import { pausedReason as pausedReasonWords, rejectReason as rejectReasonWords } from '../api';
import type { Book, BookDetail, Run } from '../api';
import { useText, type Text } from '../i18n/text';
import { Button } from '../ui/Button';
import { Callout } from '../ui/Callout';
import { counted, date, languageName, number, statusOf, translatedPercent } from './format';
import { chapters } from './units';
import styles from './About.module.css';

/**
 * Metadata of the book (remark 6), extended exactly up to the boundary of the contract. The
 * boundary is a defence of the approaches, not a gap: there is no money on the screen (§4.8), and
 * no models or pipeline stages either.
 */
export function About({ detail, onStartRun }: { detail: BookDetail; onStartRun?: () => void }) {
  const text = useText();
  const { book, run } = detail;
  const startable = statusOf(book.status).startable === true;

  return (
    <div className={styles.card}>
      <State book={book} run={run ?? null} />
      {/* The one action of the book card, and it stands where the card is: a book is translated
          from the place that says what the book is. It is offered only where a run can begin —
          which state that is, is decided by the vocabulary on the api seam, in one file. */}
      {startable && onStartRun !== undefined && (
        <Button look="primary" onPress={onStartRun}>
          {text('run.action')}
        </Button>
      )}
      <dl className={styles.about}>
        {fields(detail, text).map(([name, value]) => (
          <div className={styles.field} key={name}>
            <dt className={styles.fieldName}>{name}</dt>
            <dd className={styles.fieldValue} title={value}>
              {value}
            </dd>
          </div>
        ))}
      </dl>
    </div>
  );
}

/**
 * The states a book is IN rather than the fields it has: still arriving, being cut into sections,
 * refused, halted. Each of them is a state the list of pairs below cannot say anything about, and
 * each of them is what the person is waiting on.
 *
 * ⚠ Parsing carries NO number, and that is the contract's shape and not an omission: there is no
 * counter of it anywhere on this surface, so a percentage would have to be invented (0.2.3).
 */
function State({ book, run }: { book: Book; run: Run | null }) {
  const text = useText();

  if (book.status === 'uploading')
    return <Callout tone="quiet" caption={text('about.uploading')} />;
  if (book.status === 'parsing') return <Callout tone="quiet" caption={text('about.parsing')} />;
  if (book.status === 'rejected') {
    // The machine reason is the platform's, the phrase and the advice are the product's — and the
    // advice is the point: "the file is not one we can read" and "not us, not now" end in
    // different next actions (0.2.3, PD-173).
    const reason = rejectReasonWords.describe(book.reject_reason ?? null);
    return (
      <Callout tone="note" caption={text(reason.label)}>
        {text(reason.advice)}
      </Callout>
    );
  }
  // A halt is stated where the action is, not only in the status strip: the strip says WHAT, the
  // card is where the person looks for what to do about it. The phrase is the owner's (В-6), and
  // resume is deliberately not offered — after a ceiling stop it does not move the run at all.
  if (book.status === 'paused') {
    return (
      <Callout
        tone="note"
        caption={text(pausedReasonWords.describe(run?.paused_reason ?? null).label)}
      />
    );
  }
  return null;
}

function fields(detail: BookDetail, text: Text): [string, string][] {
  const { book, run } = detail;
  const rows: [string, string][] = [
    [text('about.title'), book.title],
    [
      text('about.languages'),
      `${languageName(book.source_lang)} → ${languageName(book.target_lang)}`,
    ],
    [text('about.genre'), book.genre ?? '—'],
    [text('about.status'), text(statusOf(book.status).label)],
    [text('about.translated'), `${String(translatedPercent(book.progress))}%`],
    [text('about.chapters'), number(book.chapter_count)],
    [text('about.blocks'), number(book.progress.draft.total)],
    // Optional on the wire, so an absent size is a dash rather than a zero — the same shape the
    // dates use for "not known".
    [
      text('about.characters'),
      book.character_count === undefined ? '—' : number(book.character_count),
    ],
    [text('about.notes'), number(book.note_count)],
    [text('about.added'), date(book.added_at)],
  ];
  if (run) {
    rows.push(
      [text('about.runStarted'), date(run.started_at)],
      // `finished_at` comes both as `null` and as altogether absent: an unfinished run may have no
      // field at all — both forms mean one and the same thing and are drawn as a dash.
      [text('about.runFinished'), run.finished_at ? date(run.finished_at) : '—'],
      // The ceiling and the stop at the signature are the person's own choice before the start,
      // not the workings of the engine: showing them is honest and useful, he set them himself.
      [text('about.ceiling'), counted(run.ceiling_chapters, chapters)],
      [text('about.verifyBank'), run.verify_bank ? text('about.yes') : text('about.no')],
    );
  }
  return rows;
}