nix: fix overlays

- color - moved to a feature . To enable install vnetod with
- suggestions

.dockerignore

@@ -1,4 +0,0 @@
-/target
-
-.env*
-!.envrc

.envrc

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

.gitignore

@@ -1,4 +1,11 @@
+# build
 /target
+/result
 
+# environments
 .env*
 !.env.example
+
+# direnv
+.envrc
+.direnv

Cargo.lock

@@ -37,7 +37,6 @@ dependencies = [
  "clap_lex",
  "indexmap",
  "once_cell",
- "strsim",
  "termcolor",
  "textwrap",
 ]
@@ -155,12 +154,6 @@ dependencies = [
  "proc-macro2",
 ]
 
-[[package]]
-name = "strsim"
-version = "0.10.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
-
 [[package]]
 name = "syn"
 version = "1.0.98"
@@ -201,9 +194,11 @@ checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 
 [[package]]
 name = "vnetod"
-version = "0.1.0"
+version = "0.4.0"
 dependencies = [
+ "atty",
  "clap",
+ "termcolor",
 ]
 
 [[package]]

Cargo.toml

@@ -1,9 +1,10 @@
 [package]
 name = "vnetod"
-description = "Dotenv state switcher"
-version = "0.2.2"
+description = "Are you still switching sections in your dotenv file manually? Try this dotenv section switcher"
+version = "0.4.0"
 edition = "2021"
 license = "GPL-3.0+"
+homepage = "https://github.com/pleshevskiy/vnetod/discussions"
 repository = "https://git.pleshevski.ru/pleshevskiy/vnetod.git"
 keywords = ["env", "dotenv", "switcher", "change"]
 categories = ["command-line-interface", "config", "development-tools"]
@@ -11,6 +12,9 @@ categories = ["command-line-interface", "config", "development-tools"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-clap = { version = "3.2.15", features = ["derive"] }
+clap = { version = "3.2.15", default-features = false, features = ["std", "env", "derive"] }
+atty = { version = "0.2.14", optional = true }
+termcolor = { version = "1.1.3", optional = true }
 
 [features]
+color = ["clap/color", "dep:atty", "dep:termcolor"]

Dockerfile

@@ -1,16 +0,0 @@
-FROM rust:1.62.0-slim-buster
-
-WORKDIR /app
-
-COPY Cargo.* ./
-COPY ./src ./src
-
-RUN cargo install --bin vnetod --path . \
-  && rm -rf ./src Cargo.*
-
-VOLUME ["/data"]
-
-WORKDIR /data
-
-ENTRYPOINT ["/usr/local/cargo/bin/vnetod"]
-

README.md

@@ -1,17 +1,20 @@
-# vnetod
+# vnetod*
 
-Dotenv state switcher
+<small><strong>*</strong> inverted word "dotenv"</small>
 
-You can create many states in your `.env` and switch between them.
+Are you still switching sections in your dotenv file manually? Try this dotenv
+section switcher!
+
+You can create many sections in your `.env` and switch between them.
 
 Rules:
 
-- State name starts on a new line with `###` symbols (Ex. `### local`)
-- State name can contain multiple comma-separated sections (Ex.
+- Section name starts on a new line with `###` symbols (Ex. `### local`)
+- Section can contain multiple comma-separated names (Ex.
   `### local,staging`)
-- Each section may specify a namespace (Ex. `### debug:on,dev:on`). If a section
-  doesn't contain a namespace, it's a global namespace.
-- State ends if line is empty or contains a new state name.
+- Each section name may specify a namespace (Ex. `### debug:on,dev:on`). If a
+  section doesn't contain a namespace, it's a global namespace.
+- Section ends if line is empty or contains a new section name.
 
 You can see the [full example].
 
