#include "config.h"

#include <avr/io.h>
#include <util/delay.h>
#include <stdbool.h>

#include "GDM1602K.h"

#define DATAPIN PC0
#define PORT PORTC
#define PIN PINC
#define DDR DDRC

bool is_high() {
	return (PIN & (1 << DATAPIN));
}

// Function to read data from the DHT22 sensor
int DHT22_Read(int *temperature, int *humidity)
{
	// Set the data pin as output
	DDR |= (1 << DATAPIN);
	PORT |= (1 << DATAPIN); // Set the pin high, if not already pulled up

	_delay_ms(100);
	
	// Send start signal
	PORT &= ~(1 << DATAPIN); // Set the pin low
	_delay_us(500);       // Hold it for a while
	PORT |= (1 << DATAPIN);  // Set the pin high
	DDR &= ~(1 << DATAPIN); // Data direction in

	_delay_us(20);       // Wait for 40 microseconds

	// Sensor should have pulled low here
	if(PIN & (1 << DATAPIN)) return -2;

	_delay_us(80);       // Wait for 80 microseconds

	// Sensor should have pulled high here
	if(!(PIN & (1 << DATAPIN))) return -1;

	// Read data from the sensor
	uint8_t data[5] = {0, 0, 0, 0, 0};
	uint8_t bitMask = 0x80; // All zeroes with MSB high
	uint8_t byteIndex = 0;

	for (byteIndex = 0; byteIndex < 5; byteIndex++)
	{
		for (bitMask = 0x80; bitMask != 0; bitMask >>= 1)
		{
			// Wait for the data bit to go low
			while (!(PIN & (1 << PC0)))
			;
			
			// Wait for the data bit to go high
			_delay_us(20);
			if (PIN & (1 << PC0))
			data[byteIndex] |= bitMask;
			
			// Wait for the data bit to go low (end of bit)
			while (PIN & (1 << PC0))
			;
		}
	}

	// Verify checksum
	uint8_t checksum = data[0] + data[1] + data[2] + data[3];
	if (checksum != data[4])
	return -1;

	// Extract temperature and humidity
	*humidity = ((data[0] << 8) | data[1]);
	*temperature = ((data[2] << 8) | data[3]);

	return 0;
}