#pragma once

/**
 * humidity and temperature sensor
 * https://asairsensors.com/wp-content/uploads/2021/09/Data-Sheet-AHT21-Humidity-and-Temperature-Sensor-ASAIR-V1.0.03.pdf
 */
template <typename I2C> class AHT2x {
	
private:

	I2C& i2c;
	static constexpr const uint8_t ADDR = 0x38;
	static constexpr const char* NAME = "AHT2x";

	static constexpr const uint8_t BIT_BUSY = 0x80;
	static constexpr const uint8_t BIT_CALIBRATED = 0x08;
	
public:

	struct Result {
		float temp;
		float humi;
	};	

public:

	AHT2x(I2C& i2c) : i2c(i2c) {
		
	}
	
	void init() {
		softReset();
		int ok = calibrate();
		printf("aht calib: %d\n", ok);
	}		
		
	/** is the device present on the bus? */
	bool isPresent() {
		return i2c.query(ADDR);
	}
	
	void softReset() {
		uint8_t cmd = 0xBA;
		i2c.writeRaw(ADDR, 1, &cmd);
		DELAY_MS(100);
	}
		
	bool calibrate() {
		uint8_t cmdCalibrate[3] = {0xBE, 0x08, 0x00};
		i2c.writeRaw(ADDR, 3, cmdCalibrate);
		waitUntilDone();
		return readStatus() & BIT_CALIBRATED;
	}
	
	void waitUntilDone() {
		for (uint8_t i = 0; i < 200; ++i) {
			printf(".");
			if (!(readStatus() & BIT_BUSY)) {break;}
			DELAY_MS(1);
		}
		printf("x\n");
	}
	
	uint8_t readStatus() {
		uint8_t status = 0;
		i2c.readRaw(ADDR, 1, &status);
		return status;
	}
	
	Result measure() {
		
		// trigger measurement
		uint8_t cmdMeasure[3] = {0xAC, 0x33, 0x00};
		i2c.writeRaw(ADDR, 3, cmdMeasure);
		
		// fetch result, also waits until the busy-bit is cleared
		uint8_t raw[6];
		for(uint8_t i = 0; i < 50; ++i) {
			DELAY_MS(10);
			i2c.readRaw(ADDR, 6, raw);
			bool busy = (raw[0] & BIT_BUSY);
			if (!busy) {break;}
		}
		
		// calculate
		Result res;
		
		uint32_t _humi = ((raw[1] << 16) | (raw[2] << 8) | (raw[3] << 0)) >> 4;
		res.humi = _humi * 100 / 1048576.0f;
		
		uint32_t _temp = ((raw[3] & 0x0F) << 16) | (raw[4] << 8) | (raw[5] << 0);
		res.temp = (_temp * 200 / 1048576.0f) - 50;
		
		return res;
		
	}
			
};