1 files changed, 137 insertions, 0 deletions
diff --git a/src/power.rs b/src/power.rs
new file mode 100644
index 0000000..2a9dd31
--- /dev/null
+++ b/src/power.rs
@@ -0,0 +1,137 @@
+use std;
+use walkdir;
+
+use std::io::Read;
+
+// XXX maybe extract this out into a separate crate?
+
+#[derive(PartialEq,Eq,Debug,Clone)]
+enum PowerSupplyType {
+    AC,
+    Battery,
+}
+
+#[derive(Debug)]
+pub struct PowerInfo {
+    power_supplies: Vec<PowerSupplyInfo>,
+}
+
+#[derive(Debug,Clone)]
+struct PowerSupplyInfo {
+    name: String,
+    ty: PowerSupplyType,
+    energy_now: Option<u64>,
+    energy_full: Option<u64>,
+    online: Option<bool>,
+}
+
+impl PowerInfo {
+    pub fn new() -> PowerInfo {
+        let mut power_supplies = vec![];
+        for entry in walkdir::WalkDir::new("/sys/class/power_supply/").min_depth(1).max_depth(1).follow_links(true) {
+            let entry = entry.unwrap();
+
+            let name = entry.path()
+                .file_name()
+                .unwrap()
+                .to_string_lossy()
+                .into_owned();
+            let ty = slurp(entry.path().join("type"))
+                .map(|t: String| PowerSupplyType::from_str(&t))
+                .expect("couldn't find power supply type");
+            let full = slurp(entry.path().join("energy_full"));
+            let now = slurp(entry.path().join("energy_now"));
+            let online = slurp(entry.path().join("online"))
+                .map(|n: u8| n != 0);
+
+            power_supplies.push(
+                PowerSupplyInfo {
+                    name: name,
+                    ty: ty,
+                    energy_now: now,
+                    energy_full: full,
+                    online: online,
+                }
+            )
+        }
+
+        PowerInfo {
+            power_supplies: power_supplies,
+        }
+    }
+
+    pub fn battery_usage(&self) -> Option<f64> {
+        let mut total_now = 0;
+        let mut total_full = 0;
+        for battery in self.batteries() {
+            if let Some(now) = battery.energy_now {
+                total_now += now;
+            }
+            else {
+                return None;
+            }
+            if let Some(full) = battery.energy_full {
+                total_full += full;
+            }
+            else {
+                return None;
+            }
+        }
+
+        if total_full > 0 {
+            Some((total_now as f64) / (total_full as f64))
+        }
+        else {
+            None
+        }
+    }
+
+    pub fn charging(&self) -> bool {
+        for mains in self.mains() {
+            if mains.online == Some(true) {
+                return true;
+            }
+        }
+        false
+    }
+
+    fn batteries(&self) -> Vec<PowerSupplyInfo> {
+        self.power_supplies
+            .iter()
+            .cloned()
+            .filter(|p| p.ty == PowerSupplyType::Battery)
+            .collect()
+    }
+
+    fn mains(&self) -> Vec<PowerSupplyInfo> {
+        self.power_supplies
+            .iter()
+            .filter(|p| p.ty == PowerSupplyType::AC)
+            .cloned()
+            .collect()
+    }
+}
+
+impl PowerSupplyType {
+    fn from_str(ty: &str) -> Self {
+        match ty {
+            "Mains" => PowerSupplyType::AC,
+            "Battery" => PowerSupplyType::Battery,
+            _ => panic!("unknown power supply type {}", ty)
+        }
+    }
+}
+
+fn slurp<T, U>(path: U) -> Option<T>
+    where T: std::str::FromStr,
+          U: AsRef<std::path::Path>
+{
+    let mut contents = String::new();
+    std::fs::File::open(path)
+        .ok()
+        .and_then(|mut fh| {
+            fh.read_to_string(&mut contents)
+                .ok()
+                .and_then(|_| contents.trim().parse().ok())
+        })
+}