/* Focus Desk — vanilla task manager */
(function () {
  'use strict';

  var KEY = 'focusdesk.tasks.v1';
  var PRIOS = ['low', 'medium', 'high'];
  var PRIO_LABEL = { low: 'Low', medium: 'Medium', high: 'High' };
  var PRIO_RANK = { high: 0, medium: 1, low: 2 };

  var tasks = [];
  var editingId = null;

  var $ = function (sel) { return document.querySelector(sel); };
  var form = $('#create-form');
  var fTitle = $('#f-title'), fNotes = $('#f-notes'), fPrio = $('#f-priority'), fDue = $('#f-due');
  var errBox = $('#title-err');
  var fSearch = $('#f-search'), fStatus = $('#f-status'), fPrioFilter = $('#f-prio');
  var listEl = $('#list'), emptyEl = $('#empty'), resultLine = $('#result-line');
  var emptyTitle = $('#empty-title'), emptyText = $('#empty-text');
  var cTotal = document.querySelector('[data-testid="count-total"]');
  var cActive = document.querySelector('[data-testid="count-active"]');
  var cDone = document.querySelector('[data-testid="count-completed"]');

  /* ---------- storage ---------- */
  function isDate(s) { return typeof s === 'string' && /^\d{4}-\d{2}-\d{2}$/.test(s); }

  function normalize(raw) {
    if (!raw || typeof raw !== 'object') return null;
    var title = typeof raw.title === 'string' ? raw.title.trim() : '';
    if (!title) return null;
    return {
      id: (typeof raw.id === 'string' || typeof raw.id === 'number') ? String(raw.id) : uid(),
      title: title,
      notes: typeof raw.notes === 'string' ? raw.notes : '',
      priority: PRIOS.indexOf(raw.priority) > -1 ? raw.priority : 'medium',
      due: isDate(raw.due) ? raw.due : '',
      completed: raw.completed === true,
      created: typeof raw.created === 'number' ? raw.created : Date.now()
    };
  }

  function load() {
    var text;
    try { text = localStorage.getItem(KEY); } catch (e) { return []; }
    if (!text) return [];
    var data;
    try { data = JSON.parse(text); } catch (e) {
      console.warn('Focus Desk: saved data was invalid JSON; starting empty.');
      try { localStorage.removeItem(KEY); } catch (e2) {}
      return [];
    }
    if (!Array.isArray(data)) return [];
    var out = [];
    for (var i = 0; i < data.length; i++) {
      var t = normalize(data[i]);
      if (t) out.push(t);
    }
    return out;
  }

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

  function uid() {
    return Date.now().toString(36) + Math.random().toString(36).slice(2, 8);
  }

  /* ---------- helpers ---------- */
  function el(tag, props, kids) {
    var n = document.createElement(tag);
    if (props) {
      for (var k in props) {
        if (k === 'text') n.textContent = props[k];
        else if (k === 'cls') n.className = props[k];
        else if (k in n && k !== 'list') n[k] = props[k];
        else n.setAttribute(k, props[k]);
      }
    }
    (kids || []).forEach(function (c) { if (c) n.appendChild(c); });
    return n;
  }

  function todayISO() {
    var d = new Date();
    return d.getFullYear() + '-' + String(d.getMonth() + 1).padStart(2, '0') + '-' + String(d.getDate()).padStart(2, '0');
  }

  function prettyDate(iso) {
    var p = iso.split('-');
    var d = new Date(Number(p[0]), Number(p[1]) - 1, Number(p[2]));
    if (isNaN(d.getTime())) return iso;
    var M = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
    return M[d.getMonth()] + ' ' + d.getDate() + ', ' + d.getFullYear();
  }

  function plural(n, w) { return n + ' ' + w + (n === 1 ? '' : 's'); }

  /* ---------- filtering ---------- */
  function visible() {
    var q = fSearch.value.trim().toLowerCase();
    var status = fStatus.value, prio = fPrioFilter.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;
    }).sort(function (a, b) {
      if (a.completed !== b.completed) return a.completed ? 1 : -1;
      if (a.priority !== b.priority) return PRIO_RANK[a.priority] - PRIO_RANK[b.priority];
      if (a.due !== b.due) { if (!a.due) return 1; if (!b.due) return -1; return a.due < b.due ? -1 : 1; }
      return b.created - a.created;
    });
  }

