.envrc

@@ -1 +0,0 @@
-use flake

.gitignore

@@ -1,7 +1,11 @@
+# build
 /target
 /result
 
-.direnv
+# environments
 .env*
 !.env.example
 
+# direnv
+.envrc
+.direnv

Cargo.lock

@@ -197,6 +197,7 @@ name = "vnetod"
 version = "0.3.3"
 dependencies = [
  "clap",
+ "termcolor",
 ]
 
 [[package]]

Cargo.toml

@@ -13,6 +13,7 @@ categories = ["command-line-interface", "config", "development-tools"]
 
 [dependencies]
 clap = { version = "3.2.15", default-features = false, features = ["std", "env", "derive"] }
+termcolor = { version = "1.1.3", optional = true }
 
 [features]
-color = ["clap/color"]
+color = ["clap/color", "dep:termcolor"]

flake.nix

@@ -11,22 +11,28 @@
       cargoToml = fromTOML (readFile ./Cargo.toml);
       version = "${cargoToml.package.version}+${substring 0 8 self.lastModifiedDate}.${self.shortRev or "dirty"}";
 
-      mkVnetod = { lib, rustPlatform, ... }:
+      mkVnetod = { lib, rustPlatform, vnetodFeatures ? [ ], ... }:
         rustPlatform.buildRustPackage {
           name = "vnetod-${version}";
 
           src = lib.cleanSource ./.;
           cargoLock.lockFile = ./Cargo.lock;
 
+          buildFeatures = vnetodFeatures;
+
           doCheck = true;
         };
     in
     {
-      overlays = rec {
-        vnetod = final: prev: {
+      overlays = {
+        default = final: prev: {
           vnetod = final.callPackage mkVnetod { };
         };
-        default = vnetod;
+        colored = final: prev: {
+          vnetod = final.callPackage mkVnetod {
+            vnetodFeatures = [ "color" ];
+          };
+        };
       };
     }
     // flake-utils.lib.eachDefaultSystem (system:
@@ -34,6 +40,7 @@
         pkgs = import nixpkgs { inherit system; };
 
         vnetod = pkgs.callPackage mkVnetod { };
+        coloredVnetod = pkgs.callPackage mkVnetod { vnetodFeatures = [ "color" ]; };
 
         docker = pkgs.dockerTools.buildLayeredImage {
           name = "pleshevskiy/vnetod";
@@ -46,14 +53,21 @@
         };
       in
       {
-        apps.default = {
-          type = "app";
-          program = "${vnetod}/bin/vnetod";
+        apps = {
+          default = {
+            type = "app";
+            program = "${vnetod}/bin/vnetod";
+          };
+          colored = {
+            type = "app";
+            program = "${coloredVnetod}/bin/vnetod";
+          };
         };
 
         packages = {
           inherit docker vnetod;
           default = vnetod;
+          colored = coloredVnetod;
         };
 
         devShell = pkgs.mkShell {

src/cli/switch.rs

@@ -14,21 +14,24 @@
 //! along with vnetod.  If not, see <https://www.gnu.org/licenses/>.
 //!
 
+#[cfg(feature = "color")]
+use termcolor::{Color, ColorChoice, ColorSpec, StandardStream, WriteColor};
+
 use crate::{cli::Args, domain};
 use std::fs::File;
-use std::io::{stdout, Write};
+use std::io::Write;
 
 #[derive(Debug)]
 pub enum Error {
     OpenFile,
-    Switch(domain::switch::Error),
+    WriteFile,
 }
 
 impl std::fmt::Display for Error {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             Error::OpenFile => f.write_str("Cannot open file"),
-            Error::Switch(inner) => write!(f, "Cannot switch between states: {}", inner),
+            Error::WriteFile => f.write_str("Cannot write file"),
         }
     }
 }
@@ -38,20 +41,39 @@ impl std::error::Error for Error {}
 pub fn execute(args: &Args) -> Result<(), Error> {
     let content = std::fs::read_to_string(&args.file).map_err(|_| Error::OpenFile)?;
 
-    let writer: Box<dyn Write> = if args.dry_run {
-        Box::new(stdout())
-    } else {
-        Box::new(
-            File::create(args.output.as_ref().unwrap_or(&args.file))
-                .map_err(|_| Error::OpenFile)?,
-        )
-    };
+    let fs_writer = (!args.dry_run)
+        .then(|| {
+            File::create(args.output.as_ref().unwrap_or(&args.file)).map_err(|_| Error::OpenFile)
+        })
+        .transpose()?;
 
