nix: add module to generate nix flake

src/cli.rs

@@ -10,13 +10,17 @@ use clap::Parser;
 
 use crate::{
     config::read_config,
-    module::{direnv::DirenvModule, gitignore::GitIgnoreModule, Module},
+    module::{direnv::DirenvModule, gitignore::GitIgnoreModule, nix_flake::NixFlakeModule, Module},
 };
 
-use self::{direnv::DirenvModuleCliArgs, gitignore::GitIgnoreModuleCliArgs};
+use self::{
+    direnv::DirenvModuleCliArgs, gitignore::GitIgnoreModuleCliArgs,
+    nix_flake::NixFlakeModuleCliArgs,
+};
 
 mod direnv;
 mod gitignore;
+mod nix_flake;
 
 #[derive(Debug, Clone, clap::Args)]
 struct MakeCommand {
@@ -28,6 +32,8 @@ enum AddModuleCommand {
     Direnv(DirenvModuleCliArgs),
     #[clap(name = "gitignore")]
     GitIgnore(GitIgnoreModuleCliArgs),
+    #[clap(name = "nix.flake")]
+    NixFlake(NixFlakeModuleCliArgs),
     #[clap(external_subcommand)]
     External(Vec<String>),
 }
@@ -140,24 +146,27 @@ pub fn run() -> Result<(), Box<dyn std::error::Error>> {
     match args.command {
         Command::Make(_make_args) => {
             let config = read_config(&current_dir)?;
-            let mut make_files: HashMap<String, String> = HashMap::new();
-
-            if let Some(cfg) = config.direnv {
-                make_files.extend(DirenvModule.make(cfg.into()))
-            }
-            if let Some(cfg) = config.gitignore {
-                make_files.extend(GitIgnoreModule.make(cfg.into()));
-            }
+            let make_files: HashMap<String, String> = [
+                config.direnv.map(|v| DirenvModule.make(v.into())),
+                config.gitignore.map(|v| GitIgnoreModule.make(v.into())),
+                config
+                    .nix
+                    .and_then(|cfg| cfg.flake.map(|v| NixFlakeModule.make(v.into()))),
+            ]
+            .into_iter()
+            .flatten()
+            .fold(HashMap::new(), |mut acc, files| {
+                acc.extend(files);
+                acc
+            });
 
             make(current_dir, make_files, true)
         }
         Command::Add { force, command } => {
-            let mut make_files: HashMap<String, String> = HashMap::new();
-            match command {
-                AddModuleCommand::Direnv(args) => make_files.extend(DirenvModule.make(args.into())),
-                AddModuleCommand::GitIgnore(args) => {
-                    make_files.extend(GitIgnoreModule.make(args.into()))
-                }
+            let make_files: HashMap<String, String> = match command {
+                AddModuleCommand::Direnv(args) => DirenvModule.make(args.into()),
+                AddModuleCommand::GitIgnore(args) => GitIgnoreModule.make(args.into()),
+                AddModuleCommand::NixFlake(args) => NixFlakeModule.make(args.into()),
                 AddModuleCommand::External(_) => {
                     unimplemented!("external commands")
                 }

src/cli/nix_flake.rs

@@ -0,0 +1,21 @@
+use crate::module::nix_flake::NixFlakeModuleArgs;
+
+#[derive(Debug, Clone, clap::Args)]
+pub struct NixFlakeModuleCliArgs {
+    #[clap(short, long)]
+    description: Option<String>,
+    #[clap(long)]
+    extra_inputs: Option<String>,
+    #[clap(long)]
+    extra_outputs: Option<String>,
+}
+
+impl From<NixFlakeModuleCliArgs> for NixFlakeModuleArgs {
+    fn from(args: NixFlakeModuleCliArgs) -> Self {
+        NixFlakeModuleArgs {
+            description: args.description,
+            extra_inputs: args.extra_inputs,
+            extra_outputs: args.extra_outputs,
+        }
+    }
+}

src/config.rs

@@ -1,12 +1,21 @@
 use std::{fs, io, path::PathBuf};
 
