const pool = require('./db');

const SUPPORTED_LOCALES = new Set(['en', 'ru']);
const DEFAULT_LOCALE = 'en';
const PUBLIC_STATUSES = ['published'];
const CURATOR_STATUSES = ['draft', 'reviewed', 'published'];

const TRANSLATABLE_FIELDS = {
  era: ['name', 'description'],
  movement: ['name', 'description'],
  artist: ['name', 'bio_short', 'bio_full'],
  artist_period: ['name', 'description'],
  painting: ['title', 'description'],
  annotation: ['label', 'body'],
  influence_source: ['notes', 'aspects', 'quote', 'period_note'],
};

function resolveLocale(req) {
  const q = req?.query?.locale;
  if (typeof q === 'string' && SUPPORTED_LOCALES.has(q.toLowerCase())) {
    return q.toLowerCase();
  }
  const accept = req?.headers?.['accept-language'];
  if (typeof accept === 'string' && /\bru\b/i.test(accept.split(',')[0])) {
    return 'ru';
  }
  return DEFAULT_LOCALE;
}

function translationStatuses(req) {
  if (req?.curatorUser && req?.query?.preview === '1') {
    return CURATOR_STATUSES;
  }
  return PUBLIC_STATUSES;
}

function translationKey(entityId, fieldName) {
  return `${entityId}:${fieldName}`;
}

async function loadTranslationsByType(entityType, ids, locale, fields, statuses) {
  const map = new Map();
  if (locale === DEFAULT_LOCALE || !ids.length || !fields.length) return map;

  const uniqueIds = [...new Set(ids.filter((id) => Number.isFinite(id)))];
  if (!uniqueIds.length) return map;

  const { rows } = await pool.query(
    `SELECT entity_id, field_name, value, status
     FROM entity_translations
     WHERE entity_type = $1
       AND entity_id = ANY($2::int[])
       AND locale = $3
       AND field_name = ANY($4::text[])
       AND status = ANY($5::text[])`,
    [entityType, uniqueIds, locale, fields, statuses],
  );

  for (const row of rows) {
    map.set(translationKey(row.entity_id, row.field_name), row.value);
  }
  return map;
}

function applyFields(row, entityType, entityId, fields, map, target = row) {
  for (const field of fields) {
    const value = map.get(translationKey(entityId, field));
    if (value != null && value !== '') {
      target[field] = value;
    }
  }
  return target;
}

async function localizeEras(eras, locale, statuses) {
  if (locale === DEFAULT_LOCALE || !eras.length) return eras;
  const map = await loadTranslationsByType(
    'era',
    eras.map((e) => e.id),
    locale,
    TRANSLATABLE_FIELDS.era,
    statuses,
  );
  return eras.map((era) => applyFields({ ...era }, 'era', era.id, TRANSLATABLE_FIELDS.era, map));
}

async function localizeMovements(movements, locale, statuses, eraNameById = new Map()) {
  if (locale === DEFAULT_LOCALE || !movements.length) return movements;
  const map = await loadTranslationsByType(
    'movement',
    movements.map((m) => m.id),
    locale,
    TRANSLATABLE_FIELDS.movement,
    statuses,
  );
  const eraIds = movements.map((m) => m.era_id).filter(Boolean);
  const eraMap = eraIds.length
    ? await loadTranslationsByType('era', eraIds, locale, ['name'], statuses)
    : new Map();

  return movements.map((movement) => {
    const out = applyFields({ ...movement }, 'movement', movement.id, TRANSLATABLE_FIELDS.movement, map);
    if (movement.era_id && eraMap.has(translationKey(movement.era_id, 'name'))) {
      out.era_name = eraMap.get(translationKey(movement.era_id, 'name'));
    } else if (movement.era_id && eraNameById.has(movement.era_id)) {
      out.era_name = eraNameById.get(movement.era_id);
    }
    return out;
  });
}

async function localizeArtists(artists, locale, statuses) {
  if (locale === DEFAULT_LOCALE || !artists.length) return artists;
  const artistMap = await loadTranslationsByType(
    'artist',
    artists.map((a) => a.id),
    locale,
    TRANSLATABLE_FIELDS.artist,
    statuses,
  );
  const movementIds = artists.map((a) => a.movement_id).filter(Boolean);
  const movementMap = movementIds.length
    ? await loadTranslationsByType('movement', movementIds, locale, ['name'], statuses)
    : new Map();

