colors: respect NO_COLOR spec

Microfetch will now respect the NO_COLOR environment variable if it has
been passed to the program. The performance overhead of this operation
is almost none. In addition, the main function has been updated to lock
stdout.

src/system.rs

@@ -1,14 +1,12 @@
+use crate::colors::COLORS;
 use color_eyre::Result;
 use nix::sys::{statvfs::statvfs, utsname::UtsName};
-
 use std::{
     env,
     fs::File,
     io::{self, Read},
 };
 
-use crate::colors::{CYAN, GREEN, RED, RESET, YELLOW};
-
 pub fn get_username_and_hostname(utsname: &UtsName) -> String {
     let username = env::var("USER").unwrap_or("unknown_user".to_string());
     let hostname = utsname
@@ -16,14 +14,18 @@ pub fn get_username_and_hostname(utsname: &UtsName) -> String {
         .to_str()
         .unwrap_or("unknown_host")
         .to_string();
-
-    format!("{YELLOW}{username}{RED}@{GREEN}{hostname}")
+    format!(
+        "{yellow}{username}{red}@{green}{hostname}{reset}",
+        yellow = COLORS.yellow,
+        red = COLORS.red,
+        green = COLORS.green,
+        reset = COLORS.reset,
+    )
 }
 
 pub fn get_shell() -> String {
     let shell_path = env::var("SHELL").unwrap_or("unknown_shell".to_string());
     let shell_name = shell_path.rsplit('/').next().unwrap_or("unknown_shell");
-
     shell_name.to_string()
 }
 
@@ -32,16 +34,15 @@ pub fn get_root_disk_usage() -> Result<String, io::Error> {
     let block_size = vfs.block_size() as u64;
     let total_blocks = vfs.blocks();
     let available_blocks = vfs.blocks_available();
-
     let total_size = block_size * total_blocks;
     let used_size = total_size - (block_size * available_blocks);
-
     let total_size = total_size as f64 / (1024.0 * 1024.0 * 1024.0);
     let used_size = used_size as f64 / (1024.0 * 1024.0 * 1024.0);
-    let usage = (used_size as f64 / total_size as f64) * 100.0;
-
+    let usage = (used_size / total_size) * 100.0;
     Ok(format!(
-        "{used_size:.2} GiB / {total_size:.2} GiB ({CYAN}{usage:.0}%{RESET})"
+        "{used_size:.2} GiB / {total_size:.2} GiB ({cyan}{usage:.0}%{reset})",
+        cyan = COLORS.cyan,
+        reset = COLORS.reset,
     ))
 }
 
@@ -50,35 +51,31 @@ pub fn get_memory_usage() -> Result<String, io::Error> {
     fn parse_memory_info() -> Result<(f64, f64), io::Error> {
         let mut total_memory_kb = 0.0;
         let mut available_memory_kb = 0.0;
-
         let mut meminfo = String::with_capacity(2048);
         File::open("/proc/meminfo")?.read_to_string(&mut meminfo)?;
-
         for line in meminfo.lines() {
             let mut split = line.split_whitespace();
             match split.next().unwrap_or_default() {
                 "MemTotal:" => total_memory_kb = split.next().unwrap_or("0").parse().unwrap_or(0.0),
                 "MemAvailable:" => {
                     available_memory_kb = split.next().unwrap_or("0").parse().unwrap_or(0.0);
-
                     // MemTotal comes before MemAvailable, stop parsing
                     break;
                 }
                 _ => (),
             }
         }
-
         let total_memory_gb = total_memory_kb / 1024.0 / 1024.0;
         let available_memory_gb = available_memory_kb / 1024.0 / 1024.0;
         let used_memory_gb = total_memory_gb - available_memory_gb;
-
         Ok((used_memory_gb, total_memory_gb))
     }
 
     let (used_memory, total_memory) = parse_memory_info()?;
     let percentage_used = (used_memory / total_memory * 100.0).round() as u64;
-
     Ok(format!(
-        "{used_memory:.2} GiB / {total_memory:.2} GiB ({CYAN}{percentage_used}%{RESET})"
+        "{used_memory:.2} GiB / {total_memory:.2} GiB ({cyan}{percentage_used}%{reset})",
+        cyan = COLORS.cyan,
+        reset = COLORS.reset,
     ))
 }