// Package lsm6dsox implements a driver for the LSM6DSOX
// a 6 axis Inertial Measurement Unit (IMU)
//
// Datasheet: https://www.st.com/resource/en/datasheet/lsm6dsox.pdf
//
package lsm6dsox // import "tinygo.org/x/drivers/lsm6dsox"

import "tinygo.org/x/drivers"

type AccelRange uint8
type AccelSampleRate uint8

type GyroRange uint8
type GyroSampleRate uint8

// Device wraps an I2C connection to a LSM6DSOX device.
type Device struct {
	bus             drivers.I2C
	Address         uint16
	dataBufferSix   []uint8
	dataBufferTwo   []uint8
	accelMultiplier int32
	gyroMultiplier  int32
}

// Configuration for LSM6DSOX device.
type Configuration struct {
	AccelRange      AccelRange
	AccelSampleRate AccelSampleRate
	GyroRange       GyroRange
	GyroSampleRate  GyroSampleRate
}

// New creates a new LSM6DSOX connection. The I2C bus must already be configured.
//
// This function only creates the Device object, it does not touch the device.
func New(bus drivers.I2C) *Device {
	return &Device{
		bus:           bus,
		Address:       Address,
		dataBufferSix: make([]uint8, 6),
		dataBufferTwo: make([]uint8, 2),
	}
}

// Configure sets up the device for communication.
func (d *Device) Configure(cfg Configuration) {

	// Multipliers come from "Table 2. Mechanical characteristics" of the datasheet * 1000
	switch cfg.AccelRange {
	case ACCEL_2G:
		d.accelMultiplier = 61
	case ACCEL_4G:
		d.accelMultiplier = 122
	case ACCEL_8G:
		d.accelMultiplier = 244
	case ACCEL_16G:
		d.accelMultiplier = 488
	}
	switch cfg.GyroRange {
	case GYRO_250DPS:
		d.gyroMultiplier = 8750
	case GYRO_500DPS:
		d.gyroMultiplier = 17500
	case GYRO_1000DPS:
		d.gyroMultiplier = 35000
	case GYRO_2000DPS:
		d.gyroMultiplier = 70000
	}

	data := make([]uint8, 1)
	// Configure accelerometer
	data[0] = uint8(cfg.AccelRange) | uint8(cfg.AccelSampleRate)
	d.bus.WriteRegister(uint8(d.Address), CTRL1_XL, data)
	// Configure gyroscope
	data[0] = uint8(cfg.GyroRange) | uint8(cfg.GyroSampleRate)
	d.bus.WriteRegister(uint8(d.Address), CTRL2_G, data)
}

// Connected returns whether a LSM6DSOX has been found.
// It does a "who am I" request and checks the response.
func (d *Device) Connected() bool {
	data := []byte{0}
	d.bus.ReadRegister(uint8(d.Address), WHO_AM_I, data)
	return data[0] == 0x6C
}

// ReadAcceleration reads the current acceleration from the device and returns
// it in µg (micro-gravity). When one of the axes is pointing straight to Earth
// and the sensor is not moving the returned value will be around 1000000 or
// -1000000.
func (d *Device) ReadAcceleration() (x int32, y int32, z int32) {
	d.bus.ReadRegister(uint8(d.Address), OUTX_L_A, d.dataBufferSix)
	x = int32(int16((uint16(d.dataBufferSix[1])<<8)|uint16(d.dataBufferSix[0]))) * d.accelMultiplier
	y = int32(int16((uint16(d.dataBufferSix[3])<<8)|uint16(d.dataBufferSix[2]))) * d.accelMultiplier
	z = int32(int16((uint16(d.dataBufferSix[5])<<8)|uint16(d.dataBufferSix[4]))) * d.accelMultiplier
	return
}

// ReadRotation reads the current rotation from the device and returns it in
// µ°/s (micro-degrees/sec). This means that if you were to do a complete
// rotation along one axis and while doing so integrate all values over time,
// you would get a value close to 360000000.
func (d *Device) ReadRotation() (x int32, y int32, z int32) {
	d.bus.ReadRegister(uint8(d.Address), OUTX_L_G, d.dataBufferSix)
	x = int32(int16((uint16(d.dataBufferSix[1])<<8)|uint16(d.dataBufferSix[0]))) * d.gyroMultiplier
	y = int32(int16((uint16(d.dataBufferSix[3])<<8)|uint16(d.dataBufferSix[2]))) * d.gyroMultiplier
	z = int32(int16((uint16(d.dataBufferSix[5])<<8)|uint16(d.dataBufferSix[4]))) * d.gyroMultiplier
	return
}

// ReadTemperature returns the temperature in celsius milli degrees (°C/1000)
func (d *Device) ReadTemperature() (int32, error) {
	d.bus.ReadRegister(uint8(d.Address), OUT_TEMP_L, d.dataBufferTwo)

	// From "Table 4. Temperature sensor characteristics"
	// temp = value/256 + 25
	t := 25000 + (int32(int16((int16(d.dataBufferTwo[1])<<8)|int16(d.dataBufferTwo[0])))*125)/32
	return t, nil
}