use std::env;
use std::process::Command;

fn git(args: &[&str]) -> Option<String> {
    let output = Command::new("git").args(args).output().ok()?;
    if !output.status.success() {
        return None;
    }
    let text = String::from_utf8(output.stdout).ok()?;
    Some(text.trim().to_string())
}

fn main() {
    println!("cargo:rerun-if-changed=.git/HEAD");
    println!("cargo:rerun-if-changed=.git/index");
    println!("cargo:rerun-if-env-changed=DOSH_BUILD_GIT_HASH");
    println!("cargo:rerun-if-env-changed=DOSH_BUILD_COMMIT_DATE");
    println!("cargo:rerun-if-env-changed=DOSH_BUILD_GIT_DIRTY");

    let hash = env::var("DOSH_BUILD_GIT_HASH")
        .ok()
        .filter(|value| !value.is_empty())
        .or_else(|| git(&["rev-parse", "--short=12", "HEAD"]))
        .unwrap_or_else(|| "unknown".into());
    let date = env::var("DOSH_BUILD_COMMIT_DATE")
        .ok()
        .filter(|value| !value.is_empty())
        .or_else(|| git(&["show", "-s", "--format=%cs", "HEAD"]))
        .unwrap_or_else(|| "unknown".into());
    let dirty = match env::var("DOSH_BUILD_GIT_DIRTY").ok().as_deref() {
        Some("1" | "true" | "yes" | "+dirty") => "+dirty",
        Some(_) => "",
        None => Command::new("git")
            .args(["diff", "--quiet", "--ignore-submodules", "--"])
            .status()
            .map(|status| if status.success() { "" } else { "+dirty" })
            .unwrap_or(""),
    };

    println!("cargo:rustc-env=DOSH_GIT_HASH={hash}{dirty}");
    println!("cargo:rustc-env=DOSH_COMMIT_DATE={date}");
}