fix: replace broken "./" output default with a derived output path

src/main.rs

@@ -1,21 +1,29 @@
 use anyhow::{Context, Result};
 use clap::Parser;
 use las::{Builder, Read, Reader, Write, Writer};
+use std::path::PathBuf;
 
 #[derive(Parser)]
 #[command(author, version, about, long_about = None)]
 struct Args {
     #[arg(short, long)]
-    path: String,
+    path: PathBuf,
 
-    #[arg(short, long, default_value_t = String::from("./"))]
-    output: String,
+    /// Output file path. Defaults to the input path with a
+    /// `.cleaned.las` extension (e.g. `/data/scan.las` -> `/data/scan.cleaned.las`).
+    #[arg(short, long)]
+    output: Option<PathBuf>,
 }
 
 fn main() -> Result<()> {
     let args = Args::parse();
 
-    let mut reader = Reader::from_path(args.path).context("Failed to open las file")?;
+    let output = args
+        .output
+        .clone()
+        .unwrap_or_else(|| args.path.with_extension("cleaned.las"));
+
+    let mut reader = Reader::from_path(&args.path).context("Failed to open las file")?;
 
     let original_header = reader.header().clone();
 
@@ -35,7 +43,7 @@ fn main() -> Result<()> {
         }
     }
 
-    let mut writer = Writer::from_path(args.output, header).context("Failed to get las writer")?;
+    let mut writer = Writer::from_path(&output, header).context("Failed to get las writer")?;
 
     for point in las_points {
         writer.write(point).context("Unable to write:")?;