#![unstable(issue = "none", feature = "windows_handle")]

use crate::cmp;
use crate::io::{self, ErrorKind, IoSlice, IoSliceMut, Read};
use crate::mem;
use crate::ops::Deref;
use crate::ptr;
use crate::sys::c;
use crate::sys::cvt;

/// `HANDLE` object 的拥有所有权的容器，在 Drop 上将其关闭。
///
/// 所有方法都是通过 `Deref` impl 继承到 `RawHandle`
pub struct Handle(RawHandle);

/// `HANDLE` 对象的包装类型，以为其提供正确的 Send/Sync 推断以及 Rust-y 方法。
///
///
/// 当它离开作用域时，它不会丢弃句柄，而是使用 `Handle` 代替那个。
///
#[derive(Copy, Clone)]
pub struct RawHandle(c::HANDLE);

unsafe impl Send for RawHandle {}
unsafe impl Sync for RawHandle {}

impl Handle {
    pub fn new(handle: c::HANDLE) -> Handle {
        Handle(RawHandle::new(handle))
    }

    pub fn new_event(manual: bool, init: bool) -> io::Result<Handle> {
        unsafe {
            let event =
                c::CreateEventW(ptr::null_mut(), manual as c::BOOL, init as c::BOOL, ptr::null());
            if event.is_null() { Err(io::Error::last_os_error()) } else { Ok(Handle::new(event)) }
        }
    }

    pub fn into_raw(self) -> c::HANDLE {
        let ret = self.raw();
        mem::forget(self);
        ret
    }
}

impl Deref for Handle {
    type Target = RawHandle;
    fn deref(&self) -> &RawHandle {
        &self.0
    }
}

impl Drop for Handle {
    fn drop(&mut self) {
        unsafe {
            let _ = c::CloseHandle(self.raw());
        }
    }
}

impl RawHandle {
    pub fn new(handle: c::HANDLE) -> RawHandle {
        RawHandle(handle)
    }

    pub fn raw(&self) -> c::HANDLE {
        self.0
    }

    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
        let mut read = 0;
        let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
        let res = cvt(unsafe {
            c::ReadFile(self.0, buf.as_mut_ptr() as c::LPVOID, len, &mut read, ptr::null_mut())
        });

        match res {
            Ok(_) => Ok(read as usize),

            // BrokenPipe 的特殊处理是处理 Windows 管道语义，当另一端关闭后从管道读取时，会产生此错误。我们将其解释为管道上的 EOF。
            //
            //
            //
            Err(ref e) if e.kind() == ErrorKind::BrokenPipe => Ok(0),

            Err(e) => Err(e),
        }
    }

    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
        crate::io::default_read_vectored(|buf| self.read(buf), bufs)
    }

    #[inline]
    pub fn is_read_vectored(&self) -> bool {
        false
    }

    pub fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
        let mut read = 0;
        let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
        let res = unsafe {
            let mut overlapped: c::OVERLAPPED = mem::zeroed();
            overlapped.Offset = offset as u32;
            overlapped.OffsetHigh = (offset >> 32) as u32;
            cvt(c::ReadFile(self.0, buf.as_mut_ptr() as c::LPVOID, len, &mut read, &mut overlapped))
        };
        match res {
            Ok(_) => Ok(read as usize),
            Err(ref e) if e.raw_os_error() == Some(c::ERROR_HANDLE_EOF as i32) => Ok(0),
            Err(e) => Err(e),
        }
    }

    pub unsafe fn read_overlapped(
        &self,
        buf: &mut [u8],
        overlapped: *mut c::OVERLAPPED,
    ) -> io::Result<Option<usize>> {
        let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
        let mut amt = 0;
        let res = cvt(c::ReadFile(self.0, buf.as_ptr() as c::LPVOID, len, &mut amt, overlapped));
        match res {
            Ok(_) => Ok(Some(amt as usize)),
            Err(e) => {
                if e.raw_os_error() == Some(c::ERROR_IO_PENDING as i32) {
                    Ok(None)
                } else if e.raw_os_error() == Some(c::ERROR_BROKEN_PIPE as i32) {
                    Ok(Some(0))
                } else {
                    Err(e)
                }
            }
        }
    }

    pub fn overlapped_result(
        &self,
        overlapped: *mut c::OVERLAPPED,
        wait: bool,
    ) -> io::Result<usize> {
        unsafe {
            let mut bytes = 0;
            let wait = if wait { c::TRUE } else { c::FALSE };
            let res = cvt(c::GetOverlappedResult(self.raw(), overlapped, &mut bytes, wait));
            match res {
                Ok(_) => Ok(bytes as usize),
                Err(e) => {
                    if e.raw_os_error() == Some(c::ERROR_HANDLE_EOF as i32)
                        || e.raw_os_error() == Some(c::ERROR_BROKEN_PIPE as i32)
                    {
                        Ok(0)
                    } else {
                        Err(e)
                    }
                }
            }
        }
    }

    pub fn cancel_io(&self) -> io::Result<()> {
        unsafe { cvt(c::CancelIo(self.raw())).map(drop) }
    }

    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
        let mut amt = 0;
        let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
        cvt(unsafe {
            c::WriteFile(self.0, buf.as_ptr() as c::LPVOID, len, &mut amt, ptr::null_mut())
        })?;
        Ok(amt as usize)
    }

    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        crate::io::default_write_vectored(|buf| self.write(buf), bufs)
    }

    #[inline]
    pub fn is_write_vectored(&self) -> bool {
        false
    }

    pub fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
        let mut written = 0;
        let len = cmp::min(buf.len(), <c::DWORD>::MAX as usize) as c::DWORD;
        unsafe {
            let mut overlapped: c::OVERLAPPED = mem::zeroed();
            overlapped.Offset = offset as u32;
            overlapped.OffsetHigh = (offset >> 32) as u32;
            cvt(c::WriteFile(
                self.0,
                buf.as_ptr() as c::LPVOID,
                len,
                &mut written,
                &mut overlapped,
            ))?;
        }
        Ok(written as usize)
    }

    pub fn duplicate(
        &self,
        access: c::DWORD,
        inherit: bool,
        options: c::DWORD,
    ) -> io::Result<Handle> {
        let mut ret = 0 as c::HANDLE;
        cvt(unsafe {
            let cur_proc = c::GetCurrentProcess();
            c::DuplicateHandle(
                cur_proc,
                self.0,
                cur_proc,
                &mut ret,
                access,
                inherit as c::BOOL,
                options,
            )
        })?;
        Ok(Handle::new(ret))
    }
}

impl<'a> Read for &'a RawHandle {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        (**self).read(buf)
    }

    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
        (**self).read_vectored(bufs)
    }
}