From 7b8412d8b84d3fd37f43c0b07a1b8049a21dd999 Mon Sep 17 00:00:00 2001
From: Yves Fischer <yvesf-git@xapek.org>
Date: Thu, 4 Jan 2018 20:34:54 +0100
Subject: seems to work

---
 src/main.rs | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 src/main.rs

(limited to 'src')

diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..b404cfa
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,81 @@
+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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