// use std::{
//     collections::HashMap,
//     env::{self, VarError},
// };

// use git2::{DescribeOptions, Repository};
// use serde::Deserialize;

fn main() {
//     features_env();
//     target_envs();
//     git_envs();
}

// /// Builds the `CARGO_FEATURES` environment variable.
// ///
// /// This function turns enabled cargo features into a simple string
// /// `+feature1 +feature2 +featureN`, which then exposes it via the
// /// `CARGO_FEATURES` environment variable.
// ///
// /// It first reads and parses the Cargo.toml in order to extract all
// /// available features (omitting "default"). It then checks for
// /// enabled features via `CARGO_FEATURE_<name>` to finally collect
// /// them into a string.
// fn features_env() {
//     #[derive(Deserialize)]
//     struct Config {
//         features: HashMap<String, Vec<String>>,
//     }

//     impl Config {
//         fn enabled_features(self) -> impl Iterator<Item = String> {
//             self.features
//                 .into_keys()
//                 .filter(|feature| feature != "default")
//                 .filter(|feature| {
//                     let feature = feature.replace('-', "_").to_uppercase();
//                     env::var(format!("CARGO_FEATURE_{feature}")).is_ok()
//                 })
//         }
//     }

//     let config: Config =
//         toml::from_str(include_str!("./Cargo.toml")).expect("should parse Cargo.toml");

//     let mut features = String::new();

//     for feature in config.enabled_features() {
//         if !features.is_empty() {
//             features.push(' ');
//         }
//         features.push_str(&format!("+{feature}"));
//     }

//     println!("cargo::rustc-env=CARGO_FEATURES={features}");
// }

// /// Builds environment variables related to the target platform.
// ///
// /// This function basically forwards existing cargo environments
// /// related to the target platform.
// fn target_envs() {
//     forward_env("CARGO_CFG_TARGET_OS");
//     forward_env("CARGO_CFG_TARGET_ENV");
//     forward_env("CARGO_CFG_TARGET_ARCH");
// }

// /// Builds environment variables related to git.
// ///
// /// This function basically tries to forward existing git environment
// /// variables. In case of failure, it tries to build them using
// /// [`git2`].
// fn git_envs() {
//     // skip the process if the current directory is not a git
//     // repository (for example, from a nix build root jail)
//     let Ok(git) = Repository::open(".") else {
//         println!("cargo::rustc-env=GIT_DESCRIBE=unknown");
//         println!("cargo::rustc-env=GIT_REV=unknown");
//         return;
//     };

//     if try_forward_env("GIT_DESCRIBE").is_err() {
//         let mut opts = DescribeOptions::new();
//         opts.describe_all();
//         opts.show_commit_oid_as_fallback(true);

//         let description = git
//             .describe(&opts)
//             .expect("should describe git object")
//             .format(None)
//             .expect("should format git object description");

//         println!("cargo::rustc-env=GIT_DESCRIBE={description}");
//     };

//     if try_forward_env("GIT_REV").is_err() {
//         let head = git.head().expect("should get git HEAD");
//         let commit = head.peel_to_commit().expect("should get git HEAD commit");
//         let rev = commit.id().to_string();

//         println!("cargo::rustc-env=GIT_REV={rev}");
//     };
// }

// /// Tries to forward the given environment variable.
// ///
// /// For a more strict version, see [`forward_env`].
// fn try_forward_env(key: &str) -> Result<String, VarError> {
//     let env = env::var(key);

//     if let Ok(val) = &env {
//         println!("cargo::rustc-env={key}={val}");
//     }

//     env
// }

// /// Forwards the given environment variable.
// ///
// /// This function panics in case the forward fails (when the
// /// environment variable does not exist for example).
// ///
// /// For a less strict version, see [`try_forward_env`].
// fn forward_env(key: &str) {
//     try_forward_env(key).expect(&format!("should get env {key}"));
// }