import { readdir, stat } from 'node:fs/promises'
import { basename, extname, join, relative, sep } from 'node:path'
import {
  detectMediaKind,
  detectMediaRole,
  escapePostgresLikeLiteral,
  extractMediaReferences,
  normalizeMediaCatalogUrl
} from '../../lib/media-catalog.js'
import {
  getPageCoverThumbnailUrl,
  getPostBodyPreviewThumbnailUrl,
  getPostBodyThumbnailUrl,
  isPageCoverThumbnailUrl,
  isPostBody1600ThumbnailUrl,
  isPostBody720ThumbnailUrl,
  isPostCardThumbnailUrl
} from '../../lib/post-card-thumbnail-url.js'
import { getPostgresClient } from './postgres-client.js'
import { getUploadRoot } from '../utils/upload-root.js'

const uploadRoot = getUploadRoot()
const catalogFilePattern = /\.(jpe?g|png|webp|gif|mp4|webm|mov|mp3|wav|ogg|m4a|pdf|zip|txt|csv|docx|xlsx|pptx)$/i

/**
 * 게시물 원본 URL의 카드 썸네일 URL을 만든다.
 * @param {string} url - 게시물 원본 이미지 URL
 * @returns {string} 카드 썸네일 URL
 */
const getCatalogPostThumbnailUrl = (url) => String(url || '').replace(
  /\/([^/]+)\.(?:jpe?g|png|webp)$/i,
  '/thumbs/$1-card.webp'
)

/**
 * 카탈로그 오류 상세를 제한된 문자열로 정리한다.
 * @param {unknown} error - 원본 오류
 * @returns {string} 저장 가능한 오류 코드
 */
const getCatalogErrorDetail = (error) => String(error?.code || error?.message || 'MEDIA_CATALOG_ERROR').slice(0, 300)

/**
 * 참조 필드의 관리자 표시 이름을 반환한다.
 * @param {string} field - 참조 필드
 * @returns {string} 표시 이름
 */
const getReferenceFieldLabel = (field) => ({
  content: '본문',
  featuredImage: '대표 이미지',
  ogImage: '공유 이미지',
  avatarUrl: '프로필 썸네일',
  headerImageUrl: '태그 헤더 이미지',
  logoUrl: '사이트 로고',
  faviconUrl: '파비콘',
  homeCoverImageUrl: '메인 화면 라이트 이미지',
  homeCoverDarkImageUrl: '메인 화면 다크 이미지',
  cachedFaviconUrl: '추천 사이트 아이콘',
  url: '네비게이션 URL'
})[field] || field

/**
 * 참조 행을 기존 미디어 사용처 계약으로 변환한다.
 * @param {Object} reference - DB 참조 행
 * @returns {Object} 사용처
 */
const mapMediaReferenceUsage = (reference) => {
  const type = reference.reference_type === 'site_setting' ? 'settings' : reference.reference_type
  const typeMetadata = {
    post: {
      typeLabel: '게시물',
      adminUrl: `/admin/posts/${reference.reference_id}`,
      publicUrl: reference.reference_slug ? `/post/${reference.reference_slug}` : ''
    },
    page: {
      typeLabel: '페이지',
      adminUrl: `/admin/pages/${reference.reference_id}`,
      publicUrl: reference.reference_slug ? `/pages/${reference.reference_slug}` : ''
    },
    tag: {
      typeLabel: '태그',
      adminUrl: `/admin/tags/${reference.reference_id}`,
      publicUrl: reference.reference_slug ? `/tag/${reference.reference_slug}` : ''
    },
    user: {
      typeLabel: '회원',
      adminUrl: `/admin/members/${reference.reference_id}`,
      publicUrl: ''
    },
    navigation: {
      typeLabel: '네비게이션',
      adminUrl: '/admin/navigation',
      publicUrl: reference.reference_slug || ''
    },
    settings: {
      typeLabel: '사이트 설정',
      adminUrl: '/admin/settings',
      publicUrl: '/'
    }
  }[type] || {
    typeLabel: '참조',
    adminUrl: '',
    publicUrl: ''
  }

  return {
    type,
    typeLabel: typeMetadata.typeLabel,
    id: reference.reference_id,
    title: reference.reference_title,
    slug: reference.reference_slug,
    status: reference.reference_status,
    location: reference.reference_field,
    label: getReferenceFieldLabel(reference.reference_field),
    adminUrl: typeMetadata.adminUrl,
    publicUrl: typeMetadata.publicUrl
  }
}

/**
 * 사용자 행을 기존 avatarOwner 계약으로 변환한다.
 * @param {Object} row - 사용자 행
 * @returns {Object} 아바타 소유자
 */
const mapAvatarOwner = (row) => ({
  id: row.id,
  username: row.username,
  email: row.email,
  roleCode: String(row.user_role || 'member'),
  lastSeenAt: row.last_seen_at ? row.last_seen_at.toISOString() : null,
  lastSeenIp: row.last_seen_ip || ''
})

