// --- Class Name Constants for MultiSelectSimple ---
const MSS_COMPONENT_WRAPPER_CLASS = "mss-component-wrapper";
const MSS_SELECTED_ITEMS_CONTAINER_CLASS = "mss-selected-items-container";
const MSS_SELECTED_ITEM_PILL_CLASS = "mss-selected-item-pill";
const MSS_SELECTED_ITEM_TEXT_CLASS = "mss-selected-item-text";
const MSS_SELECTED_ITEM_PILL_DETAIL_CLASS = "mss-selected-item-pill-detail"; // New class for pill detail
const MSS_SELECTED_ITEM_DELETE_BTN_CLASS = "mss-selected-item-delete-btn";
const MSS_INPUT_CONTROLS_CONTAINER_CLASS = "mss-input-controls-container";
const MSS_INPUT_WRAPPER_CLASS = "mss-input-wrapper";
const MSS_INPUT_WRAPPER_FOCUSED_CLASS = "mss-input-wrapper-focused";
const MSS_TEXT_INPUT_CLASS = "mss-text-input";
const MSS_CREATE_NEW_BUTTON_CLASS = "mss-create-new-button";
const MSS_OPTIONS_LIST_CLASS = "mss-options-list";
const MSS_OPTION_ITEM_CLASS = "mss-option-item";
const MSS_OPTION_ITEM_NAME_CLASS = "mss-option-item-name";
const MSS_OPTION_ITEM_DETAIL_CLASS = "mss-option-item-detail";
const MSS_HIGHLIGHTED_OPTION_CLASS = "mss-option-item-highlighted";
const MSS_HIDDEN_SELECT_CLASS = "mss-hidden-select";
const MSS_NO_ITEMS_TEXT_CLASS = "mss-no-items-text";

// State classes for MultiSelectSimple
const MSS_STATE_NO_SELECTION = "mss-state-no-selection";
const MSS_STATE_HAS_SELECTION = "mss-state-has-selection";
const MSS_STATE_LIST_OPEN = "mss-state-list-open";

// --- MultiSelectSimple Element ---
export class MultiSelectSimple extends HTMLElement {
	static formAssociated = true;

	constructor() {
		super();
		this.internals_ = this.attachInternals();
		this._value = [];
		this._options = [
			{ id: "marie_curie", name: "Marie Curie", additional_data: "Physicist and Chemist" },
			{ id: "leonardo_da_vinci", name: "Leonardo da Vinci", additional_data: "Polymath" },
			{ id: "albert_einstein", name: "Albert Einstein", additional_data: "Theoretical Physicist" },
			{ id: "ada_lovelace", name: "Ada Lovelace", additional_data: "Mathematician and Writer" },
			{ id: "isaac_newton", name: "Isaac Newton", additional_data: "Mathematician and Physicist" },
			{
				id: "galileo_galilei",
				name: "Galileo Galilei",
				additional_data: "Astronomer and Physicist",
			},
			{ id: "charles_darwin", name: "Charles Darwin", additional_data: "Naturalist" },
			{ id: "nikola_tesla", name: "Nikola Tesla", additional_data: "Inventor and Engineer" },
			{ id: "jane_austen", name: "Jane Austen", additional_data: "Novelist" },
			{
				id: "william_shakespeare",
				name: "William Shakespeare",
				additional_data: "Playwright and Poet",
			},
		];
		this._filteredOptions = [];
		this._highlightedIndex = -1;
		this._isOptionsListVisible = false;

		this._placeholder = this.getAttribute("placeholder") || "Search items...";
		this._showCreateButton = this.getAttribute("show-create-button") !== "false";

		this._setupTemplates();
		this._bindEventHandlers();
	}

	_setupTemplates() {
		this.optionTemplate = document.createElement("template");
		this.optionTemplate.innerHTML = `
                    <li role="option" class="${MSS_OPTION_ITEM_CLASS}">
                        <span data-ref="nameEl" class="${MSS_OPTION_ITEM_NAME_CLASS}"></span>
                        <span data-ref="detailEl" class="${MSS_OPTION_ITEM_DETAIL_CLASS}"></span>
                    </li>
                `;

