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

fn main() {
    let is_production = env::var("APP_ENV")
        .map(|e| e == "production")
        .unwrap_or(false);

    let version = if is_production {
        get_latest_tag().unwrap_or_else(|| panic!("Production builds must have a GIT tag."))
    } else {
        get_commit_hash().unwrap_or_else(|| env!("CARGO_PKG_VERSION").to_string())
    };

    println!("cargo:rustc-env=GIT_VERSION={}", version)
}

fn get_commit_hash() -> Option<String> {
    let output = Command::new("git")
        .args(&["rev-parse", "--short=8", "HEAD"])
        .output()
        .ok()?;

    if !output.status.success() {
        return None;
    }

    String::from_utf8(output.stdout)
        .ok()
        .map(|s| s.trim().to_string())
}

fn get_latest_tag() -> Option<String> {
    let output = Command::new("git")
        .args(&["describe", "--tags",  "--match", "v*"])
        .output()
        .ok()?;

    if !output.status.success() {
        return None;
    }

    String::from_utf8(output.stdout)
        .ok()
        .map(|s| s.trim().to_string())
}