$(document).ready(function() {
    var captchaAnswer = 0;

    function newCaptcha() {
        var a = Math.floor(Math.random() * 8) + 2;
        var b = Math.floor(Math.random() * 8) + 2;
        captchaAnswer = a + b;
        $("#captcha_label").text("What is " + a + " + " + b + "?");
        $("#captcha").val("").removeClass("error_input");
    }

    newCaptcha();
    $("#captcha_refresh").on("click", newCaptcha);

    $("#name,#email,#phone,#subject,#message,#captcha").on("input", function() {
        $(this).removeClass("error_input");
        $("#form_error").hide();
    });

    $("#send_message").click(function(e) {
        e.preventDefault();
        var invalid = false;
        var name = $.trim($("#name").val());
        var email = $.trim($("#email").val());
        var phone = $.trim($("#phone").val());
        var message = $.trim($("#message").val());
        var captcha = $.trim($("#captcha").val());
        var emailOk = /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email);
        var phoneOk = /^[6-9]\d{9}$/.test(phone.replace(/\s+/g, ""));
        var $btn = $("#send_message");
        var isButton = $btn.is("button");

        function mark(id, bad) {
            $(id).toggleClass("error_input", bad);
            if (bad) invalid = true;
        }

        mark("#name", name.length < 2);
        mark("#email", !emailOk);
        mark("#phone", !phoneOk);
        if ($("#subject").length) mark("#subject", $.trim($("#subject").val()).length < 2);
        mark("#message", message.length < 10);
        mark("#captcha", captcha !== String(captchaAnswer));

        if (invalid) {
            $("#form_error").text("Please fill every field correctly and answer the captcha.").fadeIn(200);
            return;
        }

        $("#form_error").hide();
        $btn.prop("disabled", true);
        if (isButton) $btn.text("Sending...");
        else $btn.attr("value", "Sending...");
        $.post("email.php", $("#contact_form").serialize(), function(response) {
            if (response === "sent") {
                $("#submit").hide();
                $("#send_message").hide();
                $("#mail_success").fadeIn(500);
            } else {
                $("#mail_fail").fadeIn(500);
                $btn.prop("disabled", false);
                if (isButton) $btn.text("Send Message >");
                else $btn.attr("value", "Submit Form");
                newCaptcha();
            }
        }).fail(function() {
            $("#mail_fail").fadeIn(500);
            $btn.prop("disabled", false);
            if (isButton) $btn.text("Send Message >");
            else $btn.attr("value", "Submit Form");
            newCaptcha();
        });
    });
});