From 5e5e02d6a715042c69812d26357b956d7f53f1af Mon Sep 17 00:00:00 2001
From: Vincent Ambo <mail@tazj.in>
Date: Wed, 17 Jun 2020 01:41:34 +0100
Subject: [PATCH] refactor(cheddar): Switch to clap-rs for command line
 arguments

The complexity of the arg parsing is increasing somewhat because we're
adding more features to cheddar, so to set us up for that this
switches the arg parsing to the somewhat more flexible clap.

Change-Id: I187bc0c1b6c6bd596fa0f6bb494b04e335262ba9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/445
Reviewed-by: lukegb <lukegb@tvl.fyi>
Reviewed-by: tazjin <mail@tazj.in>
---
 tools/cheddar/Cargo.lock  |  1 +
 tools/cheddar/Cargo.toml  |  1 +
 tools/cheddar/src/main.rs | 57 +++++++++++++++++++--------------------
 3 files changed, 29 insertions(+), 30 deletions(-)

diff --git a/tools/cheddar/Cargo.lock b/tools/cheddar/Cargo.lock
index be70e178a..ab1225cc6 100644
--- a/tools/cheddar/Cargo.lock
+++ b/tools/cheddar/Cargo.lock
@@ -98,6 +98,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "cheddar"
 version = "0.1.0"
 dependencies = [
+ "clap 2.33.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "comrak 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "syntect 4.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/tools/cheddar/Cargo.toml b/tools/cheddar/Cargo.toml
index ca9ed0dfe..b7d9a7758 100644
--- a/tools/cheddar/Cargo.toml
+++ b/tools/cheddar/Cargo.toml
@@ -8,3 +8,4 @@ edition = "2018"
 comrak = "0.7"
 lazy_static = "1.4"
 syntect = "4.2.0"
+clap = "2.33"
diff --git a/tools/cheddar/src/main.rs b/tools/cheddar/src/main.rs
index 01e6c868f..9e16b1de4 100644
--- a/tools/cheddar/src/main.rs
+++ b/tools/cheddar/src/main.rs
@@ -1,3 +1,4 @@
+use clap::{Arg, App};
 use comrak::arena_tree::Node;
 use comrak::nodes::{Ast, AstNode, NodeValue, NodeCodeBlock, NodeHtmlBlock};
 use comrak::{Arena, parse_document, format_html, ComrakOptions};
@@ -72,35 +73,6 @@ struct Args {
     lang_override: Option<&'static str>,
 }
 
-/// Parse the command-line flags passed to cheddar to determine
-/// whether it is running in about-filter mode (`--about-filter`) and
-/// what file extension has been supplied.
-fn parse_args() -> Args {
-    let mut args = Args::default();
-
-    for (i, arg) in env::args().enumerate() {
-        if i == 0 {
-            continue;
-        }
-
-        if arg == "--about-filter" {
-            args.about_filter = true;
-            continue;
-        }
-
-        if let Some(lang) = (*FILENAME_OVERRIDES).get(arg.as_str()) {
-            args.lang_override = Some(lang);
-        }
-
-        args.extension = Path::new(&arg)
-            .extension()
-            .and_then(OsStr::to_str)
-            .map(|s| s.to_string());
-    }
-
-    return args
-}
-
 fn should_continue(res: &io::Result<usize>) -> bool {
     match *res {
         Ok(n) => n > 0,
@@ -312,7 +284,32 @@ fn format_code(args: &Args) {
 }
 
 fn main() {
-    let args = parse_args();
+    // Parse the command-line flags passed to cheddar to determine
+    // whether it is running in about-filter mode (`--about-filter`)
+    // and what file extension has been supplied.
+    let matches = App::new("cheddar")
+        .about("TVL's syntax highlighter")
+        .arg(Arg::with_name("about-filter")
+             .help("Run as a cgit about-filter (renders Markdown)")
+             .long("about-filter")
+             .takes_value(false))
+        .arg(Arg::with_name("filename")
+             .help("File to render")
+             .index(1))
+        .get_matches();
+
+    let mut args = Args::default();
+    args.about_filter = matches.is_present("about-filter");
+
+    let filename = matches.value_of("filename").expect("filename is required");
+    if let Some(lang) = (*FILENAME_OVERRIDES).get(filename) {
+        args.lang_override = Some(lang);
+    }
+
+    args.extension = Path::new(&filename)
+        .extension()
+        .and_then(OsStr::to_str)
+        .map(|s| s.to_string());
 
     match args.extension.as_ref().map(String::as_str) {
         Some("md") if args.about_filter => format_markdown(),