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

// https://stackoverflow.com/a/44407625
fn main() {
    let output = Command::new("git")
        .args(&["rev-parse", "HEAD"])
        .output()
        .unwrap();
    let git_hash = String::from_utf8(output.stdout).unwrap();
    match fs::read_to_string("../.git/HEAD") {
        Ok(contents) => {
            if let Some(branch_path) = contents.split(" ").skip(1).next() {
                let path = PathBuf::from(".git").join(branch_path);
                let path = path.to_str().unwrap_or(".git/HEAD");
                println!("cargo:rustc-rerun-if-changed={}", path);
            }
        }
        Err(err) => {
            println!("cargo::warning=Failed to read .git/HEAD: {}", err);
        }
    }
    println!("cargo:rustc-env=GIT_HASH={}", git_hash);
}