module os

import strings

#include <dirent.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/utsname.h>
#include <sys/types.h>
#include <utime.h>

pub const (
    path_separator = '/'
    path_delimiter = ':'
)

const executable_suffixes = ['']

const (
    stdin_value  = 0
    stdout_value = 1
    stderr_value = 2
)

// (Must be realized in Syscall) (Must be specified)
// ref: http://www.ccfit.nsu.ru/~deviv/courses/unix/unix/ng7c229.html
pub const (
    s_ifmt  = 0xF000 // type of file
    s_ifdir = 0x4000 // directory
    s_iflnk = 0xa000 // link
    s_isuid = 0o4000 // SUID
    s_isgid = 0o2000 // SGID
    s_isvtx = 0o1000 // Sticky
    s_irusr = 0o0400 // Read by owner
    s_iwusr = 0o0200 // Write by owner
    s_ixusr = 0o0100 // Execute by owner
    s_irgrp = 0o0040 // Read by group
    s_iwgrp = 0o0020 // Write by group
    s_ixgrp = 0o0010 // Execute by group
    s_iroth = 0o0004 // Read by others
    s_iwoth = 0o0002 // Write by others
    s_ixoth = 0o0001 // Execute by others
)

fn C.utime(&char, voidptr) int

fn C.uname(name voidptr) int

fn C.symlink(&char, &char) int

fn C.link(&char, &char) int

fn C.gethostname(&char, int) int

// Note: not available on Android fn C.getlogin_r(&char, int) int
fn C.getlogin() &char

fn C.getppid() int

fn C.getgid() int

fn C.getegid() int

enum GlobMatch {
    exact
    ends_with
    starts_with
    start_and_ends_with
    contains
    any
}

fn glob_match(dir string, pattern string, next_pattern string, mut matches []string) []string {
    mut subdirs := []string{}
    if is_file(dir) {
        return subdirs
    }
    mut files := ls(dir) or { return subdirs }
    mut mode := GlobMatch.exact
    mut pat := pattern
    if pat == '*' {
        mode = GlobMatch.any
        if next_pattern != pattern && next_pattern != '' {
            for file in files {
                if is_dir('${dir}/${file}') {
                    subdirs << '${dir}/${file}'
                }
            }
            return subdirs
        }
    }
    if pat == '**' {
        files = walk_ext(dir, '')
        pat = next_pattern
    }
    if pat.starts_with('*') {
        mode = .ends_with
        pat = pat[1..]
    }
    if pat.ends_with('*') {
        mode = if mode == .ends_with { GlobMatch.contains } else { GlobMatch.starts_with }
        pat = pat[..pat.len - 1]
    }
    if pat.contains('*') {
        mode = .start_and_ends_with
    }
    for file in files {
        mut fpath := file
        f := if file.contains(os.path_separator) {
            pathwalk := file.split(os.path_separator)
            pathwalk[pathwalk.len - 1]
        } else {
            fpath = if dir == '.' { file } else { '${dir}/${file}' }
            file
        }
        if f in ['.', '..'] || f == '' {
            continue
        }
        hit := match mode {
            .any {
                true
            }
            .exact {
                f == pat
            }
            .starts_with {
                f.starts_with(pat)
            }
            .ends_with {
                f.ends_with(pat)
            }
            .start_and_ends_with {
                p := pat.split('*')
                f.starts_with(p[0]) && f.ends_with(p[1])
            }
            .contains {
                f.contains(pat)
            }
        }
        if hit {
            if is_dir(fpath) {
                subdirs << fpath
                if next_pattern == pattern && next_pattern != '' {
                    matches << '${fpath}${os.path_separator}'
                }
            } else {
                matches << fpath
            }
        }
    }
    return subdirs
}

fn native_glob_pattern(pattern string, mut matches []string) ! {
    steps := pattern.split(os.path_separator)
    mut cwd := if pattern.starts_with(os.path_separator) { os.path_separator } else { '.' }
    mut subdirs := [cwd]
    for i := 0; i < steps.len; i++ {
        step := steps[i]
        step2 := if i + 1 == steps.len { step } else { steps[i + 1] }
        if step == '' {
            continue
        }
        if is_dir('${cwd}${os.path_separator}${step}') {
            dd := if cwd == '/' {
                step
            } else {
                if cwd == '.' || cwd == '' {
                    step
                } else {
                    if step == '.' || step == '/' { cwd } else { '${cwd}/${step}' }
                }
            }
            if i + 1 != steps.len {
                if dd !in subdirs {
                    subdirs << dd
                }
            }
        }
        mut subs := []string{}
        for sd in subdirs {
            d := if cwd == '/' {
                sd
            } else {
                if cwd == '.' || cwd == '' {
                    sd
                } else {
                    if sd == '.' || sd == '/' { cwd } else { '${cwd}/${sd}' }
                }
            }
            subs << glob_match(d.replace('//', '/'), step, step2, mut matches)
        }
        subdirs = subs.clone()
    }
}

pub fn utime(path string, actime int, modtime int) ! {
    mut u := C.utimbuf{actime, modtime}
    if C.utime(&char(path.str), voidptr(&u)) != 0 {
        return error_with_code(posix_get_error_msg(C.errno), C.errno)
    }
}

