// Detail for one plan. Two modes: an in-progress plan (days to tick or jump into,
// its translation, catch-up / restart / remove) and a catalog plan (preview of the
// first days, pick a translation, start it).
import { useRef, useState } from 'react';
import Sheet from '../reader/Sheet.jsx';
import TranslationSelect from './TranslationSelect.jsx';
import { resizeImageToDataUrl } from './CustomPlanBuilder.jsx';
import { formatDayReadings, getPlanSchedule, daysBehindPace, nextUnreadDayIndex } from '../../utils/readingPlans.js';
import { useOfflineSave } from '../../hooks/useOfflineSave.js';
import { DownloadProgress } from '../OfflineSave.jsx';
import { canSaveOffline } from '../../utils/offline.js';

const btn = 'rounded-xl border border-[var(--r-line)] px-3 py-2 text-sm hover:bg-black/5';
const primary = 'w-full rounded-xl bg-[var(--r-accent)] py-2.5 text-sm font-medium text-[var(--r-on)] hover:opacity-90 disabled:opacity-50';

function ActiveBody({ plan, progress, onClose, actions }) {
  const schedule = getPlanSchedule(plan.id);
  const behind = daysBehindPace(plan, progress);
  const pct = plan.days > 0 ? Math.round((progress.completedDays.length / plan.days) * 100) : 0;
  const offline = useOfflineSave();
  const translation = progress.translation ?? actions.defaultTranslation;
  // The next week of readings, so a trip or a bad connection doesn't interrupt the plan
  const upcoming = (() => {
    const from = nextUnreadDayIndex(plan, progress.completedDays);
    return from == null ? [] : schedule.slice(from, from + 7).flat();
  })();
  return (
    <>
      <div className="mb-3 flex items-center justify-between text-sm">
        <span>{progress.completedDays.length} of {plan.days} days · {pct}%</span>
        <span className="flex items-center gap-2">
          <span className="text-xs text-[var(--r-sub)]">Read in</span>
          <TranslationSelect value={progress.translation ?? actions.defaultTranslation} onChange={(t) => actions.setTranslation(progress.id, t)} />
        </span>
      </div>
      <div className="mb-3 h-1.5 overflow-hidden rounded-full bg-[var(--r-line)]"><div className="h-full bg-[var(--r-accent)]" style={{ width: `${pct}%` }} /></div>
      {behind >= 2 && (
        <div className="mb-3 flex items-center justify-between rounded-xl border border-[var(--r-line)] px-3 py-2 text-xs">
          <span className="text-[var(--r-sub)]">{behind} days behind pace</span>
          <button type="button" onClick={() => actions.recalibrate(progress.id)} className="font-medium text-[var(--r-accent)] hover:underline">Catch me up</button>
        </div>
      )}
      <div className="max-h-[38vh] overflow-y-auto rounded-xl border border-[var(--r-line)]">
        {schedule.map((refs, i) => {
          const done = progress.completedDays.includes(i);
          return (
            <div key={i} className="flex items-center gap-3 border-b border-[var(--r-line)] px-3 py-2 last:border-0">
              <input type="checkbox" checked={done} onChange={() => actions.toggleDay(progress.id, i, plan.days)} className="h-4 w-4 shrink-0 accent-[var(--r-accent)]" aria-label={`Day ${i + 1} read`} />
              <span className={`flex-1 text-sm ${done ? 'text-[var(--r-sub)] line-through' : ''}`}>Day {i + 1} · {formatDayReadings(refs)}</span>
              <button type="button" onClick={() => { onClose(); actions.read(progress.id, i); }} className="shrink-0 text-xs font-medium text-[var(--r-accent)] hover:underline">Read</button>
            </div>
          );
        })}
      </div>
      {upcoming.length > 0 && canSaveOffline(translation) && (
        <div className="mt-3">
          {offline.job
            ? <DownloadProgress job={offline.job} onCancel={offline.cancel} />
            : (
              <button type="button" onClick={() => offline.saveRefs('the next 7 days', translation, upcoming)}
                className="w-full rounded-xl border border-[var(--r-line)] px-3 py-2 text-xs text-[var(--r-sub)] hover:bg-black/5">
                Save the next 7 days for offline ({translation})
              </button>
            )}
        </div>
      )}
      <div className="mt-4 flex items-center justify-between text-xs">
        <button type="button" onClick={() => { actions.restart(progress.id); onClose(); }} className="text-[var(--r-sub)] hover:text-[var(--r-text)]">Restart</button>
        <button type="button" onClick={() => { actions.remove(progress.id); onClose(); }} className="text-[var(--r-danger,#b42318)] hover:underline">Remove</button>
      </div>
    </>
  );
}