/**
 * 파생 파일의 원본 행 id를 찾는다.
 * @param {ReturnType<typeof getPostgresClient>} sql - PostgreSQL 클라이언트
 * @param {string} storageKey - 파생 저장 키
 * @returns {Promise<number|null>} 원본 행 id
 */
const findParentMediaId = async (sql, storageKey) => {
  const { parentStorageKey } = detectMediaRole(storageKey)

  if (!parentStorageKey) {
    return null
  }

  const stem = parentStorageKey.replace(/\.[^.]+$/, '')
  const rows = await sql`
    SELECT id
    FROM media_metadata
    WHERE storage_key LIKE ${`${stem}.%`}
      AND role = 'original'
    ORDER BY id ASC
    LIMIT 1
  `

  return rows[0]?.id || null
}

/**
 * 앱이 성공적으로 반영한 파일 변경 뒤 상태 집계를 현재 active 행으로 맞춘다.
 * 상태 단일 행을 잠근 뒤 집계해 동시 업로드의 마지막 갱신이 오래된 값을 쓰지 않게 한다.
 * @param {ReturnType<typeof getPostgresClient>} [client] - PostgreSQL 클라이언트
 * @returns {Promise<boolean>} 갱신 후 준비 상태
 */
export const refreshManagedMediaCatalogState = async (client = getPostgresClient()) => {
  if (!client) {
    return false
  }

  return client.begin(async (transaction) => {
    const stateRows = await transaction`
      SELECT ready, reconciled_at, error_detail
      FROM media_catalog_state
      WHERE singleton = true
      FOR UPDATE
    `

    if (!stateRows[0]) {
      return false
    }

    const summaryRows = await transaction`
      SELECT
        count(*) FILTER (WHERE status = 'active')::bigint AS active_count,
        COALESCE(sum(size_bytes) FILTER (WHERE status = 'active'), 0)::bigint AS active_bytes,
        count(*) FILTER (WHERE status IN ('staging', 'error'))::int AS incomplete_count
      FROM media_metadata
    `
    const summary = summaryRows[0]
    const ready = Boolean(stateRows[0].ready)
      && Boolean(stateRows[0].reconciled_at)
      && Number(summary.incomplete_count || 0) === 0

    await transaction`
      UPDATE media_catalog_state
      SET
        ready = ${ready},
        filesystem_count = ${summary.active_count},
        filesystem_bytes = ${summary.active_bytes},
        catalog_count = ${summary.active_count},
        catalog_bytes = ${summary.active_bytes},
        error_detail = ${ready
          ? null
          : Number(summary.incomplete_count || 0) > 0
            ? 'INCOMPLETE_MEDIA_ROWS'
            : stateRows[0].error_detail},
        updated_at = now()
      WHERE singleton = true
    `

    return ready
  })
}

/**
 * 앱에서 실제 삭제를 완료한 미디어 카탈로그 행을 제거하고 상태 집계를 맞춘다.
 * @param {Array<string>} urls - 삭제된 공개 URL 목록
 * @returns {Promise<number>} 삭제한 카탈로그 행 수
 */
export const deleteMediaCatalogEntries = async (urls) => {
  const sql = getPostgresClient()
  const normalizedUrls = [...new Set(urls.map((url) => {
    try {
      return normalizeMediaCatalogUrl(url).url
    } catch {
      return ''
    }
  }).filter(Boolean))]

  if (!sql || !normalizedUrls.length) {
    return 0
  }

  const rows = await sql`
    DELETE FROM media_metadata
    WHERE url IN ${sql(normalizedUrls)}
    RETURNING id
  `

  await refreshManagedMediaCatalogState(sql).catch(() => {
    console.warn('[media-catalog] 삭제 후 상태 집계 갱신 실패')
  })

  return rows.length
}

/**
 * 실제 파일 정보를 미디어 카탈로그에 upsert한다.
 * @param {string} inputUrl - 공개 미디어 URL
 * @param {{ category?: string, origin?: string, role?: string, refreshState?: boolean }} [options] - 기록 옵션
 * @returns {Promise<Object|null>} 카탈로그 행
 */
export const upsertMediaCatalogFile = async (inputUrl, options = {}) => {
  const sql = getPostgresClient()

