// The "Photo backup" section of Settings, on the Android application only
// (docs/MESHBAY_DESIGN.md §9.12). Loaded on demand: no other client has it.

import { html, useState, useEffect, useCallback } from './vendor/htm-preact.js';
import { t } from './i18n.js';
import * as platform from './platform.js';
import { hubFetch } from './hub-client.js';
import { formatSize } from './file-utils.js';
import { ask } from './ask.js';
import { subscribe, runPhotoSync, probeGroup } from './photo-sync.js';

function stateLine(st, status) {
  switch (st.phase) {
    case 'waiting_wifi': return t('photosync.state_waiting_wifi');
    case 'connecting': return t('photosync.state_connecting');
    case 'sending': return t('photosync.state_sending', { done: st.done, total: st.total });
    case 'offline': return t('photosync.state_offline');
    case 'interrupted': return t('photosync.state_interrupted');
    case 'up_to_date': return t('photosync.state_up_to_date');
    default: return status && status.lastCompleted ? t('photosync.state_up_to_date') : '';
  }
}

const FAILURES = {
  disk_full: 'photosync.fail_disk_full',
  root_read_only: 'photosync.fail_read_only',
  no_writable_root: 'photosync.fail_read_only',
  no_such_root: 'photosync.fail_no_folder',
  no_such_directory: 'photosync.fail_no_folder',
  root_unavailable: 'photosync.fail_unavailable',
  not_a_member: 'photosync.fail_not_member',
  permission: 'photosync.fail_permission',
};

export function PhotoSyncSection({ user, groups }) {
  const [status, setStatus] = useState(null);
  const [run, setRun] = useState({ phase: 'idle' });
  const [editing, setEditing] = useState(false);
  const [error, setError] = useState('');

  const refresh = useCallback(() => platform.photoSync.status().then(setStatus).catch(() => {}), []);
  useEffect(() => { refresh(); }, [refresh]);
  // A run that ends changes what the phone says (sent, last backup, a
  // failure); read it again then rather than on a timer.
  useEffect(() => subscribe((st) => {
    setRun(st);
    if (st.phase !== 'sending' && st.phase !== 'connecting') refresh();
  }), [refresh]);

  if (!status) return null;
  const cfg = status.config;

  const backUpNow = async () => {
    setError('');
    try {
      if (!status.unmetered) {
        const est = await platform.photoSync.estimate(cfg);
        if (est.count === 0) { await runPhotoSync({ force: true, metered: true }); return; }
        const yes = await ask(t('photosync.metered_confirm', {
          count: est.count, size: formatSize(est.bytes) }));
        if (!yes) return;
        await runPhotoSync({ force: true, metered: true });
      } else {
        await runPhotoSync({ force: true });
      }
    } catch (e) { setError(e.message); }
  };

  const turnOff = async () => {
    setError('');
    try { setStatus(await platform.photoSync.configure(null)); } catch (e) { setError(e.message); }
  };

  return html`
    <div class="settings-section">
      <h3 class="settings-heading">${t('photosync.heading')}</h3>
      ${!cfg && !editing && html`
        <p class="settings-hint">${t('photosync.intro')}</p>
        <button class="admin-btn" onClick=${() => setEditing(true)}>${t('photosync.setup')}</button>
      `}
      ${cfg && !editing && html`
        <div class="settings-row">
          <span class="settings-label settings-name">
            ${t('photosync.summary', { group: cfg.groupName, owner: cfg.owner, folder: cfg.folder })}
          </span>
        </div>
        ${cfg.account !== user.username && html`
          <p class="settings-hint">${t('photosync.other_account', { account: cfg.account })}</p>`}
        <p class="settings-hint">
          ${t('photosync.sent_total', { n: status.sent })}
          ${' · '}
          ${status.lastCompleted
            ? t('photosync.last_run', { when: new Date(status.lastCompleted).toLocaleString() })
            : t('photosync.never')}
        </p>
        ${status.permission === 'partial' && html`
          <p class="settings-hint">${t('photosync.permission_partial')}</p>`}
        ${status.failure
          ? html`<p class="error-msg">${t(FAILURES[status.failure] || 'photosync.fail_other')}</p>`
          : stateLine(run, status) && html`<p class="settings-hint">${stateLine(run, status)}</p>`}
        <div class="settings-row" style="gap:8px; justify-content:flex-start; flex-wrap:wrap">
          <button class="admin-btn" disabled=${run.phase === 'sending' || run.phase === 'connecting'}
            onClick=${backUpNow}>${t('photosync.now')}</button>
          <button class="btn-secondary" onClick=${() => setEditing(true)}>${t('photosync.change')}</button>
          <button class="btn-secondary" onClick=${turnOff}>${t('photosync.turn_off')}</button>
        </div>
      `}
      ${editing && html`
        <${Setup} user=${user} groups=${groups} status=${status}
          onPermission=${setStatus}
          onDone=${(next) => { setEditing(false); if (next) { setStatus(next); runPhotoSync(); } }} />`}
      ${error && html`<p class="error-msg">${error}</p>`}
    </div>
  `;
}

function Setup({ user, groups, status, onPermission, onDone }) {
  const cfg = status.config && status.config.account === user.username ? status.config : null;
  const [groupId, setGroupId] = useState(cfg ? cfg.groupId : '');
  const [folders, setFolders] = useState(null);       // null while unknown
  const [probe, setProbe] = useState('');             // '', 'checking', 'offline'
  const [folder, setFolder] = useState(cfg ? cfg.folder : '');
  const [albums, setAlbums] = useState(null);
  const [chosen, setChosen] = useState(() => new Set(cfg ? cfg.albums : []));
  const [existing, setExisting] = useState(cfg ? cfg.includeExisting : true);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState('');
  const permitted = status.permission !== 'denied';