function CatalogBody({ plan, active, completedCount, onClose, actions }) {
  const [translation, setTranslation] = useState(actions.defaultTranslation);
  const [imageError, setImageError] = useState('');
  const fileRef = useRef(null);
  const schedule = getPlanSchedule(plan.id);
  const chapters = schedule.reduce((n, d) => n + d.length, 0);
  const pickImage = async (e) => {
    const file = e.target.files?.[0];
    e.target.value = '';
    if (!file) return;
    try { setImageError(''); actions.updateCover(plan.id, await resizeImageToDataUrl(file)); } catch { setImageError('Couldn’t use that image.'); }
  };
  return (
    <>
      {plan.image && <img src={plan.image} alt="" onError={(e) => { e.currentTarget.style.display = 'none'; }} className="mb-3 h-32 w-full rounded-xl object-cover" style={{ objectPosition: plan.imageFocus ?? 'center' }} />}
      <p className="text-sm text-[var(--r-sub)]">{plan.description || 'A custom reading plan.'}</p>
      <p className="mt-2 text-xs text-[var(--r-sub)]">{plan.days} days · {chapters} chapters · about {(chapters / plan.days).toFixed(1)} a day{completedCount > 0 ? ` · completed ${completedCount}×` : ''}</p>

      <p className="mb-1 mt-4 text-[11px] uppercase tracking-wide text-[var(--r-sub)]">First days</p>
      <div className="rounded-xl border border-[var(--r-line)]">
        {schedule.slice(0, 5).map((refs, i) => (
          <div key={i} className="border-b border-[var(--r-line)] px-3 py-1.5 text-sm last:border-0">Day {i + 1} · {formatDayReadings(refs)}</div>
        ))}
      </div>

      {!active && (
        <div className="mt-4 flex items-center justify-between text-sm">
          <span>Read in</span>
          <TranslationSelect value={translation} onChange={setTranslation} />
        </div>
      )}
      <div className="mt-3">
        {active
          ? <button type="button" className={primary} onClick={() => { onClose(); actions.read(active.id, actions.nextDay(plan, active)); }}>Continue reading</button>
          : <button type="button" className={primary} onClick={() => { actions.start(plan.id, translation); onClose(); }}>{completedCount > 0 ? 'Start again' : 'Start plan'}</button>}
      </div>

      {plan.custom && (
        <div className="mt-4 flex flex-wrap items-center gap-3 border-t border-[var(--r-line)] pt-3 text-xs">
          <button type="button" onClick={() => { onClose(); actions.edit(plan.id); }} className="text-[var(--r-sub)] hover:text-[var(--r-text)]">Edit plan</button>
          <button type="button" onClick={() => fileRef.current?.click()} className="text-[var(--r-sub)] hover:text-[var(--r-text)]">{plan.image ? 'Change cover' : 'Add cover photo'}</button>
          {plan.image && <button type="button" onClick={() => actions.updateCover(plan.id, null)} className="text-[var(--r-sub)] hover:text-[var(--r-danger,#b42318)]">Remove cover</button>}
          <button type="button" onClick={() => { actions.delete(plan.id); onClose(); }} className="ml-auto text-[var(--r-danger,#b42318)] hover:underline">Delete</button>
          <input ref={fileRef} type="file" accept="image/*" onChange={pickImage} className="hidden" />
          {imageError && <p className="w-full text-[var(--r-danger,#b42318)]">{imageError}</p>}
        </div>
      )}
    </>
  );
}

export default function PlanDetailSheet({ plan, progress, active, completedCount, onClose, actions }) {
  if (!plan) return null;
  return (
    <Sheet open onClose={onClose} title={<span>{plan.icon ? `${plan.icon} ` : ''}{plan.title}</span>}>
      {progress
        ? <ActiveBody plan={plan} progress={progress} onClose={onClose} actions={actions} />
        : <CatalogBody plan={plan} active={active} completedCount={completedCount} onClose={onClose} actions={actions} />}
    </Sheet>
  );
}