  if (!sql) {
    return null
  }

  const { url, storageKey } = normalizeMediaCatalogUrl(inputUrl)
  const filePath = join(uploadRoot, ...storageKey.split('/'))
  const fileStat = await stat(filePath)
  const detected = detectMediaRole(storageKey)
  const role = options.role || detected.role
  const origin = options.origin || (role === 'original' ? 'upload' : 'derived')
  const parentId = await findParentMediaId(sql, storageKey)
  const rows = await sql`
    INSERT INTO media_metadata (
      url,
      category,
      file_name,
      storage_key,
      extension,
      kind,
      role,
      size_bytes,
      modified_at,
      parent_id,
      origin,
      status,
      last_seen_at,
      missing_since,
      error_detail
    )
    VALUES (
      ${url},
      ${String(options.category || '미분류').trim() || '미분류'},
      ${basename(storageKey)},
      ${storageKey},
      ${extname(storageKey).toLowerCase()},
      ${detectMediaKind(storageKey)},
      ${role},
      ${fileStat.size},
      ${fileStat.mtime},
      ${parentId},
      ${origin},
      'active',
      now(),
      NULL,
      NULL
    )
    ON CONFLICT (url) DO UPDATE
    SET
      category = CASE
        WHEN ${Boolean(options.category)} THEN EXCLUDED.category
        ELSE media_metadata.category
      END,
      file_name = EXCLUDED.file_name,
      storage_key = EXCLUDED.storage_key,
      extension = EXCLUDED.extension,
      kind = EXCLUDED.kind,
      role = EXCLUDED.role,
      size_bytes = EXCLUDED.size_bytes,
      modified_at = EXCLUDED.modified_at,
      parent_id = COALESCE(EXCLUDED.parent_id, media_metadata.parent_id),
      origin = CASE
        WHEN media_metadata.origin = 'external' THEN EXCLUDED.origin
        ELSE media_metadata.origin
      END,
      status = 'active',
      last_seen_at = now(),
      missing_since = NULL,
      error_detail = NULL,
      updated_at = now()
    RETURNING *
  `

  if (options.refreshState !== false) {
    await refreshManagedMediaCatalogState(sql).catch(() => {
      console.warn('[media-catalog] 관리 파일 상태 집계 갱신 실패')
    })
  }

  return rows[0] || null
}

/**
 * 기존 기능을 막지 않는 최선 노력 방식으로 파일을 카탈로그에 기록한다.
 * @param {string} url - 공개 미디어 URL
 * @param {{ category?: string, origin?: string, role?: string, refreshState?: boolean }} [options] - 기록 옵션
 * @returns {Promise<boolean>} 기록 성공 여부
 */
export const recordMediaCatalogFile = async (url, options = {}) => {
  try {
    await upsertMediaCatalogFile(url, options)
    return true
  } catch (error) {
    const sql = getPostgresClient()

    if (sql) {
      try {
        const normalized = normalizeMediaCatalogUrl(url)
        await sql`
          INSERT INTO media_metadata (
            url,
            category,
            file_name,
            storage_key,
            extension,
            kind,
            role,
            origin,
            status,
            error_detail
          )
          VALUES (
            ${normalized.url},
            ${String(options.category || '미분류').trim() || '미분류'},
            ${basename(normalized.storageKey)},
            ${normalized.storageKey},
            ${extname(normalized.storageKey).toLowerCase()},
            ${detectMediaKind(normalized.storageKey)},
            ${options.role || detectMediaRole(normalized.storageKey).role},
            ${options.origin || 'upload'},
            'error',
            ${getCatalogErrorDetail(error)}
          )
          ON CONFLICT (url) DO UPDATE
          SET
            status = 'error',
            error_detail = ${getCatalogErrorDetail(error)},
            updated_at = now()
        `
      } catch {
        // 기존 파일 작업 성공을 카탈로그 보조 기록 실패로 되돌리지 않는다.
      }
    }

    console.warn('[media-catalog] 파일 인덱스 기록 실패')
    return false
  }
}

/**
 * 한 대상의 미디어 참조를 현재 필드 값으로 교체한다.
 * @param {string} referenceType - 참조 종류
 * @param {string|number} referenceId - 참조 대상 id
 * @param {Record<string, unknown>} fields - URL을 포함할 수 있는 필드
 * @param {{ title?: string, slug?: string, status?: string }} [metadata] - 표시 메타
 * @returns {Promise<number>} 저장한 참조 수
 */
export const replaceMediaReferences = async (referenceType, referenceId, fields, metadata = {}) => {
  const sql = getPostgresClient()

  if (!sql) {
    return 0
  }

  const references = extractMediaReferences(fields)
  const targetId = String(referenceId)

  await sql.begin(async (tx) => {
    await tx`
      DELETE FROM media_references
      WHERE reference_type = ${referenceType}
        AND reference_id = ${targetId}
    `

    for (const reference of references) {
      await tx`
        INSERT INTO media_references (
          media_id,
          media_url,
          reference_type,
          reference_id,
          reference_field,
          reference_title,
          reference_slug,
          reference_status
        )
        SELECT
          media_metadata.id,
          ${reference.mediaUrl},
          ${referenceType},
          ${targetId},
          ${reference.referenceField},
          ${String(metadata.title || '')},
          ${String(metadata.slug || '')},
          ${String(metadata.status || '')}
        FROM (SELECT 1) AS source
        LEFT JOIN media_metadata
          ON media_metadata.url = ${reference.mediaUrl}
        ON CONFLICT (media_url, reference_type, reference_id, reference_field)
        DO UPDATE SET
          media_id = EXCLUDED.media_id,
          reference_title = EXCLUDED.reference_title,
          reference_slug = EXCLUDED.reference_slug,
          reference_status = EXCLUDED.reference_status,
          updated_at = now()
      `
    }
  })

