```ruby
class SessionsController < ApplicationController

  def new
  end

  def create
    render 'new'
  end

  def delete
  end
end
```

Handle signup with invalid email/password
user
```ruby
class SessionsController < ApplicationController

  def new
  end

  def create
    user = User.find_by(email: params[:session][:email].downcase)

    if user && user.authenticate(params[:session][:password])
      # Sign in user and redirect to user page
    else
      flash[:danger] = 'Invalid email/password combination'
      render 'new'
    end
  end

  def delete
  end
end
```
assistant