/* ==========================================================================
   Brew Log — page behaviour
   Small, dependency-free helpers.  Charts live in charts.js.
   ========================================================================== */

(function () {
    "use strict";

    /** Auto-focus the first empty field on a form. */
    function focusFirstEmpty() {
        var fields = document.querySelectorAll("input:not([type=hidden]), textarea, select");
        for (var i = 0; i < fields.length; i++) {
            if (!fields[i].value && !fields[i].readOnly) {
                fields[i].focus();
                return;
            }
        }
    }

    /** Default the reading date to today when the field is left empty. */
    function defaultDateFields() {
        var today = new Date().toISOString().slice(0, 10);
        var dateFields = document.querySelectorAll('input[type="date"][data-default-today]');
        for (var i = 0; i < dateFields.length; i++) {
            if (!dateFields[i].value) {
                dateFields[i].value = today;
            }
        }
    }

    /** Show/hide blocks driven by a checkbox. */
    function wireToggles() {
        var toggles = document.querySelectorAll("[data-toggle-target]");
        for (var i = 0; i < toggles.length; i++) {
            (function (toggle) {
                var target = document.getElementById(toggle.getAttribute("data-toggle-target"));
                if (!target) { return; }
                function apply() {
                    target.classList.toggle("hidden", !toggle.checked);
                }
                toggle.addEventListener("change", apply);
                apply();
            })(toggles[i]);
        }
    }

    /** Confirm destructive actions. */
    function wireConfirms() {
        var forms = document.querySelectorAll("[data-confirm]");
        for (var i = 0; i < forms.length; i++) {
            forms[i].addEventListener("submit", function (event) {
                if (!window.confirm(this.getAttribute("data-confirm"))) {
                    event.preventDefault();
                }
            });
        }
    }

    function init() {
        focusFirstEmpty();
        defaultDateFields();
        wireToggles();
        wireConfirms();
    }

    if (document.readyState === "loading") {
        document.addEventListener("DOMContentLoaded", init);
    } else {
        init();
    }
})();