  return references.length
}

/**
 * DB 행 묶음을 기존 관리자 미디어 항목 계약으로 변환한다.
 * @param {Array<Object>} outputRows - 응답에 포함할 미디어 행
 * @param {Array<Object>} contextRows - parent·child 판별용 행
 * @param {Array<Object>} referenceRows - 관련 참조 행
 * @param {Array<Object>} avatarRows - 관련 사용자 행
 * @returns {Array<Object>} 미디어 항목 목록
 */
const buildMediaCatalogItems = (outputRows, contextRows, referenceRows, avatarRows) => {
  const referencesByUrl = new Map()

  for (const reference of referenceRows) {
    const usages = referencesByUrl.get(reference.media_url) || []
    usages.push(mapMediaReferenceUsage(reference))
    referencesByUrl.set(reference.media_url, usages)
  }

  const avatarOwnerByUrl = new Map()

  for (const avatar of avatarRows) {
    if (avatar.avatar_url && !avatarOwnerByUrl.has(avatar.avatar_url)) {
      avatarOwnerByUrl.set(avatar.avatar_url, mapAvatarOwner(avatar))
    }
  }

  const byId = new Map(contextRows.map((row) => [String(row.id), row]))
  const childrenByParentId = new Map()

  for (const row of contextRows) {
    if (!row.parent_id) {
      continue
    }
    const children = childrenByParentId.get(String(row.parent_id)) || []
    children.push(row)
    childrenByParentId.set(String(row.parent_id), children)
  }

  return outputRows.map((row) => {
    const original = row.parent_id ? byId.get(String(row.parent_id)) : null
    const directUsage = referencesByUrl.get(row.url) || []
    const inheritedUsage = original
      ? (referencesByUrl.get(original.url) || []).filter((usage) => {
          if (row.role === 'card') {
            return usage.location === 'featuredImage'
          }
          if (row.role === 'page_cover') {
            return usage.type === 'page' && usage.location === 'featuredImage'
          }
          return usage.location === 'content'
        }).map((usage) => ({
          ...usage,
          location: row.role === 'card'
            ? 'featuredImageThumbnail'
            : row.role === 'page_cover'
              ? 'pageCoverThumbnail'
              : 'contentBodyImage',
          sourceUrl: original.url
        }))
      : []
    const children = childrenByParentId.get(String(row.id)) || []
    const cardChild = children.find((child) => child.role === 'card' && isPostCardThumbnailUrl(child.url))
    const pageCoverChild = children.find((child) => child.role === 'page_cover' && isPageCoverThumbnailUrl(child.url))
    const body1600Child = children.find((child) => child.role === 'body' && isPostBody1600ThumbnailUrl(child.url))
    const body720Child = children.find((child) => child.role === 'body' && isPostBody720ThumbnailUrl(child.url))
    const isPostUploadImage = row.role === 'original'
      && row.kind === 'image'
      && row.storage_key.startsWith('posts/')
      && !String(row.storage_key).includes('/thumbs/')
    const isFeaturedImage = directUsage.some((usage) => usage.type === 'post' && usage.location === 'featuredImage')
    const isPageCoverImage = directUsage.some((usage) => usage.type === 'page' && usage.location === 'featuredImage')
    const isContentImage = directUsage.some((usage) => usage.location === 'content')

    const avatarOwner = avatarOwnerByUrl.get(row.url) || null
    const usage = [...directUsage, ...inheritedUsage].filter((entry) => !(
      entry.type === 'user' && entry.location === 'avatarUrl'
    ))

    return {
      url: row.url,
      name: row.file_name,
      title: basename(row.file_name, row.extension || extname(row.file_name)),
      size: Number(row.size_bytes || 0),
      extension: row.extension || extname(row.file_name).toLowerCase(),
      kind: row.kind,
      updatedAt: (row.modified_at || row.updated_at).toISOString(),
      category: row.category,
      usage,
      thumbnailStatus: cardChild
        ? {
            role: 'original',
            variant: 'postCard',
            thumbnailUrl: cardChild.url,
            hasThumbnail: true,
            isFallbackActive: false
          }
        : pageCoverChild
          ? {
              role: 'original',
              variant: 'pageCover',
              thumbnailUrl: pageCoverChild.url,
              hasThumbnail: true,
              isFallbackActive: false
            }
          : isPostUploadImage && isFeaturedImage
            ? {
                role: 'original',
                variant: 'postCard',
                thumbnailUrl: getCatalogPostThumbnailUrl(row.url),
                hasThumbnail: false,
                isFallbackActive: true
              }
            : isPostUploadImage && isPageCoverImage
              ? {
                  role: 'original',
                  variant: 'pageCover',
                  thumbnailUrl: getPageCoverThumbnailUrl(row.url),
                  hasThumbnail: false,
                  isFallbackActive: true
                }
              : isPostUploadImage
                ? {
                    role: 'original',
                    variant: 'postCard',
                    thumbnailUrl: getCatalogPostThumbnailUrl(row.url),
                    hasThumbnail: false,
                    isFallbackActive: false
                  }
                : ['card', 'page_cover'].includes(row.role)
                  ? { role: row.role === 'card' ? 'card' : 'pageCover', originalUrl: original?.url || '' }
                  : null,
      bodyThumbnailStatus: isPostUploadImage
        ? {
            role: 'original',
            thumbnailUrl: body1600Child?.url || getPostBodyThumbnailUrl(row.url),
            previewThumbnailUrl: body720Child?.url || getPostBodyPreviewThumbnailUrl(row.url),
            hasThumbnail: Boolean(body1600Child),
            hasPreviewThumbnail: Boolean(body720Child),
            isFallbackActive: isContentImage && !body1600Child
          }
        : row.role === 'body'
          ? { role: 'body', originalUrl: original?.url || '' }
          : null,
      avatarOwner
    }
  })
}

