Rust build.rs file for auto copying game dev assets to target build dir

build.rs

use std::{env, fs, path::{Path, PathBuf}};

fn get_output_path() -> PathBuf {
    let manifest_dir_string = env::var("CARGO_MANIFEST_DIR").unwrap();
    let build_type = env::var("PROFILE").unwrap();
    let path = Path::new(&manifest_dir_string)
       .join("target")
       .join(build_type);
    return PathBuf::from(path);
}

fn copy_dir_all(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> std::io::Result<()> {
    fs::create_dir_all(&dst)?;
    for entry in fs::read_dir(src)? {
        let entry = entry?;
        let ty = entry.file_type()?;
        if ty.is_dir() {
            copy_dir_all(entry.path(), dst.as_ref().join(entry.file_name()))?;
        } else {
            fs::copy(entry.path(), dst.as_ref().join(entry.file_name()))?;
        }
    }
    Ok(())
}

fn main() {       
    let src = Path::join(&env::current_dir().unwrap(), "assets\\");
    let dest = Path::join(Path::new(&get_output_path()), "assets\\");

    //Since we only run if something's changed, clear out the old to catch deleted files.
    fs::remove_dir_all(&dest);
   
    copy_dir_all(src, dest);
    println!("cargo:rerun-if-changed=build.rs");
    println!("cargo:rerun-if-changed=assets\\");
}