		this.selectedItemTemplate = document.createElement("template");
		// Apply new MSS_SELECTED_ITEM_PILL_DETAIL_CLASS to the detail span
		this.selectedItemTemplate.innerHTML = `
                    <span class="${MSS_SELECTED_ITEM_PILL_CLASS} flex items-center">
                        <span data-ref="textEl" class="${MSS_SELECTED_ITEM_TEXT_CLASS}"></span>
                        <span data-ref="detailEl" class="${MSS_SELECTED_ITEM_PILL_DETAIL_CLASS} hidden"></span>
                        <button type="button" data-ref="deleteBtn" class="${MSS_SELECTED_ITEM_DELETE_BTN_CLASS}">&times;</button>
                    </span>
                `;
	}

	_bindEventHandlers() {
		this._handleInput = this._handleInput.bind(this);
		this._handleKeyDown = this._handleKeyDown.bind(this);
		this._handleFocus = this._handleFocus.bind(this);
		this._handleBlur = this._handleBlur.bind(this);
		this._handleOptionMouseDown = this._handleOptionMouseDown.bind(this);
		this._handleOptionClick = this._handleOptionClick.bind(this);
		this._handleCreateNewButtonClick = this._handleCreateNewButtonClick.bind(this);
		this._handleSelectedItemsContainerClick = this._handleSelectedItemsContainerClick.bind(this);
	}

	_getItemById(id) {
		return this._options.find((opt) => opt.id === id);
	}

	get placeholder() {
		return this._placeholder;
	}
	set placeholder(value) {
		this._placeholder = value;
		if (this.inputElement) this.inputElement.placeholder = this._placeholder;
		this.setAttribute("placeholder", value);
	}

	get showCreateButton() {
		return this._showCreateButton;
	}
	set showCreateButton(value) {
		const boolValue = String(value).toLowerCase() !== "false" && value !== false;
		if (this._showCreateButton === boolValue) return;
		this._showCreateButton = boolValue;
		if (this.createNewButton)
			this.createNewButton.classList.toggle("hidden", !this._showCreateButton);
		this.setAttribute("show-create-button", this._showCreateButton ? "true" : "false");
	}

	setOptions(newOptions) {
		if (
			Array.isArray(newOptions) &&
			newOptions.every((o) => o && typeof o.id === "string" && typeof o.name === "string")
		) {
			this._options = [...newOptions];
			const validValues = this._value.filter((id) => this._getItemById(id));
			if (validValues.length !== this._value.length) this.value = validValues;
			else if (this.selectedItemsContainer) this._renderSelectedItems();
			this._filteredOptions = [];
			this._highlightedIndex = -1;
			if (this.inputElement && this.inputElement.value)
				this._handleInput({ target: this.inputElement });
			else this._hideOptionsList();
		} else console.error("setOptions expects an array of objects with id and name properties.");
	}

	get value() {
		return this._value;
	}
	set value(newVal) {
		const oldValString = JSON.stringify(this._value.sort());
		if (Array.isArray(newVal)) {
			this._value = [
				...new Set(newVal.filter((id) => typeof id === "string" && this._getItemById(id))),
			];
		} else if (typeof newVal === "string" && newVal.trim() !== "") {
			const singleId = newVal.trim();
			if (this._getItemById(singleId) && !this._value.includes(singleId)) this._value = [singleId];
			else if (!this._getItemById(singleId))
				this._value = this._value.filter((id) => id !== singleId);
		} else this._value = [];
		const newValString = JSON.stringify(this._value.sort());
		if (oldValString !== newValString) {
			this._updateFormValue();
			if (this.selectedItemsContainer) this._renderSelectedItems();
			this._updateRootElementStateClasses();
			this.dispatchEvent(new Event("change", { bubbles: true }));
		}
	}

	get name() {
		return this.getAttribute("name");
	}
	set name(value) {
		this.setAttribute("name", value);
		if (this.hiddenSelect) this.hiddenSelect.name = value;
	}

