'use strict';

const VIEWS = [
  { id: 'today', label: 'Today', icon: '☀️' },
  { id: 'upcoming', label: 'Upcoming', icon: '📅' },
  { id: 'calendar', label: 'Calendar', icon: '🗓️' },
  { id: 'backlog', label: 'Backlog', icon: '📥' },
  { id: 'all', label: 'All open', icon: '📋' },
  { id: 'done', label: 'Done', icon: '✅' },
];
const PRIORITY_LABELS = ['', 'Low', 'Medium', 'High'];
const REPEAT_UNITS = { daily: 'day', weekly: 'week', monthly: 'month', yearly: 'year' };
const HOUR_PX = 48;
const BACKLOG_SUGGESTIONS = 2;

const state = {
  tasks: [], categories: [], projects: [],
  view: 'today', categoryId: null, projectId: null,
  search: '', calDate: null, showDoneProjects: false,
};
let editing = null; // task open in the dialog; null when creating
let editingProject = null;
let planning = null; // { task, mode } for the postpone sheet
let draftSubtasks = [];
let toastTimer = null;

const $ = (sel) => document.querySelector(sel);

// --- Small DOM helper ---------------------------------------------------------

function h(tag, attrs, ...children) {
  const el = document.createElement(tag);
  for (const [k, v] of Object.entries(attrs || {})) {
    if (v == null || v === false) continue;
    if (k === 'class') el.className = v;
    else if (k === 'style') Object.assign(el.style, v);
    else if (k.startsWith('on')) el.addEventListener(k.slice(2), v);
    else if (k === 'value' || k === 'checked') el[k] = v;
    else el.setAttribute(k, v === true ? '' : v);
  }
  for (const c of children.flat()) {
    if (c != null && c !== false) el.append(c instanceof Node ? c : String(c));
  }
  return el;
}

// --- Dates (all local, as YYYY-MM-DD strings) ---------------------------------

const pad = (n) => String(n).padStart(2, '0');
const fmtDate = (d) => `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}`;
const parseDate = (s) => { const [y, m, d] = s.split('-').map(Number); return new Date(y, m - 1, d); };
const todayStr = () => fmtDate(new Date());
const addDays = (s, n) => { const d = parseDate(s); d.setDate(d.getDate() + n); return fmtDate(d); };
const dayDiff = (a, b) => {
  const [ay, am, ad] = a.split('-').map(Number);
  const [by, bm, bd] = b.split('-').map(Number);
  return Math.round((Date.UTC(by, bm - 1, bd) - Date.UTC(ay, am - 1, ad)) / 86400000);
};
const addMonths = (s, n) => {
  const [y, m, d] = s.split('-').map(Number);
  const total = m - 1 + n;
  const yy = y + Math.floor(total / 12);
  const mm = total % 12;
  return fmtDate(new Date(yy, mm, Math.min(d, new Date(yy, mm + 1, 0).getDate())));
};
// Same stepping rules as the server, so projected repeats land where the real ones will.
function stepDate(s, recurrence, n) {
  if (recurrence === 'daily') return addDays(s, n);
  if (recurrence === 'weekly') return addDays(s, 7 * n);
  if (recurrence === 'monthly') return addMonths(s, n);
  return addMonths(s, 12 * n);
}

// Named dates used by the postpone sheet and the "Plan:" shortcuts.
function namedDate(name) {
  const t = todayStr();
  const dow = parseDate(t).getDay(); // 0 = Sunday
  const nextMonday = addDays(t, ((8 - dow) % 7) || 7);
  switch (name) {
    case 'today': return t;
    case 'tomorrow': return addDays(t, 1);
    case 'weekend': return dow === 6 || dow === 0 ? addDays(nextMonday, 5) : addDays(t, 6 - dow);
    case 'nextweek': return nextMonday;
    case 'twoweeks': return addDays(nextMonday, 7);
    case 'nextmonth': { const d = parseDate(t); return fmtDate(new Date(d.getFullYear(), d.getMonth() + 1, 1)); }
    default: return null;
  }
}

function dayName(day) {
  const diff = dayDiff(todayStr(), day);
  const d = parseDate(day);
  if (diff === 0) return 'Today';
  if (diff === 1) return 'Tomorrow';
  if (diff === -1) return 'Yesterday';
  if (diff > 1 && diff < 7) return d.toLocaleDateString(undefined, { weekday: 'long' });
  const opts = { weekday: 'short', day: 'numeric', month: 'short' };
  if (d.getFullYear() !== new Date().getFullYear()) opts.year = 'numeric';
  return d.toLocaleDateString(undefined, opts);
}

function dueInfo(due) {
  const diff = dayDiff(todayStr(), due);
  let text = dayName(due);
  if (diff < -1) text += ` · ${-diff} days late`;
  return { text, cls: diff < 0 ? 'overdue' : diff === 0 ? 'today' : '' };
}

const toMin = (t) => { const [hh, mm] = t.split(':').map(Number); return hh * 60 + mm; };
const fromMin = (m) => `${pad(Math.floor(m / 60))}:${pad(m % 60)}`;
// A start time without an end counts as one hour.
const span = (t) => {
  const start = toMin(t.start_time);
  return [start, t.end_time ? toMin(t.end_time) : Math.min(start + 60, 24 * 60)];
};
const timeText = (t) => (t.start_time ? (t.end_time ? `${t.start_time}–${t.end_time}` : t.start_time) : '');

// --- Task date semantics ------------------------------------------------------
// planned_date = when I intend to do it; due_date = when it must be done.
// The "when" date (plan, else deadline) decides where a task is scheduled; times apply to it.

const whenDate = (t) => t.planned_date || t.due_date || null;
const isOverdue = (t, today) => !t.done && t.due_date && t.due_date < today;
// Planned for today or earlier (unfinished plans roll over), or due today.
const isForToday = (t, today) => !t.done && !isOverdue(t, today)
  && ((t.planned_date && t.planned_date <= today) || t.due_date === today);
const isBacklog = (t) => !t.done && !t.planned_date && !t.due_date;

// Tasks on a given day (by "when" date), including future repeats of open recurring tasks.
function itemsOn(day) {
  const out = [];
  for (const t of state.tasks) {
    const w = whenDate(t);
    if (!w) continue;
    if (w === day) {
      out.push({ task: t, projected: false });
    } else if (!t.done && t.recurrence !== 'none' && w < day) {
      let d = w;
      for (let i = 0; d < day && i < 2000; i++) d = stepDate(d, t.recurrence, t.recur_interval);
      if (d === day) out.push({ task: t, projected: true });
    }
  }
  return out;
}

