package os

import (
	"internal/poll"
	"internal/syscall/unix"
	"runtime"
	"syscall"
)

func fixLongPath(path string) string {
	return path
}

func rename(oldname, newname string) error {
	fi, err := Lstat(newname)

		if ofi, err := Lstat(oldname); err != nil {
			if pe, ok := err.(*PathError); ok {
				err = pe.Err
			}
			return &LinkError{"rename", oldname, newname, err}
		} else if newname == oldname || !SameFile(fi, ofi) {
			return &LinkError{"rename", oldname, newname, syscall.EEXIST}
		}
	}
	err = ignoringEINTR(func() error {
		return syscall.Rename(oldname, newname)
	})
	if err != nil {
		return &LinkError{"rename", oldname, newname, err}
	}
	return nil
}

type file struct {
	pfd         poll.FD
	name        string
	dirinfo     *dirInfo // nil unless directory being read
	nonblock    bool     // whether we set nonblocking mode
	stdoutOrErr bool     // whether this is stdout or stderr
	appendMode  bool     // whether file is opened for appending
}

func (f *File) Fd() uintptr {
	if f == nil {
		return ^(uintptr(0))
	}

	if f.nonblock {
		f.pfd.SetBlocking()
	}

	return uintptr(f.pfd.Sysfd)
}

func NewFile(fd uintptr, name string) *File {
	kind := kindNewFile
	if nb, err := unix.IsNonblock(int(fd)); err == nil && nb {
		kind = kindNonBlock
	}
	return newFile(fd, name, kind)
}

type newFileKind int

const (
	kindNewFile newFileKind = iota
	kindOpenFile
	kindPipe
	kindNonBlock
)

func newFile(fd uintptr, name string, kind newFileKind) *File {
	fdi := int(fd)
	if fdi < 0 {
		return nil
	}
	f := &File{&file{
		pfd: poll.FD{
			Sysfd:         fdi,
			IsStream:      true,
			ZeroReadIsEOF: true,
		},
		name:        name,
		stdoutOrErr: fdi == 1 || fdi == 2,
	}}

	pollable := kind == kindOpenFile || kind == kindPipe || kind == kindNonBlock

	if kind == kindOpenFile {
		switch runtime.GOOS {
		case "darwin", "ios", "dragonfly", "freebsd", "netbsd", "openbsd":
			var st syscall.Stat_t
			err := ignoringEINTR(func() error {
				return syscall.Fstat(fdi, &st)
			})

			if err == nil && (typ == syscall.S_IFREG || typ == syscall.S_IFDIR) {
				pollable = false
			}

			if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && typ == syscall.S_IFIFO {
				pollable = false
			}
		}
	}

		if err := syscall.SetNonblock(fdi, true); err == nil {
			f.nonblock = true
		}
	}

	runtime.SetFinalizer(f.file, (*file).close)
	return f
}

func epipecheck(file *File, e error) {
	if e == syscall.EPIPE && file.stdoutOrErr {
		sigpipe()
	}
}

const DevNull = "/dev/null"

func openFileNolog(name string, flag int, perm FileMode) (*File, error) {
	setSticky := false
	if !supportsCreateWithStickyBit && flag&O_CREATE != 0 && perm&ModeSticky != 0 {
		if _, err := Stat(name); IsNotExist(err) {
			setSticky = true
		}
	}

	var r int
	for {
		var e error
		r, e = syscall.Open(name, flag|syscall.O_CLOEXEC, syscallMode(perm))
		if e == nil {
			break
		}

		if e == syscall.EINTR {
			continue
		}

		return nil, &PathError{Op: "open", Path: name, Err: e}
	}

	if setSticky {
		setStickyBit(name)
	}

	if !supportsCloseOnExec {
		syscall.CloseOnExec(r)
	}

	return newFile(uintptr(r), name, kindOpenFile), nil
}

func (file *file) close() error {
	if file == nil {
		return syscall.EINVAL
	}
	if file.dirinfo != nil {
		file.dirinfo.close()
	}
	var err error
	if e := file.pfd.Close(); e != nil {
		if e == poll.ErrFileClosing {
			e = ErrClosed
		}
		err = &PathError{Op: "close", Path: file.name, Err: e}
	}

	runtime.SetFinalizer(file, nil)
	return err
}

func (f *File) seek(offset int64, whence int) (ret int64, err error) {

		f.dirinfo.close()
		f.dirinfo = nil
	}
	ret, err = f.pfd.Seek(offset, whence)
	runtime.KeepAlive(f)
	return ret, err
}

func Truncate(name string, size int64) error {
	e := ignoringEINTR(func() error {
		return syscall.Truncate(name, size)
	})
	if e != nil {
		return &PathError{Op: "truncate", Path: name, Err: e}
	}
	return nil
}

	e := ignoringEINTR(func() error {
		return syscall.Unlink(name)
	})
	if e == nil {
		return nil
	}
	e1 := ignoringEINTR(func() error {
		return syscall.Rmdir(name)
	})
	if e1 == nil {
		return nil
	}

	if e1 != syscall.ENOTDIR {
		e = e1
	}
	return &PathError{Op: "remove", Path: name, Err: e}
}

func tempDir() string {
	dir := Getenv("TMPDIR")
	if dir == "" {
		if runtime.GOOS == "android" {
			dir = "/data/local/tmp"
		} else {
			dir = "/tmp"
		}
	}
	return dir
}

func Link(oldname, newname string) error {
	e := ignoringEINTR(func() error {
		return syscall.Link(oldname, newname)
	})
	if e != nil {
		return &LinkError{"link", oldname, newname, e}
	}
	return nil
}

func Symlink(oldname, newname string) error {
	e := ignoringEINTR(func() error {
		return syscall.Symlink(oldname, newname)
	})
	if e != nil {
		return &LinkError{"symlink", oldname, newname, e}
	}
	return nil
}

func Readlink(name string) (string, error) {
	for len := 128; ; len *= 2 {
		b := make([]byte, len)
		var (
			n int
			e error
		)
		for {
			n, e = fixCount(syscall.Readlink(name, b))
			if e != syscall.EINTR {
				break
			}

		if runtime.GOOS == "aix" && e == syscall.ERANGE {
			continue
		}
		if e != nil {
			return "", &PathError{Op: "readlink", Path: name, Err: e}
		}
		if n < len {
			return string(b[0:n]), nil
		}
	}
}

type unixDirent struct {
	parent string
	name   string
	typ    FileMode
	info   FileInfo
}

func (d *unixDirent) Name() string   { return d.name }
func (d *unixDirent) IsDir() bool    { return d.typ.IsDir() }
func (d *unixDirent) Type() FileMode { return d.typ }

func (d *unixDirent) Info() (FileInfo, error) {
	if d.info != nil {
		return d.info, nil
	}
	return lstat(d.parent + "/" + d.name)
}

func newUnixDirent(parent, name string, typ FileMode) (DirEntry, error) {
	ude := &unixDirent{
		parent: parent,
		name:   name,
		typ:    typ,
	}
	if typ != ^FileMode(0) && !testingForceReadDirLstat {
		return ude, nil
	}

	info, err := lstat(parent + "/" + name)
	if err != nil {
		return nil, err
	}

	ude.typ = info.Mode().Type()
	ude.info = info
	return ude, nil