// Copyright 2020 The Libc Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build linux || darwin || freebsd || netbsd
// +build linux darwin freebsd netbsd

package libc // import "modernc.org/libc"

import (
	"bufio"
	"io/ioutil"
	"os"
	gosignal "os/signal"
	"reflect"
	"strconv"
	"strings"
	"syscall"
	"unsafe"

	"golang.org/x/sys/unix"
	"modernc.org/libc/errno"
	"modernc.org/libc/grp"
	"modernc.org/libc/poll"
	"modernc.org/libc/pwd"
	"modernc.org/libc/signal"
	"modernc.org/libc/stdio"
	"modernc.org/libc/sys/types"
)

var staticGetpwnam pwd.Passwd

func init() {
	atExit = append(atExit, func() { closePasswd(&staticGetpwnam) })
}

// sighandler_t signal(int signum, sighandler_t handler);
func Xsignal(t *TLS, signum int32, handler uintptr) uintptr { //TODO use sigaction?
	signalsMu.Lock()

	defer signalsMu.Unlock()

	r := signals[signum]
	signals[signum] = handler
	switch handler {
	case signal.SIG_DFL:
		panic(todo("%v %#x", syscall.Signal(signum), handler))
	case signal.SIG_IGN:
		switch r {
		case signal.SIG_DFL:
			gosignal.Ignore(syscall.Signal(signum)) //TODO
		case signal.SIG_IGN:
			gosignal.Ignore(syscall.Signal(signum))
		default:
			panic(todo("%v %#x", syscall.Signal(signum), handler))
		}
	default:
		switch r {
		case signal.SIG_DFL:
			c := make(chan os.Signal, 1)
			gosignal.Notify(c, syscall.Signal(signum))
			go func() { //TODO mechanism to stop/cancel
				for {
					<-c
					var f func(*TLS, int32)
					*(*uintptr)(unsafe.Pointer(&f)) = handler
					tls := NewTLS()
					f(tls, signum)
					tls.Close()
				}
			}()
		case signal.SIG_IGN:
			panic(todo("%v %#x", syscall.Signal(signum), handler))
		default:
			panic(todo("%v %#x", syscall.Signal(signum), handler))
		}
	}
	return r
}

// void rewind(FILE *stream);
func Xrewind(t *TLS, stream uintptr) {
	Xfseek(t, stream, 0, stdio.SEEK_SET)
}

// int putchar(int c);
func Xputchar(t *TLS, c int32) int32 {
	if _, err := write([]byte{byte(c)}); err != nil {
		return stdio.EOF
	}

	return int32(c)
}

// int gethostname(char *name, size_t len);
func Xgethostname(t *TLS, name uintptr, slen types.Size_t) int32 {
	if slen < 0 {
		t.setErrno(errno.EINVAL)
		return -1
	}

	if slen == 0 {
		return 0
	}

	s, err := os.Hostname()
	if err != nil {
		panic(todo(""))
	}

	n := len(s)
	if len(s) >= int(slen) {
		n = int(slen) - 1
	}
	sh := (*reflect.StringHeader)(unsafe.Pointer(&s))
	copy((*RawMem)(unsafe.Pointer(name))[:n:n], (*RawMem)(unsafe.Pointer(sh.Data))[:n:n])
	*(*byte)(unsafe.Pointer(name + uintptr(n))) = 0
	return 0
}

// int remove(const char *pathname);
func Xremove(t *TLS, pathname uintptr) int32 {
	panic(todo(""))
}

// long pathconf(const char *path, int name);
func Xpathconf(t *TLS, path uintptr, name int32) long {
	panic(todo(""))
}

// ssize_t recvfrom(int sockfd, void *buf, size_t len, int flags, struct sockaddr *src_addr, socklen_t *addrlen);
func Xrecvfrom(t *TLS, sockfd int32, buf uintptr, len types.Size_t, flags int32, src_addr, addrlen uintptr) types.Ssize_t {
	panic(todo(""))
}