  /* ---------- rendering ---------- */
  function readRow(t) {
    var kids = [
      el('h3', { cls: 'title', text: t.title, 'data-testid': 'task-title-text' })
    ];
    if (t.notes) kids.push(el('p', { cls: 'notes', text: t.notes, 'data-testid': 'task-notes-text' }));

    var meta = [el('span', { cls: 'tag ' + t.priority, text: PRIO_LABEL[t.priority] })];
    if (t.due) {
      var over = !t.completed && t.due < todayISO();
      meta.push(el('span', {
        cls: 'due' + (over ? ' over' : ''),
        text: (over ? 'Overdue · ' : 'Due ') + prettyDate(t.due)
      }));
    }
    if (t.completed) meta.push(el('span', { cls: 'due', text: 'Completed' }));
    kids.push(el('div', { cls: 'meta' }, meta));

    var actions = el('div', { cls: 'actions' }, [
      el('button', { cls: 'btn small', type: 'button', 'data-testid': 'task-edit',
        'data-act': 'edit', 'aria-label': 'Edit task: ' + t.title, text: 'Edit' }),
      el('button', { cls: 'btn small danger', type: 'button', 'data-testid': 'task-delete',
        'data-act': 'delete', 'aria-label': 'Delete task: ' + t.title, text: 'Delete' })
    ]);

    return [el('div', { cls: 'body' }, kids), actions];
  }

  function editRow(t) {
    var tid = 'edit-title-' + t.id, nid = 'edit-notes-' + t.id,
        pid = 'edit-prio-' + t.id, did = 'edit-due-' + t.id;

    var titleIn = el('input', { id: tid, type: 'text', value: t.title, required: true,
      'data-testid': 'edit-title', autocomplete: 'off' });
    var notesIn = el('textarea', { id: nid, rows: 3, 'data-testid': 'edit-notes' });
    notesIn.value = t.notes;

    var prioSel = el('select', { id: pid, 'data-testid': 'edit-priority' },
      PRIOS.map(function (p) {
        return el('option', { value: p, text: PRIO_LABEL[p], selected: p === t.priority });
      }));
    prioSel.value = t.priority;

    var dueIn = el('input', { id: did, type: 'date', value: t.due, 'data-testid': 'edit-due' });
    var err = el('p', { cls: 'err', role: 'alert', 'data-testid': 'edit-error', hidden: true });

    var grid = el('form', { cls: 'edit-grid', 'data-act': 'save-form', novalidate: true }, [
      el('div', { cls: 'field' }, [el('label', { htmlFor: tid, text: 'Title' }), titleIn, err]),
      el('div', { cls: 'field' }, [el('label', { htmlFor: nid, text: 'Notes' }), notesIn]),
      el('div', { cls: 'row' }, [
        el('div', { cls: 'field' }, [el('label', { htmlFor: pid, text: 'Priority' }), prioSel]),
        el('div', { cls: 'field' }, [el('label', { htmlFor: did, text: 'Due date' }), dueIn])
      ]),
      el('div', { cls: 'edit-actions' }, [
        el('button', { cls: 'btn primary small', type: 'submit', 'data-testid': 'save-edit', text: 'Save' }),
        el('button', { cls: 'btn small', type: 'button', 'data-act': 'cancel', 'data-testid': 'cancel-edit', text: 'Cancel' })
      ])
    ]);
    return [el('div', { cls: 'body editing' }, [grid])];
  }

  function row(t) {
    var cb = el('input', { type: 'checkbox', checked: t.completed, 'data-testid': 'task-toggle',
      'data-act': 'toggle', id: 'cb-' + t.id });
    cb.setAttribute('aria-label', (t.completed ? 'Mark as active: ' : 'Mark as completed: ') + t.title);
    var li = el('li', {
      cls: 'item' + (t.completed ? ' done' : ''),
      'data-testid': 'task-item',
      'data-id': t.id,
      'data-priority': t.priority,
      'data-completed': String(t.completed)
    }, [el('div', { cls: 'check' }, [cb])].concat(editingId === t.id ? editRow(t) : readRow(t)));
    return li;
  }

  function render() {
    var total = tasks.length;
    var done = tasks.filter(function (t) { return t.completed; }).length;
    cTotal.textContent = String(total);
    cActive.textContent = String(total - done);
    cDone.textContent = String(done);

    var shown = visible();
    listEl.textContent = '';
    var frag = document.createDocumentFragment();
    shown.forEach(function (t) { frag.appendChild(row(t)); });
    listEl.appendChild(frag);