@@ -34,7 +37,7 @@ behavior with the `-f` (`--file`) flag.
 
 ```sh
 cp .env.example .env.properties
-vnetod .env.properties local
+vnetod -f .env.properties local
 ```
 
 And you can also change the output file with the `-o` (`--output`) flag, if you
@@ -82,10 +85,17 @@ docker run --rm -it -v $PWD:/data pleshevskiy/vnetod --help
 nix run git+https://git.pleshevski.ru/pleshevskiy/vnetod -- --help
 ```
 
+# Contact me
+
+- [send feedback](https://github.com/pleshevskiy/vnetod/discussions)
+- [make an issue](https://github.com/pleshevskiy/vnetod/issues)
+- matrix: @pleshevskiy:matrix.org
+- email: dmitriy@pleshevski.ru
+
 # License
 
 GNU General Public License v3.0 or later
 
-See [COPYING](./COPYING) to see the full text.
+See [COPYING] to see the full text.
 
 [COPYING]: https://git.pleshevski.ru/pleshevskiy/vnetod/src/branch/main/COPYING

docker/README.md

@@ -0,0 +1,38 @@
+# Supported tags
+
+- latest
+- 0.4
+
+# vnetod*
+
+<small><strong>*</strong> inverted word "dotenv"</small>
+
+Are you still switching sections in your dotenv file manually? Try this dotenv
+section switcher!
+
+You can create many sections in your `.env` and switch between them.
+
+Rules:
+
+- Section name starts on a new line with `###` symbols (Ex. `### local`)
+- Section can contain multiple comma-separated names (Ex.
+  `### local,staging`)
+- Each section name may specify a namespace (Ex. `### debug:on,dev:on`). If a
+  section doesn't contain a namespace, it's a global namespace.
+- Section ends if line is empty or contains a new section name.
+
+# Usage
+
+```sh
+docker run --rm -it -v $PWD:/data pleshevskiy/vnetod -f .env.example -o .env staging db:local debug:on
+```
+
+For more details see [the repo](https://git.pleshevski.ru/pleshevskiy/vnetod)
+
+# License
+
+GNU General Public License v3.0 or later
+
+See [COPYING] to see the full text.
+
+[COPYING]: https://git.pleshevski.ru/pleshevskiy/vnetod/src/branch/main/COPYING

flake.lock

@@ -1,39 +1,21 @@
 {
   "nodes": {
-    "naersk": {
-      "inputs": {
-        "nixpkgs": "nixpkgs"
-      },
+    "flake-utils": {
       "locked": {
-        "lastModified": 1655042882,
-        "narHash": "sha256-9BX8Fuez5YJlN7cdPO63InoyBy7dm3VlJkkmTt6fS1A=",
-        "owner": "nix-community",
-        "repo": "naersk",
-        "rev": "cddffb5aa211f50c4b8750adbec0bbbdfb26bb9f",
+        "lastModified": 1667395993,
+        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
         "type": "github"
       },
       "original": {
-        "owner": "nix-community",
-        "ref": "master",
-        "repo": "naersk",
+        "owner": "numtide",
+        "repo": "flake-utils",
         "type": "github"
       }
     },
     "nixpkgs": {
-      "locked": {
-        "lastModified": 1659190188,
-        "narHash": "sha256-LudYrDFPFaQMW0l68TYkPWRPKmqpxIFU1nWfylIp9AQ=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "a3fddd46a7f3418d7e3940ded94701aba569161d",
-        "type": "github"
-      },
-      "original": {
-        "id": "nixpkgs",
-        "type": "indirect"
-      }
-    },
-    "nixpkgs_2": {
       "locked": {
         "lastModified": 1659190188,
         "narHash": "sha256-LudYrDFPFaQMW0l68TYkPWRPKmqpxIFU1nWfylIp9AQ=",
@@ -51,24 +33,8 @@
     },
     "root": {
       "inputs": {
-        "naersk": "naersk",
-        "nixpkgs": "nixpkgs_2",
-        "utils": "utils"
-      }
-    },
-    "utils": {
-      "locked": {
-        "lastModified": 1656928814,
-        "narHash": "sha256-RIFfgBuKz6Hp89yRr7+NR5tzIAbn52h8vT6vXkYjZoM=",
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "rev": "7e2a3b3dfd9af950a856d66b0a7d01e3c18aa249",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "type": "github"
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
       }
     }
   },

flake.nix

@@ -1,46 +1,77 @@
 {
   inputs = {
-    naersk.url = "github:nix-community/naersk/master";
     nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
-    utils.url = "github:numtide/flake-utils";
