<?php namespace App\Services;

use App\Models\Inventory;
use App\Models\InventoryMovement;
use App\Models\InventoryWarehouse;
use App\Models\Warehouse;
use Illuminate\Support\Facades\DB;

/**
 * Servicio para gestión de movimientos de inventario
 */
class InventoryMovementService
{
    /**
     * Entrada de inventario (compra, ajuste positivo)
     */
    public function entry(array $data): InventoryMovement
    {
        return DB::transaction(function () use ($data) {
            $inventory = Inventory::findOrFail($data['inventory_id']);
            $warehouse = Warehouse::findOrFail($data['warehouse_id']);
            $quantity = $data['quantity'];

            // Actualizar stock en inventory_warehouse
            $this->updateWarehouseStock($inventory->id, $warehouse->id, $quantity);

            // Sincronizar stock global
            $inventory->syncGlobalStock();

            // Registrar movimiento
            return InventoryMovement::create([
                'inventory_id' => $inventory->id,
                'warehouse_from_id' => null, // Entrada externa
                'warehouse_to_id' => $warehouse->id,
                'movement_type' => $data['movement_type'] ?? 'entry',
                'quantity' => $quantity,
                'user_id' => auth()->id(),
                'notes' => $data['notes'] ?? null,
                'reference_type' => $data['reference_type'] ?? null,
                'reference_id' => $data['reference_id'] ?? null,
            ]);
        });
    }

    /**
     * Salida de inventario (merma, ajuste negativo, robo)
     */
    public function exit(array $data): InventoryMovement
    {
        return DB::transaction(function () use ($data) {
            $inventory = Inventory::findOrFail($data['inventory_id']);
            $warehouse = Warehouse::findOrFail($data['warehouse_id']);
            $quantity = $data['quantity'];

            // Validar stock disponible
            $this->validateStock($inventory->id, $warehouse->id, $quantity);

            // Decrementar stock en inventory_warehouse
            $this->updateWarehouseStock($inventory->id, $warehouse->id, -$quantity);

            // Sincronizar stock global
            $inventory->syncGlobalStock();

            // Registrar movimiento
            return InventoryMovement::create([
                'inventory_id' => $inventory->id,
                'warehouse_from_id' => $warehouse->id,
                'warehouse_to_id' => null, // Salida externa
                'movement_type' => $data['movement_type'] ?? 'exit',
                'quantity' => $quantity,
                'user_id' => auth()->id(),
                'notes' => $data['notes'] ?? null,
                'reference_type' => $data['reference_type'] ?? null,
                'reference_id' => $data['reference_id'] ?? null,
            ]);
        });
    }

    /**
     * Traspaso entre almacenes
     */
    public function transfer(array $data): InventoryMovement
    {
        return DB::transaction(function () use ($data) {
            $inventory = Inventory::findOrFail($data['inventory_id']);
            $warehouseFrom = Warehouse::findOrFail($data['warehouse_from_id']);
            $warehouseTo = Warehouse::findOrFail($data['warehouse_to_id']);
            $quantity = $data['quantity'];

            // Validar que no sea el mismo almacén
            if ($warehouseFrom->id === $warehouseTo->id) {
                throw new \Exception('No se puede traspasar al mismo almacén.');
            }

            // Validar stock disponible en almacén origen
            $this->validateStock($inventory->id, $warehouseFrom->id, $quantity);

            // Decrementar en origen
            $this->updateWarehouseStock($inventory->id, $warehouseFrom->id, -$quantity);

            // Incrementar en destino
            $this->updateWarehouseStock($inventory->id, $warehouseTo->id, $quantity);

            // Stock global no cambia, no es necesario sincronizar

            // Registrar movimiento
            return InventoryMovement::create([
                'inventory_id' => $inventory->id,
                'warehouse_from_id' => $warehouseFrom->id,
                'warehouse_to_id' => $warehouseTo->id,
                'movement_type' => 'transfer',
                'quantity' => $quantity,
                'user_id' => auth()->id(),
                'notes' => $data['notes'] ?? null,
            ]);
        });
    }

    /**
     * Actualizar stock en inventory_warehouse
     */
    protected function updateWarehouseStock(int $inventoryId, int $warehouseId, int $quantityChange): void
    {
        $record = InventoryWarehouse::firstOrCreate(
            [
                'inventory_id' => $inventoryId,
                'warehouse_id' => $warehouseId,
            ],
            ['stock' => 0]
        );

        $newStock = $record->stock + $quantityChange;

        // No permitir stock negativo
        if ($newStock < 0) {
            throw new \Exception('Stock insuficiente en el almacén.');
        }

        $record->update(['stock' => $newStock]);
    }

    /**
     * Validar stock disponible
     */
    protected function validateStock(int $inventoryId, int $warehouseId, int $requiredQuantity): void
    {
        $record = InventoryWarehouse::where('inventory_id', $inventoryId)
            ->where('warehouse_id', $warehouseId)
            ->first();

        $availableStock = $record?->stock ?? 0;

        if ($availableStock < $requiredQuantity) {
            throw new \Exception("Stock insuficiente. Disponible: {$availableStock}, Requerido: {$requiredQuantity}");
        }
    }

    /**
     * Registrar movimiento de venta
     */
    public function recordSale(int $inventoryId, int $warehouseId, int $quantity, int $saleId): InventoryMovement
    {
        return InventoryMovement::create([
            'inventory_id' => $inventoryId,
            'warehouse_from_id' => $warehouseId,
            'warehouse_to_id' => null,
            'movement_type' => 'sale',
            'quantity' => $quantity,
            'reference_type' => 'App\Models\Sale',
            'reference_id' => $saleId,
            'user_id' => auth()->id(),
        ]);
    }

    /**
     * Registrar movimiento de devolución
     */
    public function recordReturn(int $inventoryId, int $warehouseId, int $quantity, int $returnId): InventoryMovement
    {
        return InventoryMovement::create([
            'inventory_id' => $inventoryId,
            'warehouse_from_id' => null,
            'warehouse_to_id' => $warehouseId,
            'movement_type' => 'return',
            'quantity' => $quantity,
            'reference_type' => 'App\Models\Returns',
            'reference_id' => $returnId,
            'user_id' => auth()->id(),
        ]);
    }
}