// --- API ----------------------------------------------------------------------

async function api(path, { method = 'GET', body } = {}) {
  const headers = { 'X-WhatToDo': '1' };
  if (body !== undefined) headers['Content-Type'] = 'application/json';
  const res = await fetch(path, {
    method, headers, credentials: 'same-origin',
    body: body !== undefined ? JSON.stringify(body) : undefined,
  });
  if (res.status === 401 && path !== 'api/login') {
    showLogin();
    throw new Error('Please log in');
  }
  if (!res.ok) {
    let msg = `${res.status} ${res.statusText}`;
    try {
      const j = await res.json();
      if (typeof j.detail === 'string') msg = j.detail;
      else if (Array.isArray(j.detail)) {
        msg = j.detail.map((e) => {
          const text = e.msg.replace(/^Value error, /, '');
          const where = e.loc.slice(1).join('.');
          return where ? `${where}: ${text}` : text;
        }).join('; ');
      }
    } catch { /* not JSON */ }
    throw new Error(msg);
  }
  return res.status === 204 ? null : res.json();
}

async function loadAll() {
  const [categories, projects, tasks] = await Promise.all([
    api('api/categories'), api('api/projects'), api('api/tasks'),
  ]);
  state.categories = categories;
  state.projects = projects;
  state.tasks = tasks;
}

// Run an action, report errors as a toast, then refresh.
async function act(fn) {
  try {
    await fn();
  } catch (e) {
    toast(e.message);
  }
  try {
    await loadAll();
    render();
  } catch { /* login screen already shown */ }
}

// --- Persisted UI prefs -------------------------------------------------------

function savePrefs() {
  try {
    localStorage.setItem('whattodo.view', JSON.stringify({
      view: state.view, categoryId: state.categoryId, projectId: state.projectId,
    }));
  } catch { /* ignore */ }
}
function loadPrefs() {
  try {
    const p = JSON.parse(localStorage.getItem('whattodo.view') || 'null');
    if (p && typeof p.view === 'string') {
      state.view = p.view;
      state.categoryId = p.categoryId ?? null;
      state.projectId = p.projectId ?? null;
    }
  } catch { /* ignore */ }
}

// --- Lookups, filtering & grouping ---------------------------------------------

const catById = (id) => state.categories.find((c) => c.id === id);
const projectById = (id) => state.projects.find((p) => p.id === id);
const projectTasks = (p) => state.tasks.filter((t) => t.project_id === p.id);

function matchesSearch(t) {
  const terms = state.search.toLowerCase().split(/\s+/).filter(Boolean);
  return terms.every((term) => {
    if (term.startsWith('#') && term.length > 1) return t.tags.some((tag) => tag.startsWith(term.slice(1)));
    const cat = catById(t.category_id);
    const proj = projectById(t.project_id);
    const hay = [t.title, t.notes, cat ? cat.name : '', proj ? proj.name : '', ...t.tags,
      ...t.subtasks.map((s) => s.title)].join(' ').toLowerCase();
    return hay.includes(term);
  });
}

function cmpOpen(a, b) {
  const wa = whenDate(a);
  const wb = whenDate(b);
  if (wa !== wb) {
    if (!wa) return 1;
    if (!wb) return -1;
    return wa < wb ? -1 : 1;
  }
  if (a.start_time !== b.start_time) {
    if (!a.start_time) return 1;
    if (!b.start_time) return -1;
    return a.start_time < b.start_time ? -1 : 1;
  }
  return (b.priority - a.priority) || (a.id - b.id);
}

function viewTasks() {
  let tasks = state.tasks;
  if (state.view === 'cat') tasks = tasks.filter((t) => (t.category_id || 0) === state.categoryId);
  if (state.view === 'project') tasks = tasks.filter((t) => t.project_id === state.projectId);
  if (state.search.trim()) tasks = tasks.filter(matchesSearch);
  return tasks;
}

// Backlog tasks worth suggesting for today: highest priority first, then the oldest.
function backlogSuggestions() {
  return state.tasks.filter((t) => isBacklog(t) && t.priority < 3)
    .sort((a, b) => (b.priority - a.priority) || (a.id - b.id))
    .slice(0, BACKLOG_SUGGESTIONS);
}

function buildGroups(tasks) {
  const t = todayStr();
  const tomorrow = addDays(t, 1);
  const week = addDays(t, 7);
  if (state.view === 'done') {
    const done = tasks.filter((x) => x.done).sort((a, b) => (b.done_at || '').localeCompare(a.done_at || ''));
    return [{ title: 'Completed', tasks: done }];
  }
  const open = tasks.filter((x) => !x.done).sort(cmpOpen);
  const group = (title, pred, extra = {}) => ({ title, tasks: open.filter(pred), ...extra });
  const overdue = (x) => isOverdue(x, t);
  const today = (x) => isForToday(x, t);
  const later = (x) => !overdue(x) && !today(x);

  if (state.view === 'today') {
    const shown = new Set(open.filter((x) => overdue(x) || today(x)).map((x) => x.id));
    return [
      group('Overdue', overdue),
      group('Today', today),
      // High priority things you haven't scheduled yet keep showing up until you plan them.
      group('High priority, not planned', (x) => x.priority === 3 && !shown.has(x.id) && !x.planned_date),
      { title: 'From your backlog', tasks: state.search ? [] : backlogSuggestions(), hint: 'No date yet. Plan one for today?' },
    ];
  }
  if (state.view === 'upcoming') {
    return [
      group('Tomorrow', (x) => later(x) && whenDate(x) === tomorrow),
      group('Next 7 days', (x) => later(x) && whenDate(x) > tomorrow && whenDate(x) <= week),
      group('Later', (x) => later(x) && whenDate(x) > week),
    ];
  }
  if (state.view === 'backlog') {
    const backlog = (p) => (x) => isBacklog(x) && x.priority === p;
    return [
      group('High priority', backlog(3)),
      group('Medium priority', backlog(2)),
      group('Low priority', backlog(1)),
      group('No priority', backlog(0)),
    ];
  }
  const groups = [
    group('Overdue', overdue),
    group('Today', today),
    group('Next 7 days', (x) => later(x) && whenDate(x) && whenDate(x) <= week),
    group('Later', (x) => later(x) && whenDate(x) > week),
    group('No date', isBacklog),
  ];
  if (state.view === 'project') {
    const done = tasks.filter((x) => x.done).sort((a, b) => (b.done_at || '').localeCompare(a.done_at || ''));
    groups.push({ title: 'Completed', tasks: done });
  }
  return groups;
}

function counts() {
  const t = todayStr();
  const open = state.tasks.filter((x) => !x.done);
  const overdue = open.filter((x) => isOverdue(x, t)).length;
  const c = {
    today: open.filter((x) => isOverdue(x, t) || isForToday(x, t) || (x.priority === 3 && !x.planned_date)).length,
    upcoming: open.filter((x) => !isOverdue(x, t) && !isForToday(x, t) && whenDate(x)).length,
    backlog: open.filter(isBacklog).length,
    all: open.length,
    done: null,
    calendar: null,
    overdue,
    cats: {},
    projects: {},
  };
  for (const x of open) {
    c.cats[x.category_id || 0] = (c.cats[x.category_id || 0] || 0) + 1;
    if (x.project_id) c.projects[x.project_id] = (c.projects[x.project_id] || 0) + 1;
  }
  return c;
}

