build.rs

use git2::Repository;
use std::{env, error::Error, fs::File, io::Write, path::Path};

fn main() {
    write_git_version();
    if let Err(sass_err) = compile_sass() {
        panic!("Error compiling sass: {}", sass_err);
    }
    write_known_targets().unwrap();
}

fn write_git_version() {
    let maybe_hash = get_git_hash();
    let git_hash = maybe_hash.as_deref().unwrap_or("???????");

    let build_date = time::strftime("%Y-%m-%d", &time::now_utc()).unwrap();
    let dest_path = Path::new(&env::var("OUT_DIR").unwrap()).join("git_version");

    let mut file = File::create(&dest_path).unwrap();
    write!(file, "({} {})", git_hash, build_date).unwrap();

    // TODO: are these right?
    println!("cargo:rerun-if-changed=.git/HEAD");
    println!("cargo:rerun-if-changed=.git/index");
}

fn get_git_hash() -> Option<String> {
    let repo = Repository::open(env::current_dir().unwrap()).ok()?;
    let head = repo.head().unwrap();

    head.target().map(|h| {
        let mut h = format!("{}", h);
        h.truncate(7);
        h
    })
}

fn compile_sass_file(
    name: &str,
    target: &str,
    include_paths: &[String],
) -> Result<(), Box<dyn Error>> {
    use sass_rs::{Context, Options, OutputStyle};

    const STYLE_DIR: &str = concat!(env!("CARGO_MANIFEST_DIR"), "/templates/style");

    let include_paths = {
        let mut paths = vec![STYLE_DIR.to_owned()];
        paths.extend_from_slice(include_paths);
        paths
    };

    for path in &include_paths {
        for entry in walkdir::WalkDir::new(path) {
            println!("cargo:rerun-if-changed={}", entry?.path().display());
        }
    }

    let mut context = Context::new_file(format!("{}/{}.scss", STYLE_DIR, name))?;
    context.set_options(Options {
        output_style: OutputStyle::Compressed,
        include_paths,
        ..Default::default()
    });

    let css = context.compile()?;
    let dest_path = Path::new(&env::var("OUT_DIR")?).join(format!("{}.css", target));
    let mut file = File::create(&dest_path)?;
    file.write_all(css.as_bytes())?;

    Ok(())
}

fn compile_sass() -> Result<(), Box<dyn Error>> {
    // Compile base.scss -> style.css
    compile_sass_file("base", "style", &[])?;

    // Compile rustdoc.scss -> rustdoc.css
    compile_sass_file("rustdoc", "rustdoc", &[])?;

    // Compile vendored.scss -> vendored.css
    compile_sass_file(
        "vendored",
        "vendored",
        &[concat!(env!("CARGO_MANIFEST_DIR"), "/vendor/pure-css/css").to_owned()],
    )?;

    Ok(())
}

fn write_known_targets() -> std::io::Result<()> {
    use std::io::BufRead;

    let targets: Vec<String> = std::process::Command::new("rustc")
        .args(&["--print", "target-list"])
        .output()?
        .stdout
        .lines()
        .filter(|s| s.as_ref().map_or(true, |s| !s.is_empty()))
        .collect::<std::io::Result<_>>()?;

    string_cache_codegen::AtomType::new("target::TargetAtom", "target_atom!")
        .atoms(&targets)
        .write_to_file(&Path::new(&env::var("OUT_DIR").unwrap()).join("target_atom.rs"))?;

    Ok(())
}