const accordionClass = "bux-accordion";

	let accordions = document.querySelectorAll(`.${accordionClass}`);
	accordions = Array.prototype.slice.call(accordions);

	accordions.forEach((accordion) => {
		let triggers = accordion.querySelectorAll(`.${accordionClass}__trigger`);
		triggers = Array.prototype.slice.call(triggers);

		let panels = accordion.querySelectorAll(`.${accordionClass}__panel`);
		panels = Array.prototype.slice.call(panels);

		triggers.forEach((trigger) => {
			trigger.addEventListener("keydown", handleKeys);
			trigger.addEventListener("click", (event) => {
				const { currentTarget: currentTrigger } = event;

				if (!allowMultipleOpen(currentTrigger)) {
					closeAccordionItems(currentTrigger, triggers, panels);
				}

				toggleAccordionItem(currentTrigger);
			});
		});
	});

	function handleKeys(event) {
		const {
			key: currentKey,
			currentTarget: currentTrigger,
			currentTarget: {
				parentNode: { parentNode: currentAccordion },
			},
		} = event;

		let triggers = currentAccordion.querySelectorAll(`.${accordionClass}__trigger`);
		triggers = Array.prototype.slice.call(triggers);

		const currentTriggerIndex = triggers.indexOf(currentTrigger);

		switch (currentKey) {
			case keys.up:
				if (currentTriggerIndex === 0) {
					triggers[triggers.length - 1].focus();
				} else {
					triggers[currentTriggerIndex - 1].focus();
				}
				event.preventDefault();
				break;
			case keys.down:
				if (currentTriggerIndex === triggers.length - 1) {
					triggers[0].focus();
				} else {
					triggers[currentTriggerIndex + 1].focus();
				}
				event.preventDefault();
				break;
			case keys.home:
				triggers[0].focus();
				event.preventDefault();
				break;
			case keys.end:
				triggers[triggers.length - 1].focus();
				event.preventDefault();
				break;
		}
	}

	function isHeading(element) {
		return element && element.classList.contains(`${accordionClass}__heading`);
	}

	function toggleAccordionItem(element) {
		let currentTriggerExpanded = element.getAttribute("aria-expanded");
		currentTriggerExpanded = currentTriggerExpanded === "true" ? true : false;

		element.setAttribute("aria-expanded", !currentTriggerExpanded);

		const currentPanelId = element.getAttribute("aria-controls");
		const currentPanel = document.querySelector(`#${currentPanelId}`);
		let currentPanelHidden = currentPanel.getAttribute("hidden");

		if (currentPanelHidden !== null) {
			currentPanel.removeAttribute("hidden");
		} else {
			currentPanel.setAttribute("hidden", "hidden");
		}
	}

	function allowMultipleOpen(element) {
		const {
			parentNode: { parentNode: currentAccordion },
		} = element;

		const {
			dataset: { allowMultiple: hasAllowMultiple },
		} = currentAccordion;

		return hasAllowMultiple !== undefined ? true : false;
	}

	function closeAccordionItems(trigger, triggers, panels) {
		const otherTriggers = triggers.filter((element) => element !== trigger);

		otherTriggers.forEach((otherTrigger) => {
			otherTrigger.setAttribute("aria-expanded", false);
		});

		const currentPanelId = trigger.getAttribute("aria-controls");
		const currentPanel = document.querySelector(`#${currentPanelId}`);
		const otherPanels = panels.filter((element) => element !== currentPanel);

		otherPanels.forEach((otherPanel) => {
			otherPanel.setAttribute("hidden", "hidden");
		});
	}