// Progress and warnings for a project.
function projectHealth(p) {
  const t = todayStr();
  const tasks = projectTasks(p);
  const total = tasks.length;
  const done = tasks.filter((x) => x.done).length;
  const open = tasks.filter((x) => !x.done).sort(cmpOpen);
  const info = { total, done, pct: total ? Math.round((done / total) * 100) : 0, next: open[0] || null, warn: null, daysLeft: null };
  if (p.done) return info;
  const started = p.created_at.slice(0, 10);
  if (p.due_date) {
    info.daysLeft = dayDiff(t, p.due_date);
    const totalDays = dayDiff(started, p.due_date);
    const timeFrac = totalDays > 0 ? Math.min(1, dayDiff(started, t) / totalDays) : 1;
    if (info.daysLeft < 0) info.warn = 'Deadline passed';
    else if (total && timeFrac - done / total > 0.25) {
      info.warn = `Behind: ${Math.round(timeFrac * 100)}% of the time used, ${info.pct}% done`;
    }
  }
  if (!info.warn && !total) info.warn = 'No tasks yet. Break it into steps.';
  if (!info.warn && open.length && dayDiff(started, t) >= 7) {
    const lastDone = tasks.map((x) => x.done_at || '').sort().pop();
    if (!lastDone || dayDiff(lastDone.slice(0, 10), t) >= 7) info.warn = 'Nothing done on this in over a week';
  }
  return info;
}

function daysLeftText(n) {
  if (n == null) return '';
  if (n < 0) return `${-n} days overdue`;
  if (n === 0) return 'due today';
  if (n === 1) return '1 day left';
  if (n < 60) return `${n} days left`;
  return `${Math.round(n / 7)} weeks left`;
}

function sortedProjects() {
  return [...state.projects].sort((a, b) => {
    if (a.due_date !== b.due_date) {
      if (!a.due_date) return 1;
      if (!b.due_date) return -1;
      return a.due_date < b.due_date ? -1 : 1;
    }
    return a.id - b.id;
  });
}

// --- Rendering ----------------------------------------------------------------

function navItem({ active, icon, label, count, onclick, color, alert, muted }) {
  return h('button', {
    type: 'button', class: 'nav-item' + (active ? ' active' : '') + (muted ? ' muted' : ''), onclick,
  },
  color ? h('span', { class: 'dot', style: { background: color } }) : h('span', { class: 'nav-icon' }, icon),
  h('span', { class: 'nav-label' }, label),
  count ? h('span', { class: 'count' + (alert ? ' alert' : '') }, count) : null);
}

function renderNav(c) {
  $('#views').replaceChildren(...VIEWS.map((v) => navItem({
    active: state.view === v.id, icon: v.icon, label: v.label, count: c[v.id],
    onclick: () => setView(v.id), alert: v.id === 'today' && c.overdue > 0,
  })));

  const projects = sortedProjects();
  const active = projects.filter((p) => !p.done);
  const finished = projects.filter((p) => p.done);
  const projItem = (p) => navItem({
    active: state.view === 'project' && state.projectId === p.id, icon: p.done ? '✔' : '📁', label: p.name,
    count: c.projects[p.id], onclick: () => setView('project', { projectId: p.id }), muted: p.done,
    alert: !p.done && p.due_date && p.due_date < todayStr(),
  });
  const items = active.map(projItem);
  if (finished.length) {
    items.push(h('button', {
      type: 'button', class: 'nav-toggle',
      onclick: () => { state.showDoneProjects = !state.showDoneProjects; render(); },
    }, state.showDoneProjects ? 'Hide finished' : `Show finished (${finished.length})`));
    if (state.showDoneProjects) items.push(...finished.map(projItem));
  }
  if (!projects.length) items.push(h('div', { class: 'nav-empty' }, 'No projects yet'));
  $('#projects').replaceChildren(...items);

  const catItems = state.categories.map((cat) => navItem({
    active: state.view === 'cat' && state.categoryId === cat.id, label: cat.name, count: c.cats[cat.id],
    onclick: () => setView('cat', { categoryId: cat.id }), color: cat.color,
  }));
  if (c.cats[0]) {
    catItems.push(navItem({
      active: state.view === 'cat' && state.categoryId === 0, label: 'No category', count: c.cats[0],
      onclick: () => setView('cat', { categoryId: 0 }), color: 'var(--muted)',
    }));
  }
  $('#cats').replaceChildren(...catItems);
}

function render() {
  if (state.view === 'cat' && state.categoryId && !catById(state.categoryId)) state.view = 'today';
  if (state.view === 'project' && !projectById(state.projectId)) state.view = 'today';
  if (!['cat', 'project'].includes(state.view) && !VIEWS.some((v) => v.id === state.view)) state.view = 'today';

  renderNav(counts());

  let title = (VIEWS.find((v) => v.id === state.view) || {}).label;
  if (state.view === 'cat') title = state.categoryId ? catById(state.categoryId).name : 'No category';
  if (state.view === 'project') title = projectById(state.projectId).name;
  $('#view-title').textContent = title || '';
  document.title = `${title} · WhatToDo`;
  $('#quick-add').hidden = state.view === 'done';
  $('#search').hidden = state.view === 'calendar';
  $('#cal-nav').hidden = state.view !== 'calendar';
  if (state.view === 'calendar') {
    renderCalendar();
    return;
  }

  const sections = [];
  if (state.view === 'project') sections.push(projectHeader(projectById(state.projectId)));
  const groups = buildGroups(viewTasks());
  if (state.view === 'today' && !state.search) {
    const cards = sortedProjects().filter((p) => !p.done).map(projectCard);
    // Projects go right after the things that are due/planned today.
    const at = groups.findIndex((g) => g.title === 'High priority, not planned');
    if (cards.length) groups.splice(at, 0, { title: 'Projects', nodes: cards });
  }
  for (const g of groups) {
    const items = g.nodes || g.tasks.map(taskRow);
    if (!items.length) continue;
    sections.push(h('section', { class: 'group' },
      h('h3', { class: 'group-title' + (g.title === 'Overdue' ? ' overdue' : '') },
        g.title, g.tasks ? h('span', { class: 'muted' }, ` ${g.tasks.length}`) : null),
      g.hint ? h('p', { class: 'group-hint' }, g.hint) : null,
      items));
  }
  if (sections.length === (state.view === 'project' ? 1 : 0)) {
    const msg = state.search ? 'No tasks match your search.'
      : state.view === 'done' ? 'Nothing completed yet.'
        : state.view === 'today' ? 'Nothing planned for today. 🎉'
          : state.view === 'backlog' ? 'Backlog is empty: everything has a date.'
            : state.view === 'project' ? 'No tasks in this project yet. Add the first step above.'
              : 'No tasks here.';
    sections.push(h('div', { class: 'empty' }, msg));
  }
  $('#list').replaceChildren(...sections);
}