+    flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, utils, naersk }:
-    utils.lib.eachDefaultSystem (system:
+  outputs = { self, nixpkgs, flake-utils }:
+    let
+      inherit (builtins) fromTOML readFile substring;
+
+      cargoToml = fromTOML (readFile ./Cargo.toml);
+      version = "${cargoToml.package.version}+${substring 0 8 self.lastModifiedDate}.${self.shortRev or "dirty"}";
+
+      mkVnetod = { lib, rustPlatform, vnetodFeatures ? [ ], ... }:
+        rustPlatform.buildRustPackage {
+          name = "vnetod-${version}";
+
+          src = lib.cleanSource ./.;
+          cargoLock.lockFile = ./Cargo.lock;
+
+          buildFeatures = vnetodFeatures;
+
+          doCheck = true;
+        };
+    in
+    {
+      overlays = {
+        minimal = final: prev: {
+          vnetod = final.callPackage mkVnetod { };
+        };
+        default = final: prev: {
+          vnetod = final.callPackage mkVnetod {
+            vnetodFeatures = [ "color" ];
+          };
+        };
+      };
+    }
+    // flake-utils.lib.eachDefaultSystem (system:
       let
-        name = "vnetod";
         pkgs = import nixpkgs { inherit system; };
-        naersk-lib = pkgs.callPackage naersk { };
+
+        vnetod = pkgs.callPackage mkVnetod { vnetodFeatures = [ "color" ]; };
+        minimalVnetod = pkgs.callPackage mkVnetod { };
+
+        docker = pkgs.dockerTools.buildLayeredImage {
+          name = "pleshevskiy/vnetod";
+          tag = cargoToml.package.version;
+          config = {
+            Volumes."/data" = { };
+            WorkingDir = "/data";
+            Entrypoint = [ "${vnetod}/bin/vnetod" ];
+          };
+        };
+
+        mkApp = prog: {
+          type = "app";
+          program = "${vnetod}/bin/vnetod";
+        };
       in
-      rec {
-        # Executes by `nix build .#<name>`
-        packages = {
-         ${name} = naersk.lib.${system}.buildPackage {
-            pname = name;
-            root = ./.;
-          };
-        };
-        # Executes by `nix build .`
-        packages.default = packages.${name};
-        # the same but deprecated in Nix 2.7
-        defaultPackage = packages.default;
-
-        # Executes by `nix run .#<name> -- <args?>` 
+      {
         apps = {
-          ${name} = utils.lib.mkApp {
-            inherit name;
-            drv = packages.${name};
-          };
+          default = mkApp vnetod;
+          minimal = mkApp minimalVnetod;
         };
-        # Executes by `nix run . -- <args?>`
-        apps.default = apps.${name};
-        # the same but deprecated in Nix 2.7
-        defaultApp = apps.default;
 
-        # Used by `nix develop`
-        devShell = with pkgs; mkShell {
-          buildInputs = [ cargo rustc rustfmt pre-commit rustPackages.clippy ];
-          RUST_SRC_PATH = rustPlatform.rustLibSrc;
+        packages = {
+          inherit docker vnetod;
+          default = vnetod;
+          minimal = minimalVnetod;
+        };
+
+        devShell = pkgs.mkShell {
+          packages = with pkgs; [ cargo rustc rustfmt clippy rust-analyzer ];
+          RUST_SRC_PATH = pkgs.rustPlatform.rustLibSrc;
         };
       });
 }

src/cli.rs

@@ -1,4 +1,4 @@
-//! Copyright (C) 2022, Dmitriy Pleshevskiy <dmitriy@ideascup.me>
+//! Copyright (C) 2022, Dmitriy Pleshevskiy <dmitriy@pleshevski.ru>
 //!
 //! vnetod is free software: you can redistribute it and/or modify
 //! it under the terms of the GNU General Public License as published by
@@ -20,14 +20,14 @@ use std::path::PathBuf;
 
 use clap::Parser;
 
-#[derive(Parser)]
+#[derive(Parser, Debug)]
 #[clap(
     author,
     version,
     about = "\
 Dotenv state switcher
 ---------------------------------------------------------------------
-vnetod  Copyright (C) 2022  Dmitriy Pleshevskiy <dmitriy@ideascup.me>
+vnetod  Copyright (C) 2022  Dmitriy Pleshevskiy <dmitriy@pleshevski.ru>
 This program comes with ABSOLUTELY NO WARRANTY;
 This is free software, and you are welcome to redistribute it
