use crate::io;
use crate::mem;
use crate::ptr;

use crate::sys::process::zircon::{Handle, zx_handle_t};
use crate::sys::process::process_common::*;

use libc::size_t;

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

impl Command {
    pub fn spawn(&mut self, default: Stdio, needs_stdin: bool)
                 -> io::Result<(Process, StdioPipes)> {
        let envp = self.capture_env();

        if self.saw_nul() {
            return Err(io::Error::new(io::ErrorKind::InvalidInput,
                                      "nul byte found in provided data"));
        }

        let (ours, theirs) = self.setup_io(default, needs_stdin)?;

        let process_handle = unsafe { self.do_exec(theirs, envp.as_ref())? };

        Ok((Process { handle: Handle::new(process_handle) }, ours))
    }

    pub fn exec(&mut self, default: Stdio) -> io::Error {
        if self.saw_nul() {
            return io::Error::new(io::ErrorKind::InvalidInput,
                                  "nul byte found in provided data")
        }

        match self.setup_io(default, true) {
            Ok((_, _)) => {
                // FIXME: This is tough because we don't support the exec syscalls
                unimplemented!();
            },
            Err(e) => e,
        }
    }

    unsafe fn do_exec(&mut self, stdio: ChildPipes, maybe_envp: Option<&CStringArray>)
                      -> io::Result<zx_handle_t> {
        use crate::sys::process::zircon::*;

        let envp = match maybe_envp {
            // None means to clone the current environment, which is done in the
            // flags below.
            None => ptr::null(),
            Some(envp) => envp.as_ptr(),
        };

        let make_action = |local_io: &ChildStdio, target_fd| -> io::Result<fdio_spawn_action_t> {
            if let Some(local_fd) = local_io.fd() {
                Ok(fdio_spawn_action_t {
                    action: FDIO_SPAWN_ACTION_TRANSFER_FD,
                    local_fd,
                    target_fd,
                    ..Default::default()
                })
            } else {
                if let ChildStdio::Null = local_io {
                    // acts as no-op
                    return Ok(Default::default());
                }

                let mut handle = ZX_HANDLE_INVALID;
                let status = fdio_fd_clone(target_fd, &mut handle);
                if status == ERR_INVALID_ARGS || status == ERR_NOT_SUPPORTED {
                    // This descriptor is closed; skip it rather than generating an
                    // error.
                    return Ok(Default::default());
                }
                zx_cvt(status)?;

                let mut cloned_fd = 0;
                zx_cvt(fdio_fd_create(handle, &mut cloned_fd))?;

                Ok(fdio_spawn_action_t {
                    action: FDIO_SPAWN_ACTION_TRANSFER_FD,
                    local_fd: cloned_fd as i32,
                    target_fd,
                    ..Default::default()
                })
            }
        };

        // Clone stdin, stdout, and stderr
        let action1 = make_action(&stdio.stdin, 0)?;
        let action2 = make_action(&stdio.stdout, 1)?;
        let action3 = make_action(&stdio.stderr, 2)?;
        let actions = [action1, action2, action3];

        // We don't want FileDesc::drop to be called on any stdio. fdio_spawn_etc
        // always consumes transferred file descriptors.
        mem::forget(stdio);

        for callback in self.get_closures().iter_mut() {
            callback()?;
        }

        let mut process_handle: zx_handle_t = 0;
        zx_cvt(fdio_spawn_etc(
            ZX_HANDLE_INVALID,
            FDIO_SPAWN_CLONE_JOB | FDIO_SPAWN_CLONE_LDSVC | FDIO_SPAWN_CLONE_NAMESPACE
            | FDIO_SPAWN_CLONE_ENVIRON,  // this is ignored when envp is non-null
            self.get_argv()[0], self.get_argv().as_ptr(), envp,
            actions.len() as size_t, actions.as_ptr(),
            &mut process_handle,
            ptr::null_mut(),
        ))?;
        // FIXME: See if we want to do something with that err_msg

        Ok(process_handle)
    }
}

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

pub struct Process {
    handle: Handle,
}

impl Process {
    pub fn id(&self) -> u32 {
        self.handle.raw() as u32
    }

    pub fn kill(&mut self) -> io::Result<()> {
        use crate::sys::process::zircon::*;

        unsafe { zx_cvt(zx_task_kill(self.handle.raw()))?; }

        Ok(())
    }

    pub fn wait(&mut self) -> io::Result<ExitStatus> {
        use crate::default::Default;
        use crate::sys::process::zircon::*;

        let mut proc_info: zx_info_process_t = Default::default();
        let mut actual: size_t = 0;
        let mut avail: size_t = 0;

        unsafe {
            zx_cvt(zx_object_wait_one(self.handle.raw(), ZX_TASK_TERMINATED,
                                      ZX_TIME_INFINITE, ptr::null_mut()))?;
            zx_cvt(zx_object_get_info(self.handle.raw(), ZX_INFO_PROCESS,
                                      &mut proc_info as *mut _ as *mut libc::c_void,
                                      mem::size_of::<zx_info_process_t>(), &mut actual,
                                      &mut avail))?;
        }
        if actual != 1 {
            return Err(io::Error::new(io::ErrorKind::InvalidData,
                                      "Failed to get exit status of process"));
        }
        Ok(ExitStatus::new(proc_info.rec.return_code))
    }

    pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
        use crate::default::Default;
        use crate::sys::process::zircon::*;

        let mut proc_info: zx_info_process_t = Default::default();
        let mut actual: size_t = 0;
        let mut avail: size_t = 0;

        unsafe {
            let status = zx_object_wait_one(self.handle.raw(), ZX_TASK_TERMINATED,
                                            0, ptr::null_mut());
            match status {
                0 => { }, // Success
                x if x == ERR_TIMED_OUT => {
                    return Ok(None);
                },
                _ => { panic!("Failed to wait on process handle: {}", status); },
            }
            zx_cvt(zx_object_get_info(self.handle.raw(), ZX_INFO_PROCESS,
                                      &mut proc_info as *mut _ as *mut libc::c_void,
                                      mem::size_of::<zx_info_process_t>(), &mut actual,
                                      &mut avail))?;
        }
        if actual != 1 {
            return Err(io::Error::new(io::ErrorKind::InvalidData,
                                      "Failed to get exit status of process"));
        }
        Ok(Some(ExitStatus::new(proc_info.rec.return_code)))
    }
}
