const API_BASE = 'http://localhost:8080/api/v1';
let token = '';

const sessionState = document.getElementById('sessionState');
const loginBtn = document.getElementById('loginBtn');
const createForm = document.getElementById('createForm');
const taskList = document.getElementById('taskList');
const refreshBtn = document.getElementById('refreshBtn');
const clearBtn = document.getElementById('clearBtn');
const template = document.getElementById('taskTemplate');

function setSessionState(text) {
  sessionState.textContent = text;
}

function getHeaders() {
  return {
    'Content-Type': 'application/json',
    Authorization: token ? `Bearer ${token}` : '',
  };
}

async function login() {
  const response = await fetch(`${API_BASE}/auth/login`, {
    method: 'POST',
  });
  if (!response.ok) {
    setSessionState('Login failed');
    return;
  }
  const data = await response.json();
  token = data.token || 'demo-token';
  setSessionState('Connected');
  await loadTasks();
}

function buildMeta(task) {
  const parts = [];
  if (task.status) parts.push(task.status.toUpperCase());
  if (task.due_at) parts.push(`Due: ${task.due_at}`);
  if (task.priority) parts.push(`P${task.priority}`);
  if (task.tags && task.tags.length > 0) parts.push(task.tags.join(', '));
  return parts.join(' • ');
}

function renderTasks(tasks) {
  taskList.innerHTML = '';
  if (!tasks || tasks.length === 0) {
    taskList.innerHTML = '<div class="empty">No tasks yet.</div>';
    return;
  }
  tasks.forEach((task) => {
    const node = template.content.cloneNode(true);
    node.querySelector('h3').textContent = task.title || 'Untitled task';
    node.querySelector('.meta').textContent = buildMeta(task);
    node.querySelector('.desc').textContent = task.description || '';
    node.querySelector('.badge').textContent = task.status || 'todo';
    node.querySelector('.toggle').addEventListener('click', () => toggleStatus(task));
    node.querySelector('.delete').addEventListener('click', () => deleteTask(task));
    taskList.appendChild(node);
  });
}

async function loadTasks() {
  const response = await fetch(`${API_BASE}/tasks`, {
    headers: getHeaders(),
  });
  if (!response.ok) {
    setSessionState('Auth required');
    renderTasks([]);
    return;
  }
  const data = await response.json();
  renderTasks(data);
}

async function createTask(event) {
  event.preventDefault();
  const form = new FormData(createForm);
  const payload = {
    title: form.get('title'),
    description: form.get('description'),
    due_at: toISO(form.get('due_at')),
    priority: Number(form.get('priority') || 0),
    tags: String(form.get('tags') || '')
      .split(',')
      .map((tag) => tag.trim())
      .filter(Boolean),
  };

  const response = await fetch(`${API_BASE}/tasks`, {
    method: 'POST',
    headers: getHeaders(),
    body: JSON.stringify(payload),
  });

  if (!response.ok) {
    setSessionState('Failed to create task');
    return;
  }

  createForm.reset();
  await loadTasks();
}

async function toggleStatus(task) {
  const nextStatus = task.status === 'done' ? 'todo' : 'done';
  await fetch(`${API_BASE}/tasks/${task.id}`, {
    method: 'PUT',
    headers: getHeaders(),
    body: JSON.stringify({ status: nextStatus }),
  });
  await loadTasks();
}

async function deleteTask(task) {
  await fetch(`${API_BASE}/tasks/${task.id}`, {
    method: 'DELETE',
    headers: getHeaders(),
  });
  await loadTasks();
}

async function clearCompleted() {
  const response = await fetch(`${API_BASE}/api/tasks`, {
    headers: getHeaders(),
  });
  if (!response.ok) {
    return;
  }
  const tasks = await response.json();
  const completed = tasks.filter((task) => task.status === 'done');
  for (const task of completed) {
    await deleteTask(task);
  }
}

loginBtn.addEventListener('click', login);
createForm.addEventListener('submit', createTask);
refreshBtn.addEventListener('click', loadTasks);
clearBtn.addEventListener('click', clearCompleted);

setSessionState('Not connected');

function toISO(value) {
  if (!value) return '';
  const date = new Date(value);
  if (Number.isNaN(date.getTime())) return '';
  return date.toISOString();
}