refactor: Refactor memory_usage module to use module config. (#515)

Also addresses a number of bugs:
- the percent sign not displaying correctly on some terminal emulators, including kitty
- changing the symbol in the configuration file didn't do anything
- swap being shown even if the system didn't have any

4 files changed, 83 insertions, 57 deletions

diff --git a/docs/config/README.md b/docs/config/README.md
index c8cbee2bf..369a7febf 100644
--- a/docs/config/README.md
+++ b/docs/config/README.md
@@ -691,7 +691,7 @@ To enable it, set `disabled` to `false` in your configuration file.
 | Variable          | Default                  | Description                                                   |
 | ----------------- | ------------------------ | ------------------------------------------------------------- |
 | `show_percentage` | `false`                  | Display memory usage as a percentage of the available memory. |
-| `show_swap`       | when total swap non-zero | Display swap usage.                                           |
+| `show_swap`       | `true`                   | Display swap usage if total swap is non-zero.                 |
 | `threshold`       | `75`                     | Hide the memory usage unless it exceeds this percentage.      |
 | `symbol`          | `"🐏 "`                  | The symbol used before displaying the memory usage.           |
 | `style`           | `"bold dimmed white"`    | The style for the module.                                     |
diff --git a/src/configs/memory_usage.rs b/src/configs/memory_usage.rs
new file mode 100644
index 000000000..8b2b87982
--- /dev/null
+++ b/src/configs/memory_usage.rs
@@ -0,0 +1,29 @@
+use crate::config::{ModuleConfig, RootModuleConfig, SegmentConfig};
+
+use ansi_term::{Color, Style};
+use starship_module_config_derive::ModuleConfig;
+
+#[derive(Clone, ModuleConfig)]
+pub struct MemoryConfig<'a> {
+    pub show_percentage: bool,
+    pub show_swap: bool,
+    pub threshold: i64,
+    pub symbol: SegmentConfig<'a>,
+    pub display: SegmentConfig<'a>,
+    pub style: Style,
+    pub disabled: bool,
+}
+
+impl<'a> RootModuleConfig<'a> for MemoryConfig<'a> {
+    fn new() -> Self {
+        MemoryConfig {
+            show_percentage: false,
+            show_swap: true,
+            threshold: 75,
+            display: SegmentConfig::default(),
+            symbol: SegmentConfig::new("🐏 "),
+            style: Color::White.bold().dimmed(),
+            disabled: true,
+        }
+    }
+}
diff --git a/src/configs/mod.rs b/src/configs/mod.rs
index 95743df1c..f313a24e7 100644
--- a/src/configs/mod.rs
+++ b/src/configs/mod.rs
@@ -11,6 +11,7 @@ pub mod go;
 pub mod hostname;
 pub mod jobs;
 pub mod kubernetes;
+pub mod memory_usage;
 pub mod nodejs;
 pub mod package;
 pub mod python;
diff --git a/src/modules/memory_usage.rs b/src/modules/memory_usage.rs
index e3b7918c7..73324d83f 100644
--- a/src/modules/memory_usage.rs
+++ b/src/modules/memory_usage.rs
@@ -1,90 +1,86 @@
-use ansi_term::Color;
-
-use super::{Context, Module};
 use byte_unit::{Byte, ByteUnit};
 use sysinfo::{RefreshKind, SystemExt};
 
+use super::{Context, Module, RootModuleConfig};
+
+use crate::configs::memory_usage::MemoryConfig;
+
+fn format_kib(n_kib: u64) -> String {
+    let byte = Byte::from_unit(n_kib as f64, ByteUnit::KiB).unwrap_or_else(|_| Byte::from_bytes(0));
+    let mut display_bytes = byte.get_appropriate_unit(true).format(0);
+    display_bytes.retain(|c| c != ' ');
+    display_bytes
+}
+
 /// Creates a module with system memory usage information
 pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
-    const DEFAULT_THRESHOLD: i64 = 75;
-    const DEFAULT_SHOW_PERCENTAGE: bool = false;
-    const RAM_CHAR: &str = "🐏 ";
-
     let mut module = context.new_module("memory_usage");
+    let config = MemoryConfig::try_load(module.config);
+
+    // 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();
+    let percent_sign = match shell.as_str() {
+        "zsh" => "%%", // % is an escape in zsh, see PROMPT in `man zshmisc`
+        "powershell" => "`%",
+        _ => "%",
+    };
 