function progressBar(pct) {
  return h('div', { class: 'progress', role: 'progressbar', 'aria-valuenow': String(pct), 'aria-valuemin': '0', 'aria-valuemax': '100' },
    h('div', { class: 'progress-fill', style: { width: `${pct}%` } }));
}

function projectCard(p) {
  const info = projectHealth(p);
  const cat = catById(p.category_id);
  return h('div', {
    class: 'project-card', tabindex: '0',
    onclick: () => setView('project', { projectId: p.id }),
    onkeydown: (e) => { if (e.key === 'Enter') setView('project', { projectId: p.id }); },
    style: { borderLeftColor: cat ? cat.color : 'var(--accent)' },
  },
  h('div', { class: 'project-card-head' },
    h('span', { class: 'project-name' }, '📁 ', p.name),
    h('span', { class: 'muted small' }, [
      p.due_date ? `${dayName(p.due_date)} · ${daysLeftText(info.daysLeft)}` : 'no deadline',
    ])),
  h('div', { class: 'project-progress' }, progressBar(info.pct), h('span', { class: 'small muted' }, `${info.done}/${info.total}`)),
  info.next ? h('div', { class: 'project-next' }, h('span', { class: 'muted' }, 'Next: '), info.next.title,
    whenDate(info.next) ? h('span', { class: 'muted' }, ` · ${dayName(whenDate(info.next))}`) : null) : null,
  info.warn ? h('div', { class: 'project-warn' }, '⚠ ', info.warn) : null);
}

function projectHeader(p) {
  const info = projectHealth(p);
  const cat = catById(p.category_id);
  return h('section', { class: 'project-header' },
    h('div', { class: 'project-header-top' },
      h('div', { class: 'task-meta' },
        cat ? h('span', { class: 'chip' }, h('span', { class: 'dot', style: { background: cat.color } }), cat.name) : null,
        p.due_date ? h('span', { class: `chip due ${info.daysLeft < 0 ? 'overdue' : ''}` }, '🏁 ', dayName(p.due_date), ` · ${daysLeftText(info.daysLeft)}`) : null,
        p.done ? h('span', { class: 'chip' }, '✔ Finished') : null),
      h('button', { type: 'button', class: 'btn', onclick: () => openProject(p) }, 'Edit project')),
    h('div', { class: 'project-progress big' }, progressBar(info.pct),
      h('span', { class: 'small' }, `${info.done}/${info.total} done (${info.pct}%)`)),
    info.warn ? h('div', { class: 'project-warn' }, '⚠ ', info.warn) : null,
    p.notes.trim() ? h('p', { class: 'project-notes' }, p.notes) : null);
}

function taskRow(task) {
  const t = todayStr();
  const meta = [];
  const cat = catById(task.category_id);
  if (cat && state.view !== 'cat') {
    meta.push(h('span', { class: 'chip' }, h('span', { class: 'dot', style: { background: cat.color } }), cat.name));
  }
  const proj = projectById(task.project_id);
  if (proj && state.view !== 'project') {
    meta.push(h('button', {
      type: 'button', class: 'chip link-chip', title: 'Open project',
      onclick: (e) => { e.stopPropagation(); setView('project', { projectId: proj.id }); },
    }, '📁 ', proj.name));
  }
  const time = timeText(task);
  if (task.planned_date) {
    const diff = dayDiff(t, task.planned_date);
    const label = diff < 0 && !task.done ? `from ${dayName(task.planned_date)}` : dayName(task.planned_date);
    meta.push(h('span', { class: 'chip plan' + (diff <= 0 && !task.done ? ' now' : ''), title: 'Planned to do on' },
      '▶ ', label, time ? ` · ${time}` : ''));
  }
  if (task.due_date) {
    const d = dueInfo(task.due_date);
    meta.push(h('span', { class: `chip due ${task.done ? '' : d.cls}`, title: 'Deadline' },
      '📅 ', task.planned_date ? 'due ' : '', d.text, !task.planned_date && time ? ` · ${time}` : ''));
  }
  if (task.priority) meta.push(h('span', { class: `chip prio-label p${task.priority}` }, '⚑ ', PRIORITY_LABELS[task.priority]));
  if (task.recurrence !== 'none') {
    const unit = REPEAT_UNITS[task.recurrence];
    meta.push(h('span', { class: 'chip' }, '↻ ', task.recur_interval > 1 ? `every ${task.recur_interval} ${unit}s` : `every ${unit}`));
  }
  if (task.subtasks.length) {
    const doneCount = task.subtasks.filter((s) => s.done).length;
    meta.push(h('span', { class: 'chip' }, `☑ ${doneCount}/${task.subtasks.length}`));
  }
  if (task.notes.trim()) meta.push(h('span', { class: 'chip', title: 'Has notes' }, '📝'));
  for (const tag of task.tags) {
    meta.push(h('button', {
      type: 'button', class: 'chip tag',
      onclick: (e) => { e.stopPropagation(); setSearch(`#${tag}`); },
    }, `#${tag}`));
  }

  return h('div', {
    class: `task p${task.priority}` + (task.done ? ' done' : ''),
    tabindex: '0',
    onclick: () => openTask(task),
    onkeydown: (e) => { if (e.key === 'Enter' && e.target === e.currentTarget) openTask(task); },
  },
  h('button', {
    type: 'button', class: 'check', 'aria-label': task.done ? 'Mark as not done' : 'Mark as done',
    onclick: (e) => { e.stopPropagation(); toggleDone(task); },
  }, task.done ? '✓' : ''),
  h('div', { class: 'task-body' },
    h('div', { class: 'task-title' }, task.title),
    meta.length ? h('div', { class: 'task-meta' }, meta) : null),
  task.done ? null : h('button', {
    type: 'button', class: 'icon-btn plan-btn', 'aria-label': 'Plan or postpone', title: 'Plan / postpone',
    onclick: (e) => { e.stopPropagation(); openPlan(task); },
  }, '⏭'));
}

// --- Calendar -----------------------------------------------------------------

