class TableView extends View {
	/**
	 * The constructor accepts a DOM element as a parameter. If it is omitted, a new element is created using the constructor name in kebab case.
	 */
	constructor(element = null) {
		super(element);

		this.cells = [ ];
		this.selectedCells = [ ];
		this.selectedCell = null;
		this.sections = [ ];

		//Gather the table view cell instances from the markup.
		var cellElements = this.element.querySelectorAll("table-view-cell");
		for (var i = 0; i < cellElements.length; i++) {
			var cellInstance = UIKit.getViewInstanceForElement(cellElements[i]);

			if (!cellInstance) {
				cellInstance = new TableViewCell(cellElements[i]);
			}

			this.cells.push(cellInstance);
		}

		//Gather the section instances from the markup.
		var sectionElements = this.element.querySelectorAll("table-view-section");
		for (var i = 0; i < sectionElements.length; i++) {
			var sectionInstance = UIKit.getViewInstanceForElement(sectionElements[i]);

			if (!sectionInstance) {
				sectionInstance = new TableViewSection(sectionElements[i]);
			}

			this.sections.push(sectionInstance);
		}
	}

	/**
	 * The build function is called in the constructor when no element was passed as the base.
	 * Override it to create custom subviews or manipulate the root element.
	 * Don't forget to return the element in the end!
	 */
	build(element) {
		return element;
	}

	/**
	 * Called once the view has been processed by UIKit during the view controller initialization.
	 */
	viewDidLoad() { }

	/**
	 * Called everytime before the view is shown.
	 * The layout is already done at this step, so it's safe to use scrollWidth and scrollHeight and what not.
	 */
	viewWillAppear() { }

	/**
	 * Called everytime after the view is shown.
	 */
	viewDidAppear() { }

	/**
	 * Called everytime before the view is hidden.
	 */
	viewWillDisappear() { }

	/**
	 * Called everytime after the view is hidden.
	 */
	viewDidDisappear() { }

	/**
	 * Adds the given cell to the table view.
	 * You can optionally provide a section index to which the cell should be added.
	 */
	addCell(cell, section = 0) {
		//Add sections until there are enough to satisfy the required section index.
		while (this.sections.length <= section) {
			this.addSection();
		}

		this.sections[section].addCell(cell);
		if (this.cells.indexOf(cell) == -1) {
			this.cells.push(cell);
		}
		cell.tableView = this;
	}

	/**
	 * Removes the specified cell from the table view.
	 */
	removeCell(cell) {
		var index = this.cells.indexOf(cell);

		if (index == -1) {
			console.error("Trying to remove a cell from a table view, but the cell is not actually in there.");
			return;
		}

		//Deselect the cell using the multiselect deselection feature if it is selected.
		if (cell.selected) {
			this.onCellSelected(cell, true);
		}

		cell.section.removeCell(cell);
		this.cells.splice(index, 1);
		cell.tableView = null;
	}

	/**
	 * Adds a new section to the table view.
	 * Speficy a title to designate the section.
	 */
	addSection(title = "") {
		var section = new TableViewSection();
		section.setTitle(title);
		this.sections.push(section);
		this.element.appendChild(section.element);
	}

	/**
	 * Called by the cells when they get selected.
	 */
	onCellSelected(cell, multiselectKeyDown) {
		var alreadySelected = cell.selected;

		//First, deselect all cells if the multiselect key is not held down.
		if (!multiselectKeyDown || (multiselectKeyDown && !this.multiselect)) {
			this.deselectAll(false);
		}

		//Only deselect the cell if it is selected and the multiselect key is held down.
		if (alreadySelected && multiselectKeyDown) {
			cell.deselect();

			var index = this.selectedCells.indexOf(cell);
			if (index != -1) {
				this.selectedCells.splice(index);
			}
			this.selectedCell = null;
		}
		else {
			//Otherwise just select the cell, but only if it is the only selected cell or multiselect is enabled.
			cell.select();
			this.selectedCells.push(cell);
			this.selectedCell = cell;
		}

		var cellSelectedEvent = new Event("cellselected");
		cellSelectedEvent.cell = cell.selected ? cell : null;
		this.dispatchEvent(cellSelectedEvent);
	}

	/**
	 * Deselects all cells in the table view.
	 */
	deselectAll(callListeners = true) {
		for (var i = 0; i < this.cells.length; i++) {
			if (this.cells[i].selected) {
				this.cells[i].deselect();
			}
		}

		this.selectedCells = [ ];
		this.selectedCell = null;

		if (callListeners) {
			var cellSelectedEvent = new Event("cellselected");
			cellSelectedEvent.cell = null;
			this.dispatchEvent(cellSelectedEvent);
		}
	}

	/**
	 * Selects the given cell inside this table view.
	 */
	selectCell(cell) {
		this.onCellSelected(cell, false);
	}
}

UIKit.registerViewType(TableView, "table-view");