Attributes for products

Hello,

I'm creating a small website for myself to show some digital products. Each product belongs to a category, and a category has many products. Every category has specific attributes.

For example, a HTML website may be retina ready, responsive… A WordPress website may be retina and responsive too, but also support some plugins.

I have created a migration, but I'm not sure it is best optimized, so I would like to get your opinion and advices.

I am sure it would help other people, because it is very common to create attributes for a eCommerce, portfolio or anything else.

        Schema::create('attributes', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->integer('attribute_type_id')->unsigned()->index();
            $table->string('photo')->nullable();
            $table->boolean('visible')->default(true);
            $table->integer('position')->unsigned()->default(1);
        });

        Schema::create('attribute_type', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->boolean('visible')->default(true);
            $table->integer('position')->unsigned()->default(1);
        });

        Schema::create('attribute_category', function (Blueprint $table) {
            $table->integer('attribute_id')->unsigned()->index();
            $table->foreign('attribute_id')->references('id')->on('attributes')->onDelete('cascade');
            $table->integer('category_id')->unsigned()->index();
            $table->foreign('category_id')->references('id')->on('attributes')->onDelete('cascade');
        });