// Lay out overlapping blocks side by side: each cluster of overlaps shares its width.
function layoutBlocks(items) {
  const sorted = items.map((it) => ({ ...it, span: span(it.task) }))
    .sort((a, b) => a.span[0] - b.span[0] || b.span[1] - a.span[1]);
  let cluster = [];
  let clusterEnd = -1;
  const flush = () => {
    const cols = Math.max(...cluster.map((it) => it.col)) + 1;
    for (const it of cluster) it.cols = cols;
    cluster = [];
  };
  for (const it of sorted) {
    if (cluster.length && it.span[0] >= clusterEnd) flush();
    const colEnds = [];
    for (const other of cluster) colEnds[other.col] = Math.max(colEnds[other.col] ?? -1, other.span[1]);
    let col = 0;
    while (colEnds[col] !== undefined && colEnds[col] > it.span[0]) col++;
    it.col = col;
    cluster.push(it);
    clusterEnd = Math.max(clusterEnd, it.span[1]);
  }
  if (cluster.length) flush();
  return sorted;
}

function weekStrip(day) {
  const d = parseDate(day);
  const monday = addDays(day, -((d.getDay() + 6) % 7));
  const t = todayStr();
  return h('div', { class: 'week-strip' }, Array.from({ length: 7 }, (_, i) => {
    const date = addDays(monday, i);
    const n = itemsOn(date).filter((it) => !it.task.done).length;
    return h('button', {
      type: 'button',
      class: 'week-day' + (date === day ? ' active' : '') + (date === t ? ' today' : ''),
      onclick: () => setCalDate(date),
    },
    h('span', { class: 'wd' }, parseDate(date).toLocaleDateString(undefined, { weekday: 'short' })),
    h('span', { class: 'dn' }, parseDate(date).getDate()),
    h('span', { class: 'dots' }, n ? '•'.repeat(Math.min(n, 4)) : ' '));
  }));
}

function renderCalendar() {
  const day = state.calDate || todayStr();
  $('#cal-date').value = day;
  const items = itemsOn(day);
  const timed = items.filter((it) => it.task.start_time);
  const untimed = items.filter((it) => !it.task.start_time).map((it) => it.task).sort(cmpOpen);
  // Deadlines that fall on this day but are planned for another day, and project deadlines.
  const deadlines = state.tasks.filter((t) => t.due_date === day && t.planned_date && t.planned_date !== day);
  const projectDeadlines = state.projects.filter((p) => !p.done && p.due_date === day);

  let startHour = 7;
  let endHour = 22;
  for (const it of timed) {
    const [a, b] = span(it.task);
    startHour = Math.min(startHour, Math.floor(a / 60));
    endHour = Math.max(endHour, Math.ceil(b / 60));
  }

  const grid = h('div', { class: 'timeline', style: { height: `${(endHour - startHour) * HOUR_PX}px` } });
  for (let hr = startHour; hr < endHour; hr++) {
    grid.append(h('div', {
      class: 'hour', style: { top: `${(hr - startHour) * HOUR_PX}px`, height: `${HOUR_PX}px` },
      title: 'Add a task at this time',
      onclick: () => openTask(null, {
        planned_date: day, start_time: fromMin(hr * 60), end_time: fromMin(Math.min(hr * 60 + 60, 23 * 60 + 59)),
      }),
    }, h('span', { class: 'hour-label' }, `${pad(hr)}:00`)));
  }
  for (const it of layoutBlocks(timed)) {
    const t = it.task;
    const cat = catById(t.category_id);
    const top = ((it.span[0] - startHour * 60) / 60) * HOUR_PX;
    const height = Math.max(((it.span[1] - it.span[0]) / 60) * HOUR_PX - 2, 20);
    grid.append(h('button', {
      type: 'button',
      class: 'block' + (t.done ? ' done' : '') + (it.projected ? ' projected' : '') + (height < 40 ? ' short' : ''),
      title: it.projected ? 'Repeat of a recurring task (opens the current occurrence)' : t.title,
      style: {
        top: `${top}px`, height: `${height}px`,
        left: `calc(52px + (100% - 56px) * ${it.col / it.cols})`,
        width: `calc((100% - 56px) / ${it.cols} - 3px)`,
        borderLeftColor: cat ? cat.color : 'var(--accent)',
      },
      onclick: () => openTask(t),
    },
    h('span', { class: 'block-time' }, it.projected ? '↻ ' : '', t.start_time, t.end_time ? `–${t.end_time}` : ''),
    h('span', { class: 'block-title' }, t.title)));
  }
  if (day === todayStr()) {
    const now = new Date();
    const mins = now.getHours() * 60 + now.getMinutes();
    if (mins >= startHour * 60 && mins <= endHour * 60) {
      grid.append(h('div', { class: 'now-line', style: { top: `${((mins - startHour * 60) / 60) * HOUR_PX}px` } }));
    }
  }

  const sections = [weekStrip(day)];
  if (deadlines.length || projectDeadlines.length) {
    sections.push(h('section', { class: 'group' },
      h('h3', { class: 'group-title' }, 'Deadlines this day'),
      projectDeadlines.map((p) => h('button', {
        type: 'button', class: 'deadline-line', onclick: () => setView('project', { projectId: p.id }),
      }, '🏁 ', h('strong', {}, p.name), ' (project)')),
      deadlines.map(taskRow)));
  }
  if (untimed.length) {
    sections.push(h('section', { class: 'group' },
      h('h3', { class: 'group-title' }, 'No time set', h('span', { class: 'muted' }, ` ${untimed.length}`)),
      untimed.map(taskRow)));
  }
  sections.push(h('section', { class: 'group' }, h('h3', { class: 'group-title' }, 'Schedule'), grid));
  $('#list').replaceChildren(...sections);
}

function setCalDate(day) {
  state.calDate = day;
  render();
}

// --- Actions ------------------------------------------------------------------

function setView(view, { categoryId = null, projectId = null } = {}) {
  state.view = view;
  state.categoryId = categoryId;
  state.projectId = projectId;
  savePrefs();
  document.body.classList.remove('nav-open');
  render();
  $('#list').scrollTop = 0;
}

function setSearch(text) {
  state.search = text;
  $('#search').value = text;
  render();
}

function toggleDone(task) {
  if (task.done) {
    act(() => api(`api/tasks/${task.id}/reopen`, { method: 'POST' }));
    return;
  }
  act(async () => {
    const res = await api(`api/tasks/${task.id}/complete`, { method: 'POST', body: { today: todayStr() } });
    const extra = res.next ? ` Next one: ${dayName(whenDate(res.next))}.` : '';
    toast(`Done: ${task.title}.${extra}`, {
      label: 'Undo',
      fn: () => act(async () => {
        if (res.next) await api(`api/tasks/${res.next.id}`, { method: 'DELETE' });
        await api(`api/tasks/${task.id}/reopen`, { method: 'POST' });
      }),
    });
  });
}

