(function () {
  'use strict';

  var KEY = 'focus-desk.tasks.v1';
  var PRIORITIES = ['low', 'medium', 'high'];

  var el = {
    form: document.getElementById('create-form'),
    title: document.getElementById('task-title'),
    notes: document.getElementById('task-notes'),
    priority: document.getElementById('task-priority'),
    due: document.getElementById('task-due'),
    titleError: document.getElementById('title-error'),
    search: document.getElementById('search'),
    status: document.getElementById('status-filter'),
    prioFilter: document.getElementById('priority-filter'),
    list: document.getElementById('task-list'),
    empty: document.getElementById('empty-state'),
    emptyDetail: document.getElementById('empty-detail'),
    total: document.getElementById('count-total'),
    active: document.getElementById('count-active'),
    done: document.getElementById('count-completed')
  };

  var tasks = [];
  var editingId = null;

  function load() {
    var raw;
    try {
      raw = localStorage.getItem(KEY);
    } catch (e) {
      return [];
    }
    if (!raw) return [];
    var parsed;
    try {
      parsed = JSON.parse(raw);
    } catch (e) {
      return [];
    }
    if (!Array.isArray(parsed)) return [];
    return parsed.map(normalize).filter(function (t) { return t !== null; });
  }

  function normalize(t) {
    if (!t || typeof t !== 'object') return null;
    var title = typeof t.title === 'string' ? t.title.trim() : '';
    if (!title) return null;
    return {
      id: typeof t.id === 'string' && t.id ? t.id : uid(),
      title: title,
      notes: typeof t.notes === 'string' ? t.notes : '',
      priority: PRIORITIES.indexOf(t.priority) >= 0 ? t.priority : 'medium',
      due: typeof t.due === 'string' ? t.due : '',
      completed: t.completed === true
    };
  }

  function save() {
    try {
      localStorage.setItem(KEY, JSON.stringify(tasks));
    } catch (e) { /* storage unavailable */ }
  }

  function uid() {
    return 't' + Date.now().toString(36) + Math.random().toString(36).slice(2, 7);
  }

  function find(id) {
    for (var i = 0; i < tasks.length; i++) if (tasks[i].id === id) return tasks[i];
    return null;
  }

  function visible() {
    var q = el.search.value.trim().toLowerCase();
    var status = el.status.value;
    var prio = el.prioFilter.value;
    return tasks.filter(function (t) {
      if (status === 'active' && t.completed) return false;
      if (status === 'completed' && !t.completed) return false;
      if (prio !== 'all' && t.priority !== prio) return false;
      if (q) {
        var hay = (t.title + ' ' + t.notes).toLowerCase();
        if (hay.indexOf(q) === -1) return false;
      }
      return true;
    });
  }

  function dueLabel(t) {
    if (!t.due) return null;
    var parts = t.due.split('-');
    if (parts.length !== 3) return null;
    var d = new Date(Number(parts[0]), Number(parts[1]) - 1, Number(parts[2]));
    if (isNaN(d.getTime())) return null;
    var text = d.toLocaleDateString(undefined, { month: 'short', day: 'numeric', year: 'numeric' });
    var today = new Date();
    today.setHours(0, 0, 0, 0);
    return { text: text, overdue: !t.completed && d.getTime() < today.getTime() };
  }

  function tag(cls, text) {
    var s = document.createElement('span');
    s.className = 'tag' + (cls ? ' ' + cls : '');
    s.textContent = text;
    return s;
  }

  function renderTask(t) {
    var li = document.createElement('li');
    li.className = 'task-item' + (t.completed ? ' done' : '');
    li.dataset.testid = 'task-item';
    li.dataset.priority = t.priority;
    li.dataset.id = t.id;

    if (editingId === t.id) {
      li.appendChild(editForm(t));
      return li;
    }

    var box = document.createElement('input');
    box.type = 'checkbox';
    box.checked = t.completed;
    box.dataset.testid = 'task-toggle';
    box.setAttribute('aria-label', (t.completed ? 'Mark "' : 'Mark "') + t.title + '" ' + (t.completed ? 'incomplete' : 'complete'));
    box.addEventListener('change', function () {
      t.completed = box.checked;
      save();
      render();
    });
    li.appendChild(box);

    var body = document.createElement('div');
    body.className = 'body';

    var h = document.createElement('p');
    h.className = 'title';
    h.textContent = t.title;
    body.appendChild(h);

    if (t.notes) {
      var n = document.createElement('p');
      n.className = 'notes';
      n.textContent = t.notes;
      body.appendChild(n);
    }

    var meta = document.createElement('div');
    meta.className = 'meta';
    meta.appendChild(tag(t.priority, t.priority));
    var d = dueLabel(t);
    if (d) meta.appendChild(tag(d.overdue ? 'due overdue' : 'due', d.overdue ? 'Overdue ' + d.text : 'Due ' + d.text));
    body.appendChild(meta);
    li.appendChild(body);