	connectedCallback() {
		this._render();
		this.inputControlsContainer = this.querySelector(`.${MSS_INPUT_CONTROLS_CONTAINER_CLASS}`);
		this.inputWrapper = this.querySelector(`.${MSS_INPUT_WRAPPER_CLASS}`);
		this.inputElement = this.querySelector(`.${MSS_TEXT_INPUT_CLASS}`);
		this.createNewButton = this.querySelector(`.${MSS_CREATE_NEW_BUTTON_CLASS}`);
		this.optionsListElement = this.querySelector(`.${MSS_OPTIONS_LIST_CLASS}`);
		this.selectedItemsContainer = this.querySelector(`.${MSS_SELECTED_ITEMS_CONTAINER_CLASS}`);
		this.hiddenSelect = this.querySelector(`.${MSS_HIDDEN_SELECT_CLASS}`);

		this.placeholder = this.getAttribute("placeholder") || "Search items...";
		this.showCreateButton = this.getAttribute("show-create-button") !== "false";

		if (this.name && this.hiddenSelect) this.hiddenSelect.name = this.name;

		this.inputElement.addEventListener("input", this._handleInput);
		this.inputElement.addEventListener("keydown", this._handleKeyDown);
		this.inputElement.addEventListener("focus", this._handleFocus);
		this.inputElement.addEventListener("blur", this._handleBlur);
		this.optionsListElement.addEventListener("mousedown", this._handleOptionMouseDown);
		this.optionsListElement.addEventListener("click", this._handleOptionClick);
		this.createNewButton.addEventListener("click", this._handleCreateNewButtonClick);
		this.selectedItemsContainer.addEventListener("click", this._handleSelectedItemsContainerClick);

		this._updateRootElementStateClasses();
		if (this.hasAttribute("value")) {
			const attrValue = this.getAttribute("value");
			try {
				this.value = JSON.parse(attrValue);
			} catch (e) {
				this.value = attrValue
					.split(",")
					.map((s) => s.trim())
					.filter(Boolean);
			}
		} else {
			this._renderSelectedItems();
			this._synchronizeHiddenSelect();
		}
		if (this.hasAttribute("disabled")) this.disabledCallback(true);
	}

	disconnectedCallback() {
		if (this.inputElement) {
			this.inputElement.removeEventListener("input", this._handleInput);
			this.inputElement.removeEventListener("keydown", this._handleKeyDown);
			this.inputElement.removeEventListener("focus", this._handleFocus);
			this.inputElement.removeEventListener("blur", this._handleBlur);
		}
		if (this.optionsListElement) {
			this.optionsListElement.removeEventListener("mousedown", this._handleOptionMouseDown);
			this.optionsListElement.removeEventListener("click", this._handleOptionClick);
		}
		if (this.createNewButton)
			this.createNewButton.removeEventListener("click", this._handleCreateNewButtonClick);
		if (this.selectedItemsContainer)
			this.selectedItemsContainer.removeEventListener(
				"click",
				this._handleSelectedItemsContainerClick,
			);
		clearTimeout(this._blurTimeout);
	}

	static get observedAttributes() {
		return ["disabled", "name", "value", "placeholder", "show-create-button"];
	}
	attributeChangedCallback(name, oldValue, newValue) {
		if (oldValue === newValue) return;
		if (name === "disabled") this.disabledCallback(this.hasAttribute("disabled"));
		else if (name === "name" && this.hiddenSelect) this.hiddenSelect.name = newValue;
		else if (name === "value" && this.inputElement) {
			try {
				this.value = JSON.parse(newValue);
			} catch (e) {
				this.value = newValue
					.split(",")
					.map((s) => s.trim())
					.filter(Boolean);
			}
		} else if (name === "placeholder") this.placeholder = newValue;
		else if (name === "show-create-button") this.showCreateButton = newValue;
	}

	formAssociatedCallback(form) {}
	formDisabledCallback(disabled) {
		this.disabledCallback(disabled);
	}
	formResetCallback() {
		this.value = [];
		this._hideOptionsList();
		if (this.inputElement) this.inputElement.value = "";
		this.placeholder = this.getAttribute("placeholder") || "Search items...";
		this.showCreateButton = this.getAttribute("show-create-button") !== "false";
		this._updateRootElementStateClasses();
		this._renderSelectedItems();
	}
	formStateRestoreCallback(state, mode) {
		this.value = Array.isArray(state) ? state : [];
		this._updateRootElementStateClasses();
	}

