_core

#! /hint/sh
# i_was_not_set__check=
alias \
\
puts='printf %s\\n' \
command.='command >/dev/null -v' \
\
fori='for i in' fori{{='for i;{{' '{{=do' '}}=done' \
loop\{='while :; do' \
and='(exit $?)&&' or='(exit $?)||' \
goto_continue='while :;' \
goto_break='break;' \
\
\
print-error-trace='printf %s "warning: ${BASH_SOURCE+"(in file $BASH_SOURCE +$BASH_LINENO ) "}${FUNCNAME+"(in fn $FUNCNAME) "}"' \
expect-unseted-i='{ case ${i+x} in x) print-error-trace >&2; puts >&2   "i is defined, i=${i+"\'\''"}${i-(unseted)}${i+"\'\''"}";   esac; }' \
expect-seted-i='{ case ${i+x} in "")  print-error-trace >&2; puts >&2   "i is unset, i=${i+"\'\''"}${i-(unseted)}${i+"\'\''"}";   esac; }' \
unset-unseted-i='{ expect-unseted-i; unset i; }' \
unset-seted-i='{ expect-seted-i; unset i; }' \
i{=unset-unseted-i \
}i=unset-seted-i \
i='print-error-trace >&2 ; arg "i called" >&2' \
ii='print-error-trace >&2 ; arg "ii called" >&2' \
I='print-error-trace >&2 ; arg "I called" >&2' \
;


# alternative to local command, (local is not POSIX)
_vars=':'
var_local() {
	case $_vars: in *:$1:*)
		printf %s\\n >&2 "atempted to local var that is already local: $1"
		return 1
	esac
	eval "case \${${1}+x} in x) false; esac" || { # return 2 if var is defined, can not requre it as owned
		printf %s\\n >&2 "atempted to local var that is already defined: $1"
		return 3
	}
	_vars=${_vars%:}:$1:
}
var_unlocal() {
	case $_vars in *:$1:*) ;; *)
		printf %s\\n >&2 "atempted to unlocal var: $1"
		return 1
	esac
	_vars=${_vars%%":$1:"*}:${_vars#*":$1:"}
	eval "unset $1"
}


case $- in
	-|'')
		case $PS1 in
		'') unset shell_is_interactive;;
		*) shell_is_interactive='';;
		esac
	;;
	*i*) shell_is_interactive='';;
	*) unset shell_is_interactive;;
esac

# if ( i=_; : "${!i}" ) 2>/dev/null 1>/dev/null; then
# DONT: unset i inside of _toi fns. instead the top level fn/script should check if it is set.
case $sh_is in
	bash|zsh)  shuf_1_toi() { expect-unseted-i; i=$(( ( ${RANDOM:?}   % $# ) + 1 )); i="${!i}"; unset shuf_1_ind; };;
	*)         shuf_1_toi() { expect-unseted-i; i=$(( ( ${RANDOM:-$$} % $# ) + 1 )); eval "i=\"\${${i}}\""; unset shuf_1_ind; };; # "$$" still got for 1 time usage
esac

case $sh_is in
	bash|yash|dash) shell_supports_local='';;
	sh) shell_supports_local='';; # (todo: does variables for example BASH_VERSION are present where sylnink is used) note: not detecting if its sh, then provide POSIX experience with overwriting variables
	*)
		if command. local; then
			shell_supports_local=''
		fi
	;;
esac

# GNUtector detect if GNU coreutils options are supported
unset os_gnu os_an os_busybox os_toybox os_win
case ${OSTYPE:-$(uname -o)} in
	linux-gnu|GNU/Linux)   os_gnu='';; # check for GNU+Busybox is not important for now
	linux-android|Android) os_an='';; # Termux? but it could be busybox toybox termux or any other shell app ..
	# todo: detect if its termux or native android shell

	MS/Windows) os_win='';;
	linux-musl|Linux) # Alpine, KISS
		unset-unseted-i
		i=$(unalias ls 2>/dev/null; command -v ls)
		case $i in # note: this will fail if ls is alias or fn
			ls) os_bb='';; # applet is build in
			*/ls) false;;
			*)
			puts >&2 \
				"\$B/_core: got unexpected output" \
				"\$B/_core: \$ command -v ls -> $i" \
				"\$B/_core: \$?:$?" \
			;
			unset-seted-i
			return 1
		esac || { [ -L "$i" ] && os_bb=''; } || {
			i=$(readlink -- "$i" 2>/dev/null)
			case $?:$i in
				0:*/busybox|busybox) os_bb='';;
				0:*/toybox|toybox) os_toybox='';;
				*)
				puts >&2 \
					"\$B/_core: well idk then what this OS this is, 'ls' seems to not be a symlink" \
					"\$B/_core: \$ readlink -- \$(command -v ls) -> $i" \
					"\$B/_core: \$?:$?" \
				;
				unset-seted-i
				return 1
			esac
		}
		unset-seted-i
	;;
	*) puts >&2 "\$B/_core: cannot detect current os ${OSTYPE:-$(uname -o)} in GNU || (Busybox+Musl) || Android || WINDOWS"; return 1;;
esac



return

#command_fn() { # never used , uncomment when needed
#  # type "$1" 2>/dev/null | grep -qe function\$ # POSIX
#  # [[ `type -- "$1" 2>/dev/null` = *\ function ]] # bashism
#  # WARING: tested in (bash,zsh,dash,ksh,yash), test more?
#  
#  case "$(command -V -- "$1" 2>/dev/null | head -n 1)" in
#  (*\ function) return 0;;
#  (*) return 1;
#  esac
#}
#

# shuf_1(){
	# eval "printf %s\\n \"\${10}\""
	# eval "printf %s\\n \"\${$(( ( ${RANDOM:-1$(\dd if=/dev/urandom count=3 2>&- | tr -d -c '0-9' | head -c 10)} % $# ) + 1 ))}\""
	# shift "$(( ${RANDOM:-1$(\dd if=/dev/urandom count=8 bs=1000 2>&- | tr -d -c '0-9' | head -c 10)} % $# ))"
	# printf %s\\n "$1"
# }
#bash shuf:


_tr_s(){ ( set -f; IFS=$1; set -- $(cat); IFS=$2; printf %s\\n "$*"; ); }
# command. env: || alias env:='IFS="${PATHseparator:-":"}" var_1l'

# alias alias--='alias 2>&- --' # was used only 1 and now no mire since `alias cd-='cd -' -='cd -'`