// ssize_t sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen);
func Xsendto(t *TLS, sockfd int32, buf uintptr, len types.Size_t, flags int32, src_addr uintptr, addrlen socklen_t) types.Ssize_t {
	panic(todo(""))
}

// void srand48(long int seedval);
func Xsrand48(t *TLS, seedval long) {
	panic(todo(""))
}

// long int lrand48(void);
func Xlrand48(t *TLS) long {
	panic(todo(""))
}

// ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags);
func Xsendmsg(t *TLS, sockfd int32, msg uintptr, flags int32) types.Ssize_t {
	panic(todo(""))
}

// int poll(struct pollfd *fds, nfds_t nfds, int timeout);
func Xpoll(t *TLS, fds uintptr, nfds poll.Nfds_t, timeout int32) int32 {
	if nfds == 0 {
		panic(todo(""))
	}

	// if dmesgs {
	// 	dmesg("%v: %#x %v %v, %+v", origin(1), fds, nfds, timeout, (*[1000]unix.PollFd)(unsafe.Pointer(fds))[:nfds:nfds])
	// }
	n, err := unix.Poll((*[1000]unix.PollFd)(unsafe.Pointer(fds))[:nfds:nfds], int(timeout))
	// if dmesgs {
	// 	dmesg("%v: %v %v", origin(1), n, err)
	// }
	if err != nil {
		t.setErrno(err)
		return -1
	}

	return int32(n)
}

// ssize_t recvmsg(int sockfd, struct msghdr *msg, int flags);
func Xrecvmsg(t *TLS, sockfd int32, msg uintptr, flags int32) types.Ssize_t {
	n, _, err := unix.Syscall(unix.SYS_RECVMSG, uintptr(sockfd), msg, uintptr(flags))
	if err != 0 {
		t.setErrno(err)
		return -1
	}

	return types.Ssize_t(n)
}

// struct cmsghdr *CMSG_NXTHDR(struct msghdr *msgh, struct cmsghdr *cmsg);
func X__cmsg_nxthdr(t *TLS, msgh, cmsg uintptr) uintptr {
	panic(todo(""))
}

// wchar_t *wcschr(const wchar_t *wcs, wchar_t wc);
func Xwcschr(t *TLS, wcs uintptr, wc wchar_t) wchar_t {
	panic(todo(""))
}

// gid_t getegid(void);
func Xgetegid(t *TLS) types.Gid_t {
	panic(todo(""))
}

// gid_t getgid(void);
func Xgetgid(t *TLS) types.Gid_t {
	panic(todo(""))
}

// void *shmat(int shmid, const void *shmaddr, int shmflg);
func Xshmat(t *TLS, shmid int32, shmaddr uintptr, shmflg int32) uintptr {
	panic(todo(""))
}

// int shmctl(int shmid, int cmd, struct shmid_ds *buf);
func Xshmctl(t *TLS, shmid, cmd int32, buf uintptr) int32 {
	panic(todo(""))
}

// int shmdt(const void *shmaddr);
func Xshmdt(t *TLS, shmaddr uintptr) int32 {
	panic(todo(""))
}

// int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid);
func Xgetresuid(t *TLS, ruid, euid, suid uintptr) int32 {
	panic(todo(""))
}

// int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid);
func Xgetresgid(t *TLS, rgid, egid, sgid uintptr) int32 {
	panic(todo(""))
}

// FILE *tmpfile(void);
func Xtmpfile(t *TLS) uintptr {
	f, err := ioutil.TempFile("", "tmpfile-")
	if err != nil {
		t.setErrno(err)
		return 0
	}

	cf := newFile(t, int32(f.Fd()))
	AtExit(func() {
		nm := f.Name()
		file(cf).close(t)
		os.Remove(nm)
	})

	return cf
}

// FILE *fdopen(int fd, const char *mode);
func Xfdopen(t *TLS, fd int32, mode uintptr) uintptr {
	m := strings.ReplaceAll(GoString(mode), "b", "")
	switch m {
	case
		"a",
		"a+",
		"r",
		"r+",
		"w",
		"w+":
	default:
		t.setErrno(errno.EINVAL)
		return 0
	}

