
                $newAttributes[$key] = $value;
            }

            // Save without triggering events (prevents duplicate log)
            $order->saveQuietly();

            // 2. Capture old items with product names for diffing
            $oldItems = $order->items()->with('product', 'unit')->get()->map(function($item) {
                return [
                    'id' => $item->id,
                    'product_id' => $item->product_id,
                    'product_name' => $item->product?->name,
                    'quantity' => (float) $item->quantity,
                    'unit_id' => $item->unit_id,
                    'unit_name' => $item->unit?->name,
                    'subtotal' => (float) $item->subtotal,
                ];
            })->keyBy('product_id');

            // Sync items (Original logic)
            $order->items()->delete();
            
            $newItemsData = [];
            foreach ($validated['items'] as $item) {
                // 反算單價
                $unitPrice = $item['quantity'] > 0 ? $item['subtotal'] / $item['quantity'] : 0;

                $newItem = $order->items()->create([
                    'product_id' => $item['productId'],
                    'quantity' => $item['quantity'],
                    'unit_id' => $item['unitId'] ?? null, 
                    'unit_price' => $unitPrice,
                    'subtotal' => $item['subtotal'],
                ]);
                $newItemsData[] = $newItem;
            }

            // 3. Calculate Item Diffs
            $itemDiffs = [
                'added' => [],
                'removed' => [],
                'updated' => [],
            ];

            // Re-fetch new items to ensure we have fresh relations
            $newItemsFormatted = $order->items()->with('product', 'unit')->get()->map(function($item) {
                return [
                    'product_id' => $item->product_id,
                    'product_name' => $item->product?->name,
                    'quantity' => (float) $item->quantity,
                    'unit_id' => $item->unit_id,
                    'unit_name' => $item->unit?->name,
                    'subtotal' => (float) $item->subtotal,
                ];
            })->keyBy('product_id');

            // Find removed
            foreach ($oldItems as $productId => $oldItem) {
                if (!$newItemsFormatted->has($productId)) {
                    $itemDiffs['removed'][] = $oldItem;
                }
            }

            // Find added and updated
            foreach ($newItemsFormatted as $productId => $newItem) {
                if (!$oldItems->has($productId)) {
                    $itemDiffs['added'][] = $newItem;
                } else {
                    $oldItem = $oldItems[$productId];
                    // Compare fields
                    if (
                        $oldItem['quantity'] != $newItem['quantity'] || 
                        $oldItem['unit_id'] != $newItem['unit_id'] ||
                        $oldItem['subtotal'] != $newItem['subtotal']
                    ) {
                        $itemDiffs['updated'][] = [
                            'product_name' => $newItem['product_name'],
                            'old' => [
                                'quantity' => $oldItem['quantity'],
                                'unit_name' => $oldItem['unit_name'],
                                'subtotal' => $oldItem['subtotal'],
                            ],
                            'new' => [
                                'quantity' => $newItem['quantity'],
                                'unit_name' => $newItem['unit_name'],
                                'subtotal' => $newItem['subtotal'],
                            ]
                        ];
                    }
                }
            }

            // 4. Manually Log activity (Single Consolidated Log)
            // Log if there are attribute changes OR item changes
            if (!empty($newAttributes) || !empty($itemDiffs['added']) || !empty($itemDiffs['removed']) || !empty($itemDiffs['updated'])) {
                activity()
                    ->performedOn($order)
                    ->causedBy(auth()->user())
                    ->event('updated')
                    ->withProperties([
                        'attributes' => $newAttributes,
                        'old' => $oldAttributes,
                        'items_diff' => $itemDiffs,
                        'snapshot' => [
                            'po_number' => $order->code,
                            'vendor_name' => $order->vendor?->name,
                            'warehouse_name' => $order->warehouse?->name,
                            'user_name' => $order->user?->name,
                        ]
                    ])
                    ->log('updated');
            }

            DB::commit();

            return redirect()->route('purchase-orders.index')->with('success', '採購單已更新');

        } catch (\Exception $e) {
            DB::rollBack();
            return back()->withErrors(['error' => '更新失敗：' . $e->getMessage()]);
        }
    }

    public function destroy($id)
    {
        try {
            DB::beginTransaction();
            
            $order = PurchaseOrder::with(['items.product', 'items.unit'])->findOrFail($id);
            
            // Capture items for logging
            $items = $order->items->map(function ($item) {
                return [
                    'product_name' => $item->product_name,
                    'quantity' => floatval($item->quantity),
                    'unit_name' => $item->unit_name,
                    'subtotal' => floatval($item->subtotal),
                ];
            })->toArray();

            // Manually log the deletion with items
            activity()
                ->performedOn($order)
                ->causedBy(auth()->user())
                ->event('deleted')
                ->withProperties([
                    'attributes' => $order->getAttributes(),
                    'items_diff' => [
                        'added' => [],
                        'removed' => $items,
                        'updated' => [],
                    ],
                    'snapshot' => [
                        'po_number' => $order->code,
                        'vendor_name' => $order->vendor?->name,
                        'warehouse_name' => $order->warehouse?->name,
                        'user_name' => $order->user?->name,
                    ]
                ])
                ->log('deleted');

            // Disable automatic logging for this operation
            $order->disableLogging();
            
            // Delete associated items first
            $order->items()->delete();
            $order->delete();
            
            DB::commit();
            
            return redirect()->route('purchase-orders.index')->with('success', '採購單已刪除');
        } catch (\Exception $e) {
            DB::rollBack();
            return back()->withErrors(['error' => '刪除失敗：' . $e->getMessage()]);
        }
    }
}