feat: add --list-formats command, support auto-generated man pages

src/args.rs

@@ -15,11 +15,15 @@
 use clap::Parser;
 use std::path::PathBuf;
 
-pub const VERSION: &str = include_str!(concat!(env!("OUT_DIR"), "/version.txt"));
-
 #[derive(Parser, Debug)]
-#[command(version = VERSION, about = "A file converter program.", long_about = None)]
+#[command(about = "A file converter program.", long_about = None)]
 pub struct Args {
+    #[arg(
+        long,
+        help = "List all supported formats.",
+        exclusive = true
+    )]
+    pub list_formats: bool,
     #[arg(
         short = 'v',
         long,
@@ -58,7 +62,7 @@ pub struct Args {
     pub priority: String,
 
     #[arg(help = "The input file path.")]
-    pub input_path: String,
+    pub input_path: Option<String>,
 
     #[arg(help = "The output file path (optional).")]
     pub output_path: Option<String>,

src/main.rs

@@ -21,13 +21,18 @@ pub mod runner;
 include!(concat!(env!("OUT_DIR"), "/plugins_gen.rs"));
 
 use args::Args;
-use clap::Parser;
+use clap::{Parser, CommandFactory, FromArgMatches};
 use std::fs;
 use std::io::{self, IsTerminal, Write};
 use std::process;
 
+pub const VERSION: &str = include_str!(concat!(env!("OUT_DIR"), "/version.txt"));
+
 fn main() {
-    let args = Args::parse();
+    let mut command = Args::command();
+    command = command.version(VERSION);
+    let matches = command.get_matches();
+    let args = Args::from_arg_matches(&matches).expect("Failed to parse arguments");
 
     let level_filter = if args.quiet {
         tracing_subscriber::filter::LevelFilter::OFF
@@ -39,8 +44,35 @@ fn main() {
         .with_max_level(level_filter)
         .init();
 
+    let plugins = get_plugins();
+
+    if args.list_formats {
+        let mut formats: std::collections::HashSet<&str> = std::collections::HashSet::new();
+        for p in &plugins {
+            formats.extend(p.from_formats());
+            formats.extend(p.to_formats());
+        }
+        let mut formats_vec: Vec<_> = formats.into_iter().collect();
+        formats_vec.sort();
+
+        println!("Supported Formats:");
+        for chunk in formats_vec.chunks(6) {
+            let row = chunk.iter().map(|s| format!("{:<10}", s)).collect::<Vec<_>>().join(" ");
+            println!("  {}", row);
+        }
+        return;
+    }
+
+    let input_path = match &args.input_path {
+        Some(path) => path,
+        None => {
+            tracing::error!("Input file path is required unless --list-formats is used.");
+            process::exit(1);
+        }
+    };
+
     // Read input file
-    let input_bytes = match fs::read(&args.input_path) {
+    let input_bytes = match fs::read(input_path) {
         Ok(b) => b,
         Err(e) => {
             tracing::error!("Error reading input file: {}", e);
@@ -48,9 +80,7 @@ fn main() {
         }
     };
 
-    let plugins = get_plugins();
-
-    let from_format = match identifier::identify_format(&args.input_path, &plugins) {
+    let from_format = match identifier::identify_format(input_path, &plugins) {
         Some(f) => f,
         None => {
             tracing::error!("Unknown input format.");