	if p := newFile(t, fd); p != 0 {
		return p
	}

	t.setErrno(errno.EINVAL)
	return 0
}

// struct passwd *getpwnam(const char *name);
func Xgetpwnam(t *TLS, name uintptr) uintptr {
	f, err := os.Open("/etc/passwd")
	if err != nil {
		panic(todo("", err))
	}

	defer f.Close()

	sname := GoString(name)
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		s := strings.TrimSpace(sc.Text())
		if s == "" || strings.HasPrefix(s, "#") {
			continue
		}

		// eg. "root:x:0:0:root:/root:/bin/bash"
		a := strings.Split(s, ":")
		if len(a) < 7 {
			panic(todo(""))
		}

		if a[0] == sname {
			uid, err := strconv.Atoi(a[2])
			if err != nil {
				panic(todo(""))
			}

			gid, err := strconv.Atoi(a[3])
			if err != nil {
				panic(todo(""))
			}

			closePasswd(&staticGetpwnam)
			gecos := a[4]
			if strings.Contains(gecos, ",") {
				a := strings.Split(gecos, ",")
				gecos = a[0]
			}
			initPasswd(t, &staticGetpwnam, a[0], a[1], uint32(uid), uint32(gid), gecos, a[5], a[6])
			return uintptr(unsafe.Pointer(&staticGetpwnam))
		}
	}

	if sc.Err() != nil {
		panic(todo(""))
	}

	return 0
}

// int getpwnam_r(char *name, struct passwd *pwd, char *buf, size_t buflen, struct passwd **result);
func Xgetpwnam_r(t *TLS, name, cpwd, buf uintptr, buflen types.Size_t, result uintptr) int32 {
	f, err := os.Open("/etc/passwd")
	if err != nil {
		panic(todo("", err))
	}

	defer f.Close()

	sname := GoString(name)
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		s := strings.TrimSpace(sc.Text())
		if s == "" || strings.HasPrefix(s, "#") {
			continue
		}

		// eg. "root:x:0:0:root:/root:/bin/bash"
		a := strings.Split(s, ":")
		if len(a) < 7 {
			panic(todo("%q", s))
		}

		if a[0] == sname {
			uid, err := strconv.Atoi(a[2])
			if err != nil {
				panic(todo(""))
			}

			gid, err := strconv.Atoi(a[3])
			if err != nil {
				panic(todo(""))
			}

			gecos := a[4]
			if strings.Contains(gecos, ",") {
				a := strings.Split(gecos, ",")
				gecos = a[0]
			}
			var v pwd.Passwd
			if initPasswd2(t, buf, buflen, &v, a[0], a[1], uint32(uid), uint32(gid), gecos, a[5], a[6]) {
				*(*pwd.Passwd)(unsafe.Pointer(cpwd)) = v
				*(*uintptr)(unsafe.Pointer(result)) = cpwd
				return 0
			}

			*(*uintptr)(unsafe.Pointer(result)) = 0
			return errno.ERANGE
		}
	}

	if sc.Err() != nil {
		panic(todo(""))
	}

	*(*uintptr)(unsafe.Pointer(result)) = 0
	return 0
}

func init() {
	atExit = append(atExit, func() { closeGroup(&staticGetgrgid) })
}

var staticGetgrgid grp.Group

// struct group *getgrgid(gid_t gid);
func Xgetgrgid(t *TLS, gid uint32) uintptr {
	f, err := os.Open("/etc/group")
	if err != nil {
		panic(todo(""))
	}

	defer f.Close()

	sid := strconv.Itoa(int(gid))
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		s := strings.TrimSpace(sc.Text())
		if s == "" || strings.HasPrefix(s, "#") {
			continue
		}