  return artists.map((artist) => {
    const out = applyFields({ ...artist }, 'artist', artist.id, TRANSLATABLE_FIELDS.artist, artistMap);
    if (artist.movement_id && movementMap.has(translationKey(artist.movement_id, 'name'))) {
      out.movement_name = movementMap.get(translationKey(artist.movement_id, 'name'));
    }
    return out;
  });
}

async function localizePeriods(periods, locale, statuses) {
  if (locale === DEFAULT_LOCALE || !periods.length) return periods;
  const map = await loadTranslationsByType(
    'artist_period',
    periods.map((p) => p.id),
    locale,
    TRANSLATABLE_FIELDS.artist_period,
    statuses,
  );
  return periods.map((period) =>
    applyFields({ ...period }, 'artist_period', period.id, TRANSLATABLE_FIELDS.artist_period, map),
  );
}

async function localizePaintings(paintings, locale, statuses) {
  if (locale === DEFAULT_LOCALE || !paintings.length) return paintings;
  const paintingMap = await loadTranslationsByType(
    'painting',
    paintings.map((p) => p.id),
    locale,
    TRANSLATABLE_FIELDS.painting,
    statuses,
  );
  const artistIds = paintings.map((p) => p.artist_id).filter(Boolean);
  const artistMap = artistIds.length
    ? await loadTranslationsByType('artist', artistIds, locale, ['name'], statuses)
    : new Map();

  return paintings.map((painting) => {
    const out = applyFields({ ...painting }, 'painting', painting.id, TRANSLATABLE_FIELDS.painting, paintingMap);
    const artistId = painting.artist_id;
    if (artistId && artistMap.has(translationKey(artistId, 'name'))) {
      out.artist_name = artistMap.get(translationKey(artistId, 'name'));
    }
    return out;
  });
}

async function localizeAnnotations(annotations, locale, statuses) {
  if (locale === DEFAULT_LOCALE || !annotations.length) return annotations;
  const map = await loadTranslationsByType(
    'annotation',
    annotations.map((a) => a.id),
    locale,
    TRANSLATABLE_FIELDS.annotation,
    statuses,
  );
  return annotations.map((ann) =>
    applyFields({ ...ann }, 'annotation', ann.id, TRANSLATABLE_FIELDS.annotation, map),
  );
}

async function localizeInfluenceSources(rows, locale, statuses) {
  if (locale === DEFAULT_LOCALE || !rows.length) return rows;
  const sourceIds = rows.map((r) => r.influence_source_id || r.id).filter(Boolean);
  const map = await loadTranslationsByType(
    'influence_source',
    sourceIds,
    locale,
    TRANSLATABLE_FIELDS.influence_source,
    statuses,
  );

  const paintingIds = rows.map((r) => r.id).filter(Boolean);
  const artistIds = rows.map((r) => r.artist_id || r.source_artist_id).filter(Boolean);
  const movementIds = rows.map((r) => r.movement_id).filter(Boolean);

  const [paintingMap, artistMap, movementMap] = await Promise.all([
    paintingIds.length
      ? loadTranslationsByType('painting', paintingIds, locale, ['title'], statuses)
      : Promise.resolve(new Map()),
    artistIds.length
      ? loadTranslationsByType('artist', artistIds, locale, ['name'], statuses)
      : Promise.resolve(new Map()),
    movementIds.length
      ? loadTranslationsByType('movement', movementIds, locale, ['name'], statuses)
      : Promise.resolve(new Map()),
  ]);

  return rows.map((row) => {
    const sourceId = row.influence_source_id || row.id;
    const out = applyFields(
      { ...row },
      'influence_source',
      sourceId,
      TRANSLATABLE_FIELDS.influence_source,
      map,
    );
    if (row.id && paintingMap.has(translationKey(row.id, 'title'))) {
      out.title = paintingMap.get(translationKey(row.id, 'title'));
    }
    const artistId = row.artist_id || row.source_artist_id;
    if (artistId && artistMap.has(translationKey(artistId, 'name'))) {
      if (row.source_artist_name != null) out.source_artist_name = artistMap.get(translationKey(artistId, 'name'));
      if (row.artist_name != null) out.artist_name = artistMap.get(translationKey(artistId, 'name'));
    }
    if (row.movement_id && movementMap.has(translationKey(row.movement_id, 'name'))) {
      out.movement_name = movementMap.get(translationKey(row.movement_id, 'name'));
    }
    return out;
  });
}