	_synchronizeHiddenSelect() {
		if (!this.hiddenSelect) return;
		this.hiddenSelect.innerHTML = "";
		this._value.forEach((id) => {
			const option = document.createElement("option");
			option.value = id;
			const itemData = this._getItemById(id);
			option.textContent = itemData ? itemData.name : id;
			option.selected = true;
			this.hiddenSelect.appendChild(option);
		});
	}
	_updateFormValue() {
		this.internals_.setFormValue(null);
		this._synchronizeHiddenSelect();
	}
	disabledCallback(disabled) {
		if (this.inputElement) this.inputElement.disabled = disabled;
		if (this.createNewButton) this.createNewButton.disabled = disabled;
		this.toggleAttribute("disabled", disabled);
		this.querySelectorAll(`.${MSS_SELECTED_ITEM_DELETE_BTN_CLASS}`).forEach(
			(btn) => (btn.disabled = disabled),
		);
		if (this.hiddenSelect) this.hiddenSelect.disabled = disabled;
		if (disabled) this._hideOptionsList();
	}
	_updateRootElementStateClasses() {
		this.classList.toggle(MSS_STATE_NO_SELECTION, this._value.length === 0);
		this.classList.toggle(MSS_STATE_HAS_SELECTION, this._value.length > 0);
		this.classList.toggle(MSS_STATE_LIST_OPEN, this._isOptionsListVisible);
	}
	_render() {
		const componentId = this.id || `mss-${crypto.randomUUID().slice(0, 8)}`;
		if (!this.id) this.setAttribute("id", componentId);
		this.innerHTML = `
                    <style>
                        .${MSS_HIDDEN_SELECT_CLASS} { display: block !important; visibility: hidden !important; position: absolute !important; width: 0px !important; height: 0px !important; opacity: 0 !important; pointer-events: none !important; margin: -1px !important; padding: 0 !important; border: 0 !important; overflow: hidden !important; clip: rect(0, 0, 0, 0) !important; white-space: nowrap !important; }
                    </style>
                    <div class="${MSS_COMPONENT_WRAPPER_CLASS} relative">
                        <div class="${MSS_SELECTED_ITEMS_CONTAINER_CLASS} flex flex-wrap gap-1 mb-1 min-h-[38px]" aria-live="polite" tabindex="-1"></div>
                        <div class="${MSS_INPUT_CONTROLS_CONTAINER_CLASS} flex items-center space-x-2">
                            <div class="${MSS_INPUT_WRAPPER_CLASS} relative rounded-md flex items-center flex-grow">
                                <input type="text"
                                       class="${MSS_TEXT_INPUT_CLASS} w-full outline-none bg-transparent text-sm"
                                       placeholder="${this.placeholder}"
                                       aria-autocomplete="list"
                                       aria-expanded="${this._isOptionsListVisible}"
                                       aria-controls="options-list-${componentId}"
                                       autocomplete="off" autocorrect="off" autocapitalize="none" spellcheck="false" role="combobox" />
                            </div>
                            <button type="button" class="${MSS_CREATE_NEW_BUTTON_CLASS} ${!this.showCreateButton ? "hidden" : ""}" title="Create new item from input">+</button>
                        </div>
                        <ul id="options-list-${componentId}" role="listbox" class="${MSS_OPTIONS_LIST_CLASS} absolute z-20 w-full max-h-60 overflow-y-auto mt-1 hidden"></ul>
                        <select multiple name="${this.getAttribute("name") || "mss_default_name"}" id="hidden-select-${componentId}" class="${MSS_HIDDEN_SELECT_CLASS}" aria-hidden="true"></select>
                    </div>
                `;
	}
	_createSelectedItemElement(itemId) {
		const itemData = this._getItemById(itemId);
		if (!itemData) return null;
		const fragment = this.selectedItemTemplate.content.cloneNode(true);
		const pillEl = fragment.firstElementChild;
