#ifndef SENS_INA_219
#define SENS_INA_219

/** 1-Channel i2c volt/ampere sensor */
template <typename I2C> class INA219 {
	
private:

	I2C& i2c;
	static constexpr const uint8_t ADDR = 0b1000000;
	static constexpr const char* NAME = "INA219";
	
	static constexpr const uint8_t REG_CFG = 0x00;
	
	static constexpr const uint8_t REG_VS = 0x01;	// shunt voltage
	static constexpr const uint8_t REG_VB = 0x02;	// bus voltage
	
public:

	struct Voltages {
		
		int		vShunt;	// in uV * 10(!!!)
		int16_t	vBus;	// in mV
		
		int getMilliAmps(int shunt_milliOhm) const {
			return (vShunt * 10) / shunt_milliOhm;
		}
		
	};

public:

	INA219(I2C& i2c) : i2c(i2c) {
		
	}
	
	/** get the current config */
	uint16_t getConfig() {
		uint8_t buf[2];
		i2c.readReg(ADDR, REG_CFG, 2, (uint8_t*)&buf); 
		return getU16(buf);
	}
	
	/** read both voltages (shunt and bus) */
	Voltages getVoltages() {
		
		uint8_t buf[2];
		Voltages res;
		
		i2c.readReg(ADDR, REG_VS, sizeof(buf), buf);
		res.vShunt =	getShuntVoltage(buf);
		i2c.readReg(ADDR, REG_VB, sizeof(buf), buf);
		res.vBus =		getBusVoltage(buf);
		
		return res;
	}
	
	/** is an INA219 present on the bus? */
	bool isPresent() {
		return i2c.query(ADDR);
	}
	
	void dumpConfig() {
		const uint16_t cfg = getConfig();
		const uint8_t mode =	(cfg & 0b00000000000111) >> 0;
		const uint8_t sadc =	(cfg & 0b00000001111000) >> 3;
		const uint8_t badc =	(cfg & 0b00011110000000) >> 7;
		const uint8_t pg =		(cfg & 0b01100000000000) >> 11;
		const uint8_t brng =	(cfg & 0b10000000000000) >> 13;
		printf("INA219\n");
		printf("- Mode: %d", mode);
		printf("- SADC: %d", sadc);
		printf("- BADC: %d", badc);
		printf("PG (shunt divider) %d", (1<<pg));
		if (brng)	{printf("- bus voltage range [0:16]");}
		else		{printf("- bus voltage range [0:32]");}		
	}
	
private:

	/** convert to bytes into a mV reading */
	int16_t getBusVoltage(const uint8_t* buf) {
		return (getU16(buf) >> 3) * 4;				// lower 3 bits are status indicators -> remove, the LSB equals 4 mV -> * 4
	}
	
	/** convert to bytes into a uV reading */
	int getShuntVoltage(const uint8_t* buf) {
		return ((int)((int16_t)getU16(buf)));		// NOTE: LSB = 10 uV
	}
	
	uint16_t getU16(const uint8_t* buf) {
		return ((buf[0] << 8) | (buf[1] << 0));
	}
	
};


#endif // SENS_INA_219