/**
 * 선택된 미디어 행의 parent·child·참조·아바타 소유자를 함께 조회한다.
 * @param {ReturnType<typeof getPostgresClient>} sql - PostgreSQL 클라이언트
 * @param {Array<Object>} rows - 응답 미디어 행
 * @returns {Promise<Array<Object>>} 기존 계약 미디어 항목
 */
const hydrateMediaCatalogRows = async (sql, rows) => {
  if (!rows.length) {
    return []
  }

  const rowIds = rows.map((row) => row.id)
  const parentIds = rows.map((row) => row.parent_id).filter(Boolean)
  const contextRows = await sql`
    SELECT *
    FROM media_metadata
    WHERE status = 'active'
      AND (
        id IN ${sql([...new Set([...rowIds, ...parentIds])])}
        OR parent_id IN ${sql(rowIds)}
      )
  `
  const contextById = new Map(contextRows.map((row) => [String(row.id), row]))
  const referenceUrls = [...new Set(rows.flatMap((row) => {
    const parent = row.parent_id ? contextById.get(String(row.parent_id)) : null
    return [row.url, parent?.url].filter(Boolean)
  }))]
  const [referenceRows, avatarRows] = await Promise.all([
    sql`
      SELECT *
      FROM media_references
      WHERE media_url IN ${sql(referenceUrls)}
      ORDER BY id ASC
    `,
    sql`
      SELECT id, username, email, user_role, last_seen_at, last_seen_ip, avatar_url
      FROM users
      WHERE avatar_url IN ${sql(rows.map((row) => row.url))}
    `
  ])

  return buildMediaCatalogItems(rows, contextRows, referenceRows, avatarRows)
}

/**
 * DB 카탈로그 준비 상태를 DB 조회만으로 판정한다.
 * @returns {Promise<{ ready: boolean, reason: string }>} 준비 상태
 */
export const getMediaCatalogReadiness = async () => {
  const sql = getPostgresClient()

  if (!sql) {
    return { ready: false, reason: 'database-unavailable' }
  }

  const rows = await sql`
    SELECT
      state.ready,
      state.reconciled_at,
      state.filesystem_count,
      state.filesystem_bytes,
      state.catalog_count,
      state.catalog_bytes,
      (
        SELECT count(*)::int
        FROM media_metadata
        WHERE status IN ('staging', 'error')
      ) AS incomplete_count,
      (
        SELECT count(*)::int
        FROM media_metadata
        WHERE status = 'active'
      ) AS live_catalog_count,
      (
        SELECT COALESCE(sum(size_bytes), 0)::bigint
        FROM media_metadata
        WHERE status = 'active'
      ) AS live_catalog_bytes
    FROM media_catalog_state AS state
    WHERE state.singleton = true
  `
  const state = rows[0]

  if (!state?.reconciled_at) {
    return { ready: false, reason: 'reconcile-required' }
  }
  if (Number(state.incomplete_count || 0) > 0) {
    return { ready: false, reason: 'incomplete-rows' }
  }
  if (!state.ready
    || Number(state.filesystem_count) !== Number(state.catalog_count)
    || Number(state.filesystem_bytes) !== Number(state.catalog_bytes)
    || Number(state.live_catalog_count) !== Number(state.catalog_count)
    || Number(state.live_catalog_bytes) !== Number(state.catalog_bytes)) {
    return { ready: false, reason: 'catalog-difference' }
  }

  return { ready: true, reason: 'ready' }
}

/**
 * DB 카탈로그 전체를 기존 관리자 미디어 항목 계약으로 조회한다.
 * @returns {Promise<Array<Object>>} 미디어 항목 목록
 */
export const listMediaCatalogItems = async () => {
  const sql = getPostgresClient()

  if (!sql) {
    throw new Error('DATABASE_REQUIRED')
  }

  const rows = await sql`
    SELECT *
    FROM media_metadata
    WHERE status = 'active'
    ORDER BY modified_at DESC NULLS LAST, updated_at DESC
  `

  return hydrateMediaCatalogRows(sql, rows)
}

/**
 * 관리자 미디어 DB 페이지 조회 입력을 정규화한다.
 * @param {Record<string, unknown>} query - API query
 * @returns {Object} 정규화된 조회 입력
 */
const normalizePagedMediaQuery = (query) => {
  const tabValue = String(query.tab || 'library')
  const kindValue = String(query.kind || 'all')
  const pageSizeValue = Number(query.pageSize) || 50