		// eg. "root:x:0:"
		a := strings.Split(s, ":")
		if len(a) < 4 {
			panic(todo("%q", s))
		}

		if a[2] == sid {
			closeGroup(&staticGetgrgid)
			var names []string
			if a[3] != "" {
				names = strings.Split(a[3], ",")
			}
			initGroup(t, &staticGetgrgid, a[0], a[1], gid, names)
			return uintptr(unsafe.Pointer(&staticGetgrgid))
		}
	}

	if sc.Err() != nil {
		panic(todo(""))
	}

	return 0
}

// int getgrgid_r(gid_t gid, struct group *grp, char *buf, size_t buflen, struct group **result);
func Xgetgrgid_r(t *TLS, gid uint32, pGrp, buf uintptr, buflen types.Size_t, result uintptr) int32 {
	f, err := os.Open("/etc/group")
	if err != nil {
		panic(todo(""))
	}

	defer f.Close()

	sid := strconv.Itoa(int(gid))
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		s := strings.TrimSpace(sc.Text())
		if s == "" || strings.HasPrefix(s, "#") {
			continue
		}

		// eg. "root:x:0:"
		a := strings.Split(s, ":")
		if len(a) < 4 {
			panic(todo("%q", s))
		}

		if a[2] == sid {
			var names []string
			if a[3] != "" {
				names = strings.Split(a[3], ",")
			}
			var x grp.Group
			if initGroup2(buf, buflen, &x, a[0], a[1], gid, names) {
				*(*grp.Group)(unsafe.Pointer(pGrp)) = x
				*(*uintptr)(unsafe.Pointer(result)) = pGrp
				return 0
			}

			*(*uintptr)(unsafe.Pointer(result)) = 0
			return 0
		}
	}

	if sc.Err() != nil {
		panic(todo(""))
	}

	*(*uintptr)(unsafe.Pointer(result)) = 0
	return 0
}

func initPasswd2(t *TLS, buf uintptr, buflen types.Size_t, p *pwd.Passwd, name, pwd string, uid, gid uint32, gecos, dir, shell string) bool {
	p.Fpw_name, buf, buflen = bufString(buf, buflen, name)
	if buf == 0 {
		return false
	}

	p.Fpw_passwd, buf, buflen = bufString(buf, buflen, pwd)
	if buf == 0 {
		return false
	}

	p.Fpw_uid = uid
	p.Fpw_gid = gid
	if buf == 0 {
		return false
	}

	p.Fpw_gecos, buf, buflen = bufString(buf, buflen, gecos)
	if buf == 0 {
		return false
	}

	p.Fpw_dir, buf, buflen = bufString(buf, buflen, dir)
	if buf == 0 {
		return false
	}

	p.Fpw_shell, buf, buflen = bufString(buf, buflen, shell)
	if buf == 0 {
		return false
	}

	return true
}

func bufString(buf uintptr, buflen types.Size_t, s string) (uintptr, uintptr, types.Size_t) {
	buf0 := buf
	rq := len(s) + 1
	if rq > int(buflen) {
		return 0, 0, 0
	}

	copy((*RawMem)(unsafe.Pointer(buf))[:len(s):len(s)], s)
	buf += uintptr(len(s))
	*(*byte)(unsafe.Pointer(buf)) = 0
	return buf0, buf + 1, buflen - types.Size_t(rq)
}

func closeGroup(p *grp.Group) {
	Xfree(nil, p.Fgr_name)
	Xfree(nil, p.Fgr_passwd)
	if p := p.Fgr_mem; p != 0 {
		for {
			q := *(*uintptr)(unsafe.Pointer(p))
			if q == 0 {
				break
			}

			Xfree(nil, q)
			p += unsafe.Sizeof(uintptr(0))
		}
	}
	*p = grp.Group{}
}

func initGroup(t *TLS, p *grp.Group, name, pwd string, gid uint32, names []string) {
	p.Fgr_name = cString(t, name)
	p.Fgr_passwd = cString(t, pwd)
	p.Fgr_gid = gid
	a := Xcalloc(t, 1, types.Size_t(unsafe.Sizeof(uintptr(0)))*types.Size_t((len(names)+1)))
	if a == 0 {
		panic("OOM")
	}

