/* ==========================================================================
   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();
                }
            });
        }
    }

    /**
     * The brewing advice pop-out.
     *
     * On a desktop the panel opens on hover, which the CSS does.  A
     * phone has no hover, so the trigger is a button that toggles it -
     * and it is a real button, so it works with a keyboard and with a
     * screen reader.
     */
    /**
     * The brewing advice pop-out.
     *
     * The advice runs to several hundred characters.  In a table cell it
     * pushed the table past the width of a phone, so it is a compact
     * trigger instead and the text is shown in a floating panel.
     *
     * The panel is position:fixed so it escapes the table's scroll
     * container - absolutely positioned inside the cell it was clipped
     * by the container and sliced in half by the card's edge.
     *
     * It opens on hover on a desktop, and on tap on a phone, which has
     * no hover.  The trigger is a real button, so it also works with a
     * keyboard.
     */
    function wireAdvicePopouts() {
        var triggers = document.querySelectorAll(".advice-trigger");
        for (var i = 0; i < triggers.length; i++) {
            (function (trigger) {
                var panel = trigger.parentNode.querySelector(".advice-pop");
                if (!panel) { return; }

                var closeTimer = null;

                function isPhone() {
                    return window.matchMedia("(max-width: 720px)").matches;
                }

                function place() {
                    if (isPhone()) {
                        /* The CSS centres it on a phone - clear any
                           inline position left over from a desktop
                           resize. */
                        panel.style.top = "";
                        panel.style.left = "";
                        return;
                    }

                    var box = trigger.getBoundingClientRect();
                    var gap = 10;
                    var height = panel.offsetHeight;
                    var width = panel.offsetWidth;
                    var spaceBelow = window.innerHeight - box.bottom - gap;
                    var spaceAbove = box.top - gap;

                    /* Prefer below; flip above when there is not enough
                       room and there is more room above. */
                    var top;
                    if (height <= spaceBelow || spaceBelow >= spaceAbove) {
                        top = box.bottom + gap;
                    } else {
                        top = Math.max(gap, box.top - height - gap);
                    }

                    /* Keep it on screen horizontally. */
                    var left = Math.min(box.left, window.innerWidth - width - gap);
                    left = Math.max(gap, left);

                    panel.style.top = Math.round(top) + "px";
                    panel.style.left = Math.round(left) + "px";
                }

                function open() {
                    if (closeTimer) {
                        clearTimeout(closeTimer);
                        closeTimer = null;
                    }
                    panel.classList.add("is-open");
                    trigger.setAttribute("aria-expanded", "true");
                    place();
                }

                function close() {
                    panel.classList.remove("is-open");
                    trigger.setAttribute("aria-expanded", "false");
                }

                function closeSoon() {
                    /* A short delay, so the mouse can travel from the
                       trigger into the panel without it closing. */
                    if (closeTimer) { clearTimeout(closeTimer); }
                    closeTimer = setTimeout(function () {
                        closeTimer = null;
                        if (!panel.matches(":hover") && !trigger.matches(":hover")) {
                            close();
                        }
                    }, 180);
                }

                trigger.addEventListener("click", function (event) {
                    event.preventDefault();
                    event.stopPropagation();
                    if (panel.classList.contains("is-open")) {
                        close();
                    } else {
                        open();
                    }
                });

                trigger.addEventListener("mouseenter", function () {
                    if (!isPhone()) { open(); }
                });
                trigger.addEventListener("mouseleave", closeSoon);
                panel.addEventListener("mouseenter", function () {
                    if (closeTimer) {
                        clearTimeout(closeTimer);
                        closeTimer = null;
                    }
                });
                panel.addEventListener("mouseleave", closeSoon);

                var closeButton = panel.querySelector(".advice-pop__close");
                if (closeButton) {
                    closeButton.addEventListener("click", function (event) {
                        event.preventDefault();
                        event.stopPropagation();
                        close();
                        trigger.focus();
                    });
                }

                document.addEventListener("keydown", function (event) {
                    if (event.key === "Escape" && panel.classList.contains("is-open")) {
                        close();
                        trigger.focus();
                    }
                });
                document.addEventListener("click", function (event) {
                    if (!panel.contains(event.target) && event.target !== trigger) {
                        close();
                    }
                });

                window.addEventListener("resize", function () {
                    if (panel.classList.contains("is-open")) { place(); }
                });
                window.addEventListener("scroll", function () {
                    if (panel.classList.contains("is-open")) { close(); }
                }, true);
            })(triggers[i]);
        }
    }

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

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