// Defaults for a task created from the current view.
function viewDefaults() {
  const d = {};
  if (state.view === 'cat' && state.categoryId) d.category_id = state.categoryId;
  if (state.view === 'project') {
    const p = projectById(state.projectId);
    d.project_id = p.id;
    if (p.category_id) d.category_id = p.category_id;
  }
  if (state.view === 'today') d.planned_date = todayStr();
  if (state.view === 'upcoming') d.planned_date = addDays(todayStr(), 1);
  if (state.view === 'calendar') d.planned_date = state.calDate || todayStr();
  return d;
}

function quickAdd(title) {
  act(() => api('api/tasks', { method: 'POST', body: { title, ...viewDefaults() } }));
}

function toast(message, action) {
  const el = $('#toast');
  el.replaceChildren(h('span', {}, message));
  if (action) {
    el.append(h('button', {
      type: 'button', class: 'link',
      onclick: () => { el.hidden = true; action.fn(); },
    }, action.label));
  }
  el.hidden = false;
  clearTimeout(toastTimer);
  toastTimer = setTimeout(() => { el.hidden = true; }, action ? 6000 : 4000);
}

// --- Postpone / plan sheet ----------------------------------------------------

const PLAN_OPTIONS = [
  ['today', 'Today'], ['tomorrow', 'Tomorrow'], ['weekend', 'This weekend'],
  ['nextweek', 'Next week'], ['twoweeks', 'In 2 weeks'], ['nextmonth', 'Next month'],
];

function openPlan(task) {
  // Overdue tasks can't be fixed by planning, so default to moving the deadline for them.
  const mode = task.due_date && task.due_date < todayStr() ? 'due' : 'plan';
  planning = { task, mode };
  $('#p-title').textContent = task.title;
  renderPlan();
  $('#plan-dialog').showModal();
}

function renderPlan() {
  const { task, mode } = planning;
  const field = mode === 'plan' ? 'planned_date' : 'due_date';
  $('#p-mode').hidden = !task.due_date;
  for (const btn of $('#p-mode').querySelectorAll('button')) btn.classList.toggle('active', btn.dataset.mode === mode);
  const current = task[field];
  $('#p-current').textContent = mode === 'plan'
    ? (current ? `Planned for ${dayName(current)}. Move it to:` : 'Not planned yet. Do it on:')
    : `Deadline is ${dayName(current)}. Move it to:`;
  $('#p-options').replaceChildren(...PLAN_OPTIONS.map(([key, label]) => {
    const date = namedDate(key);
    if (key === 'weekend' && [0, 6].includes(parseDate(todayStr()).getDay())) label = 'Next weekend';
    return h('button', { type: 'button', class: 'plan-option', onclick: () => applyPlan(date) },
      h('span', {}, label),
      h('span', { class: 'muted small' }, parseDate(date).toLocaleDateString(undefined, { weekday: 'short', day: 'numeric', month: 'short' })));
  }));
  $('#p-date').value = current || '';
  $('#p-clear').textContent = mode === 'plan' ? 'Remove plan date' : 'Remove deadline';
  $('#p-clear').hidden = !current;
}

function applyPlan(date) {
  const { task, mode } = planning;
  const field = mode === 'plan' ? 'planned_date' : 'due_date';
  const before = {
    planned_date: task.planned_date, due_date: task.due_date, start_time: task.start_time, end_time: task.end_time,
  };
  const body = { [field]: date };
  const after = { ...before, ...body };
  if (!after.planned_date && !after.due_date) { body.start_time = null; body.end_time = null; }
  $('#plan-dialog').close();
  act(async () => {
    await api(`api/tasks/${task.id}`, { method: 'PATCH', body });
    const what = mode === 'plan' ? 'Planned for' : 'Deadline moved to';
    toast(date ? `${what} ${dayName(date)}.` : (mode === 'plan' ? 'Plan date removed.' : 'Deadline removed.'), {
      label: 'Undo',
      fn: () => act(() => api(`api/tasks/${task.id}`, { method: 'PATCH', body: before })),
    });
  });
}

// --- Task dialog --------------------------------------------------------------

function fillSelect(select, items, selected, noneLabel = '— None —') {
  select.replaceChildren(
    h('option', { value: '' }, noneLabel),
    ...items.map((x) => h('option', { value: String(x.id) }, x.name)),
  );
  select.value = selected ? String(selected) : '';
}

function updateIntervalVisibility() {
  $('#t-interval-wrap').hidden = $('#t-repeat').value === 'none';
}

function openTask(task, defaults = {}) {
  editing = task;
  const t = task || {
    title: '', notes: '', category_id: null, project_id: null, priority: 0, due_date: null, planned_date: null,
    tags: [], recurrence: 'none', recur_interval: 1, subtasks: [], ...defaults,
  };
  $('#task-dialog-title').textContent = task ? 'Edit task' : 'New task';
  $('#t-title').value = t.title;
  fillSelect($('#t-category'), state.categories, t.category_id);
  // Finished projects are only listed for the task already in one.
  fillSelect($('#t-project'), sortedProjects().filter((p) => !p.done || p.id === t.project_id), t.project_id);
  $('#t-priority').value = String(t.priority);
  $('#t-planned').value = t.planned_date || '';
  $('#t-due').value = t.due_date || '';
  $('#t-start').value = t.start_time || '';
  $('#t-end').value = t.end_time || '';
  $('#t-repeat').value = t.recurrence;
  $('#t-interval').value = t.recur_interval;
  $('#t-tags').value = t.tags.join(', ');
  $('#t-notes').value = t.notes;
  $('#t-subtask-new').value = '';
  $('#t-delete').hidden = !task;
  draftSubtasks = t.subtasks.map((s) => ({ title: s.title, done: s.done }));
  renderDraftSubtasks();
  updateIntervalVisibility();
  updateTimeFields();
  $('#task-dialog').showModal();
  if (!task) $('#t-title').focus();
}

// Times apply to the plan date (or the deadline). Show what else is scheduled that day and flag overlaps.
function updateTimeFields() {
  const day = $('#t-planned').value || $('#t-due').value;
  for (const id of ['#t-start', '#t-end']) {
    $(id).disabled = !day;
    if (!day) $(id).value = '';
  }
  const box = $('#t-day');
  const others = day ? itemsOn(day)
    .filter((it) => it.task.start_time && !it.task.done && !(editing && it.task.id === editing.id))
    .sort((a, b) => toMin(a.task.start_time) - toMin(b.task.start_time)) : [];
  if (!others.length) { box.hidden = true; return; }
  const start = $('#t-start').value;
  const end = $('#t-end').value;
  const mine = start ? [toMin(start), end ? toMin(end) : toMin(start) + 60] : null;
  let clashes = 0;
  const rows = others.map((it) => {
    const [a, b] = span(it.task);
    const clash = mine && a < mine[1] && mine[0] < b;
    if (clash) clashes++;
    return h('li', { class: clash ? 'clash' : '' },
      h('span', { class: 'day-time' }, timeText(it.task)), ' ', it.task.title, it.projected ? ' ↻' : '');
  });
  box.replaceChildren(
    h('div', { class: 'day-head' + (clashes ? ' clash' : '') },
      clashes ? `⚠ Overlaps with ${clashes} item${clashes > 1 ? 's' : ''} on this day` : `Already planned on ${dayName(day)}`),
    h('ul', {}, rows));
  box.hidden = false;
}