    var actions = document.createElement('div');
    actions.className = 'actions';
    actions.appendChild(button('Edit', 'task-edit', 'ghost small', function () {
      editingId = t.id;
      render();
      var input = el.list.querySelector('[data-testid="edit-title"]');
      if (input) input.focus();
    }));
    actions.appendChild(button('Delete', 'task-delete', 'ghost small danger', function () {
      tasks = tasks.filter(function (x) { return x.id !== t.id; });
      if (editingId === t.id) editingId = null;
      save();
      render();
    }));
    li.appendChild(actions);

    return li;
  }

  function button(label, testid, cls, onClick) {
    var b = document.createElement('button');
    b.type = 'button';
    b.className = 'btn ' + cls;
    b.dataset.testid = testid;
    b.textContent = label;
    b.addEventListener('click', onClick);
    return b;
  }

  function field(id, labelText, node) {
    var wrap = document.createElement('div');
    wrap.className = 'field';
    var l = document.createElement('label');
    l.setAttribute('for', id);
    l.textContent = labelText;
    node.id = id;
    wrap.appendChild(l);
    wrap.appendChild(node);
    return wrap;
  }

  function editForm(t) {
    var form = document.createElement('form');
    form.className = 'edit-form';
    form.noValidate = true;

    var title = document.createElement('input');
    title.type = 'text';
    title.value = t.title;
    title.dataset.testid = 'edit-title';
    title.setAttribute('aria-label', 'Edit title');

    var notes = document.createElement('textarea');
    notes.rows = 2;
    notes.value = t.notes;
    notes.dataset.testid = 'edit-notes';
    notes.setAttribute('aria-label', 'Edit notes');

    var prio = document.createElement('select');
    prio.dataset.testid = 'edit-priority';
    prio.setAttribute('aria-label', 'Edit priority');
    PRIORITIES.forEach(function (p) {
      var o = document.createElement('option');
      o.value = p;
      o.textContent = p.charAt(0).toUpperCase() + p.slice(1);
      if (p === t.priority) o.selected = true;
      prio.appendChild(o);
    });

    var due = document.createElement('input');
    due.type = 'date';
    due.value = t.due;
    due.dataset.testid = 'edit-due';
    due.setAttribute('aria-label', 'Edit due date');

    var row = document.createElement('div');
    row.className = 'edit-row';
    row.appendChild(field('edit-priority-' + t.id, 'Priority', prio));
    row.appendChild(field('edit-due-' + t.id, 'Due date', due));

    var actions = document.createElement('div');
    actions.className = 'edit-actions';
    var saveBtn = button('Save', 'save-edit', 'primary small', function () { commit(t, title, notes, prio, due); });
    saveBtn.type = 'submit';
    actions.appendChild(saveBtn);
    actions.appendChild(button('Cancel', 'cancel-edit', 'ghost small', function () {
      editingId = null;
      render();
    }));

    form.appendChild(field('edit-title-' + t.id, 'Title', title));
    form.appendChild(field('edit-notes-' + t.id, 'Notes', notes));
    form.appendChild(row);
    form.appendChild(actions);

    form.addEventListener('submit', function (e) {
      e.preventDefault();
      commit(t, title, notes, prio, due);
    });

    return form;
  }

  function commit(t, title, notes, prio, due) {
    var v = title.value.trim();
    if (!v) {
      title.focus();
      return;
    }
    t.title = v;
    t.notes = notes.value;
    t.priority = PRIORITIES.indexOf(prio.value) >= 0 ? prio.value : t.priority;
    t.due = due.value;
    editingId = null;
    save();
    render();
  }

  function render() {
    var list = visible();
    el.list.textContent = '';
    list.forEach(function (t) { el.list.appendChild(renderTask(t)); });

    var total = tasks.length;
    var done = tasks.filter(function (t) { return t.completed; }).length;
    el.total.textContent = String(total);
    el.active.textContent = String(total - done);
    el.done.textContent = String(done);

    var empty = list.length === 0;
    el.empty.hidden = !empty;
    if (empty) {
      el.emptyDetail.textContent = tasks.length === 0
        ? 'Add your first task above to get started.'
        : 'No tasks match your current search and filters.';
    }
  }

  el.form.addEventListener('submit', function (e) {
    e.preventDefault();
    var title = el.title.value.trim();
    if (!title) {
      el.titleError.hidden = false;
      el.title.focus();
      return;
    }
    el.titleError.hidden = true;
    tasks.unshift({
      id: uid(),
      title: title,
      notes: el.notes.value.trim(),
      priority: PRIORITIES.indexOf(el.priority.value) >= 0 ? el.priority.value : 'medium',
      due: el.due.value,
      completed: false
    });
    save();
    el.form.reset();
    el.priority.value = 'medium';
    el.title.focus();
    render();
  });

  el.title.addEventListener('input', function () {
    if (el.title.value.trim()) el.titleError.hidden = true;
  });

  ['input', 'change'].forEach(function (evt) {
    el.search.addEventListener(evt, render);
    el.status.addEventListener(evt, render);
    el.prioFilter.addEventListener(evt, render);
  });

  tasks = load();
  render();
})();