feat(lua): Add a Lua module (#1815)

* feat: add lua module

* docs: add lua module

* fix: lua version test

* feat: lua module can be detected if the current dir contains a "lua" dir

* feat: enable to use luajit

* fix: improve regex

* fix based on https://github.com/starship/starship/pull/1815#discussion_r510932742

* fix based on https://github.com/starship/starship/pull/1815#discussion_r511362581

* fix based on https://github.com/starship/starship/pull/1815#discussion_r510941252

docs/config/README.md

@@ -229,6 +229,7 @@ $crystal\
 $cmd_duration\
 $custom\
 $line_break\
+$lua\
 $jobs\
 $battery\
 $time\
@@ -1494,6 +1495,44 @@ The `line_break` module separates the prompt into two lines.
 disabled = true
 ```
 
+## Lua
+
+The `lua` module shows the currently installed version of Lua.
+The module will be shown if any of the following conditions are met:
+
+- The current directory contains a `.lua-version` file
+- The current directory contains a `lua` directory
+- The current directory contains a file with the `.lua` extension
+
+### Options
+
+| Option       | Default                            | Description                                                                   |
+| ------------ | ---------------------------------- | ----------------------------------------------------------------------------- |
+| `format`     | `"via [$symbol$version]($style) "` | The format for the module.                                                    |
+| `symbol`     | `"🌙 "`                            | A format string representing the symbol of Lua.                               |
+| `style`      | `"bold blue"`                      | The style for the module.                                                     |
+| `lua_binary` | `"lua"`                            | Configures the lua binary that Starship executes when getting the version.    |
+| `disabled`   | `false`                            | Disables the `lua` module.                                                    |
+
+### Variables
+
+| Variable | Example   | Description                          |
+| -------- | --------- | ------------------------------------ |
+| version  | `v5.4.0`  | The version of `lua`                 |
+| symbol   |           | Mirrors the value of option `symbol` |
+| style\*  |           | Mirrors the value of option `style`  |
+
+\*: This variable can only be used as a part of a style string
+
+### Example
+
+```toml
+# ~/.config/starship.toml
+
+[lua]
+format = "via [🌕 $version](bold blue) "
+```
+
 ## Memory Usage
 
 The `memory_usage` module shows current system memory and swap usage.

src/configs/lua.rs

@@ -0,0 +1,24 @@
+use crate::config::{ModuleConfig, RootModuleConfig};
+
+use starship_module_config_derive::ModuleConfig;
+
+#[derive(Clone, ModuleConfig)]
+pub struct LuaConfig<'a> {
+    pub format: &'a str,
+    pub symbol: &'a str,
+    pub style: &'a str,
+    pub lua_binary: &'a str,
+    pub disabled: bool,
+}
+
+impl<'a> RootModuleConfig<'a> for LuaConfig<'a> {
+    fn new() -> Self {
+        LuaConfig {
+            format: "via [$symbol$version]($style) ",
+            symbol: "🌙 ",
+            style: "bold blue",
+            lua_binary: "lua",
+            disabled: false,
+        }
+    }
+}

src/configs/mod.rs

@@ -27,6 +27,7 @@ pub mod java;
 pub mod jobs;
 pub mod julia;
 pub mod kubernetes;
+pub mod lua;
 pub mod memory_usage;
 pub mod nim;
 pub mod nix_shell;

src/configs/starship_root.rs

@@ -38,6 +38,7 @@ pub const PROMPT_ORDER: &[&str] = &[
     "helm",
     "java",
     "julia",
+    "lua",
     "nim",
     "nodejs",
     "ocaml",

src/module.rs

@@ -38,6 +38,7 @@ pub const ALL_MODULES: &[&str] = &[
     "julia",
     "kubernetes",
     "line_break",
+    "lua",
     "memory_usage",
     "nim",
     "nix_shell",

src/modules/lua.rs

@@ -0,0 +1,166 @@
+use super::{Context, Module, RootModuleConfig};
+
+use crate::configs::lua::LuaConfig;
+use crate::formatter::StringFormatter;
+use crate::utils;
+
+use regex::Regex;
+const LUA_VERSION_PATERN: &str = "(?P<version>[\\d\\.]+[a-z\\-]*[1-9]*)[^\\s]*";
+
+/// Creates a module with the current Lua version
+///
+/// Will display the Lua version if any of the following criteria are met:
+///     - Current directory contains a `.lua-version` file
+///     - Current directory contains a `lua` directory
+///     - Current directory contains a file with the `.lua` extension
+pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
+    let is_lua_project = context
+        .try_begin_scan()?
+        .set_files(&[".lua-version"])
+        .set_folders(&["lua"])
+        .set_extensions(&["lua"])
+        .is_match();
+
+    if !is_lua_project {
+        return None;
+    }
+
+    let mut module = context.new_module("lua");
+    let config = LuaConfig::try_load(module.config);
+    let lua_version = format_lua_version(&get_lua_version(&config.lua_binary)?)?;
+    let parsed = StringFormatter::new(config.format).and_then(|formatter| {
+        formatter
+            .map_meta(|var, _| match var {
+                "symbol" => Some(config.symbol),
+                _ => None,
+            })
+            .map_style(|variable| match variable {
+                "style" => Some(Ok(config.style)),
+                _ => None,
+            })
+            .map(|variable| match variable {
+                "version" => Some(Ok(&lua_version)),
+                _ => None,
+            })
+            .parse(None)
+    });