function onStartChange() {
  const start = $('#t-start').value;
  const end = $('#t-end').value;
  if (start && (!end || end <= start)) $('#t-end').value = fromMin(Math.min(toMin(start) + 60, 23 * 60 + 59));
  if (!start) $('#t-end').value = '';
  updateTimeFields();
}

function onProjectChange() {
  const p = projectById(Number($('#t-project').value));
  if (p && p.category_id && !$('#t-category').value) $('#t-category').value = String(p.category_id);
}

function renderDraftSubtasks() {
  $('#t-subtasks').replaceChildren(...draftSubtasks.map((s, i) => h('li', { class: 'subtask' },
    h('input', { type: 'checkbox', checked: s.done, 'aria-label': 'Done', onchange: (e) => { s.done = e.target.checked; } }),
    h('input', { type: 'text', value: s.title, maxlength: '500', oninput: (e) => { s.title = e.target.value; } }),
    h('button', {
      type: 'button', class: 'icon-btn', 'aria-label': 'Remove step',
      onclick: () => { draftSubtasks.splice(i, 1); renderDraftSubtasks(); },
    }, '✕'))));
}

function addDraftSubtask() {
  const input = $('#t-subtask-new');
  const title = input.value.trim();
  if (!title) return;
  draftSubtasks.push({ title, done: false });
  input.value = '';
  renderDraftSubtasks();
  input.focus();
}

function saveTask(e) {
  e.preventDefault();
  addDraftSubtask();
  const body = {
    title: $('#t-title').value.trim(),
    category_id: $('#t-category').value ? Number($('#t-category').value) : null,
    project_id: $('#t-project').value ? Number($('#t-project').value) : null,
    priority: Number($('#t-priority').value),
    planned_date: $('#t-planned').value || null,
    due_date: $('#t-due').value || null,
    start_time: $('#t-start').value || null,
    end_time: ($('#t-start').value && $('#t-end').value) || null,
    recurrence: $('#t-repeat').value,
    recur_interval: Math.max(1, Number($('#t-interval').value) || 1),
    tags: $('#t-tags').value.split(',').map((s) => s.trim()).filter(Boolean),
    notes: $('#t-notes').value,
    subtasks: draftSubtasks.map((s) => ({ title: s.title.trim(), done: s.done })).filter((s) => s.title),
  };
  if (!body.title) return;
  const task = editing;
  $('#task-dialog').close();
  act(() => (task
    ? api(`api/tasks/${task.id}`, { method: 'PATCH', body })
    : api('api/tasks', { method: 'POST', body })));
}

function deleteTask() {
  const task = editing;
  if (!task || !confirm(`Delete "${task.title}"?`)) return;
  $('#task-dialog').close();
  act(() => api(`api/tasks/${task.id}`, { method: 'DELETE' }));
}

// --- Project dialog -----------------------------------------------------------

function openProject(project) {
  editingProject = project;
  document.body.classList.remove('nav-open');
  const p = project || { name: '', notes: '', category_id: null, due_date: null, done: false };
  $('#pr-dialog-title').textContent = project ? 'Edit project' : 'New project';
  $('#pr-name').value = p.name;
  fillSelect($('#pr-category'), state.categories, p.category_id);
  $('#pr-due').value = p.due_date || '';
  $('#pr-notes').value = p.notes;
  $('#pr-done').checked = p.done;
  $('#pr-done').closest('label').hidden = !project;
  $('#pr-delete').hidden = !project;
  $('#project-dialog').showModal();
  if (!project) $('#pr-name').focus();
}

function saveProject(e) {
  e.preventDefault();
  const body = {
    name: $('#pr-name').value.trim(),
    category_id: $('#pr-category').value ? Number($('#pr-category').value) : null,
    due_date: $('#pr-due').value || null,
    notes: $('#pr-notes').value,
    done: $('#pr-done').checked,
  };
  if (!body.name) return;
  const project = editingProject;
  $('#project-dialog').close();
  act(async () => {
    if (project) {
      await api(`api/projects/${project.id}`, { method: 'PATCH', body });
    } else {
      const created = await api('api/projects', { method: 'POST', body });
      state.view = 'project';
      state.projectId = created.id;
      savePrefs();
      toast('Project created. Add its steps as tasks, with deadlines for milestones.');
    }
  });
}

function deleteProject() {
  const p = editingProject;
  if (!p) return;
  const n = projectTasks(p).length;
  if (!confirm(`Delete project "${p.name}"? Its ${n} task(s) are kept, just no longer in a project.`)) return;
  $('#project-dialog').close();
  act(() => api(`api/projects/${p.id}`, { method: 'DELETE' }));
}

// --- Settings dialog ----------------------------------------------------------

function renderSettingsCategories() {
  const cats = state.categories;
  const patch = (cat, body) => act(async () => { await api(`api/categories/${cat.id}`, { method: 'PATCH', body }); })
    .then(renderSettingsCategories);
  const move = (i, dir) => {
    const other = cats[i + dir];
    if (!other) return;
    const order = cats.map((c) => c.id);
    [order[i], order[i + dir]] = [order[i + dir], order[i]];
    act(() => Promise.all(order.map((id, pos) => api(`api/categories/${id}`, { method: 'PATCH', body: { position: pos } }))))
      .then(renderSettingsCategories);
  };
  $('#s-cats').replaceChildren(...cats.map((cat, i) => h('li', { class: 'cat-edit' },
    h('input', { type: 'color', value: cat.color, 'aria-label': 'Color', onchange: (e) => patch(cat, { color: e.target.value }) }),
    h('input', {
      type: 'text', value: cat.name, maxlength: '50', 'aria-label': 'Name',
      onchange: (e) => { const name = e.target.value.trim(); if (name) patch(cat, { name }); },
    }),
    h('button', { type: 'button', class: 'icon-btn', 'aria-label': 'Move up', disabled: i === 0, onclick: () => move(i, -1) }, '↑'),
    h('button', { type: 'button', class: 'icon-btn', 'aria-label': 'Move down', disabled: i === cats.length - 1, onclick: () => move(i, 1) }, '↓'),
    h('button', {
      type: 'button', class: 'icon-btn danger', 'aria-label': 'Delete category',
      onclick: () => {
        if (!confirm(`Delete category "${cat.name}"? Its tasks are kept but will have no category.`)) return;
        act(() => api(`api/categories/${cat.id}`, { method: 'DELETE' })).then(renderSettingsCategories);
      },
    }, '🗑'))));
}

async function importFile() {
  const file = $('#s-import-file').files[0];
  if (!file) { toast('Choose an export file first.'); return; }
  const mode = $('#s-import-mode').value;
  let data;
  try {
    data = JSON.parse(await file.text());
  } catch {
    toast('That file is not valid JSON.');
    return;
  }
  const n = Array.isArray(data.tasks) ? data.tasks.length : 0;
  const warning = mode === 'replace'
    ? `REPLACE: this deletes ALL current tasks, projects and categories and loads ${n} tasks from the file. Continue?`
    : `MERGE: add ${n} tasks from the file to your current data. Continue?`;
  if (!confirm(warning)) return;
  await act(async () => {
    const res = await api(`api/import?mode=${mode}`, { method: 'POST', body: data });
    toast(`Imported ${res.tasks} tasks, ${res.projects} projects and ${res.categories} categories (${res.mode}).`);
  });
  $('#s-import-file').value = '';
  renderSettingsCategories();
}

