package mad.location.manager.lib.Filters;

/**
 * Created by lezh1k on 2/13/18.
 */

public class MadgwickAHRS {
    private float gain;
    private float sampleFreq;
    private float q0, q1, q2, q3; //quaternion

    public MadgwickAHRS(float sampleFreq, float gain) {
        this.gain = gain;
        this.sampleFreq = sampleFreq;
        q0 = 1.0f;
        q1 = q2 = q3 = 0.0f;
    }

    private static float invSqrt(float x) {
        return (float) (1.0f / Math.sqrt(x));
    }

    public void MadgwickAHRSupdate(float gx, float gy, float gz,
                                   float ax, float ay, float az,
                                   float mx, float my, float mz) {
        float recipNorm;
        float s0, s1, s2, s3;
        float qDot1, qDot2, qDot3, qDot4;
        float hx, hy;
        float _2q0mx, _2q0my, _2q0mz, _2q1mx, _2bx, _2bz, _4bx, _4bz, _2q0, _2q1, _2q2, _2q3, _2q0q2, _2q2q3, q0q0, q0q1, q0q2, q0q3, q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;

        // Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation)
        if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) {
            MadgwickAHRSupdateIMU(gx, gy, gz, ax, ay, az);
            return;
        }

        // Rate of change of quaternion from gyroscope
        qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
        qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
        qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
        qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);

        // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
        if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {

            // Normalise accelerometer measurement
            recipNorm = invSqrt(ax * ax + ay * ay + az * az);
            ax *= recipNorm;
            ay *= recipNorm;
            az *= recipNorm;

            // Normalise magnetometer measurement
            recipNorm = invSqrt(mx * mx + my * my + mz * mz);
            mx *= recipNorm;
            my *= recipNorm;
            mz *= recipNorm;

            // Auxiliary variables to avoid repeated arithmetic
            _2q0mx = 2.0f * q0 * mx;
            _2q0my = 2.0f * q0 * my;
            _2q0mz = 2.0f * q0 * mz;
            _2q1mx = 2.0f * q1 * mx;
            _2q0 = 2.0f * q0;
            _2q1 = 2.0f * q1;
            _2q2 = 2.0f * q2;
            _2q3 = 2.0f * q3;
            _2q0q2 = 2.0f * q0 * q2;
            _2q2q3 = 2.0f * q2 * q3;
            q0q0 = q0 * q0;
            q0q1 = q0 * q1;
            q0q2 = q0 * q2;
            q0q3 = q0 * q3;
            q1q1 = q1 * q1;
            q1q2 = q1 * q2;
            q1q3 = q1 * q3;
            q2q2 = q2 * q2;
            q2q3 = q2 * q3;
            q3q3 = q3 * q3;

            // Reference direction of Earth's magnetic field
            hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3;
            hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3;
            _2bx = (float) Math.sqrt(hx * hx + hy * hy);
            _2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3;
            _4bx = 2.0f * _2bx;
            _4bz = 2.0f * _2bz;

            // Gradient decent algorithm corrective step
            s0 = -_2q2 * (2.0f * q1q3 - _2q0q2 - ax) + _2q1 * (2.0f * q0q1 + _2q2q3 - ay) - _2bz * q2 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q3 + _2bz * q1) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q2 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
            s1 = _2q3 * (2.0f * q1q3 - _2q0q2 - ax) + _2q0 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q1 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + _2bz * q3 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q2 + _2bz * q0) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q3 - _4bz * q1) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
            s2 = -_2q0 * (2.0f * q1q3 - _2q0q2 - ax) + _2q3 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q2 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + (-_4bx * q2 - _2bz * q0) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q1 + _2bz * q3) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q0 - _4bz * q2) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
            s3 = _2q1 * (2.0f * q1q3 - _2q0q2 - ax) + _2q2 * (2.0f * q0q1 + _2q2q3 - ay) + (-_4bx * q3 + _2bz * q1) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q0 + _2bz * q2) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q1 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
            recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
            s0 *= recipNorm;
            s1 *= recipNorm;
            s2 *= recipNorm;
            s3 *= recipNorm;

            // Apply feedback step
            qDot1 -= gain * s0;
            qDot2 -= gain * s1;
            qDot3 -= gain * s2;
            qDot4 -= gain * s3;
        }

        // Integrate rate of change of quaternion to yield quaternion
        q0 += qDot1 * (1.0f / sampleFreq);
        q1 += qDot2 * (1.0f / sampleFreq);
        q2 += qDot3 * (1.0f / sampleFreq);
        q3 += qDot4 * (1.0f / sampleFreq);

        // Normalise quaternion
        recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
        q0 *= recipNorm;
        q1 *= recipNorm;
        q2 *= recipNorm;
        q3 *= recipNorm;
    }

    public void MadgwickAHRSupdateIMU(float gx, float gy, float gz, float ax, float ay, float az) {
        float recipNorm;
        float s0, s1, s2, s3;
        float qDot1, qDot2, qDot3, qDot4;
        float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3;

        // Rate of change of quaternion from gyroscope
        qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
        qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
        qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
        qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);

        // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
        if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {

            // Normalise accelerometer measurement
            recipNorm = invSqrt(ax * ax + ay * ay + az * az);
            ax *= recipNorm;
            ay *= recipNorm;
            az *= recipNorm;

            // Auxiliary variables to avoid repeated arithmetic
            _2q0 = 2.0f * q0;
            _2q1 = 2.0f * q1;
            _2q2 = 2.0f * q2;
            _2q3 = 2.0f * q3;
            _4q0 = 4.0f * q0;
            _4q1 = 4.0f * q1;
            _4q2 = 4.0f * q2;
            _8q1 = 8.0f * q1;
            _8q2 = 8.0f * q2;
            q0q0 = q0 * q0;
            q1q1 = q1 * q1;
            q2q2 = q2 * q2;
            q3q3 = q3 * q3;

            // Gradient decent algorithm corrective step
            s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay;
            s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az;
            s2 = 4.0f * q0q0 * q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az;
            s3 = 4.0f * q1q1 * q3 - _2q1 * ax + 4.0f * q2q2 * q3 - _2q2 * ay;
            recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
            s0 *= recipNorm;
            s1 *= recipNorm;
            s2 *= recipNorm;
            s3 *= recipNorm;

            // Apply feedback step
            qDot1 -= gain * s0;
            qDot2 -= gain * s1;
            qDot3 -= gain * s2;
            qDot4 -= gain * s3;
        }

        // Integrate rate of change of quaternion to yield quaternion
        q0 += qDot1 * (1.0f / sampleFreq);
        q1 += qDot2 * (1.0f / sampleFreq);
        q2 += qDot3 * (1.0f / sampleFreq);
        q3 += qDot4 * (1.0f / sampleFreq);

        // Normalise quaternion
        recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
        q0 *= recipNorm;
        q1 *= recipNorm;
        q2 *= recipNorm;
        q3 *= recipNorm;
    }
}
