Add battery level to web UI

daemon/src/battery/tmobile.rs

@@ -0,0 +1,16 @@
+use std::path::Path;
+
+use crate::{
+    battery::{BatteryState, get_level_from_percentage_file, is_plugged_in_from_file},
+    error::RayhunterError,
+};
+
+const BATTERY_LEVEL_FILE: &str = "/sys/class/power_supply/bms/capacity";
+const PLUGGED_IN_STATE_FILE: &str = "/sys/devices/78d9000.usb/power_supply/usb/online";
+
+pub async fn get_battery_state() -> Result<BatteryState, RayhunterError> {
+    Ok(BatteryState {
+        level: get_level_from_percentage_file(Path::new(BATTERY_LEVEL_FILE)).await?,
+        is_plugged_in: is_plugged_in_from_file(Path::new(PLUGGED_IN_STATE_FILE)).await?,
+    })
+}