-    domain::switch::execute(domain::switch::Request {
+    let new_content = domain::switch::execute(domain::switch::Request {
         content: &content,
-        writer,
         sections: &args.sections,
-        on_line: None,
-    })
-    .map_err(Error::Switch)
+        on_line: Some(Box::new(print_line)),
+    });
+    if let Some(mut fs_writer) = fs_writer {
+        fs_writer
+            .write_all(new_content.as_bytes())
+            .map_err(|_| Error::WriteFile)?;
+    }
+
+    Ok(())
+}
+
+#[cfg(feature = "color")]
+fn print_line(line: &String) {
+    let mut stdout = StandardStream::stdout(ColorChoice::Always);
+    let color = line
+        .starts_with("###")
+        .then_some(Color::Yellow)
+        .or_else(|| (!line.starts_with("#")).then_some(Color::Green));
+    stdout.set_color(ColorSpec::new().set_fg(color)).ok();
+    write!(&mut stdout, "{}", line).unwrap();
+    stdout.reset().ok();
+}
+
+#[cfg(not(feature = "color"))]
+fn print_line(line: &String) {
+    print!("{}", line)
 }

src/domain.rs

@@ -44,7 +44,7 @@ impl Section {
     }
 }
 
-pub(crate) struct SectionInfo {
+pub struct SectionInfo {
     enable_variable: bool,
     disable_variable: bool,
 }

src/domain/switch.rs

@@ -14,43 +14,17 @@
 //! along with vnetod.  If not, see <https://www.gnu.org/licenses/>.
 //!
 
-use std::io::{BufWriter, Write};
-
 use super::{Section, SectionInfo};
 
-#[derive(Debug)]
-pub enum Error {
-    WriteData,
-}
+pub type OnLineFn = Box<dyn Fn(&String)>;
 
-impl std::fmt::Display for Error {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Error::WriteData => f.write_str("Cannot write data"),
-        }
-    }
-}
-
-impl std::error::Error for Error {}
-
-pub type OnLineFn = Box<dyn Fn(Option<&SectionInfo>, &String)>;
-
-pub struct Request<'args, W>
-where
-    W: Write,
-{
+pub struct Request<'args> {
     pub content: &'args str,
-    pub writer: W,
     pub sections: &'args [String],
     pub on_line: Option<OnLineFn>,
 }
 
-pub fn execute<W>(req: Request<W>) -> Result<(), Error>
-where
-    W: Write,
-{
-    let mut writer = BufWriter::new(req.writer);
-
+pub fn execute(req: Request) -> String {
     let choose_sections = req
         .sections
         .iter()
@@ -58,6 +32,7 @@ where
         .collect::<Vec<_>>();
 
     let mut current_section: Option<SectionInfo> = None;
+    let mut new_content = String::new();
 
     for line in req.content.split_inclusive('\n') {
         let new_line = if is_section_end(line) {
@@ -86,16 +61,13 @@ where
             line.to_string()
         };
 
-        writer
-            .write_all(new_line.as_bytes())
-            .map_err(|_| Error::WriteData)?;
-
+        new_content.push_str(&new_line);
         if let Some(on_line) = req.on_line.as_ref() {
-            on_line(current_section.as_ref(), &new_line);
+            on_line(&new_line);
         }
     }
 
-    writer.flush().map_err(|_| Error::WriteData)
+    new_content
 }
 
 fn is_variable(trimmed_line: &str) -> bool {
@@ -151,28 +123,19 @@ fn should_disable_variable(choose_sections: &[Section], current_sections: &[Sect
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::io::Cursor;
 
     const BASE_ENV: &str = include_str!("../../test_data/base_env");
 
     fn make_test(input: &str, expected_output: &str, sections: Vec<&str>) {
-        let mut output_data = vec![];
-        let writer = Cursor::new(&mut output_data);
-
-        match execute(Request {
+        let output_data = execute(Request {
             content: input,
-            writer,
             sections: &sections.into_iter().map(String::from).collect::<Vec<_>>(),
-        }) {
-            Ok(()) => {
-                let output = String::from_utf8(output_data).unwrap();
-                assert_eq!(
-                    output.lines().collect::<Vec<_>>(),
-                    expected_output.lines().collect::<Vec<_>>()
-                );
-            }
-            _ => unreachable!(),
-        }
+            on_line: None,
+        });
+        assert_eq!(
+            output_data.lines().collect::<Vec<_>>(),
+            expected_output.lines().collect::<Vec<_>>()
+        );
     }
 
     #[test]