-    if module.config_value_bool("disabled").unwrap_or(true) {
+    if config.disabled {
         return None;
     }
 
-    let module_style = module
-        .config_value_style("style")
-        .unwrap_or_else(|| Color::White.bold().dimmed());
+    module.set_style(config.style);
 
     let system = sysinfo::System::new_with_specifics(RefreshKind::new().with_system());
 
     let used_memory_kib = system.get_used_memory();
     let total_memory_kib = system.get_total_memory();
-    let used_swap_kib = system.get_used_swap();
-    let total_swap_kib = system.get_total_swap();
 
     let percent_mem_used = (used_memory_kib as f64 / total_memory_kib as f64) * 100.;
-    let percent_swap_used = (used_swap_kib as f64 / total_swap_kib as f64) * 100.;
 
-    let threshold = module
-        .config_value_i64("threshold")
-        .unwrap_or(DEFAULT_THRESHOLD);
+    let threshold = config.threshold;
 
     if percent_mem_used.round() < threshold as f64 {
         return None;
     }
 
-    let show_percentage = module
-        .config_value_bool("show_percentage")
-        .unwrap_or(DEFAULT_SHOW_PERCENTAGE);
+    let show_percentage = config.show_percentage;
 
-    let (display_mem, display_swap) = if show_percentage {
-        (
-            format!("{:.0}%", percent_mem_used),
-            format!("{:.0}%", percent_swap_used),
-        )
+    let mut display = if show_percentage {
+        format!("{:.0}{}", percent_mem_used, percent_sign)
     } else {
-        fn format_kib(n_kib: u64) -> String {
-            let byte = Byte::from_unit(n_kib as f64, ByteUnit::KiB)
-                .unwrap_or_else(|_| Byte::from_bytes(0));
-            let mut display_bytes = byte.get_appropriate_unit(true).format(0);
-            display_bytes.retain(|c| c != ' ');
-            display_bytes
-        }
-        (
-            format!(
-                "{}/{}",
-                format_kib(used_memory_kib),
-                format_kib(total_memory_kib)
-            ),
-            format!(
-                "{}/{}",
-                format_kib(used_swap_kib),
-                format_kib(total_swap_kib)
-            ),
+        format!(
+            "{}/{}",
+            format_kib(used_memory_kib),
+            format_kib(total_memory_kib)
         )
     };
 
-    let show_swap = module
-        .config_value_bool("show_swap")
-        .unwrap_or(total_swap_kib != 0);
-
-    module.new_segment("symbol", RAM_CHAR);
-
-    module.set_style(module_style);
-    if show_swap {
-        module.new_segment(
-            "memory_usage",
-            &format!("{} | {}", display_mem, display_swap),
+    // swap only shown if enabled and there is swap on the system
+    let total_swap_kib = system.get_total_swap();
+    if config.show_swap && total_swap_kib > 0 {
+        let used_swap_kib = system.get_used_swap();
+        let percent_swap_used = (used_swap_kib as f64 / total_swap_kib as f64) * 100.;
+
+        display = format!(
+            "{} | {}",
+            display,
+            if show_percentage {
+                format!("{:.0}{}", percent_swap_used, percent_sign)
+            } else {
+                format!(
+                    "{}/{}",
+                    format_kib(used_swap_kib),
+                    format_kib(total_swap_kib)
+                )
+            }
         );
-    } else {
-        module.new_segment("memory_usage", &display_mem);
     }
 
+    module.create_segment("symbol", &config.symbol);
+    module.create_segment("memory_usage", &config.display.with_value(&display));
+
     module.get_prefix().set_value("");
 
     Some(module)