+
+    module.set_segments(match parsed {
+        Ok(segments) => segments,
+        Err(error) => {
+            log::warn!("Error in module `lua`:\n{}", error);
+            return None;
+        }
+    });
+
+    Some(module)
+}
+
+fn get_lua_version(lua_binary: &str) -> Option<String> {
+    match utils::exec_cmd(lua_binary, &["-v"]) {
+        Some(output) => {
+            if output.stdout.is_empty() {
+                Some(output.stderr)
+            } else {
+                Some(output.stdout)
+            }
+        }
+        None => None,
+    }
+}
+
+fn format_lua_version(lua_stdout: &str) -> Option<String> {
+    // lua -v output looks like this:
+    // Lua 5.4.0  Copyright (C) 1994-2020 Lua.org, PUC-Rio
+
+    // luajit -v output looks like this:
+    // LuaJIT 2.0.5 -- Copyright (C) 2005-2017 Mike Pall. http://luajit.org/
+    let re = Regex::new(LUA_VERSION_PATERN).ok()?;
+    let captures = re.captures(lua_stdout)?;
+    let version = &captures["version"];
+    Some(format!("v{}", version))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test::ModuleRenderer;
+    use ansi_term::Color;
+    use std::fs::{self, File};
+    use std::io;
+
+    #[test]
+    fn folder_without_lua_files() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        let actual = ModuleRenderer::new("lua").path(dir.path()).collect();
+        let expected = None;
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
+    #[test]
+    fn folder_with_lua_file() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        File::create(dir.path().join("main.lua"))?.sync_all()?;
+        let actual = ModuleRenderer::new("lua").path(dir.path()).collect();
+        let expected = Some(format!("via {} ", Color::Blue.bold().paint("🌙 v5.4.0")));
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
+    #[test]
+    fn folder_with_lua_version() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        File::create(dir.path().join(".lua-version"))?.sync_all()?;
+
+        let actual = ModuleRenderer::new("lua").path(dir.path()).collect();
+        let expected = Some(format!("via {} ", Color::Blue.bold().paint("🌙 v5.4.0")));
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
+    #[test]
+    fn folder_with_lua_folder() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        let lua_dir = dir.path().join("lua");
+        fs::create_dir_all(&lua_dir)?;
+
+        let actual = ModuleRenderer::new("lua").path(dir.path()).collect();
+        let expected = Some(format!("via {} ", Color::Blue.bold().paint("🌙 v5.4.0")));
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
+    #[test]
+    fn lua_binary_is_luajit() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        File::create(dir.path().join("main.lua"))?.sync_all()?;
+
+        let config = toml::toml! {
+             [lua]
+             lua_binary = "luajit"
+        };
+
+        let actual = ModuleRenderer::new("lua")
+            .path(dir.path())
+            .config(config)
+            .collect();
+
+        let expected = Some(format!("via {} ", Color::Blue.bold().paint("🌙 v2.0.5")));
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
+    #[test]
+    fn test_format_lua_version() {
+        let lua_input = "Lua 5.4.0  Copyright (C) 1994-2020 Lua.org, PUC-Rio";
+        assert_eq!(format_lua_version(lua_input), Some("v5.4.0".to_string()));
+
+        let luajit_input =
+            "LuaJIT 2.1.0-beta3 -- Copyright (C) 2005-2017 Mike Pall. http://luajit.org/";
+        assert_eq!(
+            format_lua_version(luajit_input),
+            Some("v2.1.0-beta3".to_string())
+        );
+    }
+}

src/modules/mod.rs

@@ -28,6 +28,7 @@ mod jobs;
 mod julia;
 mod kubernetes;
 mod line_break;
+mod lua;
 mod memory_usage;
 mod nim;
 mod nix_shell;
@@ -95,6 +96,7 @@ pub fn handle<'a>(module: &str, context: &'a Context) -> Option<Module<'a>> {
             "julia" => julia::module(context),
             "kubernetes" => kubernetes::module(context),
             "line_break" => line_break::module(context),
+            "lua" => lua::module(context),
             "memory_usage" => memory_usage::module(context),
             "nim" => nim::module(context),
             "nix_shell" => nix_shell::module(context),
@@ -169,6 +171,7 @@ pub fn description(module: &str) -> &'static str {
         "julia" => "The currently installed version of Julia",
         "kubernetes" => "The current Kubernetes context name and, if set, the namespace",
         "line_break" => "Separates the prompt into two lines",
+        "lua" => "The currently installed version of Lua",
         "memory_usage" => "Current system memory and swap usage",
         "nim" => "The currently installed version of Nim",
         "nix_shell" => "The nix-shell environment",

src/utils.rs

@@ -88,6 +88,14 @@ Elixir 1.10 (compiled with Erlang/OTP 22)\n",
             stdout: String::from("julia version 1.4.0\n"),
             stderr: String::default(),
         }),
+        "lua -v" => Some(CommandOutput{
+            stdout: String::from("Lua 5.4.0  Copyright (C) 1994-2020 Lua.org, PUC-Rio\n"),
+            stderr: String::default(),
+        }),
+        "luajit -v" => Some(CommandOutput{
+            stdout: String::from("LuaJIT 2.0.5 -- Copyright (C) 2005-2017 Mike Pall. http://luajit.org/\n"),
+            stderr: String::default(),
+        }),
         "nim --version" => Some(CommandOutput {
             stdout: String::from(
                 "\