use std::process::Command;

/// Exposes the current commit and the crate name to the code through `env!()`
fn main() {
    // The docker build has no git repository: CI passes the commit in instead
    // (`--build-arg GIT_HASH=...`), so the running image stays traceable.
    let git_hash = std::env::var("GIT_HASH")
        .ok()
        .filter(|hash| !hash.is_empty() && hash != "unknown")
        .or_else(|| {
            Command::new("git")
                .args(["rev-parse", "HEAD"])
                .output()
                .ok()
                .filter(|output| output.status.success())
                .and_then(|output| String::from_utf8(output.stdout).ok())
        })
        .map(|hash| hash.trim().chars().take(8).collect::<String>())
        .unwrap_or_else(|| "unknown".to_owned());

    println!("cargo:rustc-env=GIT_HASH={git_hash}");
    println!("cargo:rerun-if-env-changed=GIT_HASH");
    println!(
        "cargo:rustc-env=CRATE_NAME={}",
        env!("CARGO_PKG_NAME").replace("-", "_")
    );
    println!("cargo:rerun-if-changed=.git/HEAD");
}