moss/cli: Add support for --generate-manpages

Signed-off-by: Ikey Doherty <ikey@serpentos.com>

Cargo.toml

@@ -19,6 +19,8 @@ blsforme = { git = "https://github.com/serpent-os/blsforme.git", rev = "59a8f12f
 bytes = "1.6.0"
 chrono = "0.4.38"
 clap = { version = "4.5.8", features = ["derive", "string"] }
+clap_complete = "4.5.37"
+clap_mangen = "0.2.24"
 criterion = { version = "0.5.1", features = ["html_reports"] }
 crossterm = "0.27.0"
 derive_more = "0.99.18"

moss/Cargo.toml

@@ -17,6 +17,8 @@ vfs = { path = "../crates/vfs" }
 blsforme.workspace = true
 bytes.workspace = true
 chrono.workspace = true
+clap_mangen.workspace = true
+clap_complete.workspace = true
 clap.workspace = true
 derive_more.workspace = true
 diesel.workspace = true

moss/src/cli/mod.rs

@@ -5,6 +5,7 @@
 use std::{env, path::PathBuf};
 
 use clap::{Arg, ArgAction, Command};
+use clap_mangen::Man;
 use moss::{installation, runtime, Installation};
 use thiserror::Error;
 
@@ -59,6 +60,14 @@ fn command() -> Command {
                 .help("Assume yes for all questions")
                 .action(ArgAction::SetTrue),
         )
+        .arg(
+            Arg::new("generate-manpages")
+                .long("generate-manpages")
+                .help("Generate manpages")
+                .action(ArgAction::Set)
+                .value_name("DIR")
+                .hide(true),
+        )
         .arg_required_else_help(true)
         .subcommand(extract::command())
         .subcommand(index::command())
@@ -74,11 +83,44 @@ fn command() -> Command {
         .subcommand(version::command())
 }
 
+/// Generate manpages for all commands recursively
+fn generate_manpages(cmd: &Command, dir: &std::path::Path, prefix: Option<&str>) -> std::io::Result<()> {
+    let name = cmd.get_name();
+    let man = Man::new(cmd.to_owned());
+    let mut buffer: Vec<u8> = Default::default();
+    man.render(&mut buffer)?;
+
+    let filename = if let Some(prefix) = prefix {
+        format!("{}-{}.1", prefix, name)
+    } else {
+        format!("{}.1", name)
+    };
+
+    std::fs::write(dir.join(filename), buffer)?;
+
+    for subcmd in cmd.get_subcommands() {
+        let new_prefix = if let Some(p) = prefix {
+            format!("{}-{}", p, name)
+        } else {
+            name.to_string()
+        };
+        generate_manpages(subcmd, dir, Some(&new_prefix))?;
+    }
+    Ok(())
+}
+
 /// Process all CLI arguments
 pub fn process() -> Result<(), Error> {
     let args = replace_aliases(env::args());
     let matches = command().get_matches_from(args);
 
+    if let Some(dir) = matches.get_one::<String>("generate-manpages") {
+        let dir = std::path::Path::new(dir);
+        std::fs::create_dir_all(dir)?;
+        generate_manpages(&command(), dir, None)?;
+        return Ok(());
+    }
+
     // Print the version, but not if the user is using the version subcommand
     if matches.get_flag("verbose") {
         if let Some(command) = matches.subcommand_name() {
@@ -190,4 +232,7 @@ pub enum Error {
 
     #[error("installation")]
     Installation(#[from] installation::Error),
+
+    #[error("I/O error: {0}")]
+    Io(#[from] std::io::Error),
 }