extern crate hmc5883l;
use hmc5883l::*;

use std::thread;
use std::time::Duration;
use std::f32::consts::PI;

/// based on https://github.com/adafruit/Adafruit_HMC5883_Unified/blob/master/examples/magsensor/magsensor.ino
fn main() {

    let mut mag = HMC5883L::new("/dev/i2c-1", 0x1E).unwrap();

    let gauss_lsb_xy = 1100.0;
    let gauss_lsb_z  =  980.0;

    // You need to determine the correct magnetic declination for your location for accurate
    // readings. Find yours at http://www.magnetic-declination.com/
    let declination_angle = 0.22; // in radians, not degrees

    loop {

        // read raw values
        let (x, y, z) = mag.read().unwrap();

        // convert to micro-teslas
        let (x, y, z) = (x/gauss_lsb_xy*100.0, y/gauss_lsb_xy*100.0, z/gauss_lsb_z*100.0);

        let mut heading = y.atan2(x) + declination_angle;

        if heading < 0.0 {
            heading += 2.0 * PI;
        }

        if heading > 2.0 * PI {
            heading -= 2.0 * PI;
        }

        // Convert radians to degrees for readability.
        heading = heading * 180.0 / PI;

        println!("x={:.*}, y={:.*}, z={:.*} uT: heading={:.*}", 1, x, 1, y, 1, z, 1, heading);

        thread::sleep(Duration::from_millis(500));
    }

}