 under certain conditions;
@@ -35,12 +35,90 @@ under certain conditions;
 "
 )]
 pub struct Args {
-    #[clap(short = 'f', long, default_value = ".env")]
+    #[clap(
+        short = 'f',
+        long,
+        default_value = ".env",
+        env = "VNETOD_FILE",
+        help = "Change source file with environment variables."
+    )]
     pub file: PathBuf,
 
-    #[clap(short = 'o', long)]
+    #[clap(
+        short = 'o',
+        long,
+        help = "Change output file with modified environment variables. It uses `file` argument by default if the output is not specified."
+    )]
     pub output: Option<PathBuf>,
 
-    #[clap(value_parser)]
+    #[clap(
+        long,
+        help = "Writes modified environment variables to stdout instead of a file. `Output` argument will be ignored."
+    )]
+    pub dry_run: bool,
+
+    #[clap(
+        value_parser,
+        help = "Environment varible sections that will be enabled."
+    )]
     pub sections: Vec<String>,
+
+    #[cfg(feature = "color")]
+    #[clap(
+        long,
+        value_enum,
+        default_value = "auto",
+        help = "This flag controls when to use colors.",
+        long_help = "
+This flag controls when to use colors. The default setting is 'auto', which
+means vnetod will try to guess when to use colors. For example, if vnetod is
+printing to a terminal, then it will use colors, but if it is redirected to a
+file or a pipe, then it will suppress color output. vnetod will suppress color
+output in some other circumstances as well. For example, if the TERM
+environment variable is not set or set to 'dumb', then vnetod will not use
+colors.
+
+The possible values for this flag are:
+
+never    Colors will never be used.
+auto     The default. vnetod tries to be smart.
+always   Colors will always be used regardless of where output is sent.
+ansi     Like 'always', but emits ANSI escapes (even in a Windows console).
+"
+    )]
+    pub color: ColorVariant,
+}
+
+#[cfg(feature = "color")]
+#[derive(clap::ValueEnum, Clone, Debug)]
+pub enum ColorVariant {
+    Auto,
+    Always,
+    Ansi,
+    Never,
+}
+
+#[cfg(feature = "color")]
+impl From<ColorVariant> for termcolor::ColorChoice {
+    fn from(col: ColorVariant) -> Self {
+        match col {
+            ColorVariant::Never => Self::Never,
+            ColorVariant::Always => Self::Always,
+            ColorVariant::Ansi => Self::AlwaysAnsi,
+            ColorVariant::Auto => {
+                if atty::is(atty::Stream::Stdout) {
+                    // Otherwise let's `termcolor` decide by inspecting the environment. From the [doc]:
+                    // - If `NO_COLOR` is set to any value, then colors will be suppressed.
+                    // - If `TERM` is set to dumb, then colors will be suppressed.
+                    // - In non-Windows environments, if `TERM` is not set, then colors will be suppressed.
+                    //
+                    // [doc]: https://github.com/BurntSushi/termcolor#automatic-color-selection
+                    Self::Auto
+                } else {
+                    // Colors should be deactivated if the terminal is not a tty.
+                    Self::Never
+                }
+            }
+        }
+    }
 }

src/cli/switch.rs

@@ -1,17 +1,37 @@
+//! Copyright (C) 2022, Dmitriy Pleshevskiy <dmitriy@pleshevski.ru>
+//!
+//! vnetod is free software: you can redistribute it and/or modify
+//! it under the terms of the GNU General Public License as published by
+//! the Free Software Foundation, either version 3 of the License, or
+//! (at your option) any later version.
+//!
+//! vnetod is distributed in the hope that it will be useful,
+//! but WITHOUT ANY WARRANTY; without even the implied warranty of
+//! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//! GNU General Public License for more details.
+//!
+//! You should have received a copy of the GNU General Public License
+//! along with vnetod.  If not, see <https://www.gnu.org/licenses/>.
