#!/bin/bash
# Notice: only work when in PATH, or call using absolute path.

trap 'quit' 2 15

b=$(tput bold)
n=$(tput sgr0)

# Operators

function disj {
	[[ $1 == "T" ]] && echo "T" && return
	[[ $2 == "T" ]] && echo "T" && return
	echo "F" && return
}

function conj {
	[[ $1 == "T" && $2 == "T" ]] && echo "T" && return
	echo "F" && return
}

function impl {
	[[ $1 == "T" && $2 == "F" ]] && echo "F" && return
	echo "T" && return
}

function req {
	impl $2 $1
}

function eq {
	[[ $1 == $2 ]] && echo "T" && return
	echo "F" && return
}

function not {
	[[ $1 == "T" ]] && echo "F" && return
	echo "T" && return
}

[[ $1 == source ]] && return

# Codegen

function mkcode {
	tmp="$(mktemp)"

	expr_src="$(cat)"
	vars="$(_uppercase <<< "$expr_src")"
	core_expr="$(sed -e 's/(/$(/g; s/[A-Z]/$&/g;s/^$//; ' <<< "$expr_src")"

	{

	echo -e '#!/bin/bash\n. '$0' source'

	for var in $vars; do echo 'echo -n "'$var'; "'; done;

	[[ ! -z $vars ]] && echo 'echo'

	for var in $vars; do
		echo 'for '$var' in T F; do '
	done

		for _var in $vars; do
			echo 'echo -n "$'$_var'; "'
		done

		echo 'echo "'$b'=>'$n' '$core_expr';"; '

	for var in $vars; do echo 'done; '; done

	} > $tmp

	bash $tmp
	rm $tmp
}

function _uppercase {
	tr ' ' '\n' | grep -E '[A-Z]' | sed 's/.*\([A-Z]\).*/\1/' | sort | uniq | tr '\n' ' '
}

function quit {

	[[ -e "$tmpd" ]] && rm -r "$tmpd"
	exit 0

}

function main {

	tmpd="$(mktemp -d)"
	cd $tmpd; touch disj conj impl req eq not

	echo "nato's logic evaluator (truth table listing) tool, "
	echo "version: 0.1.2; "
	echo
	echo "commands: "
	echo "  disj <p> <q>: disjunction of p and q. (or)"
	echo "  conj <p> <q>: conjunction of p and q. (and)"
	echo "  impl <p> <q>: p implies q. (condition)"
	echo "   req <p> <q>: p require q. (n. condition)"
	echo "    eq <p> <q>: p equals q."
	echo "   not <p>    : not p."
	echo
	echo "example: (P ⊃ (~R · I)) will be written as: "
	echo "(impl P (conj (not R) I))"
	echo
	echo "note that the outer parentheses are REQUIRED, "
	echo "anything outside the paren will be treated as formating string. e.g.: "
	echo "?> conjoining A and B is: (conj A B)"
	echo "A; B; "
	echo "T; T; => conjoining T and T is: T;"
	echo "T; F; => conjoining T and F is: F;"
	echo "F; T; => conjoining F and T is: F;"
	echo "F; F; => conjoining F and F is: F;"
	echo
	echo "You can also evaluate multiple expressions in same time: e.g.:"
	echo "?> (not A), (eq (not B) A)"
	echo "A; B; "
	echo "T; T; => F, F;"
	echo "T; F; => F, T;"
	echo "F; T; => T, T;"
	echo "F; F; => T, F;"
	echo

	while IFS="" read -r -e -d $'\n' -p "$flags$b?>$n " expr_; do 
		history -s "$expr_"
		mkcode <<< "$expr_"
	done
}

main
quit