refactor(app): create application controller

systeroid/src/app.rs

@@ -0,0 +1,70 @@
+use std::io::{self, Stdout};
+use systeroid_core::config::Config;
+use systeroid_core::error::Result;
+use systeroid_core::sysctl::Sysctl;
+
+/// Application controller.
+#[derive(Debug)]
+pub struct App<'a> {
+    /// Sysctl manager.
+    sysctl: &'a mut Sysctl,
+    /// Configuration.
+    config: &'a Config,
+    /// Standard output.
+    stdout: Stdout,
+}
+
+impl<'a> App<'a> {
+    /// Constructs a new instance.
+    pub fn new(sysctl: &'a mut Sysctl, config: &'a Config) -> Self {
+        let stdout = io::stdout();
+        Self {
+            sysctl,
+            config,
+            stdout,
+        }
+    }
+
+    /// Displays all of the available kernel modules.
+    pub fn display_parameters(&mut self) -> Result<()> {
+        self.sysctl
+            .parameters
+            .iter()
+            .try_for_each(|parameter| parameter.display(&self.config.color, &mut self.stdout))
+    }
+
+    /// Updates the parameter if it has the format `name=value`, displays it otherwise.
+    pub fn process_parameter(&mut self, mut param_name: String) -> Result<()> {
+        let new_value = if param_name.contains('=') {
+            let fields = param_name
+                .split('=')
+                .take(2)
+                .map(String::from)
+                .collect::<Vec<String>>();
+            param_name = fields[0].to_string();
+            Some(fields[1].to_string())
+        } else {
+            None
+        };
+        match self
+            .sysctl
+            .parameters
+            .iter_mut()
+            .find(|param| param.name == *param_name)
+        {
+            Some(parameter) => {
+                if let Some(new_value) = new_value {
+                    parameter.update(&new_value, &self.config.color, &mut self.stdout)?;
+                } else {
+                    parameter.display(&self.config.color, &mut self.stdout)?;
+                }
+            }
+            None => eprintln!(
+                "{}: cannot stat /proc/{}: No such file or directory",
+                env!("CARGO_PKG_NAME"),
+                param_name.replace(".", "/")
+            ),
+        }
+        Ok(())
+    }
+}

systeroid/src/lib.rs

@@ -2,11 +2,13 @@
 
 #![warn(missing_docs, clippy::unwrap_used)]
 
+/// Main application.
+pub mod app;
 /// Command-line argument parser.
 pub mod args;
 
+use crate::app::App;
 use crate::args::Args;
-use std::io::{self, Write};
 use systeroid_core::config::Config;
 use systeroid_core::error::Result;
 use systeroid_core::sysctl::Sysctl;
@@ -15,50 +17,19 @@ use systeroid_core::sysctl::Sysctl;
 pub fn run(args: Args) -> Result<()> {
     let mut config = Config::default();
     config.color.no_color = args.no_color;
-    let (mut stdout, mut stderr) = (io::stdout(), io::stderr());
     let mut sysctl = Sysctl::init()?;
 
     if let Some(kernel_docs) = args.kernel_docs {
         sysctl.update_docs(&kernel_docs)?;
     }
 
+    let mut app = App::new(&mut sysctl, &config);
+
     if args.param_names.is_empty() {
-        sysctl
-            .parameters
-            .iter()
-            .try_for_each(|parameter| parameter.display(&config.color, &mut stdout))?;
+        app.display_parameters()?;
     } else {
-        for mut param_name in args.param_names {
-            let new_value = if param_name.contains('=') {
-                let fields = param_name
-                    .split('=')
-                    .take(2)
-                    .map(String::from)
-                    .collect::<Vec<String>>();
-                param_name = fields[0].to_string();
-                Some(fields[1].to_string())
-            } else {
-                None
-            };
-            match sysctl
-                .parameters
-                .iter_mut()
-                .find(|param| param.name == *param_name)
-            {
-                Some(parameter) => {
-                    if let Some(new_value) = new_value {
-                        parameter.update(&new_value, &config.color, &mut stdout)?;
-                    } else {
-                        parameter.display(&config.color, &mut stdout)?;
-                    }
-                }
-                None => writeln!(
-                    stderr,
-                    "{}: cannot stat /proc/{}: No such file or directory",
-                    env!("CARGO_PKG_NAME"),
-                    param_name.replace(".", "/")
-                )?,
-            }
+        for param_name in args.param_names {
+            app.process_parameter(param_name)?;
         }
     }