document.addEventListener('DOMContentLoaded', () => {
    // DOM Elements
    const taskForm = document.getElementById('task-form');
    const taskInput = document.getElementById('task-input');
    const taskList = document.getElementById('task-list');
    const garden = document.getElementById('garden');
    const soundToggle = document.getElementById('sound-toggle');
    const ambientSound = document.getElementById('ambient-sound');
    const soundOnIcon = document.getElementById('sound-on-icon');
    const soundOffIcon = document.getElementById('sound-off-icon');

    // App State
    let tasks = JSON.parse(localStorage.getItem('tasks')) || [];
    let gardenElements = JSON.parse(localStorage.getItem('gardenElements')) || [];
    const flowerColors = ['pink', 'yellow', 'purple', 'white'];

    // --- Initialization ---
    function init() {
        tasks.forEach(renderTask);
        // Filter out garden elements whose tasks are no longer completed or no longer exist
        const completedTaskIds = new Set(tasks.filter(t => t.completed).map(t => t.id));
        gardenElements = gardenElements.filter(el => completedTaskIds.has(el.taskId));
        gardenElements.forEach(renderGardenElement);
        saveState(); // Resync localStorage with the filtered elements
    }

    // --- State Management ---
    function saveState() {
        localStorage.setItem('tasks', JSON.stringify(tasks));
        localStorage.setItem('gardenElements', JSON.stringify(gardenElements));
    }

    // --- Task Management ---
    taskForm.addEventListener('submit', e => {
        e.preventDefault();
        const title = taskInput.value.trim();
        if (title) {
            const newTask = { id: Date.now(), title, completed: false };
            tasks.push(newTask);
            renderTask(newTask);
            saveState();
            taskInput.value = '';
        }
    });

    function renderTask(task) {
        const li = document.createElement('li');
        li.dataset.id = task.id;
        if (task.completed) {
            li.classList.add('completed');
        }
        li.innerHTML = `
            <input type="checkbox" ${task.completed ? 'checked' : ''}>
            <span>${escapeHTML(task.title)}</span>
            <button class="delete-btn">&times;</button>
        `;
        taskList.appendChild(li);

        li.querySelector('input[type="checkbox"]').addEventListener('change', (e) => {
            toggleTaskCompletion(task.id, e.target.checked);
        });
        li.querySelector('.delete-btn').addEventListener('click', () => {
            deleteTask(task.id);
        });
    }

    function toggleTaskCompletion(id, isCompleted) {
        const taskIndex = tasks.findIndex(t => t.id === id);
        if (taskIndex > -1) {
            tasks[taskIndex].completed = isCompleted;
            const taskElement = taskList.querySelector(`[data-id='${id}']`);
            if (taskElement) {
                taskElement.classList.toggle('completed', isCompleted);
            }

            if (isCompleted) {
                addGardenElement(id);
            } else {
                removeGardenElement(id);
            }
            saveState();
        }
    }

    function deleteTask(id) {
        tasks = tasks.filter(t => t.id !== id);
        const taskElement = taskList.querySelector(`[data-id='${id}']`);
        if (taskElement) {
            taskElement.remove();
        }
        removeGardenElement(id);
        saveState();
    }

    // --- Garden Management ---
    function addGardenElement(taskId) {
        if (gardenElements.some(el => el.taskId === taskId)) return;

        const newElement = {
            id: Date.now(),
            taskId: taskId,
            x: Math.random() * 80 + 10, // 10% to 90% to avoid edges
            color: flowerColors[Math.floor(Math.random() * flowerColors.length)]
        };
        gardenElements.push(newElement);
        renderGardenElement(newElement);
        saveState();
    }

    function renderGardenElement(element) {
        const el = document.createElement('div');
        el.dataset.id = element.id;
        el.classList.add('garden-element', 'grow');
        el.style.left = `${element.x}%`;

        el.innerHTML = `
            <div class="flower-daisy">
                <div class="stem"></div>
                <div class="leaf left"></div>
                <div class="leaf right"></div>
                <div class="flower-head">
                    <div class="flower-center"></div>
                    <div class="petal petal-${element.color}">
                        <div class="p1"></div>
                        <div class="p2"></div>
                        <div class="p3"></div>
                        <div class="p4"></div>
                        <div class="p5"></div>
                        <div class="p6"></div>
                        <div class="p7"></div>
                        <div class="p8"></div>
                    </div>
                </div>
            </div>
        `;
        
        garden.appendChild(el);
    }

    function removeGardenElement(taskId) {
        const elementToRemoveIdx = gardenElements.findIndex(el => el.taskId === taskId);
        if (elementToRemoveIdx > -1) {
            const elementToRemove = gardenElements[elementToRemoveIdx];
            const el = garden.querySelector(`[data-id='${elementToRemove.id}']`);
            if (el) {
                el.classList.remove('grow');
                el.classList.add('shrink');
                setTimeout(() => {
                    el.remove();
                }, 500);
            }
            gardenElements.splice(elementToRemoveIdx, 1);
            saveState();
        }
    }

    // --- Controls ---
    soundToggle.addEventListener('click', () => {
        if (ambientSound.paused) {
            ambientSound.play().catch(e => console.error("Audio play failed: ", e));
            soundOnIcon.style.display = 'block';
            soundOffIcon.style.display = 'none';
        } else {
            ambientSound.pause();
            soundOnIcon.style.display = 'none';
            soundOffIcon.style.display = 'block';
        }
    });

    // --- Utility ---
    function escapeHTML(str) {
        return str.replace(/[&<>"']/g, s => ({
            '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'" : '&#39;'
        }[s]));
    }

    // --- Run App ---
    init();
});