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use std::str;
use std::fs::OpenOptions;
use std::io::{Result, Read, Write, Error, ErrorKind};
use std::convert::AsRef;
use std::path::Path;
use std::thread::sleep;
use std::time::Duration;
const PATH_ENERGY_NOW: &'static str = "/sys/class/power_supply/BAT0/energy_now";
const PATH_ENERGY_FULL: &'static str = "/sys/class/power_supply/BAT0/energy_full_design";
const PATH_LIGHT: &'static str = "/sys/devices/platform/thinkpad_acpi/leds/tpacpi::power/brightness";
fn file_read_integer<P: AsRef<Path>>(path: P) -> Result<u64> {
let mut buf = [0; 20];
let mut file = OpenOptions::new().read(true).open(path.as_ref())?;
let len = file.read(&mut buf)?;
if len < 1 {
return Err(Error::new(ErrorKind::Other, "Empty file"));
};
let s = str::from_utf8(&buf[0..len])
.map_err(|e| Error::new(ErrorKind::Other, e))?;
s.trim().parse()
.map_err(|err| Error::new(ErrorKind::Other, format!("String parse failed: {}", err)))
}
fn read_battery_percentage() -> Result<u32> {
let now = file_read_integer(PATH_ENERGY_NOW)?;
let full = file_read_integer(PATH_ENERGY_FULL)?;
Ok(((now * 100) / full) as u32)
}
fn write_brightness(level: u8) -> Result<()> {
let string = format!("{}\n", level);
let mut file = OpenOptions::new().write(true).open(PATH_LIGHT)?;
if file.write(string.as_bytes())? == string.len() {
Ok(())
} else {
Err(Error::new(ErrorKind::Other, "Failed to write brightness"))
}
}
fn read_brightness() -> Result<u8> {
let level = file_read_integer(PATH_LIGHT)?;
Ok(level as u8)
}
fn indicate_battery_level(level: u32) -> Result<()> {
let led_state = read_brightness()?;
let flashing_time: u32 = 10000;
let offtime: u32 = 40;
let ontime: u32 = 20;
let n = flashing_time / (level * offtime + level * ontime);
for _ in 0..n {
write_brightness(0)?;
sleep(Duration::from_millis((level * offtime) as u64));
write_brightness(1)?;
sleep(Duration::from_millis((level * ontime) as u64));
}
write_brightness(led_state)?;
Ok(())
}
#[allow(unused)]
fn main() {
loop {
let p = read_battery_percentage();
match p {
Ok(level) => {
println!("Battery Level: {}", level);
if level < 20 {
match indicate_battery_level(level) {
Err(e) => panic!("Error: {}", e),
_ => {}
}
}
}
Err(e) => panic!("Error: {}", e),
}
}
}
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