package unix

import (
	"unsafe"
)

func bytes2iovec(bs [][]byte) []Iovec {
	iovecs := make([]Iovec, len(bs))
	for i, b := range bs {
		iovecs[i].SetLen(len(b))
		if len(b) > 0 {
			iovecs[i].Base = &b[0]
		} else {
			iovecs[i].Base = (*byte)(unsafe.Pointer(&_zero))
		}
	}
	return iovecs
}

//sys	readv(fd int, iovs []Iovec) (n int, err error)

func Readv(fd int, iovs [][]byte) (n int, err error) {

var (
	procreadv,
	procpreadv,
	procwritev,
	procpwritev,
	procaccept4 syscallFunc
)

// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT

func readv(fd int, iovs []Iovec) (n int, err error) {
	var _p0 *Iovec
	if len(iovs) > 0 {
		_p0 = &iovs[0]
	}
	r0, _, e1 := sysvicall6(uintptr(unsafe.Pointer(&procreadv)), 3, uintptr(fd), uintptr(unsafe.Pointer(_p0)), uintptr(len(iovs)), 0, 0, 0)
	n = int(r0)

	if err := fd.writeLock(); err != nil {
		return 0, err
	}
	defer fd.writeUnlock()
	if err := fd.pd.prepareWrite(fd.isFile); err != nil {
		return 0, err
	}

	var iovecs []syscall.Iovec
	if fd.iovecs != nil {
		iovecs = *fd.iovecs
	}
	// TODO: read from sysconf(_SC_IOV_MAX)? The Linux default is
	// 1024 and this seems conservative enough for now. Darwin's
	// UIO_MAXIOV also seems to be 1024.

//sys	readv(fd int, iovs []Iovec) (n int, err error) = SYS_READV
//sys	writev(fd int, iovs []Iovec) (n int, err error) = SYS_WRITEV
//sys	preadv(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PREADV
//sys	pwritev(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PWRITEV

type clockid = uint32

const (
	clockRealtime  clockid = 0
	clockMonotonic clockid = 1
)

// https://github.com/WebAssembly/WASI/blob/a2b96e81c0586125cc4dc79a5be0b78d9a059925/legacy/preview1/docs.md#-iovec-record
type iovec struct {
	buf    uintptr32
	bufLen size
}

//go:wasmimport wasi_snapshot_preview1 proc_exit
func exit(code int32)

//go:wasmimport wasi_snapshot_preview1 args_get
//go:noescape

	return Timeval{Sec: sec, Usec: int32(usec)}
}

func SetKevent(k *Kevent_t, fd, mode, flags int) {
	k.Ident = uint64(fd)
	k.Filter = uint32(mode)
	k.Flags = uint32(flags)
}

func (iov *Iovec) SetLen(length int) {
	iov.Len = uint64(length)
}

func (msghdr *Msghdr) SetControllen(length int) {
	msghdr.Controllen = uint32(length)
}

func (msghdr *Msghdr) SetIovlen(length int) {

	return Timeval{Sec: sec, Usec: int32(usec)}
}

func SetKevent(k *Kevent_t, fd, mode, flags int) {
	k.Ident = uint32(fd)
	k.Filter = uint32(mode)
	k.Flags = uint32(flags)
}

func (iov *Iovec) SetLen(length int) {
	iov.Len = uint32(length)
}

func (msghdr *Msghdr) SetControllen(length int) {
	msghdr.Controllen = uint32(length)
}

func (msghdr *Msghdr) SetIovlen(length int) {

	return Timeval{Sec: sec, Usec: int32(usec)}
}

func SetKevent(k *Kevent_t, fd, mode, flags int) {
	k.Ident = uint64(fd)
	k.Filter = uint32(mode)
	k.Flags = uint32(flags)
}

func (iov *Iovec) SetLen(length int) {
	iov.Len = uint64(length)
}

func (msghdr *Msghdr) SetControllen(length int) {
	msghdr.Controllen = uint32(length)
}

func (msghdr *Msghdr) SetIovlen(length int) {

	return Timeval{Sec: sec, Usec: int32(usec)}
}

func SetKevent(k *Kevent_t, fd, mode, flags int) {
	k.Ident = uint32(fd)
	k.Filter = int16(mode)
	k.Flags = uint16(flags)
}

func (iov *Iovec) SetLen(length int) {
	iov.Len = uint32(length)
}

func (msghdr *Msghdr) SetControllen(length int) {
	msghdr.Controllen = uint32(length)
}

func (msghdr *Msghdr) SetIovlen(length int) {

	SYS_GETSOCKOPT               = 118 // { int getsockopt(int s, int level, int name, caddr_t val, int *avalsize); }
	SYS_READV                    = 120 // { int readv(int fd, struct iovec *iovp, u_int iovcnt); }
	SYS_WRITEV                   = 121 // { int writev(int fd, struct iovec *iovp, u_int iovcnt); }
	SYS_SETTIMEOFDAY             = 122 // { int settimeofday(struct timeval *tv, struct timezone *tzp); }