+//!
+
+#[cfg(feature = "color")]
+use termcolor::{Color, ColorSpec, StandardStream, WriteColor};
+
 use crate::{cli::Args, domain};
 use std::fs::File;
+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"),
         }
     }
 }
@@ -20,13 +40,52 @@ 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 =
-        File::create(args.output.as_ref().unwrap_or(&args.file)).map_err(|_| Error::OpenFile)?;
 
-    domain::switch::execute(domain::switch::Request {
-        content: &content,
-        writer,
+    if args.dry_run {
+        println!("Your file will be changed to the following")
+    }
+
+    let fs_writer = (!args.dry_run)
+        .then(|| {
+            File::create(args.output.as_ref().unwrap_or(&args.file)).map_err(|_| Error::OpenFile)
+        })
+        .transpose()?;
+
+    #[cfg(feature = "color")]
+    let color = args.color.clone();
+
+    println!();
+
+    let new_content = domain::switch::execute(domain::switch::Request {
+        content: &content.trim(),
         sections: &args.sections,
-    })
-    .map_err(Error::Switch)
+        on_line: Some(Box::new(move |line| {
+            #[cfg(feature = "color")]
+            print_line(line, color.clone());
+            #[cfg(not(feature = "color"))]
+            print!("{}", line)
+        })),
+    });
+
+    println!();
+
+    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, color: crate::cli::ColorVariant) {
+    let mut stdout = StandardStream::stdout(color.into());
+    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();
 }

src/domain.rs

@@ -1,3 +1,19 @@
+//! Copyright (C) 2022, Dmitriy Pleshevskiy <dmitriy@pleshevski.ru>
+//!
+//! vnetod is free software: you can redistribute it and/or modify
+//! it under the terms of the GNU General Public License as published by
+//! the Free Software Foundation, either version 3 of the License, or
+//! (at your option) any later version.
+//!
+//! vnetod is distributed in the hope that it will be useful,
+//! but WITHOUT ANY WARRANTY; without even the implied warranty of
+//! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//! GNU General Public License for more details.
+//!
+//! You should have received a copy of the GNU General Public License
+//! along with vnetod.  If not, see <https://www.gnu.org/licenses/>.
+//!
+
 pub mod switch;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -27,3 +43,8 @@ impl Section {
             .map_or_else(|| Self::new(s), |(ns, name)| Self::with_namespace(ns, name))
     }
 }
+
+pub struct SectionInfo {
+    enable_variable: bool,
+    disable_variable: bool,
+}

src/domain/switch.rs

@@ -1,60 +1,58 @@
-use std::io::{BufWriter, Write};
+//! Copyright (C) 2022, Dmitriy Pleshevskiy <dmitriy@pleshevski.ru>
+//!
+//! vnetod is free software: you can redistribute it and/or modify
+//! it under the terms of the GNU General Public License as published by
+//! the Free Software Foundation, either version 3 of the License, or
+//! (at your option) any later version.
+//!
+//! vnetod is distributed in the hope that it will be useful,
+//! but WITHOUT ANY WARRANTY; without even the implied warranty of
+//! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//! GNU General Public License for more details.
+//!
+//! You should have received a copy of the GNU General Public License
+//! along with vnetod.  If not, see <https://www.gnu.org/licenses/>.
+//!
 
-use super::Section;
+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 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()
         .map(|s| Section::parse(s.as_str()))
         .collect::<Vec<_>>();
 
-    let mut current_sections: Option<Vec<Section>> = None;
+    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) {
-            current_sections = None;
+            current_section = None;
             line.to_string()
         } else if let Some(section_info) = line.strip_prefix("### ") {
-            current_sections = section_info
-                .split_whitespace()
-                .next()