	for p := a; len(names) != 0; p += unsafe.Sizeof(uintptr(0)) {
		*(*uintptr)(unsafe.Pointer(p)) = cString(t, names[0])
		names = names[1:]
	}
	p.Fgr_mem = a
}

func initGroup2(buf uintptr, buflen types.Size_t, p *grp.Group, name, pwd string, gid uint32, names []string) bool {
	p.Fgr_name, buf, buflen = bufString(buf, buflen, name)
	if buf == 0 {
		return false
	}

	p.Fgr_passwd, buf, buflen = bufString(buf, buflen, pwd)
	if buf == 0 {
		return false
	}

	p.Fgr_gid = gid
	rq := unsafe.Sizeof(uintptr(0)) * uintptr(len(names)+1)
	if rq > uintptr(buflen) {
		return false
	}

	a := buf
	buf += rq
	for ; len(names) != 0; buf += unsafe.Sizeof(uintptr(0)) {
		if len(names[0])+1 > int(buflen) {
			return false
		}

		*(*uintptr)(unsafe.Pointer(buf)), buf, buflen = bufString(buf, buflen, names[0])
		names = names[1:]
	}
	*(*uintptr)(unsafe.Pointer(buf)) = 0
	p.Fgr_mem = a
	return true
}

func init() {
	atExit = append(atExit, func() { closeGroup(&staticGetgrgid) })
}

var staticGetpwuid pwd.Passwd

func init() {
	atExit = append(atExit, func() { closePasswd(&staticGetpwuid) })
}

func closePasswd(p *pwd.Passwd) {
	Xfree(nil, p.Fpw_name)
	Xfree(nil, p.Fpw_passwd)
	Xfree(nil, p.Fpw_gecos)
	Xfree(nil, p.Fpw_dir)
	Xfree(nil, p.Fpw_shell)
	*p = pwd.Passwd{}
}

var staticGetgrnam grp.Group

func init() {
	atExit = append(atExit, func() { closeGroup(&staticGetgrnam) })
}

// struct passwd *getpwuid(uid_t uid);
func Xgetpwuid(t *TLS, uid uint32) uintptr {
	f, err := os.Open("/etc/passwd")
	if err != nil {
		panic(todo("", err))
	}

	defer f.Close()

	sid := strconv.Itoa(int(uid))
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		s := strings.TrimSpace(sc.Text())
		if len(s) == 0 || strings.HasPrefix(s, "#") {
			continue
		}

		// eg. "root:x:0:0:root:/root:/bin/bash"
		a := strings.Split(s, ":")
		if len(a) < 7 {
			panic(todo("%q", s))
		}

		if a[2] == sid {
			uid, err := strconv.Atoi(a[2])
			if err != nil {
				panic(todo(""))
			}

			gid, err := strconv.Atoi(a[3])
			if err != nil {
				panic(todo(""))
			}

			closePasswd(&staticGetpwuid)
			gecos := a[4]
			if strings.Contains(gecos, ",") {
				a := strings.Split(gecos, ",")
				gecos = a[0]
			}
			initPasswd(t, &staticGetpwuid, a[0], a[1], uint32(uid), uint32(gid), gecos, a[5], a[6])
			return uintptr(unsafe.Pointer(&staticGetpwuid))
		}
	}

	if sc.Err() != nil {
		panic(todo(""))
	}

	return 0
}

func initPasswd(t *TLS, p *pwd.Passwd, name, pwd string, uid, gid uint32, gecos, dir, shell string) {
	p.Fpw_name = cString(t, name)
	p.Fpw_passwd = cString(t, pwd)
	p.Fpw_uid = uid
	p.Fpw_gid = gid
	p.Fpw_gecos = cString(t, gecos)
	p.Fpw_dir = cString(t, dir)
	p.Fpw_shell = cString(t, shell)
}

// struct group *getgrnam(const char *name);
func Xgetgrnam(t *TLS, name uintptr) uintptr {
	f, err := os.Open("/etc/group")
	if err != nil {
		panic(todo(""))
	}

	defer f.Close()

	sname := GoString(name)
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		s := strings.TrimSpace(sc.Text())
		if len(s) == 0 || strings.HasPrefix(s, "#") {
			continue
		}

