learn-wgpu/code/wasm-builder/src/main.rs

use std::{process::Command, path::PathBuf};

use rayon::prelude::{IntoParallelRefIterator, ParallelIterator};
use wasm_bindgen_cli_support::Bindgen;

#[derive(Debug, serde::Deserialize, serde::Serialize)]
struct WasmTarget {
    package: String,
    out: String,
}

fn main() -> anyhow::Result<()> {
    env_logger::init();

    let input = match std::env::args().skip(1).next() {
        Some(s) => s,
        None => {
            log::info!("No input file supplied");
            std::process::exit(1);
        }
    };

    let json = std::fs::read_to_string(input)?;

    let targets: Vec<WasmTarget> = serde_json::from_str(&json)?;

    // Tell cargo to build all targets as wasm32-unknown-unknown
    let mut command = Command::new("cargo");

    let start_time = std::time::Instant::now();

    command
        .arg("build")
        .arg("--release")
        .arg("--target")
        .arg("wasm32-unknown-unknown");
    for target in &targets {
        command.arg("-p").arg(&target.package);
    }
    command.spawn()?.wait()?;

    let errors = targets
        .par_iter()
        .map(|target| {
            let path = PathBuf::from(&target.out);

            // Ignore contents to prevent cargo-watch looping
            std::fs::create_dir_all(&path)?;
            std::fs::write(path.join(".gitignore"), "*\n")?;

            Bindgen::new()
                .bundler(true)?
                .input_path(format!(
                    "target/wasm32-unknown-unknown/release/{}.wasm",
                    target.package
                ))
                .out_name("demo")
                .generate(path)
        })
        .filter_map(|r| r.err())
        .collect::<Vec<_>>();

    if !errors.is_empty() {
        for error in &errors {
            log::error!("{}", error);
        }
        log::error!("Encountered {} error(s)", errors.len());
        std::process::exit(1);
    }

    let time_taken = std::time::Instant::now() - start_time;
    log::info!("Success fully processed {} target(s) in {:?}", targets.len(), time_taken);

    Ok(())
}