use hidapi::{HidApi, HidDevice};

fn find_device(api: &HidApi, usage_id: u16, usage_page: u16) -> anyhow::Result<HidDevice> {
    Ok({
        let devs = api
            .device_list()
            .filter(|dev| dev.usage() == usage_id && dev.usage_page() == usage_page)
            .collect::<Vec<_>>();

        assert_eq!(
            devs.len(),
            1,
            "Only one device should have such a usage:usage_page value"
        );

        api.open(devs[0].vendor_id(), devs[0].product_id())?
    })
}

pub fn monitor(api: &HidApi, usage_id: u16, usage_page: u16) -> anyhow::Result<()> {
    let device = find_device(api, usage_id, usage_page)?;

    loop {
        // Read data from device
        let mut buf = [0u8; 4];
        let res = device.read(&mut buf[..]).unwrap();

        let value = u32::from_le_bytes([buf[0], buf[1], buf[2], buf[3]]);

        println!("Read: {:?} ({} bytes) -> {value:x}", &buf[..res], res);
    }
}
pub fn send(api: &HidApi, usage_id: u16, usage_page: u16, message: u8) -> anyhow::Result<()> {
    let device = find_device(api, usage_id, usage_page)?;

    // Write data to device
    let mut buf = [0u8; 33];
    buf[1] = message;

    let res = device.write(&buf)?;
    println!("Wrote: {:#?} byte(s)", res);

    Ok(())
}