import { Menu } from 'obsidian';
import type { TodoItem } from '../core/types';

export interface TodoItemCallbacks {
	onToggle: (todo: TodoItem) => void;
	onMoveClick: (todo: TodoItem) => void;
	onClick: (todo: TodoItem) => void;
}

/**
 * Collect all line numbers for a todo and its descendants (for drag data).
 */
export function collectChildLineNumbers(todo: TodoItem): number[] {
	const lines: number[] = [];
	for (const child of todo.children) {
		lines.push(child.lineNumber);
		lines.push(...collectChildLineNumbers(child));
	}
	return lines;
}

/**
 * Creates a DOM element for a todo item with checkbox, right-click menu,
 * drag support, and recursive child rendering.
 */
export function createTodoItemEl(
	container: HTMLElement,
	todo: TodoItem,
	callbacks: TodoItemCallbacks
): HTMLElement {
	const itemEl = container.createEl('li', { cls: 'todo-tracker-item' });
	itemEl.dataset.lineNumber = String(todo.lineNumber);

	// Checkbox
	const checkboxEl = itemEl.createEl('input', { type: 'checkbox' });
	checkboxEl.checked = todo.completed;
	checkboxEl.addEventListener('change', () => {
		callbacks.onToggle(todo);
	});

	// Text content — click to navigate to editor
	const textEl = itemEl.createEl('span', { cls: 'todo-tracker-item-text' });
	textEl.setText(todo.text);
	if (todo.completed) {
		textEl.addClass('todo-tracker-item-completed');
	}
	textEl.addEventListener('click', (evt) => {
		evt.stopPropagation();
		callbacks.onClick(todo);
	});

	// Right-click context menu
	itemEl.addEventListener('contextmenu', (evt) => {
		evt.preventDefault();
		evt.stopPropagation();

		const menu = new Menu();
		menu.addItem((item) => {
			item
				.setTitle('Move to...')
				.setIcon('arrow-right')
				.onClick(() => {
					callbacks.onMoveClick(todo);
				});
		});

		menu.showAtMouseEvent(evt);
	});

	// Render children recursively
	if (todo.children.length > 0) {
		const nestedList = itemEl.createEl('ul', { cls: 'todo-tracker-nested-list' });
		for (const child of todo.children) {
			createTodoItemEl(nestedList, child, callbacks);
		}
	}

	return itemEl;
}