  useEffect(() => {
    if (!permitted) return;
    platform.photoSync.albums().then((list) => {
      setAlbums(list);
      // The camera, and only the camera, unless the person chose before:
      // screenshots and saved images are where photos nobody meant to share live.
      if (!cfg) setChosen(new Set(list.filter((a) => a.camera).map((a) => a.id)));
    }).catch((e) => setError(e.message));
  }, [permitted]);

  useEffect(() => {
    setFolders(null);
    if (!groupId) return;
    let gone = false;
    setProbe('checking');
    probeGroup(groupId).then((r) => {
      if (gone) return;
      setProbe('');
      setFolders(r.folders);
      setFolder((f) => (r.folders.includes(f) ? f : (r.folders[0] || '')));
    }).catch(() => { if (!gone) setProbe('offline'); });
    return () => { gone = true; };
  }, [groupId]);

  const allow = async () => {
    setError('');
    try { onPermission(await platform.photoSync.permit()); } catch (e) { setError(e.message); }
  };

  const toggle = (id) => setChosen((prev) => {
    const next = new Set(prev);
    if (next.has(id)) next.delete(id); else next.add(id);
    return next;
  });

  const start = async () => {
    const group = groups.find((g) => g.id === groupId);
    if (!group || !folder || !chosen.size) return;
    setBusy(true);
    setError('');
    try {
      const settings = {
        account: user.username, groupId, groupName: group.name,
        owner: group.owner_username || '', folder, albums: [...chosen], includeExisting: existing,
      };
      // Asked when the photos would go somewhere new, or from somewhere new in
      // time — never for a change of albums alone, which the person just made.
      const same = cfg && cfg.groupId === groupId && cfg.folder === folder
        && cfg.includeExisting === existing;
      if (!same) {
        const [est, members] = await Promise.all([
          platform.photoSync.estimate(settings),
          hubFetch(`/v1/groups/${groupId}/members`, { token: user.token })
            .then((r) => (r.members || []).length).catch(() => null),
        ]);
        const params = {
          group: group.name, owner: group.owner_username || '', folder,
          members: members == null ? '?' : members,
          count: est.count, size: formatSize(est.bytes),
        };
        const yes = await ask(t(existing && est.count > 0 ? 'photosync.confirm'
                                                           : 'photosync.confirm_new', params));
        if (!yes) { setBusy(false); return; }
      }
      onDone(await platform.photoSync.configure(settings));
    } catch (e) {
      setError(e.message);
      setBusy(false);
    }
  };

  return html`
    <div>
      ${!permitted && html`
        <p class="settings-hint">${t('photosync.permission_needed')}</p>
        <button class="admin-btn" onClick=${allow}>${t('photosync.permission_allow')}</button>
      `}
      ${status.permission === 'partial' && html`
        <p class="settings-hint">${t('photosync.permission_partial')}</p>
        <button class="btn-secondary" onClick=${allow}>${t('photosync.permission_allow')}</button>
      `}
      ${permitted && html`
        <div class="settings-row">
          <span class="settings-label">${t('photosync.group')}</span>
          <select class="settings-select" value=${groupId}
            onChange=${(e) => setGroupId(e.target.value)}>
            <option value="">${t('photosync.choose_group')}</option>
            ${groups.map((g) => html`<option key=${g.id} value=${g.id}>
              ${g.owner_username ? `${g.name} (@${g.owner_username})` : g.name}</option>`)}
          </select>
        </div>
        ${probe === 'checking' && html`<p class="settings-hint">${t('photosync.checking_group')}</p>`}
        ${probe === 'offline' && html`<p class="settings-hint">${t('photosync.group_offline')}</p>`}
        ${folders && !folders.length && html`<p class="settings-hint">${t('photosync.no_folder')}</p>`}
        ${folders && folders.length > 0 && html`
          <div class="settings-row">
            <span class="settings-label">${t('photosync.folder')}</span>
            <select class="settings-select" value=${folder} onChange=${(e) => setFolder(e.target.value)}>
              ${folders.map((f) => html`<option key=${f} value=${f}>${f}</option>`)}
            </select>
          </div>
        `}
        <p class="settings-label" style="margin-top:10px">${t('photosync.albums')}</p>
        ${(albums || []).map((a) => html`
          <label class="settings-choice" key=${a.id}>
            <input type="checkbox" checked=${chosen.has(a.id)} onChange=${() => toggle(a.id)} />
            <span class="settings-name">
              <strong>${a.camera ? t('photosync.album_camera') : a.name}</strong>
              <span class="settings-hint">
                ${t('photosync.album_count', { n: a.count, size: formatSize(a.bytes) })}</span>
            </span>
          </label>
        `)}
        <label class="settings-choice">
          <input type="radio" name="photosync-scope" checked=${existing}
            onChange=${() => setExisting(true)} />
          <span><strong>${t('photosync.scope_existing')}</strong></span>
        </label>
        <label class="settings-choice">
          <input type="radio" name="photosync-scope" checked=${!existing}
            onChange=${() => setExisting(false)} />
          <span><strong>${t('photosync.scope_new')}</strong></span>
        </label>
        <div class="settings-row" style="gap:8px; justify-content:flex-start">
          <button class="admin-btn" onClick=${start}
            disabled=${busy || !groupId || !folder || !chosen.size}>${t('photosync.start')}</button>
          <button class="btn-secondary" onClick=${() => onDone(null)}>${t('dialog.cancel')}</button>
        </div>
      `}
      ${!permitted && html`
        <button class="btn-secondary" onClick=${() => onDone(null)}>${t('dialog.cancel')}</button>`}
      ${error && html`<p class="error-msg">${error}</p>`}
    </div>
  `;
}