// uname returns information about the platform on which the program is running
// For example:
// os.Uname{
//    sysname: 'Linux'
//    nodename: 'nemesis'
//    release: '5.15.0-57-generic'
//    version: '#63~20.04.1-Ubuntu SMP Wed Nov 30 13:40:16 UTC 2022'
//    machine: 'x86_64'
// }
// where the fields have the following meaning:
//    sysname is the name of this implementation of the operating system
//    nodename is the name of this node within an implementation-dependent communications network
//    release is the current release level of this implementation
//    version is the current version level of this release
//    machine is the name of the hardware type, on which the system is running
// See also https://pubs.opengroup.org/onlinepubs/7908799/xsh/sysutsname.h.html
pub fn uname() Uname {
    mut u := Uname{}
    utsize := sizeof(C.utsname)
    unsafe {
        x := malloc_noscan(int(utsize))
        d := &C.utsname(x)
        if C.uname(d) == 0 {
            u.sysname = cstring_to_vstring(d.sysname)
            u.nodename = cstring_to_vstring(d.nodename)
            u.release = cstring_to_vstring(d.release)
            u.version = cstring_to_vstring(d.version)
            u.machine = cstring_to_vstring(d.machine)
        }
        free(d)
    }
    return u
}

pub fn hostname() !string {
    mut hstnme := ''
    size := 256
    mut buf := unsafe { &char(malloc_noscan(size)) }
    if C.gethostname(buf, size) == 0 {
        hstnme = unsafe { cstring_to_vstring(buf) }
        unsafe { free(buf) }
        return hstnme
    }
    return error(posix_get_error_msg(C.errno))
}

pub fn loginname() !string {
    x := C.getlogin()
    if !isnil(x) {
        return unsafe { cstring_to_vstring(x) }
    }
    return error(posix_get_error_msg(C.errno))
}

fn init_os_args(argc int, argv &&u8) []string {
    mut args_ := []string{len: argc}
    for i in 0 .. argc {
        args_[i] = unsafe { tos_clone(argv[i]) }
    }
    return args_
}

pub fn ls(path string) ![]string {
    if path.len == 0 {
        return error('ls() expects a folder, not an empty string')
    }
    mut res := []string{cap: 50}
    dir := unsafe { C.opendir(&char(path.str)) }
    if isnil(dir) {
        return error('ls() couldnt open dir "${path}"')
    }
    mut ent := &C.dirent(unsafe { nil })
    // mut ent := &C.dirent{!}
    for {
        ent = C.readdir(dir)
        if isnil(ent) {
            break
        }
        unsafe {
            bptr := &u8(&ent.d_name[0])
            if bptr[0] == 0 || (bptr[0] == `.` && bptr[1] == 0)
                || (bptr[0] == `.` && bptr[1] == `.` && bptr[2] == 0) {
                continue
            }
            res << tos_clone(bptr)
        }
    }
    C.closedir(dir)
    return res
}

// mkdir creates a new directory with the specified path.
pub fn mkdir(path string, params MkdirParams) ! {
    if path == '.' {
        return
    }
    apath := real_path(path)
    r := unsafe { C.mkdir(&char(apath.str), params.mode) }
    if r == -1 {
        return error(posix_get_error_msg(C.errno))
    }
}

// execute starts the specified command, waits for it to complete, and returns its output.
[manualfree]
pub fn execute(cmd string) Result {
    // if cmd.contains(';') || cmd.contains('&&') || cmd.contains('||') || cmd.contains('\n') {
    // return Result{ exit_code: -1, output: ';, &&, || and \\n are not allowed in shell commands' }
    // }
    pcmd := if cmd.contains('2>') { cmd.clone() } else { '${cmd} 2>&1' }
    defer {
        unsafe { pcmd.free() }
    }
    f := vpopen(pcmd)
    if isnil(f) {
        return Result{
            exit_code: -1
            output: 'exec("${cmd}") failed'
        }
    }
    fd := fileno(f)
    mut res := strings.new_builder(1024)
    defer {
        unsafe { res.free() }
    }
    buf := [4096]u8{}
    unsafe {
        pbuf := &buf[0]
        for {
            len := C.read(fd, pbuf, 4096)
            if len == 0 {
                break
            }
            res.write_ptr(pbuf, len)
        }
    }
    soutput := res.str()
    exit_code := vpclose(f)
    return Result{
        exit_code: exit_code
        output: soutput
    }
}

