use std::{fs::OpenOptions, io::Write, thread, time::Duration};
use anyhow::{Result, Context};
use tracing::{info, warn};

#[derive(Clone)]
pub struct UsbGadget {
    udc_file: &'static str,
}

impl UsbGadget {
    pub fn new(name: &'static str) -> Self {
        // /sys/kernel/config/usb_gadget/<name>/UDC
        Self { udc_file: Box::leak(
            format!("/sys/kernel/config/usb_gadget/{name}/UDC").into_boxed_str())
        }
    }

    /// Force the host to re‑enumerate our HID gadget.
    pub fn cycle(&self) -> Result<()> {
        info!("UDC‑cycle: detaching gadget");
        OpenOptions::new().write(true).open(self.udc_file)?.write_all(b"")?;
        thread::sleep(Duration::from_millis(200));

        let udc_name = std::fs::read_dir("/sys/class/udc")?
            .next()
            .transpose()?
            .context("no UDC present")?
            .file_name();
        info!("UDC‑cycle: re‑attaching to {}", udc_name.to_string_lossy());
        OpenOptions::new().write(true).open(self.udc_file)?
            .write_all(udc_name.to_str().unwrap().as_bytes())?;
        info!("USB‑gadget cycled");
        Ok(())
    }
}