use std::process::Command;

extern crate libc;
use libc::{c_int, c_char};

#[macro_use] extern crate redhook;

static mut BUTTON_STATE: [bool; 5] = [false; 5];
hook! {
    unsafe fn read(fd: c_int, buf: *const c_char, count: c_int) -> c_int => read_hook {
        let res = real!(read)(fd, buf, count);

        if fd != 6 {
            return res;
        }

        // The data being read is an evdev input_event.
        // The data we care about is the `code` which is used as the key identifier (102 for Middle button, 105 for Left button, 106 for Right button, 116 for power).
        // offset 10 -> key identifier
        // offset 12 -> state change -> 0=release/1=press

        let code = *buf.offset(10);
        let state = *buf.offset(12);

        let button_index = match code {
            102 => 0,
            105 => 1,
            106 => 2,
            116 => 3,
            _ => 4, // any unknown buttons just write their state to an extra slot. this is to avoid an extra branch in the code / early return.
        };

        match state {
            0 => BUTTON_STATE[button_index] = false,
            1 => BUTTON_STATE[button_index] = true,
            _ => {},
        }

        if BUTTON_STATE[1] && BUTTON_STATE[2] {
            println!("I want to exit now...");
            Command::new("systemctl")
                .arg("stop")
                .arg("xochitl")
                .output()
                .expect("failed to call systemctl");
        }

        res
    }
}