Add build script for man generation

Author: andrews05

Cargo.lock

@@ -78,6 +78,8 @@ features = ["png"]
 version = "0.24.6"
 
 [build-dependencies]
+clap = "4.3.8"
+clap_mangen = "0.2.20"
 rustc_version = "0.4.0"
 
 [features]

Cargo.toml

@@ -0,0 +1,35 @@
+use clap_mangen::Man;
+use std::{env, fs::File, io::Error, path::Path};
+
+include!("src/cli.rs");
+
+fn build_manpages(outdir: &Path) -> Result<(), Error> {
+    let app = build_command();
+
+    let file = Path::new(&outdir).join("oxipng.1");
+    let mut file = File::create(file)?;
+
+    Man::new(app).render(&mut file)?;
+
+    Ok(())
+}
+
+fn main() -> Result<(), Error> {
+    println!("cargo:rerun-if-changed=src/cli.rs");
+    println!("cargo:rerun-if-changed=man");
+
+    let outdir = match env::var_os("OUT_DIR") {
+        None => return Ok(()),
+        Some(outdir) => outdir,
+    };
+
+    // Create `target/assets/` folder.
+    let out_path = PathBuf::from(outdir);
+    let mut path = out_path.ancestors().nth(4).unwrap().to_owned();
+    path.push("assets");
+    std::fs::create_dir_all(&path).unwrap();
+
+    build_manpages(&path)?;
+
+    Ok(())
+}