// raw_execute does the same as `execute` on Unix platforms.
// On Windows raw_execute starts the specified command, waits for it to complete, and returns its output.
// It's marked as `unsafe` to help emphasize the problems that may arise by allowing, for example,
// user provided escape sequences.
[unsafe]
pub fn raw_execute(cmd string) Result {
    return execute(cmd)
}

[manualfree]
pub fn (mut c Command) start() ! {
    pcmd := c.path + ' 2>&1'
    defer {
        unsafe { pcmd.free() }
    }
    c.f = vpopen(pcmd)
    if isnil(c.f) {
        return error('exec("${c.path}") failed')
    }
}

[manualfree]
pub fn (mut c Command) read_line() string {
    buf := [4096]u8{}
    mut res := strings.new_builder(1024)
    defer {
        unsafe { res.free() }
    }
    unsafe {
        bufbp := &buf[0]
        for C.fgets(&char(bufbp), 4096, c.f) != 0 {
            len := vstrlen(bufbp)
            for i in 0 .. len {
                if bufbp[i] == `\n` {
                    res.write_ptr(bufbp, i)
                    final := res.str()
                    return final
                }
            }
            res.write_ptr(bufbp, len)
        }
    }
    c.eof = true
    final := res.str()
    return final
}

pub fn (mut c Command) close() ! {
    c.exit_code = vpclose(c.f)
    if c.exit_code == 127 {
        return error_with_code('error', 127)
    }
}

pub fn symlink(origin string, target string) ! {
    res := C.symlink(&char(origin.str), &char(target.str))
    if res == 0 {
        return
    }
    return error(posix_get_error_msg(C.errno))
}

pub fn link(origin string, target string) ! {
    res := C.link(&char(origin.str), &char(target.str))
    if res == 0 {
        return
    }
    return error(posix_get_error_msg(C.errno))
}

// get_error_msg return error code representation in string.
pub fn get_error_msg(code int) string {
    return posix_get_error_msg(code)
}

pub fn (mut f File) close() {
    if !f.is_opened {
        return
    }
    f.is_opened = false
    C.fflush(f.cfile)
    C.fclose(f.cfile)
}

fn C.mkstemp(stemplate &u8) int

// ensure_folder_is_writable checks that `folder` exists, and is writable to the process
// by creating an empty file in it, then deleting it.
[manualfree]
pub fn ensure_folder_is_writable(folder string) ! {
    if !exists(folder) {
        return error_with_code('`${folder}` does not exist', 1)
    }
    if !is_dir(folder) {
        return error_with_code('`${folder}` is not a folder', 2)
    }
    tmp_perm_check := join_path_single(folder, 'XXXXXX')
    defer {
        unsafe { tmp_perm_check.free() }
    }
    unsafe {
        x := C.mkstemp(&char(tmp_perm_check.str))
        if -1 == x {
            return error_with_code('folder `${folder}` is not writable', 3)
        }
        C.close(x)
    }
    rm(tmp_perm_check)!
}

[inline]
pub fn getpid() int {
    return C.getpid()
}

[inline]
pub fn getppid() int {
    return C.getppid()
}

[inline]
pub fn getuid() int {
    return C.getuid()
}

[inline]
pub fn geteuid() int {
    return C.geteuid()
}

[inline]
pub fn getgid() int {
    return C.getgid()
}

[inline]
pub fn getegid() int {
    return C.getegid()
}

// Turns the given bit on or off, depending on the `enable` parameter
pub fn posix_set_permission_bit(path_s string, mode u32, enable bool) {
    mut s := C.stat{}
    mut new_mode := u32(0)
    path := &char(path_s.str)
    unsafe {
        C.stat(path, &s)
        new_mode = s.st_mode
    }
    match enable {
        true { new_mode |= mode }
        false { new_mode &= (0o7777 - mode) }
    }
    C.chmod(path, int(new_mode))
}

// get_long_path has no meaning for *nix, but has for windows, where `c:\folder\some~1` for example
// can be the equivalent of `c:\folder\some spa ces`. On *nix, it just returns a copy of the input path.
fn get_long_path(path string) !string {
    return path
}