Altera DE0-nano. Struggling to make a SPI slave device

Hi. I'm new to VHDL and I thought I could try to make a slave SPI device as training, but it's not working quite as expected. Below my current code. It's compiles and upload just fine, but it's not working as intended. Right now I have the leds connected to the signal "bitnumber", bitnumber is supposed to increment on each rising edge of CLK and then reset to zero when the SS pin is pulled LOW (indicating that the transfer is complete), but it doesn't do that. I've connected my Altera DE0-nano to my arduino which is simply pulling the SS LOW, sends four clock pulses and then pulls the SS back high, I've put a 1s delay between each transition. The leds on my altera board does change it's pattern every second, but it does so on both rising and falling edge of the clock, also the led pattern seems completely random, even showing some leds in a dimmed state. The leds become black when the SS pin goes back HIGH though, that's good.