use turkos_os_shell_foreground::{Adapter, Cause, Error, Foreground, Outcome, Pid};

#[derive(Default)]
struct Fake { next: u64, fail_spawn: bool, fail_wait: bool, waits: Vec<Pid> }
impl Adapter for Fake {
    fn spawn(&mut self) -> Result<Pid, Cause> {
        if self.fail_spawn { self.fail_spawn = false; return Err(Cause::Injected); }
        self.next += 1;
        Ok(Pid(self.next))
    }
    fn wait(&mut self, pid: Pid) -> Result<Outcome, Cause> {
        self.waits.push(pid);
        if self.fail_wait { self.fail_wait = false; return Err(Cause::Busy); }
        if pid == Pid(2) { Ok(Outcome::Fault(0x9000_0000)) }
        else { Ok(Outcome::Exited(42)) }
    }
}

#[test]
fn os_shell_foreground_runs_one_child_and_returns_outcome() {
    let mut foreground = Foreground::new();
    let mut adapter = Fake::default();
    assert_eq!(foreground.launch(&mut adapter), Ok(Pid(1)));
    assert_eq!(foreground.owner(), Some(Pid(1)));
    assert_eq!(foreground.launch(&mut adapter), Err(Error::AlreadyRunning));
    assert_eq!(foreground.collect(&mut adapter), Ok(Outcome::Exited(42)));
    assert_eq!(foreground.owner(), None);
    assert_eq!(foreground.launch(&mut adapter), Ok(Pid(2)));
    assert_eq!(foreground.collect(&mut adapter), Ok(Outcome::Fault(0x9000_0000)));
    assert_eq!(adapter.waits, [Pid(1), Pid(2)]);
}

#[test]
fn os_shell_foreground_rejects_empty_and_failed_spawn() {
    let mut foreground = Foreground::new();
    let mut adapter = Fake {fail_spawn: true, ..Fake::default()};
    assert_eq!(foreground.collect(&mut adapter), Err(Error::NoForeground));
    assert_eq!(foreground.launch(&mut adapter), Err(Error::Spawn(Cause::Injected)));
    assert_eq!(foreground.owner(), None);
    struct Zero;
    impl Adapter for Zero {
        fn spawn(&mut self) -> Result<Pid, Cause> { Ok(Pid(0)) }
        fn wait(&mut self, _: Pid) -> Result<Outcome, Cause> { unreachable!() }
    }
    assert_eq!(foreground.launch(&mut Zero), Err(Error::InvalidPid));
    assert_eq!(foreground.owner(), None);
}

#[test]
fn os_shell_foreground_wait_error_retains_owner() {
    let mut foreground = Foreground::new();
    let mut adapter = Fake {fail_wait: true, ..Fake::default()};
    foreground.launch(&mut adapter).unwrap();
    assert_eq!(foreground.collect(&mut adapter), Err(Error::Wait(Cause::Busy)));
    assert_eq!(foreground.owner(), Some(Pid(1)));
    assert_eq!(foreground.launch(&mut adapter), Err(Error::AlreadyRunning));
    assert_eq!(foreground.collect(&mut adapter), Ok(Outcome::Exited(42)));
    assert_eq!(foreground.owner(), None);
    assert_eq!(adapter.waits, [Pid(1), Pid(1)]);
}