use std::process::Command;

fn main() {
    // Git commit hash
    let git_commit = Command::new("git")
        .args(["rev-parse", "--short", "HEAD"])
        .output()
        .ok()
        .and_then(|o| String::from_utf8(o.stdout).ok())
        .map(|s| s.trim().to_string())
        .filter(|s| !s.is_empty())
        .unwrap_or_else(|| "unknown".to_string());

    // Build timestamp (UTC)
    let build_date = Command::new("date")
        .args(["-u", "+%Y-%m-%dT%H:%M:%SZ"])
        .output()
        .ok()
        .and_then(|o| String::from_utf8(o.stdout).ok())
        .map(|s| s.trim().to_string())
        .filter(|s| !s.is_empty())
        .unwrap_or_else(|| "unknown".to_string());

    // Rust version
    let rust_version = Command::new("rustc")
        .arg("--version")
        .output()
        .ok()
        .and_then(|o| String::from_utf8(o.stdout).ok())
        .map(|s| s.trim().to_string())
        .filter(|s| !s.is_empty())
        .unwrap_or_else(|| "unknown".to_string());

    println!("cargo:rustc-env=GIT_COMMIT={git_commit}");
    println!("cargo:rustc-env=BUILD_DATE={build_date}");
    println!("cargo:rustc-env=RUST_VERSION={rust_version}");

    // Re-run if git HEAD changes
    println!("cargo:rerun-if-changed=.git/HEAD");
    println!("cargo:rerun-if-changed=.git/refs/heads");
}