const STATUSES = ['Backlog', 'Todo', 'In Progress', 'Review', 'Done'];

const board = document.getElementById('board');
const template = document.getElementById('task-template');
const form = document.getElementById('task-form');

let tasks = [];

function renderBoard() {
  board.innerHTML = '';

  for (const status of STATUSES) {
    const column = document.createElement('section');
    column.className = 'column';

    const heading = document.createElement('h2');
    heading.textContent = `${status} (${tasks.filter((t) => t.status === status).length})`;

    const cards = document.createElement('div');
    cards.className = 'cards';

    tasks
      .filter((task) => task.status === status)
      .forEach((task) => cards.appendChild(renderCard(task)));

    column.appendChild(heading);
    column.appendChild(cards);
    board.appendChild(column);
  }
}

function renderCard(task) {
  const node = template.content.firstElementChild.cloneNode(true);

  node.querySelector('.card-title').textContent = task.title;
  node.querySelector('.card-desc').textContent = task.description || 'No description';
  node.querySelector('.assignee').textContent = `Assignee: ${task.assignee || 'Unassigned'}`;
  node.querySelector('.tags').textContent = `Tags: ${(task.tags || []).join(', ') || 'None'}`;

  const badge = node.querySelector('.priority');
  badge.textContent = task.priority;
  badge.classList.add((task.priority || '').toLowerCase());

  const statusSelect = node.querySelector('.status-select');
  statusSelect.value = task.status;
  statusSelect.addEventListener('change', async () => {
    await updateTask(task.id, { status: statusSelect.value });
  });

  return node;
}

async function loadTasks() {
  const res = await fetch('/api/tasks');
  tasks = await res.json();
  renderBoard();
}

async function createTask(payload) {
  const res = await fetch('/api/tasks', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(payload),
  });

  if (!res.ok) {
    const data = await res.json().catch(() => ({}));
    throw new Error(data.error || 'failed_to_create_task');
  }

  return res.json();
}

async function updateTask(id, payload) {
  const res = await fetch(`/api/tasks/${id}`, {
    method: 'PATCH',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(payload),
  });

  if (!res.ok) {
    const data = await res.json().catch(() => ({}));
    throw new Error(data.error || 'failed_to_update_task');
  }

  return res.json();
}

form.addEventListener('submit', async (e) => {
  e.preventDefault();

  const payload = {
    title: form.title.value,
    description: form.description.value,
    assignee: form.assignee.value,
    priority: form.priority.value,
    status: form.status.value,
    tags: form.tags.value
      .split(',')
      .map((s) => s.trim())
      .filter(Boolean),
  };

  try {
    await createTask(payload);
    form.reset();
    form.priority.value = 'Medium';
    form.status.value = 'Backlog';
  } catch (err) {
    alert(err.message);
  }
});

function upsertTask(task) {
  const idx = tasks.findIndex((t) => t.id === task.id);
  if (idx === -1) {
    tasks.unshift(task);
  } else {
    tasks[idx] = task;
  }
  renderBoard();
}

function connectWebSocket() {
  const proto = location.protocol === 'https:' ? 'wss:' : 'ws:';
  const ws = new WebSocket(`${proto}//${location.host}`);

  ws.onmessage = (event) => {
    const msg = JSON.parse(event.data);
    if (msg.type === 'task_created' || msg.type === 'task_updated') {
      upsertTask(msg.payload);
    }
  };

  ws.onclose = () => {
    setTimeout(connectWebSocket, 1200);
  };
}

loadTasks();
connectWebSocket();