		const textEl = pillEl.querySelector('[data-ref="textEl"]');
		const detailEl = pillEl.querySelector('[data-ref="detailEl"]'); // This now uses MSS_SELECTED_ITEM_PILL_DETAIL_CLASS
		const deleteBtn = pillEl.querySelector('[data-ref="deleteBtn"]');
		textEl.textContent = itemData.name;
		if (itemData.additional_data) {
			detailEl.textContent = `(${itemData.additional_data})`;
			detailEl.classList.remove("hidden"); // Toggle visibility via JS
		} else {
			detailEl.classList.add("hidden"); // Toggle visibility via JS
		}
		deleteBtn.setAttribute("aria-label", `Remove ${itemData.name}`);
		deleteBtn.dataset.id = itemId;
		deleteBtn.disabled = this.hasAttribute("disabled");
		deleteBtn.addEventListener("click", (e) => {
			e.stopPropagation();
			this._handleDeleteSelectedItem(itemId);
		});
		return pillEl;
	}
	_renderSelectedItems() {
		if (!this.selectedItemsContainer) return;
		this.selectedItemsContainer.innerHTML = "";
		if (this._value.length === 0) {
			this.selectedItemsContainer.innerHTML = `<span class="${MSS_NO_ITEMS_TEXT_CLASS}">No items selected</span>`;
		} else {
			this._value.forEach((id) => {
				const pillEl = this._createSelectedItemElement(id);
				if (pillEl) this.selectedItemsContainer.appendChild(pillEl);
			});
		}
		this._updateRootElementStateClasses();
	}
	_createOptionElement(itemData, index) {
		const fragment = this.optionTemplate.content.cloneNode(true);
		const li = fragment.firstElementChild;
		const nameEl = li.querySelector('[data-ref="nameEl"]');
		const detailEl = li.querySelector('[data-ref="detailEl"]');
		nameEl.textContent = itemData.name;
		detailEl.textContent = itemData.additional_data ? `(${itemData.additional_data})` : "";
		li.dataset.id = itemData.id;
		li.setAttribute("aria-selected", String(index === this._highlightedIndex));
		const optionElementId = `option-${this.id || "mss"}-${itemData.id}`;
		li.id = optionElementId;
		if (index === this._highlightedIndex) {
			li.classList.add(MSS_HIGHLIGHTED_OPTION_CLASS);
			if (this.inputElement)
				this.inputElement.setAttribute("aria-activedescendant", optionElementId);
		}
		return li;
	}
	_renderOptionsList() {
		if (!this.optionsListElement || !this.inputElement) return;
		this.optionsListElement.innerHTML = "";
		this.inputElement.removeAttribute("aria-activedescendant");
		if (this._filteredOptions.length === 0 || !this._isOptionsListVisible) {
			this.optionsListElement.classList.add("hidden");
			this.inputElement.setAttribute("aria-expanded", "false");
		} else {
			this.optionsListElement.classList.remove("hidden");
			this.inputElement.setAttribute("aria-expanded", "true");
			this._filteredOptions.forEach((item, index) => {
				const optionEl = this._createOptionElement(item, index);
				this.optionsListElement.appendChild(optionEl);
			});
			const highlightedElement = this.optionsListElement.querySelector(
				`.${MSS_HIGHLIGHTED_OPTION_CLASS}`,
			);
			if (highlightedElement) {
				highlightedElement.scrollIntoView({ block: "nearest" });
				this.inputElement.setAttribute("aria-activedescendant", highlightedElement.id);
			}
		}
		this._updateRootElementStateClasses();
	}
	_handleSelectedItemsContainerClick(event) {
		if (
			event.target === this.selectedItemsContainer &&
			this.inputElement &&
			!this.inputElement.disabled
		) {
			this.inputElement.focus();
		}
	}
	_handleCreateNewButtonClick() {
		if (this.hasAttribute("disabled") || !this.showCreateButton) return;
		const inputValue = this.inputElement ? this.inputElement.value.trim() : "";
		this.dispatchEvent(
			new CustomEvent("createnew", {
				detail: { value: inputValue },
				bubbles: true,
				composed: true,
			}),
		);
	}
	_handleInput(event) {
		const searchTerm = event.target.value;