		// eg. "root:x:0:"
		a := strings.Split(s, ":")
		if len(a) < 4 {
			panic(todo("%q", s))
		}

		if a[0] == sname {
			closeGroup(&staticGetgrnam)
			gid, err := strconv.Atoi(a[2])
			if err != nil {
				panic(todo(""))
			}

			var names []string
			if a[3] != "" {
				names = strings.Split(a[3], ",")
			}
			initGroup(t, &staticGetgrnam, a[0], a[1], uint32(gid), names)
			return uintptr(unsafe.Pointer(&staticGetgrnam))
		}
	}

	if sc.Err() != nil {
		panic(todo(""))
	}

	return 0
}

// int getgrnam_r(const char *name, struct group *grp, char *buf, size_t buflen, struct group **result);
func Xgetgrnam_r(t *TLS, name, pGrp, buf uintptr, buflen types.Size_t, result uintptr) int32 {
	f, err := os.Open("/etc/group")
	if err != nil {
		panic(todo(""))
	}

	defer f.Close()

	sname := GoString(name)
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		s := strings.TrimSpace(sc.Text())
		if len(s) == 0 || strings.HasPrefix(s, "#") {
			continue
		}

		// eg. "root:x:0:"
		a := strings.Split(s, ":")
		if len(a) < 4 {
			panic(todo("%q", s))
		}

		if a[0] == sname {
			gid, err := strconv.Atoi(a[2])
			if err != nil {
				panic(todo(""))
			}

			var names []string
			if a[3] != "" {
				names = strings.Split(a[3], ",")
			}
			var x grp.Group
			if initGroup2(buf, buflen, &x, a[0], a[1], uint32(gid), names) {
				*(*grp.Group)(unsafe.Pointer(pGrp)) = x
				*(*uintptr)(unsafe.Pointer(result)) = pGrp
				return 0
			}

			*(*uintptr)(unsafe.Pointer(result)) = 0
			return 0
		}
	}

	if sc.Err() != nil {
		panic(todo(""))
	}

	*(*uintptr)(unsafe.Pointer(result)) = 0
	return 0
}

// int getpwuid_r(uid_t uid, struct passwd *pwd, char *buf, size_t buflen, struct passwd **result);
func Xgetpwuid_r(t *TLS, uid types.Uid_t, cpwd, buf uintptr, buflen types.Size_t, result uintptr) int32 {
	f, err := os.Open("/etc/passwd")
	if err != nil {
		panic(todo("", err))
	}

	defer f.Close()

	sid := strconv.Itoa(int(uid))
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		s := strings.TrimSpace(sc.Text())
		if len(s) == 0 || strings.HasPrefix(s, "#") {
			continue
		}

		// eg. "root:x:0:0:root:/root:/bin/bash"
		a := strings.Split(s, ":")
		if len(a) < 7 {
			panic(todo("%q", s))
		}

		if a[2] == sid {
			uid, err := strconv.Atoi(a[2])
			if err != nil {
				panic(todo(""))
			}

			gid, err := strconv.Atoi(a[3])
			if err != nil {
				panic(todo(""))
			}

			gecos := a[4]
			if strings.Contains(gecos, ",") {
				a := strings.Split(gecos, ",")
				gecos = a[0]
			}
			var v pwd.Passwd
			if initPasswd2(t, buf, buflen, &v, a[0], a[1], uint32(uid), uint32(gid), gecos, a[5], a[6]) {
				*(*pwd.Passwd)(unsafe.Pointer(cpwd)) = v
				*(*uintptr)(unsafe.Pointer(result)) = cpwd
				return 0
			}

			*(*uintptr)(unsafe.Pointer(result)) = 0
			return errno.ERANGE
		}
	}

	if sc.Err() != nil {
		panic(todo(""))
	}

	*(*uintptr)(unsafe.Pointer(result)) = 0
	return 0
}