@[has_globals]
module pwd

import sync

$if windows {
	$compile_error('pwd: MS Windows is not supported')
}

#include <errno.h>
#include <pwd.h>

__global pwd_mutex &sync.Mutex

fn init() {
	pwd_mutex = sync.new_mutex()
}

fn cleanup() {
	pwd_mutex.destroy()
	unsafe { free(pwd_mutex) }
}

struct C.passwd {
	pw_name   &char
	pw_passwd &char
	pw_uid    i32
	pw_gid    i32
	pw_gecos  &char
	pw_dir    &char
	pw_shell  &char
}

fn C.getpwuid(i32) &C.passwd
fn C.getpwnam(&char) &C.passwd
fn C.setpwent()
fn C.endpwent()
fn C.getpwent() &C.passwd

pub struct Passwd {
pub:
	name   string // username
	passwd string // user password, usually set to 'x'
	uid    int    // user ID
	gid    int    // group ID
	gecos  string // user information
	dir    string // home directory
	shell  string // shell program
}

fn make_passwd(pw &C.passwd) Passwd {
	return unsafe {
		Passwd{
			name:   cstring_to_vstring(pw.pw_name)
			passwd: cstring_to_vstring(pw.pw_passwd)
			uid:    int(pw.pw_uid)
			gid:    int(pw.pw_gid)
			gecos:  cstring_to_vstring(pw.pw_gecos)
			dir:    cstring_to_vstring(pw.pw_dir)
			shell:  cstring_to_vstring(pw.pw_shell)
		}
	}
}

fn make_error(name string, uid int) IError {
	err := C.errno
	if err !in [4, 5, 12, 23, 24, 34] {
		// Error is not EINTR, EIO, ENOMEM, ENFILE, EMFILE or ERANGE
		return EntryNotFoundError{
			name: name
			uid:  uid
		}
	}
	return error_with_code(c_error_number_str(err), err)
}

// get_by_uid returns the passwd database entry by user ID.
// If the entry is not found, the EntryNotFoundError error will be returned.
pub fn get_by_uid(uid int) !Passwd {
	pwd_mutex.lock()
	defer {
		pwd_mutex.unlock()
	}
	pw := C.getpwuid(uid)
	if isnil(pw) {
		return make_error('', uid)
	}
	return make_passwd(pw)
}

// get_by_uid returns the passwd database entry by user name.
// If the entry is not found, the EntryNotFoundError error will be returned.
pub fn get_by_name(name string) !Passwd {
	pwd_mutex.lock()
	defer {
		pwd_mutex.unlock()
	}
	pw := C.getpwnam(&char(name.str))
	if isnil(pw) {
		return make_error(name, -1)
	}
	return make_passwd(pw)
}

// get_all returns all entries from passwd database in arbitrary order.
pub fn get_all() []Passwd {
	mut pwds := []Passwd{}
	pwd_mutex.lock()
	C.setpwent()
	defer {
		C.endpwent()
		pwd_mutex.unlock()
	}
	for {
		pw := C.getpwent()
		if isnil(pw) {
			break
		}
		pwds << make_passwd(pw)
	}
	return pwds
}

// EntryNotFoundError designates that an entry with the specified UID or name was not found.
pub struct EntryNotFoundError {
	Error
	name string
	uid  int
}

// msg returns the EntryNotFoundError error message.
pub fn (e EntryNotFoundError) msg() string {
	if e.name != '' {
		return "no passwd entry found by username '${e.name}'"
	}
	return 'no passwd entry found by user ID ${e.uid}'
}