async function upsertTranslation({
  entityType,
  entityId,
  locale,
  fieldName,
  value,
  status = 'draft',
  source = 'manual',
}) {
  const { rows } = await pool.query(
    `INSERT INTO entity_translations (entity_type, entity_id, locale, field_name, value, status, source)
     VALUES ($1, $2, $3, $4, $5, $6, $7)
     ON CONFLICT (entity_type, entity_id, locale, field_name)
     DO UPDATE SET value = EXCLUDED.value, status = EXCLUDED.status, source = EXCLUDED.source, updated_at = now()
     RETURNING *`,
    [entityType, entityId, locale, fieldName, value, status, source],
  );
  return rows[0];
}

async function getEntityCanonical(entityType, entityId) {
  const tables = {
    era: { table: 'historical_eras', fields: ['name', 'description'] },
    movement: { table: 'art_movements', fields: ['name', 'description'] },
    artist: { table: 'artists', fields: ['name', 'bio_short', 'bio_full'] },
    artist_period: { table: 'artist_periods', fields: ['name', 'description'] },
    painting: { table: 'paintings', fields: ['title', 'description'] },
    annotation: { table: 'painting_annotations', fields: ['label', 'body'] },
    influence_source: {
      table: 'painting_influence_sources',
      fields: ['notes', 'aspects', 'quote', 'period_note'],
    },
  };
  const spec = tables[entityType];
  if (!spec) return null;
  const cols = ['id', ...spec.fields].join(', ');
  const { rows } = await pool.query(
    `SELECT ${cols} FROM ${spec.table} WHERE id = $1`,
    [entityId],
  );
  return rows[0] || null;
}

async function listTranslations(filters = {}) {
  const conditions = [];
  const params = [];
  if (filters.entityType) {
    params.push(filters.entityType);
    conditions.push(`entity_type = $${params.length}`);
  }
  if (filters.locale) {
    params.push(filters.locale);
    conditions.push(`locale = $${params.length}`);
  }
  if (filters.status) {
    params.push(filters.status);
    conditions.push(`status = $${params.length}`);
  }
  const where = conditions.length ? `WHERE ${conditions.join(' AND ')}` : '';
  const { rows } = await pool.query(
    `SELECT * FROM entity_translations ${where} ORDER BY entity_type, entity_id, field_name LIMIT 5000`,
    params,
  );
  return rows;
}

async function getTranslationCoverage(locale = 'ru') {
  const { rows } = await pool.query(
    `SELECT
      (SELECT COUNT(*)::int FROM artists) AS artists_total,
      (SELECT COUNT(DISTINCT entity_id)::int FROM entity_translations
        WHERE entity_type = 'artist' AND locale = $1 AND field_name = 'bio_full' AND status = 'published') AS artists_bio_full,
      (SELECT COUNT(*)::int FROM paintings) AS paintings_total,
      (SELECT COUNT(DISTINCT entity_id)::int FROM entity_translations
        WHERE entity_type = 'painting' AND locale = $1 AND field_name = 'title' AND status = 'published') AS paintings_title,
      (SELECT COUNT(*)::int FROM entity_translations WHERE locale = $1 AND status = 'draft') AS draft_count,
      (SELECT COUNT(*)::int FROM entity_translations WHERE locale = $1 AND status = 'published') AS published_count`,
    [locale],
  );
  return rows[0];
}

module.exports = {
  SUPPORTED_LOCALES,
  DEFAULT_LOCALE,
  TRANSLATABLE_FIELDS,
  PUBLIC_STATUSES,
  CURATOR_STATUSES,
  resolveLocale,
  translationStatuses,
  loadTranslationsByType,
  localizeEras,
  localizeMovements,
  localizeArtists,
  localizePeriods,
  localizePaintings,
  localizeAnnotations,
  localizeInfluenceSources,
  upsertTranslation,
  getEntityCanonical,
  listTranslations,
  getTranslationCoverage,
};