    var filtering = fSearch.value.trim() !== '' || fStatus.value !== 'all' || fPrioFilter.value !== 'all';
    if (shown.length === 0) {
      emptyEl.hidden = false;
      listEl.hidden = true;
      if (total === 0) {
        emptyTitle.textContent = 'No tasks yet';
        emptyText.textContent = 'Add your first task using the form to get started.';
      } else {
        emptyTitle.textContent = 'No matching tasks';
        emptyText.textContent = 'No tasks match your search and filters. Try clearing the search box or resetting the filters.';
      }
    } else {
      emptyEl.hidden = true;
      listEl.hidden = false;
    }
    resultLine.textContent = total === 0 ? 'No tasks yet.'
      : (filtering ? 'Showing ' + plural(shown.length, 'task') + ' of ' + total
                   : 'Showing all ' + plural(total, 'task'));
  }

  /* ---------- actions ---------- */
  function showError(msg) {
    errBox.textContent = msg;
    errBox.hidden = false;
    fTitle.setAttribute('aria-invalid', 'true');
  }
  function clearError() {
    errBox.hidden = true;
    errBox.textContent = '';
    fTitle.removeAttribute('aria-invalid');
  }

  form.addEventListener('submit', function (e) {
    e.preventDefault();
    var title = fTitle.value.trim();
    if (!title) {
      showError('Please enter a task title.');
      fTitle.focus();
      return;
    }
    clearError();
    tasks.push({
      id: uid(), title: title, notes: fNotes.value.trim(),
      priority: PRIOS.indexOf(fPrio.value) > -1 ? fPrio.value : 'medium',
      due: isDate(fDue.value) ? fDue.value : '',
      completed: false, created: Date.now()
    });
    save();
    form.reset();
    fPrio.value = 'medium';
    render();
    fTitle.focus();
  });

  fTitle.addEventListener('input', function () { if (!errBox.hidden && fTitle.value.trim()) clearError(); });

  [fSearch, fStatus, fPrioFilter].forEach(function (n) {
    n.addEventListener('input', render);
    n.addEventListener('change', render);
  });

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

  listEl.addEventListener('click', function (e) {
    var btn = e.target.closest('[data-act]');
    if (!btn || btn.tagName === 'FORM' || btn.type === 'checkbox') return;
    var li = btn.closest('[data-id]');
    if (!li) return;
    var id = li.getAttribute('data-id');
    var act = btn.getAttribute('data-act');
    if (act === 'edit') {
      editingId = id;
      render();
      var input = listEl.querySelector('[data-id="' + id + '"] [data-testid="edit-title"]');
      if (input) { input.focus(); input.select(); }
    } else if (act === 'cancel') {
      editingId = null;
      render();
    } else if (act === 'delete') {
      var t = find(id);
      if (!t) return;
      if (!window.confirm('Delete "' + t.title + '"? This cannot be undone.')) return;
      tasks = tasks.filter(function (x) { return x.id !== id; });
      if (editingId === id) editingId = null;
      save();
      render();
    }
  });

  listEl.addEventListener('change', function (e) {
    if (e.target.getAttribute && e.target.getAttribute('data-act') === 'toggle') {
      var li = e.target.closest('[data-id]');
      var t = find(li && li.getAttribute('data-id'));
      if (!t) return;
      t.completed = e.target.checked;
      save();
      render();
    }
  });

  listEl.addEventListener('submit', function (e) {
    var f = e.target;
    if (!f.matches('[data-act="save-form"]')) return;
    e.preventDefault();
    var li = f.closest('[data-id]');
    var t = find(li && li.getAttribute('data-id'));
    if (!t) return;
    var titleIn = f.querySelector('[data-testid="edit-title"]');
    var err = f.querySelector('[data-testid="edit-error"]');
    var title = titleIn.value.trim();
    if (!title) {
      err.textContent = 'Title cannot be empty.';
      err.hidden = false;
      titleIn.setAttribute('aria-invalid', 'true');
      titleIn.focus();
      return;
    }
    var dueVal = f.querySelector('[data-testid="edit-due"]').value;
    t.title = title;
    t.notes = f.querySelector('[data-testid="edit-notes"]').value.trim();
    t.priority = f.querySelector('[data-testid="edit-priority"]').value;
    t.due = isDate(dueVal) ? dueVal : '';
    editingId = null;
    save();
    render();
  });

  listEl.addEventListener('keydown', function (e) {
    if (e.key === 'Escape' && editingId && e.target.closest('[data-act="save-form"]')) {
      editingId = null;
      render();
    }
  });

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