var main_display = "0";
var sub_display = "";
var ok_to_clear_main = false;

var operationChars = /[x\/\-+]/;

var setting_negative_number = false;

function clear_main_display() {
	main_display = "0";
	update_main_display_text();
}

function clear_sub_display() {
	sub_display = "";
	update_sub_display_text();
}

function update_main_display_text() {
	$(".disp_main").text(main_display);
}

function update_sub_display_text() {
	$(".disp_sub").text(sub_display);
}

function recalculate_variables() {
	main_display = $(".disp_main").text();
	sub_display = $(".disp_sub").text();
}

function add_text_to_main_display(text) {
	var previous = $(".disp_main").text();
	if(setting_negative_number) {
		setting_negative_number = false;
	}
	else if(previous.match(operationChars) || previous == "0" || ok_to_clear_main) {
		previous = "";
		ok_to_clear_main = false;
	}
	$(".disp_main").text(previous + text);
}

function set_main_display_text(text) {
	$(".disp_main").text(text);
}
function set_sub_display_text(text) {
	$(".disp_sub").text(text);
}

$(document).ready(function() {
	update_main_display_text();
});

function ac() {
	clear_main_display();
	clear_sub_display();
}

function ce() {
	clear_main_display();
}

function n0() { add_text_to_main_display("0"); }
function n1() { add_text_to_main_display("1"); }
function n2() { add_text_to_main_display("2"); }
function n3() { add_text_to_main_display("3"); }
function n4() { add_text_to_main_display("4"); }
function n5() { add_text_to_main_display("5"); }
function n6() { add_text_to_main_display("6"); }
function n7() { add_text_to_main_display("7"); }
function n8() { add_text_to_main_display("8"); }
function n9() { add_text_to_main_display("9"); }

function divide() {
	recalculate_variables();
	if(sub_display.match(operationChars)) {
		equals();
	}
	set_sub_display_text(main_display + "/");
	set_main_display_text("/");
}
function x() {
	recalculate_variables();
	if(sub_display.match(operationChars)) {
		equals();
	}
	set_sub_display_text(main_display + "x");
	set_main_display_text("x");
}
function minus() {
	recalculate_variables();
	if(sub_display.match(operationChars)) {
		equals();
	}
	
	if(sub_display == "") {
		setting_negative_number = true;
		//set_sub_display_text("-");
	}
	else {
		set_sub_display_text(main_display + "-");
	}
	set_main_display_text("-");
}
function plus() {
	recalculate_variables();
	if(sub_display.match(operationChars)) {
		equals();
	}
	set_sub_display_text(main_display + "+");
	set_main_display_text("+");
}

function equals() {
	recalculate_variables();
	console.log(main_display);
	console.log(main_display.charAt(main_display.length - 1).match(operationChars) !== null);
	if(main_display.charAt(main_display.length - 1).match(operationChars) !== null) {
		main_display = sub_display.substring(0,sub_display.length - 1);
		console.log("new: " + main_display);
	}
	else {
		var left = parseFloat(sub_display.substring(0,sub_display.length - 1));
		var right = parseFloat(main_display);
		var total;
		if(sub_display.charAt(sub_display.length - 1) === "/") {
			total = Math.round(left / right * 10000000000) / 10000000000;
		}
		else if(sub_display.charAt(sub_display.length - 1) === "x") {
			total = Math.round(left * right * 10000000000) / 10000000000;
		}
		else if(sub_display.charAt(sub_display.length - 1) === "-") {
			total = left - right;
		}
		else if(sub_display.charAt(sub_display.length - 1) === "+") {
			total = left + right;
		}
		else {
			total = main_display;
		}
		main_display = String(total);
	}
	set_sub_display_text("=" + main_display);
	set_main_display_text(main_display);
	ok_to_clear_main = true;
}

$(".ac").click(ac);

$(".ce").click(ce);

$(".n0").click(n0);
$(".n1").click(n1);
$(".n2").click(n2);
$(".n3").click(n3);
$(".n4").click(n4);
$(".n5").click(n5);
$(".n6").click(n6);
$(".n7").click(n7);
$(".n8").click(n8);
$(".n9").click(n9);

$(".dot").click(function() {
	recalculate_variables();
	console.log(main_display.indexOf("."));
	
	if(main_display.indexOf(".") === -1) {
		 add_text_to_main_display(".");
	}
	recalculate_variables();
	console.log(main_display);
});

$(".plus").click(plus);
$(".minus").click(minus);
$(".divide").click(divide);
$(".x").click(x);
$(".equals").click(equals);