/**
 * Full screen for the trading-network graph.
 *
 * What goes full screen is the graph's own box: its header (caption, subtext,
 * spread and full-screen buttons), the canvas and the time-lapse panel - not
 * the page around it. Esc leaves it; that is the browser's own handling.
 *
 * In full screen the header floats over the canvas (see the markup), and it
 * and the playback panel fade out after IDLE_MS without activity, so the graph
 * has the whole screen. Any pointer movement, tap, drag, wheel or key brings
 * them back for another IDLE_MS.
 */

const IDLE_MS = 2000;

/**
 * @param {object}      opts
 * @param {HTMLElement} opts.screenBox  The box that goes full screen.
 * @param {HTMLElement} opts.frameBox   The graph's box; fills the screen (by CSS).
 * @param {HTMLElement} opts.headerBox  The header row that hides.
 * @param {HTMLElement} opts.button     The full-screen toggle.
 * @param {Function}    opts.panel      -> the playback panel, or null.
 * @param {AbortSignal} opts.signal     Removes every listener on rebuild.
 * @param {Function}    opts.onResize   (inFullscreen, headerHeight) after a switch.
 */
function setupFullscreen({ screenBox, frameBox, headerBox, button, panel, signal, onResize }) {
    if (!screenBox || !frameBox || !button) {
        return;
    }

    // Prefixed for older Safari; absent altogether on iPhone, where only video
    // can go full screen - the button then goes rather than doing nothing.
    const enter = screenBox.requestFullscreen || screenBox.webkitRequestFullscreen;
    const leave = document.exitFullscreen || document.webkitExitFullscreen;

    if (!enter || !leave) {
        button.hidden = true;

        return;
    }

    const active = () => document.fullscreenElement || document.webkitFullscreenElement || null;
    const options = { capture: true, passive: true, signal };

    let idleTimer = null;
    // What the pointer is doing, for busy().
    let pointerType = 'mouse';
    let pressed = false;
    let lastPoint = null;

    // Whether the pointer's last known position lies on an element.
    //
    // By position rather than ":hover": hidden controls take no pointer
    // events, so a mouse that wakes them by moving onto them and then rests
    // there never makes them ":hover" - they hid from under it.
    const under = (el) => {
        if (!el || !lastPoint) {
            return false;
        }

        const r = el.getBoundingClientRect();

        return lastPoint.x >= r.left && lastPoint.x <= r.right
            && lastPoint.y >= r.top && lastPoint.y <= r.bottom;
    };

    const busy = () => {
        if (pressed) {
            // Mid-drag: a slider, or panning the graph.
            return true;
        }

        // Kept up while the mouse rests on them. Mouse only: a finger lifted
        // after a tap is not resting anywhere, and the last tap would
        // otherwise keep them up for ever.
        //
        // Focus deliberately does NOT count. Clicking the full-screen button
        // leaves it focused inside the header, and treating focus as "in use"
        // meant the controls never hid at all.
        return pointerType === 'mouse'
            && [headerBox, panel ? panel() : null].some(under);
    };

    const scheduleHide = () => {
        clearTimeout(idleTimer);
        idleTimer = setTimeout(() => {
            if (active() !== screenBox) {
                return;
            }

            if (busy()) {
                scheduleHide();

                return;
            }

            screenBox.classList.add('controls-hidden');
        }, IDLE_MS);
    };

    const wake = () => {
        if (active() !== screenBox) {
            return;
        }

        screenBox.classList.remove('controls-hidden');
        scheduleHide();
    };

    // Capture phase on the document: the canvas handles pointer events
    // itself, and a drag on it must still count as movement. On the document
    // rather than the screen box so that nothing inside the box - whatever
    // element ends up under the pointer after a rebuild - can keep the
    // controls from coming back; wake() itself ignores anything while the box
    // is not full screen. mousemove as well, for browsers that leave out
    // pointer events in some cases.
    ['pointermove', 'mousemove', 'pointerdown', 'touchstart', 'wheel', 'keydown'].forEach((type) => {
        document.addEventListener(type, wake, options);
    });

    // A rebuild aborts these listeners and sets up afresh. A hide still
    // pending from the old setup would otherwise fire later and hide the
    // controls behind the new one's back.
    if (signal) {
        signal.addEventListener('abort', () => clearTimeout(idleTimer), { once: true });
    }

    screenBox.addEventListener('pointerdown', (event) => {
        pressed = true;
        pointerType = event.pointerType || 'mouse';
        lastPoint = { x: event.clientX, y: event.clientY };
    }, options);

    screenBox.addEventListener('pointermove', (event) => {
        pointerType = event.pointerType || pointerType;
        lastPoint = { x: event.clientX, y: event.clientY };
    }, options);

    // Gone from the screen box altogether (another window, the taskbar).
    screenBox.addEventListener('pointerleave', () => {
        lastPoint = null;
    }, { signal });

    // On the document: a drag can end outside the box. Waking again on
    // release restarts the countdown from the end of the drag, not its start.
    ['pointerup', 'pointercancel'].forEach((type) => {
        document.addEventListener(type, () => {
            if (pressed) {
                pressed = false;
                wake();
            }
        }, options);
    });

    button.addEventListener('click', (event) => {
        event.preventDefault();

        const result = active() === screenBox
            ? leave.call(document)
            : enter.call(screenBox);

        if (result && typeof result.catch === 'function') {
            result.catch(() => {});
        }
    }, { signal });

    const onChange = () => {
        const on = active() === screenBox;
        const label = on ? button.dataset.labelExit : button.dataset.labelEnter;

        button.setAttribute('title', label);
        button.setAttribute('aria-label', label);
        button.querySelector('[data-fullscreen-enter]')?.classList.toggle('hidden', on);
        button.querySelector('[data-fullscreen-exit]')?.classList.toggle('hidden', !on);

        // The layout itself - the header floating over the canvas, the graph
        // taking the whole screen - is pure CSS on :fullscreen (the
        // group-fullscreen variant in the markup). Not a class or inline
        // height set here: the time-lapse settings are wire:model.live, and
        // the morph after each one reset both to the server's markup while
        // the box stayed full screen, leaving the graph at its normal height.
        screenBox.classList.remove('controls-hidden');
        clearTimeout(idleTimer);

        if (on) {
            scheduleHide();
        }

        if (onResize) {
            requestAnimationFrame(() => onResize(on, headerBox ? headerBox.offsetHeight : 0));
        }
    };

    document.addEventListener('fullscreenchange', onChange, { signal });
    document.addEventListener('webkitfullscreenchange', onChange, { signal });
}

export { setupFullscreen, IDLE_MS };