const DEFAULT_POPOVER_CLASS = 'absolute left-0 right-0 top-full mt-2 z-[50] transition-all duration-200 pointer-events-none';
const DEFAULT_POPOVER_STYLE = 'opacity:0; transform:translateY(-6px) scale(0.98);';
const DEFAULT_PANEL_CLASS = 'rounded-[1.35rem] py-3';
const DEFAULT_PANEL_STYLE = 'background:rgb(var(--sunken-rgb)); border:1px solid rgb(var(--border-input-rgb)); box-shadow:var(--shadow-shell);';

const DEFAULT_OPEN_TRIGGER_STYLE = {
    background: 'rgb(var(--sunken-rgb))',
    borderColor: 'rgb(var(--border-input-rgb))',
};

const DEFAULT_CLOSED_TRIGGER_STYLE = {
    background: 'rgb(var(--card-rgb))',
    borderColor: 'rgb(var(--border-card-rgb))',
};

function byId(idOrElement) {
    if (!idOrElement) return null;
    if (typeof idOrElement === 'string') return document.getElementById(idOrElement);
    return idOrElement;
}

function setStyles(el, styles = {}, important = false) {
    if (!el) return;
    Object.entries(styles).forEach(([name, value]) => {
        if (value == null) return;
        if (important) {
            const cssName = name.replace(/[A-Z]/g, (letter) => `-${letter.toLowerCase()}`);
            el.style.setProperty(cssName, value, 'important');
        }
        else el.style[name] = value;
    });
}

export function createCalendarPopoverHTML({
    id,
    calendarHTML,
    popoverClass = DEFAULT_POPOVER_CLASS,
    popoverStyle = DEFAULT_POPOVER_STYLE,
    panelClass = DEFAULT_PANEL_CLASS,
    panelStyle = DEFAULT_PANEL_STYLE,
    wrapInPanel = true,
}) {
    const body = wrapInPanel
        ? `<div class="${panelClass}" style="${panelStyle}">${calendarHTML}</div>`
        : calendarHTML;
    return `
        <div id="${id}" class="${popoverClass}" style="${popoverStyle}">
            ${body}
        </div>
    `;
}

export function syncCalendarPopoverVisibility({
    popup,
    isOpen,
    chevron,
    trigger,
    openTriggerStyle = DEFAULT_OPEN_TRIGGER_STYLE,
    closedTriggerStyle = DEFAULT_CLOSED_TRIGGER_STYLE,
    triggerImportant = false,
}) {
    const popupEl = byId(popup);
    if (popupEl) {
        popupEl.style.opacity = isOpen ? '1' : '0';
        popupEl.style.transform = isOpen ? 'translateY(0) scale(1)' : 'translateY(-6px) scale(0.98)';
        popupEl.style.pointerEvents = isOpen ? 'auto' : 'none';
    }

    const chevronEl = byId(chevron);
    if (chevronEl) chevronEl.style.transform = isOpen ? 'rotate(180deg)' : 'rotate(0deg)';

    setStyles(
        byId(trigger),
        isOpen ? openTriggerStyle : closedTriggerStyle,
        triggerImportant,
    );
}

export function stabilizeSwipeCalendarLayout({
    calendar,
    viewport,
    hideViewport = false,
    maxAttempts = 8,
}) {
    const viewportEl = byId(viewport);
    if (hideViewport && viewportEl) {
        viewportEl.style.opacity = '0';
        viewportEl.style.visibility = 'hidden';
        viewportEl.style.transition = 'opacity 120ms ease';
    }

    calendar?.render?.();

    const ensureStableLayout = (attempt = 0) => {
        const width = viewportEl ? (viewportEl.clientWidth || viewportEl.getBoundingClientRect().width) : 0;
        if (viewportEl && width < 8 && attempt < maxAttempts) {
            requestAnimationFrame(() => ensureStableLayout(attempt + 1));
            return;
        }

        calendar?.reapplyLayout?.();
        calendar?.resetTrackPosition?.();
        requestAnimationFrame(() => {
            calendar?.reapplyLayout?.();
            calendar?.resetTrackPosition?.();
            if (hideViewport && viewportEl) {
                viewportEl.style.visibility = 'visible';
                viewportEl.style.opacity = '1';
            }
        });
    };

    requestAnimationFrame(() => ensureStableLayout());
}

export function createCalendarPopoverController({
    popupId,
    viewportId,
    triggerId,
    chevronId,
    getCalendar,
    openTriggerStyle = DEFAULT_OPEN_TRIGGER_STYLE,
    closedTriggerStyle = DEFAULT_CLOSED_TRIGGER_STYLE,
    triggerImportant = false,
    hideViewportDuringLayout = false,
}) {
    const calendar = () => (typeof getCalendar === 'function' ? getCalendar() : null);

    const sync = (isOpen) => {
        syncCalendarPopoverVisibility({
            popup: popupId,
            isOpen,
            chevron: chevronId,
            trigger: triggerId,
            openTriggerStyle,
            closedTriggerStyle,
            triggerImportant,
        });
    };

    const stabilize = () => {
        stabilizeSwipeCalendarLayout({
            calendar: calendar(),
            viewport: viewportId,
            hideViewport: hideViewportDuringLayout,
        });
    };

    const close = ({ clearPendingRange = false } = {}) => {
        sync(false);
        const instance = calendar();
        if (clearPendingRange) instance?.clearPendingRange?.();
        instance?.resetTrackPosition?.();
    };

    const open = () => {
        sync(true);
        stabilize();
    };

    return {
        sync,
        open,
        close,
        stabilize,
    };
}