use crate::fmt;
use crate::io;
use crate::num::NonZeroI32;
use crate::sys::process::process_common::*;
use crate::sys::unix::unsupported::*;
use core::ffi::NonZero_c_int;

use libc::{c_int, pid_t};

////////////////////////////////////////////////////////////////////////////////
// Command
////////////////////////////////////////////////////////////////////////////////

impl Command {
    pub fn spawn(
        &mut self,
        _default: Stdio,
        _needs_stdin: bool,
    ) -> io::Result<(Process, StdioPipes)> {
        unsupported()
    }

    pub fn exec(&mut self, _default: Stdio) -> io::Error {
        unsupported_err()
    }
}

////////////////////////////////////////////////////////////////////////////////
// Processes
////////////////////////////////////////////////////////////////////////////////

pub struct Process {
    _handle: pid_t,
}

impl Process {
    pub fn id(&self) -> u32 {
        0
    }

    pub fn kill(&mut self) -> io::Result<()> {
        unsupported()
    }

    pub fn wait(&mut self) -> io::Result<ExitStatus> {
        unsupported()
    }

    pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
        unsupported()
    }
}

#[derive(PartialEq, Eq, Clone, Copy, Debug)]
pub struct ExitStatus(c_int);

impl ExitStatus {
    #[cfg_attr(target_os = "horizon", allow(unused))]
    pub fn success(&self) -> bool {
        self.code() == Some(0)
    }

    pub fn exit_ok(&self) -> Result<(), ExitStatusError> {
        Err(ExitStatusError(1.try_into().unwrap()))
    }

    pub fn code(&self) -> Option<i32> {
        None
    }

    pub fn signal(&self) -> Option<i32> {
        None
    }

    pub fn core_dumped(&self) -> bool {
        false
    }

    pub fn stopped_signal(&self) -> Option<i32> {
        None
    }

    pub fn continued(&self) -> bool {
        false
    }

    pub fn into_raw(&self) -> c_int {
        0
    }
}

/// Converts a raw `c_int` to a type-safe `ExitStatus` by wrapping it without copying.
impl From<c_int> for ExitStatus {
    fn from(a: c_int) -> ExitStatus {
        ExitStatus(a as i32)
    }
}

impl fmt::Display for ExitStatus {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "exit code: {}", self.0)
    }
}

#[derive(PartialEq, Eq, Clone, Copy, Debug)]
pub struct ExitStatusError(NonZero_c_int);

impl Into<ExitStatus> for ExitStatusError {
    fn into(self) -> ExitStatus {
        ExitStatus(self.0.into())
    }
}

impl ExitStatusError {
    pub fn code(self) -> Option<NonZeroI32> {
        ExitStatus(self.0.into()).code().map(|st| st.try_into().unwrap())
    }
}