other: Dynamic battery widget (#975)

* Added dynamic battery widget

For bottom to know that there are no batteries on the system,
I added the battery::Manager to the options.rs file because
here is the first moment bottom verifies battery configuration
by reading the config file, which may or may not contain the
battery field, but for a better UX, it doesn't matter what bottom
finds in the config file now, if it doesn't retrieve battery data,
it just ignores the battery widget all together.
If needed, it can be adjusted so that if the config file contains
the battery field, it will still show the widget.

* CFG guarding for BATTERY module

I guarded the options.rs in two places for battery module that can be missing in the feature list.

Co-authored-by: RaresCon <RaresCon>
Co-authored-by: NitrogenDev <44950964+NitrogenDev@users.noreply.github.com>

docs/content/usage/widgets/battery.md

@@ -2,7 +2,7 @@
 
 !!! Warning
 
-    The battery features are unavailable if the binary is compiled with the `battery` feature disabled!
+    The battery features are unavailable if the binary is compiled with the `battery` feature disabled or if there are no batteries on the system!
 
 The battery widget provides information about batteries on the system.
 

src/options.rs

@@ -10,6 +10,10 @@ use clap::ArgMatches;
 use layout_options::*;
 use regex::Regex;
 use serde::{Deserialize, Serialize};
+
+#[cfg(feature = "battery")]
+use starship_battery::Manager;
+
 use typed_builder::*;
 
 use crate::{
@@ -844,6 +848,15 @@ fn get_hide_table_gap(matches: &ArgMatches, config: &Config) -> bool {
 }
 
 fn get_use_battery(matches: &ArgMatches, config: &Config) -> bool {
+    #[cfg(feature = "battery")]
+    if let Ok(battery_manager) = Manager::new() {
+        if let Ok(batteries) = battery_manager.batteries() {
+            if batteries.count() == 0 {
+                return false;
+            }
+        }
+    }
+
     if cfg!(feature = "battery") {
         if matches.is_present("battery") {
             return true;