// --- Login --------------------------------------------------------------------

function showLogin() {
  $('#app').hidden = true;
  $('#login').hidden = false;
  for (const d of document.querySelectorAll('dialog[open]')) d.close();
  $('#login-password').focus();
}

async function showApp() {
  await loadAll();
  $('#login').hidden = true;
  $('#app').hidden = false;
  render();
}

// --- Wiring -------------------------------------------------------------------

function bind() {
  $('#login-form').addEventListener('submit', async (e) => {
    e.preventDefault();
    const err = $('#login-error');
    err.hidden = true;
    try {
      await api('api/login', { method: 'POST', body: { password: $('#login-password').value } });
      $('#login-password').value = '';
      await showApp();
    } catch (ex) {
      err.textContent = ex.message;
      err.hidden = false;
    }
  });

  $('#quick-add').addEventListener('submit', (e) => {
    e.preventDefault();
    const title = $('#quick-title').value.trim();
    if (!title) return;
    $('#quick-title').value = '';
    quickAdd(title);
  });
  $('#new-detailed').addEventListener('click', () => {
    const defaults = { ...viewDefaults(), title: $('#quick-title').value.trim() };
    $('#quick-title').value = '';
    openTask(null, defaults);
  });

  $('#search').addEventListener('input', (e) => { state.search = e.target.value; render(); });

  $('#menu-btn').addEventListener('click', () => document.body.classList.add('nav-open'));
  $('#scrim').addEventListener('click', () => document.body.classList.remove('nav-open'));

  // Task dialog
  $('#task-form').addEventListener('submit', saveTask);
  $('#t-cancel').addEventListener('click', () => $('#task-dialog').close());
  $('#t-delete').addEventListener('click', deleteTask);
  $('#t-repeat').addEventListener('change', updateIntervalVisibility);
  $('#t-planned').addEventListener('change', updateTimeFields);
  $('#t-due').addEventListener('change', updateTimeFields);
  $('#t-start').addEventListener('change', onStartChange);
  $('#t-end').addEventListener('change', updateTimeFields);
  $('#t-project').addEventListener('change', onProjectChange);
  $('#t-subtask-add').addEventListener('click', addDraftSubtask);
  $('#t-subtask-new').addEventListener('keydown', (e) => {
    if (e.key === 'Enter') { e.preventDefault(); addDraftSubtask(); }
  });
  for (const btn of document.querySelectorAll('.quick-dates .chip-btn')) {
    btn.addEventListener('click', () => {
      $('#t-planned').value = namedDate(btn.dataset.plan) || '';
      updateTimeFields();
    });
  }

  // Calendar
  $('#cal-prev').addEventListener('click', () => setCalDate(addDays(state.calDate || todayStr(), -1)));
  $('#cal-next').addEventListener('click', () => setCalDate(addDays(state.calDate || todayStr(), 1)));
  $('#cal-today').addEventListener('click', () => setCalDate(todayStr()));
  $('#cal-date').addEventListener('change', (e) => { if (e.target.value) setCalDate(e.target.value); });

  // Postpone sheet
  for (const btn of $('#p-mode').querySelectorAll('button')) {
    btn.addEventListener('click', () => { planning.mode = btn.dataset.mode; renderPlan(); });
  }
  $('#p-set').addEventListener('click', () => { if ($('#p-date').value) applyPlan($('#p-date').value); });
  $('#p-clear').addEventListener('click', () => applyPlan(null));
  $('#p-cancel').addEventListener('click', () => $('#plan-dialog').close());

  // Projects
  $('#new-project').addEventListener('click', () => openProject(null));
  $('#project-form').addEventListener('submit', saveProject);
  $('#pr-cancel').addEventListener('click', () => $('#project-dialog').close());
  $('#pr-delete').addEventListener('click', deleteProject);

  // Settings dialog
  $('#settings-btn').addEventListener('click', () => {
    document.body.classList.remove('nav-open');
    renderSettingsCategories();
    $('#settings-dialog').showModal();
  });
  $('#s-close').addEventListener('click', () => $('#settings-dialog').close());
  $('#s-cat-add').addEventListener('submit', (e) => {
    e.preventDefault();
    const name = $('#s-cat-name').value.trim();
    if (!name) return;
    act(() => api('api/categories', { method: 'POST', body: { name, color: $('#s-cat-color').value } }))
      .then(() => { $('#s-cat-name').value = ''; renderSettingsCategories(); });
  });
  $('#s-import-btn').addEventListener('click', importFile);
  $('#s-logout').addEventListener('click', async () => {
    try { await api('api/logout', { method: 'POST' }); } catch { /* ignore */ }
    $('#settings-dialog').close();
    showLogin();
  });

  // Clicking the backdrop closes a dialog.
  for (const dlg of document.querySelectorAll('dialog')) {
    dlg.addEventListener('click', (e) => { if (e.target === dlg) dlg.close(); });
  }

  // Keyboard shortcuts: "/" search, "n" new task.
  document.addEventListener('keydown', (e) => {
    if (document.querySelector('dialog[open]') || $('#app').hidden) return;
    if (['INPUT', 'TEXTAREA', 'SELECT'].includes(document.activeElement.tagName)) return;
    if (e.key === '/') { e.preventDefault(); $('#search').focus(); }
    if (e.key === 'n') { e.preventDefault(); $('#quick-title').focus(); }
  });

  // Refresh when returning to the app (e.g. phone unlocked, day changed).
  document.addEventListener('visibilitychange', () => {
    if (document.visibilityState === 'visible' && !$('#app').hidden) act(async () => {});
  });
}

async function init() {
  loadPrefs();
  bind();
  if ('serviceWorker' in navigator) navigator.serviceWorker.register('sw.js').catch(() => {});
  try {
    await showApp();
  } catch (e) {
    // A 401 already switched to the login screen; anything else is worth reporting.
    if ($('#login').hidden) toast(`Could not load: ${e.message}`);
  }
}

init();