		if (searchTerm.length === 0) {
			this._filteredOptions = [];
			this._isOptionsListVisible = false;
		} else {
			const searchTermLower = searchTerm.toLowerCase();
			this._filteredOptions = this._options.filter((item) => {
				if (this._value.includes(item.id)) return false;
				const nameMatch = item.name.toLowerCase().includes(searchTermLower);
				const additionalDataMatch =
					item.additional_data && item.additional_data.toLowerCase().includes(searchTermLower);
				return nameMatch || additionalDataMatch;
			});
			this._isOptionsListVisible = this._filteredOptions.length > 0;
		}
		this._highlightedIndex = this._filteredOptions.length > 0 ? 0 : -1;
		this._renderOptionsList();
	}
	_handleKeyDown(event) {
		if (this.inputElement.disabled) return;
		// Removed: Backspace on empty input to delete last item
		// if (event.key === "Backspace" && this.inputElement.value === "" && this._value.length > 0) {
		//      event.preventDefault();
		//      const lastItemId = this._value[this._value.length - 1];
		//      this._handleDeleteSelectedItem(lastItemId);
		//      return;
		// }
		if (!this._isOptionsListVisible || this._filteredOptions.length === 0) {
			if (event.key === "Escape") this._hideOptionsList();
			if (
				(event.key === "ArrowDown" || event.key === "ArrowUp") &&
				this.inputElement.value.length > 0
			) {
				this._handleInput({ target: this.inputElement });
			}
			return;
		}
		switch (event.key) {
			case "ArrowDown":
				event.preventDefault();
				this._highlightedIndex = (this._highlightedIndex + 1) % this._filteredOptions.length;
				this._renderOptionsList();
				break;
			case "ArrowUp":
				event.preventDefault();
				this._highlightedIndex =
					(this._highlightedIndex - 1 + this._filteredOptions.length) %
					this._filteredOptions.length;
				this._renderOptionsList();
				break;
			case "Enter":
				event.preventDefault();
				if (this._highlightedIndex > -1 && this._filteredOptions[this._highlightedIndex]) {
					this._selectItem(this._filteredOptions[this._highlightedIndex].id);
				}
				break;
			case "Escape":
				event.preventDefault();
				this._hideOptionsList();
				break;
			case "Tab":
				this._hideOptionsList();
				break;
		}
	}
	_hideOptionsList() {
		this._isOptionsListVisible = false;
		this._highlightedIndex = -1;
		if (this.optionsListElement) this._renderOptionsList();
	}
	_handleFocus() {
		if (this.inputElement.disabled) return;
		if (this.inputWrapper) this.inputWrapper.classList.add(MSS_INPUT_WRAPPER_FOCUSED_CLASS);
		if (this.inputElement.value.length > 0) this._handleInput({ target: this.inputElement });
		this._updateRootElementStateClasses();
	}
	_blurTimeout = null;
	_handleBlur() {
		if (this.inputWrapper) this.inputWrapper.classList.remove(MSS_INPUT_WRAPPER_FOCUSED_CLASS);
		this._blurTimeout = setTimeout(() => {
			if (!this.contains(document.activeElement)) this._hideOptionsList();
		}, 150);
	}
	_handleOptionMouseDown(event) {
		event.preventDefault();
	}
	_handleOptionClick(event) {
		const li = event.target.closest("li[data-id]");
		if (li && li.dataset.id) this._selectItem(li.dataset.id);
	}
	_selectItem(itemId) {
		if (itemId && !this._value.includes(itemId)) this.value = [...this._value, itemId];
		if (this.inputElement) this.inputElement.value = "";
		this._filteredOptions = [];
		this._hideOptionsList();
		if (this.inputElement && !this.hasAttribute("disabled")) this.inputElement.focus();
	}
	_handleDeleteSelectedItem(itemId) {
		this.value = this._value.filter((id) => id !== itemId);
		if (this.inputElement && this.inputElement.value)
			this._handleInput({ target: this.inputElement });
		if (this.inputElement && !this.hasAttribute("disabled")) this.inputElement.focus();
	}
}