Add internal command to render CLI usage text for manual

Cargo.lock

@@ -11,6 +11,16 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "ansi-to-html"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "19ee82de0545b181a17cbdef44fce80ecaf394e001da7ea279008bf2e0944bee"
+dependencies = [
+ "regex",
+ "thiserror",
+]
+
 [[package]]
 name = "ansi_term"
 version = "0.11.0"
@@ -112,6 +122,7 @@ dependencies = [
 name = "colmena"
 version = "0.1.0"
 dependencies = [
+ "ansi-to-html",
  "async-trait",
  "atty",
  "clap",
@@ -781,6 +792,26 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "thiserror"
+version = "1.0.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "854babe52e4df1653706b98fcfc05843010039b406875930a70e4d9644e5c417"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa32fd3f627f367fe16f893e2597ae3c05020f8bba2666a4e6ea73d377e5714b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "tinyvec"
 version = "1.5.0"

Cargo.toml

@@ -7,6 +7,7 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+ansi-to-html = "0.1.0"
 async-trait = "0.1.42"
 atty = "0.2"
 clap = "2.33.3"

src/cli.rs

@@ -66,6 +66,10 @@ For a sample configuration, see <https://github.com/zhaofengli/colmena>.
                 .required(true)
                 .takes_value(true)));
 
+        app = app.subcommand(SubCommand::with_name("gen-help-markdown")
+            .about("Generate CLI usage guide as Markdown (Internal)")
+            .setting(AppSettings::Hidden));
+
         // deprecated alias
         app = app.subcommand(command::eval::deprecated_alias());
 
@@ -104,6 +108,10 @@ pub async fn run() {
         return gen_completions(args);
     }
 
+    if let Some(_) = matches.subcommand_matches("gen-help-markdown") {
+        return gen_help_markdown();
+    };
+
     app.print_long_help().unwrap();
     println!();
 }
@@ -115,3 +123,52 @@ fn gen_completions(args: &ArgMatches<'_>) {
 
     app.gen_completions_to("colmena", shell, &mut std::io::stdout());
 }
+
+fn gen_help_markdown() {
+    // This is tailered only for the manual, with output injected to `reference/cli.md`.
+    // <pre><div class="hljs">
+    let mut commands = vec![
+        build_cli(false),
+        command::apply::subcommand(),
+        command::apply_local::subcommand(),
+        command::build::subcommand(),
+        command::upload_keys::subcommand(),
+        command::eval::subcommand(),
+        command::exec::subcommand(),
+        command::nix_info::subcommand(),
+    ];
+
+    for command in commands.drain(..) {
+        let full_command = match command.get_name() {
+            "Colmena" => "colmena".to_string(),
+            sub => format!("colmena {}", sub),
+        };
+
+        let mut command = {
+            let c = command
+                .setting(AppSettings::ColoredHelp)
+                .setting(AppSettings::ColorAlways);
+
+            if full_command != "colmena" {
+                c.bin_name(&full_command)
+            } else {
+                c
+            }
+        };
+
+        println!("## `{}`", full_command);
+        print!("<pre><div class=\"hljs\">");
+
+        let help_message = {
+            let mut bytes = Vec::new();
+            command.write_long_help(&mut bytes).unwrap();
+            String::from_utf8(bytes).unwrap()
+        };
+
+        let help_html = ansi_to_html::convert(&help_message, true, true)
+            .expect("Could not convert terminal output to HTML");
+
+        print!("{}", help_html);
+        println!("</div></pre>");
+    }
+}