#pragma once

/**
 * humidity and temperature sensor
 * https://www.mouser.com/datasheet/2/682/Sensirion_Humidity_Sensors_SHT3x_Datasheet_digital-971521.pdf
 * 
 * sensor seems to be really good! and very easy to use!
 * 
 */
template <typename I2C> class SHT3x {
	
private:

	I2C& i2c;
	static constexpr const uint8_t ADDR = 0x44;
	static constexpr const char* NAME = "SHT3x";
	

public:

	SHT3x(I2C& i2c) : i2c(i2c) {
		
	}
			
	/** is the device present on the bus? */
	bool isPresent() {
		return i2c.query(ADDR);
	}
			
	struct Result {
		float temp;
		float humi;
	};
			
	/** trigger a single measurement */	
	Result singleMeasure() {
		
		uint16_t cmd = 0x2400;	// high quality, no clock stretching
		sendCommand(cmd);
		vTaskDelay(100 / portTICK_PERIOD_MS);
		
		return readResult();
		
	}
	
	void startPeriodicMeasure() {
		uint16_t cmd = 0x2130;	// high quality, 1 measurement per second
		sendCommand(cmd);
	}
	
	Result getLastResult() {
		return readResult();
	}
		
private:

	Result readResult() {
		
		uint8_t tmp[6];
		i2c.readRaw(ADDR, 6, (uint8_t*)&tmp);
		
		Result res;
		res.temp = -45 + 175 * 	((tmp[0]<<8) | (tmp[1]<<0)) / float((1<<16)-1);
		res.humi = 100 * 		((tmp[3]<<8) | (tmp[4]<<0)) / float((1<<16)-1);
		return res;
		
	}

	void sendCommand(uint16_t cmd) {
		uint8_t tmp[2];
		tmp[0] = cmd >> 8;
		tmp[1] = cmd >> 0;
		i2c.writeRaw(ADDR, 2, tmp);
	}
	
	static uint8_t calcCRC(const uint8_t* data, uint8_t len) {
		uint8_t crc = 0xff;
		for (uint8_t i = 0; i < len; i++) {
			crc ^= data[i];
			for (uint8_t j = 0; j < 8; j++) {
				if ((crc & 0x80) != 0) {
					crc = (uint8_t)((crc << 1) ^ 0x31);
				} else {
					crc <<= 1;
				}
			}
		}
		return crc;
	}

	
};