-use self::{direnv::DirenvModuleConfig, gitignore::GitIgnoreModuleConfig};
+use self::{
+    direnv::DirenvModuleConfig, gitignore::GitIgnoreModuleConfig, nix_flake::NixFlakeModuleConfig,
+};
 
 mod direnv;
 mod gitignore;
+mod nix_flake;
+
+#[derive(serde::Deserialize, serde::Serialize)]
+pub struct NixConfig {
+    pub flake: Option<NixFlakeModuleConfig>,
+}
 
 #[derive(serde::Deserialize, serde::Serialize)]
 pub struct Config {
+    pub nix: Option<NixConfig>,
     pub direnv: Option<DirenvModuleConfig>,
     pub gitignore: Option<GitIgnoreModuleConfig>,
 }

src/config/nix_flake.rs

@@ -0,0 +1,18 @@
+use crate::module::nix_flake::NixFlakeModuleArgs;
+
+#[derive(Default, serde::Deserialize, serde::Serialize)]
+pub struct NixFlakeModuleConfig {
+    description: Option<String>,
+    extra_inputs: Option<String>,
+    extra_outputs: Option<String>,
+}
+
+impl From<NixFlakeModuleConfig> for NixFlakeModuleArgs {
+    fn from(cfg: NixFlakeModuleConfig) -> Self {
+        NixFlakeModuleArgs {
+            description: cfg.description,
+            extra_inputs: cfg.extra_inputs,
+            extra_outputs: cfg.extra_outputs,
+        }
+    }
+}

src/module.rs

@@ -2,6 +2,7 @@ use std::collections::HashMap;
 
 pub mod direnv;
 pub mod gitignore;
+pub mod nix_flake;
 
 pub trait Module {
     type ModuleArgs;

src/module/nix_flake.rs

@@ -0,0 +1,57 @@
+use std::collections::HashMap;
+use std::io::{self, Write};
+
+use super::Module;
+
+pub struct NixFlakeModuleArgs {
+    pub description: Option<String>,
+    pub extra_inputs: Option<String>,
+    pub extra_outputs: Option<String>,
+}
+
+fn make_flakenix_content(args: NixFlakeModuleArgs) -> Result<String, io::Error> {
+    let mut s = Vec::new();
+    writeln!(s, "{{")?;
+    #[rustfmt::skip]
+    writeln!(s, "  description = \"{}\";", args.description.unwrap_or_default())?;
+
+    // ----------------------
+    // INPUTS
+    writeln!(s, "  inputs = {{")?;
+    if let Some(extra_inputs) = args.extra_inputs {
+        writeln!(s, "{}", extra_inputs.trim())?;
+    }
+    writeln!(s, "  }};")?;
+
+    // ----------------------
+    // OUTPUTS
+    writeln!(s, "  outputs =")?;
+    writeln!(s, "    {{ self")?;
+    writeln!(s, "    , nixpkgs")?;
+    writeln!(s, "    , ...")?;
+    writeln!(s, "    }} @ inputs:")?;
+
+    if let Some(extra_outputs) = args.extra_outputs {
+        write!(s, "    ({});", extra_outputs.trim())?;
+    } else {
+        writeln!(s, "    {{")?;
+        writeln!(s, "    }};")?;
+    }
+
+    writeln!(s, "}}")?;
+
+    Ok(String::from_utf8(s).unwrap())
+}
+
+pub struct NixFlakeModule;
+
+impl Module for NixFlakeModule {
+    type ModuleArgs = NixFlakeModuleArgs;
+
+    fn make(&self, args: Self::ModuleArgs) -> HashMap<String, String> {
+        HashMap::from([(
+            String::from("flake.nix"),
+            make_flakenix_content(args).unwrap(),
+        )])
+    }
+}