#include <stdint.h>
#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <stdbool.h>
#include <avr/cpufunc.h>
#include <avr/eeprom.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

extern "C" {
#include "usbdrv.h"
}

enum {
	COMMAND_HEARTBEAT = 1,
	COMMAND_SET_FAN = 2,
};

volatile uint32_t second;
volatile uint32_t lastSeenSec;

ISR(RTC_PIT_vect)
{
	RTC_PITINTFLAGS = RTC_PI_bm;
	PORTC_OUTTGL = PIN3_bm;
	++second;
}

constexpr uint8_t FAN_A_PIN = PIN6_bm;
constexpr uint8_t FAN_B_PIN = PIN4_bm;
constexpr uint8_t FAN_C_PIN = PIN7_bm;
constexpr uint8_t FAN_D_PIN = PIN5_bm;

constexpr uint8_t fanNumToPin(uint8_t num)
{
	switch(num)
	{
		case 0:
			return FAN_A_PIN;
		case 1:
			return FAN_B_PIN;
		case 2:
			return FAN_C_PIN;
		case 3:
			return FAN_D_PIN;
	}
	return FAN_A_PIN;
};

volatile bool irq = true;
static uint8_t fanSpeeds[4] = {0x07, 0x07, 0x07, 0x07};

usbMsgLen_t usbFunctionSetup(uchar data[8])
{
	usbRequest_t *rq = (usbRequest_t *)data;
	static uint8_t dataBuffer[8];
	usbMsgLen_t ret = 0;

	if(rq->bRequest == COMMAND_HEARTBEAT)
	{
		lastSeenSec = second;
		ret = 0;
	}
	else if(rq->bRequest == COMMAND_SET_FAN)
	{
		lastSeenSec = second;
		if(rq->wIndex.word > 3 || rq->wValue.word > 255)
		{
			dataBuffer[0] = 0xFF;
		}
		else
		{
			PORTC_OUTSET = PIN3_bm;
			fanSpeeds[rq->wIndex.word] = rq->wValue.word>>4;
			dataBuffer[0] = 0;
		}
		ret = 1;
	}

	usbMsgPtr = (short unsigned int)dataBuffer;
    return ret;
}

static void setup_tca(void)
{
	PORTB_DIR |= PIN0_bm | PIN1_bm;

	TCA0_SINGLE_CMP0 = 1000;
	TCA0_SINGLE_CTRLA = TCA_SINGLE_ENABLE_bm; //enable TCA with /1 clock scaler
	TCA0_SINGLE_CTRLB = 1 | TCA_SINGLE_CMP0EN_bm; //output on WO0
}

static void setup_tcb(void)
{
	TCB0_CTRLA = TCB_ENABLE_bm;
}

static void setup_pit(void)
{
	while(RTC_PITSTATUS & RTC_CTRLBUSY_bm);
	RTC_PITINTCTRL = RTC_PI_bm; // enable pit isr
	while(RTC_PITSTATUS & RTC_CTRLBUSY_bm);
	RTC_PITCTRLA = RTC_PERIOD_CYC32768_gc | RTC_PITEN_bm; // 256hz
	RTC_CNT = 0;
}

void setup_clock(void)
{
	CPU_CCP = CCP_IOREG_gc; //unlock MCLKCTRLB
	CLKCTRL_MCLKCTRLB = 0; //disable main clock divider

	_PROTECTED_WRITE(CLKCTRL_OSC20MCALIBA, 42);
}

int main(void)
{
	PORTA_DIR |= fanNumToPin(0) | fanNumToPin(1) | fanNumToPin(2) | fanNumToPin(3);
	PORTC_DIR |= PIN2_bm | PIN3_bm;

	_delay_ms(100);

	setup_clock();
	setup_tca();
	setup_pit();
	setup_tcb();

	usbInit();
	usbDeviceDisconnect();

	PORTC_OUTSET = PIN2_bm;

	usbDeviceConnect();

	sei();
	uint8_t pwmTimer = 0;
	while(true)
	{
		usbPoll();

		if(second-lastSeenSec > 60)
		{
			for(uint8_t i = 0; i < 4; ++i)
				fanSpeeds[i] = 0x07;
		}

		if(TCB0_CNT > 100)
		{

			if(++pwmTimer > 0x0F)
			{
				for(uint8_t i = 0; i < 4; ++i)
				{
					if(fanSpeeds[i] > 0)
						PORTA_OUTSET = fanNumToPin(i);
				}
				pwmTimer = 0;
			}

			for(uint8_t i = 0; i < 4; ++i)
			{
				if(fanSpeeds[i] < pwmTimer)
					PORTA_OUTCLR = fanNumToPin(i);
			}

			TCB0_CNT = 0;
		}

	}
}