  return {
    tab: ['library', 'postThumbnails', 'postBodyThumbnails', 'thumbnails'].includes(tabValue) ? tabValue : 'library',
    kind: ['all', 'image', 'video', 'audio', 'file'].includes(kindValue) ? kindValue : 'all',
    pageSize: [50, 100, 200].includes(pageSizeValue) ? pageSizeValue : 50,
    requestedPage: Math.max(1, Number(query.page) || 1),
    search: String(query.search || '').trim().toLowerCase(),
    folder: String(query.folder || '').trim(),
    unusedOnly: query.unused === '1' || query.unused === 'true'
  }
}

/**
 * DB 페이지 조회용 탭 조건을 만든다.
 * @param {ReturnType<typeof getPostgresClient>} sql - PostgreSQL 클라이언트
 * @param {string} tab - 탭
 * @returns {Object} SQL 조각
 */
const getCatalogTabCondition = (sql, tab) => {
  if (tab === 'thumbnails') {
    return sql`metadata.storage_key LIKE 'members/avatars/%'`
  }
  if (tab === 'postThumbnails') {
    return sql`metadata.role IN ('card', 'page_cover')`
  }
  if (tab === 'postBodyThumbnails') {
    return sql`metadata.role = 'body'`
  }
  return sql`metadata.storage_key NOT LIKE 'members/avatars/%' AND metadata.role NOT IN ('card', 'page_cover', 'body')`
}

/**
 * DB 페이지 조회용 잠금 조건을 만든다.
 * @param {ReturnType<typeof getPostgresClient>} sql - PostgreSQL 클라이언트
 * @returns {Object} SQL 조각
 */
const getCatalogLockedCondition = (sql) => sql`
  EXISTS (
    SELECT 1
    FROM media_references AS direct_reference
    WHERE direct_reference.media_url = metadata.url
  )
  OR EXISTS (
    SELECT 1
    FROM users AS avatar_user
    WHERE avatar_user.avatar_url = metadata.url
  )
  OR (
    metadata.parent_id IS NOT NULL
    AND EXISTS (
      SELECT 1
      FROM media_metadata AS parent_metadata
      JOIN media_references AS parent_reference
        ON parent_reference.media_url = parent_metadata.url
      WHERE parent_metadata.id = metadata.parent_id
        AND (
          (metadata.role = 'card' AND parent_reference.reference_field = 'featuredImage')
          OR (
            metadata.role = 'page_cover'
            AND parent_reference.reference_type = 'page'
            AND parent_reference.reference_field = 'featuredImage'
          )
          OR (metadata.role = 'body' AND parent_reference.reference_field = 'content')
        )
    )
  )
`

/**
 * DB에서 필터·검색·페이지 slice를 수행해 기존 paged 응답 계약을 반환한다.
 * counts는 SQL 집계 후 작은 객체만 메모리에서 조립한다.
 * @param {Record<string, unknown>} query - API query
 * @returns {Promise<Object>} paged 응답
 */
export const listPagedMediaCatalogItems = async (query) => {
  const sql = getPostgresClient()

