Post is not updating in website

hi m trying to update a post but its not updating and it says that page not found and also the image on the edit-page is not showing. is there any solution to resolve it, here is my code:

controller:

     public function editProduct(Request $request, $id=null){

     if($request->isMethod('post')){
     $data = $request->all();
     //echo "<pre>"; print_r($data); die;

      //Upload Image
      if($request->hasFile('image')){
        $image_tmp = Input::file('image');
        if($image_tmp->isValid()){
         $extension = $image_tmp->getClientOriginalExtension();
         $filename = rand(111,99999).'.'.$extension;
         $large_image_path = 'images/backend_images/products/large/'.             $filename;
         $medium_image_path = 'images/backend_images/products/medium/'.             $filename;
         $small_image_path = 'images/backend_images/products/small/'.             $filename;
         // Resize Images
         Image::make($image_tmp)->save($large_image_path);
         Image::make($image_tmp)->resize(600,600)->save             ($medium_image_path);
         Image::make($image_tmp)->resize(300,300)->save($small_image_path);

         // Store image name in products table
         $product->image = $filename;
        }
      }
      else{
        $filename = $data['current_image'];
      }

      if(empty($data['description'])){
       $data['description'] = '';
      }


      Product::where(['id'=>$id])- 
     >update(['status'=>$status,'category_id'=>$data                ['category_id'],'product_name'=>$data['product_name'], 

    'product_code'=>$data['product_code'],'product_color'=>$data                ['product_color'],'description'=>$ 
    data['description'],'care'=>$data['care'],'price'=>$data['price'],'image'=>                $fileName]);

    return redirect()->back()->with('flash_message_success', 'Product has been              edited 
    successfully');
   }

    //Get product details
    $productDetails = Product::where(['id'=>$id])->first();

    //Categories dropdown start
    $categories = Category::where(['parent_id'=>0])->get();
    $categories_dropdown = "<option value='' selected         disabled>Select</option>";
    foreach($categories as $cat){
    if($cat->id==$productDetails->category_id){
      $selected = "selected";
    }
    else{
      $selected = "";
    }
    $categories_dropdown .= "<option value='".$cat->id."' ".$selected.">".$cat-        >name." 
    </option>";
     $sub_categories = Category::where(['parent_id'=>$cat->id])->get();
     foreach ($sub_categories as $sub_cat) {
      if($sub_cat->id==$productDetails->category_id){
        $selected = "selected";
      }
      else{
        $selected = "";
      }
      $categories_dropdown .= "<option value = '".$sub_cat->id."' ".          $selected.">&nbsp;-- 
     &nbsp;".$sub_cat->name."</option>";
      }
     }
     //Categories dropdown start

      return view('admin.products.edit_product')- 
     >with(compact('productDetails','categories_dropdown'));
     }

this is form:

     <form enctype="multipart/form-data" class="form-horizontal" method="post" action="{{ 
     url('/admin/edit-product'.$productDetails->id) }}" name="edit_product" id="edit_product" 
     novalidate="novalidate"> {{ csrf_field() }}
          <div class="control-group">
            <label class="control-label">Under Category</label>
            <div class="controls">
              <select name="category_id" id="category_id" style="width: 220px;">  
                <?php echo $categories_dropdown; ?>
              </select>
            </div>
          </div>
          <div class="control-group">
            <label class="control-label">Product Name</label>
            <div class="controls">
              <input type="text" name="product_name" id="product_name" value="{{ 
         $productDetails->product_name }}">
            </div>
          </div>
          <div class="control-group">
            <label class="control-label">Product Code</label>
            <div class="controls">
              <input type="text" name="product_code" id="product_code" value="{{ 
       $productDetails->product_code }}">
            </div>
          </div>
          <div class="control-group">
            <label class="control-label">Product Color</label>
            <div class="controls">
              <input type="text" name="product_color" id="product_color" value="{{ 
      $productDetails->product_color }}">
            </div>
          </div>
          <div class="control-group">
            <label class="control-label">Description</label>
            <div class="controls">
              <textarea name="description" id="description">{{ $productDetails->description }} 
     </textarea>
            </div>
          </div>
          <div class="control-group">
            <label class="control-label">Price</label>
            <div class="controls">
              <input type="text" name="price" id="price" value="{{ $productDetails->price }}">
            </div>
          </div>
          <div class="control-group">
            <label class="control-label">Image</label>
            <div class="controls">
              <input type="file" name="image" id="image">
              <img style="width:30px;" src="{{ 
      asset('/images/backend_images/product/small/'.$productDetails->image) }}">
            </div>
          </div>
          <div class="form-actions">
            <input type="submit" value="Edit Product" class="btn btn-success">
          </div>
        </form>

Route:

    Route::match(['get','post'],'/admin/edit-product/{id}','ProductsController@editProduct');