feat: Implement threshold based styling for battery module (#318)

docs/config/README.md

@@ -110,11 +110,11 @@ The module is only visible when the device's battery is below 10%.
 ### Options
 
 | Variable             | Default                  | Description                                       |
-| -------------------- | ------------ | ------------------------------------------------- |
+| -------------------- | ------------------------ | ------------------------------------------------- |
 | `full_symbol`        | `"•"`                    | The symbol shown when the battery is full.        |
 | `charging_symbol`    | `"⇡"`                    | The symbol shown when the battery is charging.    |
 | `discharging_symbol` | `"⇣"`                    | The symbol shown when the battery is discharging. |
-| `style`              | `"bold red"` | The style for the module.                         |
+| `display`            | [link](#battery-display) | Display threshold and style for the module.       |
 | `disabled`           | `false`                  | Disables the `battery` module.                    |
 
 ### Example
@@ -128,6 +128,41 @@ charging_symbol = "⚡️"
 discharging_symbol = "💀"
 ```
 
+### Battery Display
+
+The `display` configuration option is used to define when the battery indicator should be shown (threshold) and what it looks like (style).
+If no `display` is provided. The default is as shown:
+
+```toml
+[[battery.display]]
+threshold = 10
+style = "bold red"
+```
+
+#### Options
+
+The `display` option is an array of the following table.
+
+| Variable    | Description                                     |
+|-------------|-------------------------------------------------|
+| `threshold` | The upper bound for the display option.         |
+| `style`     | The style used if the display option is in use. |
+
+#### Example
+
+```toml
+[[battery.display]]  # "bold red" style when capacity is between 0% and 10%
+threshold = 10
+style = "bold red"
+
+[[battery.display]]  # "bold yellow" style when capacity is between 10% and 30%
+threshold = 30
+style = "bold yellow"
+
+# when capacity is over 30%, the battery indicator will not be displayed
+
+```
+
 ## Character
 
 The `character` module shows a character (usually an arrow) beside where the text

src/module.rs

@@ -145,6 +145,11 @@ impl<'a> Module<'a> {
     pub fn config_value_style(&self, key: &str) -> Option<Style> {
         self.config.and_then(|config| config.get_as_ansi_style(key))
     }
+
+    /// Get a module's config value as an array
+    pub fn config_value_array(&self, key: &str) -> Option<&Vec<toml::Value>> {
+        self.config.and_then(|config| config.get_as_array(key))
+    }
 }
 
 impl<'a> fmt::Display for Module<'a> {

src/modules/battery.rs

@@ -1,13 +1,13 @@
-use ansi_term::Color;
+use ansi_term::{Color, Style};
 
 use super::{Context, Module};
+use crate::config::Config;
 
 /// Creates a module for the battery percentage and charging state
 pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
     const BATTERY_FULL: &str = "•";
     const BATTERY_CHARGING: &str = "⇡";
     const BATTERY_DISCHARGING: &str = "⇣";
-    const BATTERY_THRESHOLD: f32 = 10.0;
     // TODO: Update when v1.0 printing refactor is implemented to only
     // print escapes in a prompt context.
     let shell = std::env::var("STARSHIP_SHELL").unwrap_or_default();
@@ -19,21 +19,20 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
     let battery_status = get_battery_status()?;
     let BatteryStatus { state, percentage } = battery_status;
 
-    if percentage > BATTERY_THRESHOLD {
-        log::debug!(
-            "Battery percentage is higher than threshold ({} > {})",
-            percentage,
-            BATTERY_THRESHOLD
-        );
-        return None;
-    }
-
-    // TODO: Set style based on percentage when threshold is modifiable
     let mut module = context.new_module("battery");
-    let module_style = module
+
-        .config_value_style("style")
+    // Parse config under `display`
-        .unwrap_or_else(|| Color::Red.bold());
+    let display_styles = get_display_styles(&module);
-    module.set_style(module_style);
+    let display_style = display_styles.iter().find(|display_style| {
+        let BatteryDisplayStyle { threshold, .. } = display_style;
+        percentage <= *threshold as f32
+    });
+
+    if let Some(display_style) = display_style {
+        let BatteryDisplayStyle { style, .. } = display_style;
+
+        // Set style based on percentage
+        module.set_style(*style);
         module.get_prefix().set_value("");
 
         match state {
@@ -56,6 +55,31 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
         module.new_segment("percentage", percent_string.join("").as_ref());
 
         Some(module)
+    } else {
+        None
+    }
+}
+
+fn get_display_styles(module: &Module) -> Vec<BatteryDisplayStyle> {
+    if let Some(display_configs) = module.config_value_array("display") {
+        let mut display_styles: Vec<BatteryDisplayStyle> = vec![];
+        for display_config in display_configs.iter() {
+            if let toml::Value::Table(config) = display_config {
+                if let Some(display_style) = BatteryDisplayStyle::from_config(config) {
+                    display_styles.push(display_style);
+                }
+            }
+        }
+
+        // Return display styles as long as display array exists, even if it is empty.
+        display_styles
+    } else {
+        // Default display styles: [{ threshold = 10, style = "red bold" }]
+        vec![BatteryDisplayStyle {
+            threshold: 10,
+            style: Color::Red.bold(),
+        }]
+    }
 }
 
 fn get_battery_status() -> Option<BatteryStatus> {
@@ -85,3 +109,19 @@ struct BatteryStatus {
     percentage: f32,
     state: battery::State,
 }
+
+#[derive(Clone, Debug)]
+struct BatteryDisplayStyle {
+    threshold: i64,
+    style: Style,
+}
+
+impl BatteryDisplayStyle {
+    /// construct battery display style from toml table
+    pub fn from_config(config: &toml::value::Table) -> Option<BatteryDisplayStyle> {
+        let threshold = config.get_as_i64("threshold")?;
+        let style = config.get_as_ansi_style("style")?;
+
+        Some(BatteryDisplayStyle { threshold, style })
+    }
+}