  if (!sql) {
    throw new Error('DATABASE_REQUIRED')
  }

  const input = normalizePagedMediaQuery(query)
  const escapedSearch = escapePostgresLikeLiteral(input.search)
  const escapedFolder = escapePostgresLikeLiteral(input.folder)
  const tabCondition = getCatalogTabCondition(sql, input.tab)
  const libraryCondition = getCatalogTabCondition(sql, 'library')
  const folderCondition = input.tab === 'library' && input.folder
    ? sql`
        AND (
          metadata.category = ${input.folder}
          OR metadata.category LIKE ${`${escapedFolder}/%`} ESCAPE '!'
        )
      `
    : sql``
  const kindCondition = input.kind === 'all' ? sql`` : sql`AND metadata.kind = ${input.kind}`
  const lockedCondition = getCatalogLockedCondition(sql)
  const unusedCondition = input.unusedOnly ? sql`AND NOT (${lockedCondition})` : sql``
  const searchCondition = input.search
    ? sql`
        AND (
          lower(metadata.file_name) LIKE ${`%${escapedSearch}%`} ESCAPE '!'
          OR EXISTS (
            SELECT 1
            FROM media_references AS search_reference
            LEFT JOIN media_metadata AS search_parent
              ON search_parent.id = metadata.parent_id
            WHERE lower(search_reference.reference_title) LIKE ${`%${escapedSearch}%`} ESCAPE '!'
              AND (
                search_reference.media_url = metadata.url
                OR (
                  search_reference.media_url = search_parent.url
                  AND (
                    (metadata.role = 'card' AND search_reference.reference_field = 'featuredImage')
                    OR (
                      metadata.role = 'page_cover'
                      AND search_reference.reference_type = 'page'
                      AND search_reference.reference_field = 'featuredImage'
                    )
                    OR (metadata.role = 'body' AND search_reference.reference_field = 'content')
                  )
                )
              )
          )
        )
      `
    : sql``
  const totalRows = await sql`
    SELECT count(*)::int AS total
    FROM media_metadata AS metadata
    WHERE metadata.status = 'active'
      AND ${tabCondition}
      ${folderCondition}
      ${kindCondition}
      ${unusedCondition}
      ${searchCondition}
  `
  const total = Number(totalRows[0]?.total || 0)
  const pageCount = Math.max(1, Math.ceil(total / input.pageSize))
  const page = Math.min(input.requestedPage, pageCount)
  const offset = (page - 1) * input.pageSize
  const [rows, tabCountRows, folderCountRows, kindCountRows, usageCountRows] = await Promise.all([
    sql`
      SELECT metadata.*
      FROM media_metadata AS metadata
      WHERE metadata.status = 'active'
        AND ${tabCondition}
        ${folderCondition}
        ${kindCondition}
        ${unusedCondition}
        ${searchCondition}
      ORDER BY metadata.modified_at DESC NULLS LAST, metadata.updated_at DESC
      LIMIT ${input.pageSize}
      OFFSET ${offset}
    `,
    sql`
      SELECT
        count(*) FILTER (
          WHERE storage_key NOT LIKE 'members/avatars/%'
            AND role NOT IN ('card', 'page_cover', 'body')
        )::int AS library,
        count(*) FILTER (WHERE role IN ('card', 'page_cover'))::int AS post_thumbnails,
        count(*) FILTER (WHERE role = 'body')::int AS post_body_thumbnails,
        count(*) FILTER (WHERE storage_key LIKE 'members/avatars/%')::int AS thumbnails
      FROM media_metadata
      WHERE status = 'active'
    `,
    sql`
      SELECT
        array_to_string(category_parts[1:depth], '/') AS folder,
        count(*)::int AS count
      FROM media_metadata AS metadata
      CROSS JOIN LATERAL (
        SELECT string_to_array(COALESCE(NULLIF(metadata.category, ''), '미분류'), '/') AS category_parts
      ) AS category_values
      CROSS JOIN LATERAL generate_series(1, array_length(category_parts, 1)) AS depth
      WHERE metadata.status = 'active'
        AND ${libraryCondition}
      GROUP BY folder
    `,
    sql`
      SELECT metadata.kind, count(*)::int AS count
      FROM media_metadata AS metadata
      WHERE metadata.status = 'active'
        AND ${tabCondition}
        ${folderCondition}
      GROUP BY metadata.kind
    `,
    sql`
      SELECT
        count(*)::int AS all_count,
        count(*) FILTER (WHERE NOT (${lockedCondition}))::int AS unused_count
      FROM media_metadata AS metadata
      WHERE metadata.status = 'active'
        AND ${tabCondition}
        ${folderCondition}
        ${kindCondition}
    `
  ])
  const items = await hydrateMediaCatalogRows(sql, rows)
  const folders = {}

  for (const row of folderCountRows) {
    folders[row.folder] = Number(row.count)
  }
  const kinds = { all: 0, image: 0, video: 0, audio: 0, file: 0 }

  for (const row of kindCountRows) {
    kinds[row.kind] = Number(row.count)
    kinds.all += Number(row.count)
  }

  return {
    items,
    pagination: {
      page,
      pageSize: input.pageSize,
      total,
      pageCount
    },
    counts: {
      tabs: {
        library: Number(tabCountRows[0]?.library || 0),
        postThumbnails: Number(tabCountRows[0]?.post_thumbnails || 0),
        postBodyThumbnails: Number(tabCountRows[0]?.post_body_thumbnails || 0),
        thumbnails: Number(tabCountRows[0]?.thumbnails || 0)
      },
      folders,
      kinds,
      usage: {
        all: Number(usageCountRows[0]?.all_count || 0),
        unused: Number(usageCountRows[0]?.unused_count || 0)
      }
    }
  }
}

/**
 * 업로드 루트의 지원 파일 경로를 재귀적으로 읽는다.
 * @param {string} directoryPath - 스캔 디렉터리
 * @returns {Promise<Array<string>>} 절대 파일 경로
 */
const scanCatalogFiles = async (directoryPath) => {
  const entries = await readdir(directoryPath, { withFileTypes: true }).catch(() => [])
  const nested = await Promise.all(entries.map((entry) => {
    const path = join(directoryPath, entry.name)

    if (entry.isDirectory()) {
      return scanCatalogFiles(path)
    }
    return catalogFilePattern.test(entry.name) ? [path] : []
  }))

  return nested.flat()
}

/**
 * 콘텐츠 전반의 현재 미디어 참조를 초기 백필한다.
 * @returns {Promise<number>} 저장된 참조 수
 */
export const backfillMediaReferences = async () => {
  const sql = getPostgresClient()

