use gitbaby::command::env::Env;
use std::sync::{Mutex, MutexGuard, PoisonError};

static ENV_LOCK: Mutex<()> = Mutex::new(());

fn lock_or_recover() -> MutexGuard<'static, ()> {
    match ENV_LOCK.lock() {
        Ok(g) => g,
        Err(PoisonError { .. }) => panic!("env lock poisoned"),
    }
}

fn unique_key(suffix: &str) -> String {
    format!("GITBABY_TEST_ENV_{suffix}")
}

unsafe fn set_var(key: &str, val: &str) {
    unsafe { std::env::set_var(key, val) }
}

unsafe fn remove_var(key: &str) {
    unsafe { std::env::remove_var(key) }
}

#[test]
fn from_current_env_includes_system_var() {
    let _guard = lock_or_recover();
    let key = unique_key("FROM_CUR");
    unsafe { set_var(&key, "from-system") };

    let env = Env::from_current_env();
    assert_eq!(env.get(&key), Some("from-system"));

    unsafe { remove_var(&key) };
}

#[test]
fn from_current_env_contains_path_like_var() {
    let env = Env::from_current_env();
    assert!(env.get("PATH").is_some() || env.get("Path").is_some() || !env.is_empty());
}

#[test]
fn set_overrides_system_var_after_from_current_env() {
    let _guard = lock_or_recover();
    let key = unique_key("OVERRIDE");
    unsafe { set_var(&key, "system-value") };

    let mut env = Env::from_current_env();
    env.set(&key, "user-value");
    assert_eq!(env.get(&key), Some("user-value"));

    unsafe { remove_var(&key) };
}

#[test]
fn with_current_env_overrides_user_added_var() {
    let _guard = lock_or_recover();
    let key = unique_key("WC_OVERRIDE");
    unsafe { set_var(&key, "system-wins") };

    let env = Env::new().with(&key, "user-loses").with_current_env();
    assert_eq!(env.get(&key), Some("system-wins"));

    unsafe { remove_var(&key) };
}

#[test]
fn overlay_current_env_preserves_user_added_var() {
    let _guard = lock_or_recover();
    let key = unique_key("OVERLAY");
    unsafe { set_var(&key, "system-value") };

    let env = Env::new().with(&key, "user-keeps").overlay_current_env();
    assert_eq!(env.get(&key), Some("user-keeps"));

    unsafe { remove_var(&key) };
}

#[test]
fn overlay_current_env_fills_missing_keys() {
    let _guard = lock_or_recover();
    let mut iter = std::env::vars_os();
    let known = match iter.next() {
        Some(v) => v,
        None => panic!("process should have at least one env var"),
    };
    let known_key = known.0.to_string_lossy().into_owned();

    let env = Env::new().overlay_current_env();
    assert!(env.get(&known_key).is_some());
}

#[test]
fn unset_removes_system_var_when_loaded() {
    let _guard = lock_or_recover();
    let key = unique_key("UNSET");
    unsafe { set_var(&key, "temp") };

    let mut env = Env::from_current_env();
    assert_eq!(env.get(&key), Some("temp"));

    env.unset(&key);
    assert_eq!(env.get(&key), None);

    unsafe { remove_var(&key) };
}

#[test]
fn from_current_env_is_cloneable() {
    let _guard = lock_or_recover();
    let key = unique_key("CLONE");
    unsafe { set_var(&key, "v") };

    let env = Env::from_current_env();
    let copy = env.clone();
    assert_eq!(env.get(&key), Some("v"));
    assert_eq!(copy.get(&key), Some("v"));

    unsafe { remove_var(&key) };
}

#[test]
fn set_after_from_current_env_does_not_grow_pairs_when_key_known() {
    let _guard = lock_or_recover();
    let key = unique_key("NOGROW");
    unsafe { set_var(&key, "system") };

    let mut env = Env::from_current_env();
    let before = env.len();
    env.set(&key, "user");
    let after = env.len();
    assert_eq!(before, after, "set 应替换而非新增");
    assert_eq!(env.get(&key), Some("user"));

    unsafe { remove_var(&key) };
}