-                .map(|r| r.split(',').map(Section::parse).collect());
+            current_section = section_info.split_whitespace().next().map(|r| {
+                let current_sections = r.split(',').map(Section::parse).collect::<Vec<_>>();
+                SectionInfo {
+                    enable_variable: should_enable_variable(&choose_sections, &current_sections),
+                    disable_variable: should_disable_variable(&choose_sections, &current_sections),
+                }
+            });
             line.to_string()
-        } else if let Some(cur_sections) = current_sections.clone() {
+        } else if let Some(section_info) = current_section.as_ref() {
             let trimmed_line = line.trim_start_matches(['#', ' ']);
-            if should_enable_variable(&choose_sections, &cur_sections) {
+            let is_var = is_variable(trimmed_line);
+            if is_var && section_info.enable_variable {
                 String::from(trimmed_line)
-            } else if should_disable_variable(&choose_sections, &cur_sections) {
+            } else if is_var && section_info.disable_variable {
                 format!("# {}", trimmed_line)
             } else {
                 line.to_string()
@@ -63,12 +61,22 @@ 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(&new_line);
+        }
     }
 
-    writer.flush().map_err(|_| Error::WriteData)
+    new_content
+}
+
+fn is_variable(trimmed_line: &str) -> bool {
+    trimmed_line
+        .chars()
+        .filter(|ch| (*ch != '_' && ch.is_ascii_punctuation()) || ch.is_whitespace())
+        .enumerate()
+        .find(|(_, ch)| *ch == '=')
+        .map_or(false, |(i, _)| i == 0)
 }
 
 fn is_section_end(line: &str) -> bool {
@@ -115,28 +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]
@@ -258,5 +257,20 @@ mod tests {
                 &[Section::with_namespace("debug", "off")]
             ));
         }
+
+        #[test]
+        fn should_check_line_on_variable() {
+            let test_cases = [
+                ("VAR=10", true),
+                ("THIS_IS_MY_VAR='hello world'", true),
+                ("hello world", false),
+                ("staging/production", false),
+                ("staging/production=value", false),
+            ];
+
+            for (input, expected) in test_cases {
+                assert_eq!(is_variable(input), expected);
+            }
+        }
     }
 }

src/main.rs

@@ -1,4 +1,4 @@
-//! Copyright (C) 2022, Dmitriy Pleshevskiy <dmitriy@ideascup.me>
+//! Copyright (C) 2022, Dmitriy Pleshevskiy <dmitriy@pleshevski.ru>
 //!
 //! vnetod is free software: you can redistribute it and/or modify
 //! it under the terms of the GNU General Public License as published by

test_data/all_env

@@ -2,6 +2,7 @@ VITE_STRIPE_PK=
 VITE_SENTRY_ENABLED=
 VITE_SENTRY_DSN=
 ### local,staging
+# staging/production
 VITE_SENTRY_ENV=staging
 ### prod
 VITE_SENTRY_ENV=production

test_data/base_env

@@ -2,6 +2,7 @@ VITE_STRIPE_PK=
 VITE_SENTRY_ENABLED=
 VITE_SENTRY_DSN=
 ### local,staging
+# staging/production
 # VITE_SENTRY_ENV=staging
 ### prod
 # VITE_SENTRY_ENV=production

test_data/should_enable_local

@@ -2,6 +2,7 @@ VITE_STRIPE_PK=
 VITE_SENTRY_ENABLED=
 VITE_SENTRY_DSN=
 ### local,staging
+# staging/production
 VITE_SENTRY_ENV=staging
 ### prod
 # VITE_SENTRY_ENV=production

test_data/should_enable_staging

@@ -2,6 +2,7 @@ VITE_STRIPE_PK=
 VITE_SENTRY_ENABLED=
 VITE_SENTRY_DSN=
 ### local,staging
+# staging/production
 VITE_SENTRY_ENV=staging
 ### prod
 # VITE_SENTRY_ENV=production

test_data/should_use_debug_in_staging

@@ -2,6 +2,7 @@ VITE_STRIPE_PK=
 VITE_SENTRY_ENABLED=
 VITE_SENTRY_DSN=
 ### local,staging
+# staging/production
 VITE_SENTRY_ENV=staging
 ### prod
 # VITE_SENTRY_ENV=production

test_data/should_use_staging_db_in_local

@@ -2,6 +2,7 @@ VITE_STRIPE_PK=
 VITE_SENTRY_ENABLED=
 VITE_SENTRY_DSN=
 ### local,staging
+# staging/production
 VITE_SENTRY_ENV=staging
 ### prod
 # VITE_SENTRY_ENV=production