  if (!sql) {
    return 0
  }

  const [posts, pages, tags, users, settings, navigation] = await Promise.all([
    sql`SELECT id, title, slug, status, content, featured_image FROM posts`,
    sql`SELECT id, title, slug, status, content, featured_image FROM pages`,
    sql`SELECT id, name, slug, tag_type, header_image_url FROM tags`,
    sql`SELECT id, username, avatar_url FROM users WHERE avatar_url IS NOT NULL`,
    sql`SELECT * FROM site_settings LIMIT 1`,
    sql`SELECT id, label, url, cached_favicon_url FROM navigation_items`
  ])
  let count = 0

  for (const post of posts) {
    count += await replaceMediaReferences('post', post.id, {
      content: post.content,
      featuredImage: post.featured_image
    }, post)
  }
  for (const page of pages) {
    count += await replaceMediaReferences('page', page.id, {
      content: page.content,
      featuredImage: page.featured_image
    }, page)
  }
  for (const tag of tags) {
    count += await replaceMediaReferences('tag', tag.id, {
      headerImageUrl: tag.header_image_url
    }, {
      title: tag.name,
      slug: tag.slug,
      status: tag.tag_type
    })
  }
  for (const user of users) {
    count += await replaceMediaReferences('user', user.id, {
      avatarUrl: user.avatar_url
    }, {
      title: user.username
    })
  }
  if (settings[0]) {
    count += await replaceMediaReferences('site_setting', 'site', {
      logoUrl: settings[0].logo_url,
      faviconUrl: settings[0].favicon_url,
      homeCoverImageUrl: settings[0].home_cover_image_url,
      homeCoverDarkImageUrl: settings[0].home_cover_dark_image_url
    }, {
      title: '사이트 설정'
    })
  }
  for (const item of navigation) {
    count += await replaceMediaReferences('navigation', item.id, {
      url: item.url,
      cachedFaviconUrl: item.cached_favicon_url
    }, {
      title: item.label,
      slug: item.url,
      status: 'navigation'
    })
  }

  return count
}

/**
 * 파일을 변경하지 않고 카탈로그를 실제 업로드 디렉터리와 재동기화한다.
 * @returns {Promise<Object>} 비교 보고
 */
export const reconcileMediaCatalog = async () => {
  const sql = getPostgresClient()

  if (!sql) {
    throw new Error('DATABASE_REQUIRED')
  }

  await sql`
    UPDATE media_catalog_state
    SET
      ready = false,
      error_detail = NULL,
      updated_at = now()
    WHERE singleton = true
  `
  const startedAt = new Date()
  const files = await scanCatalogFiles(uploadRoot)
  const derivativeUrls = []
  let totalBytes = 0
  const kinds = { image: 0, video: 0, audio: 0, file: 0 }

  for (const filePath of files) {
    const storageKey = relative(uploadRoot, filePath).split(sep).join('/')
    const url = `/uploads/${storageKey}`
    const fileStat = await stat(filePath)
    const kind = detectMediaKind(storageKey)
    totalBytes += fileStat.size
    kinds[kind] += 1
    await upsertMediaCatalogFile(url, {
      origin: 'external',
      refreshState: false
    })
    if (detectMediaRole(storageKey).role !== 'original') {
      derivativeUrls.push(url)
    }
  }

  for (const url of derivativeUrls) {
    await upsertMediaCatalogFile(url, {
      origin: 'external',
      refreshState: false
    })
  }

  const missingRows = await sql`
    UPDATE media_metadata
    SET
      status = 'missing',
      missing_since = COALESCE(missing_since, now()),
      updated_at = now()
    WHERE status IN ('active', 'error', 'staging')
      AND (last_seen_at IS NULL OR last_seen_at < ${startedAt})
    RETURNING id
  `
  const referenceCount = await backfillMediaReferences()
  const catalogRows = await sql`
    SELECT
      count(*) FILTER (WHERE status = 'active')::int AS active_count,
      COALESCE(sum(size_bytes) FILTER (WHERE status = 'active'), 0)::bigint AS active_bytes,
      count(*) FILTER (WHERE status IN ('staging', 'error'))::int AS incomplete_count
    FROM media_metadata
  `
  const activeCount = Number(catalogRows[0]?.active_count || 0)
  const activeBytes = Number(catalogRows[0]?.active_bytes || 0)
  const isReady = activeCount === files.length
    && activeBytes === totalBytes
    && Number(catalogRows[0]?.incomplete_count || 0) === 0

  await sql`
    UPDATE media_catalog_state
    SET
      ready = ${isReady},
      reconciled_at = now(),
      filesystem_count = ${files.length},
      filesystem_bytes = ${totalBytes},
      catalog_count = ${activeCount},
      catalog_bytes = ${activeBytes},
      error_detail = ${isReady ? null : 'CATALOG_DIFFERENCE'},
      updated_at = now()
    WHERE singleton = true
  `

  return {
    scanned: {
      count: files.length,
      bytes: totalBytes,
      kinds
    },
    catalog: {
      activeCount,
      activeBytes,
      markedMissing: missingRows.length,
      references: referenceCount,
      ready: isReady
    },
    difference: {
      count: activeCount - files.length,
      bytes: activeBytes - totalBytes
    }
  }
}