import {
  createDailyVisitorHash,
  getAnalyticsDayKey
} from '../../lib/analytics.js'
import { getPostgresClient } from './postgres-client.js'
import { getRuntimeEnvValue } from '../utils/runtime-env.js'

/**
 * 통계 해시용 시크릿을 반환한다.
 * @returns {string} 시크릿
 */
const getAnalyticsHashSecret = () => {
  return getRuntimeEnvValue(
    'ANALYTICS_HASH_SECRET',
    'analyticsHashSecret',
    getRuntimeEnvValue('MEMBER_SESSION_SECRET', 'memberSessionSecret', 'analytics-fallback-secret')
  ).trim()
}

/**
 * 일별 사이트 통계 행을 보장한다.
 * @param {import('postgres').Sql} sql - DB 클라이언트
 * @param {string} day - YYYY-MM-DD
 * @returns {Promise<void>}
 */
const ensureSiteDailyRow = async (sql, day) => {
  await sql`
    INSERT INTO site_analytics_daily (day)
    VALUES (${day})
    ON CONFLICT (day) DO NOTHING
  `
}

/**
 * 일별 게시물 통계 행을 보장한다.
 * @param {import('postgres').Sql} sql - DB 클라이언트
 * @param {string} day - YYYY-MM-DD
 * @param {string} postId - 게시물 ID
 * @returns {Promise<void>}
 */
const ensurePostDailyRow = async (sql, day, postId) => {
  await sql`
    INSERT INTO post_analytics_daily (day, post_id)
    VALUES (${day}, ${postId})
    ON CONFLICT (day, post_id) DO NOTHING
  `
}

/**
 * 사이트 방문자를 등록하고 신규 방문자면 true를 반환한다.
 * @param {import('postgres').Sql} sql - DB 클라이언트
 * @param {string} day - YYYY-MM-DD
 * @param {string} visitorHash - 방문자 해시
 * @returns {Promise<boolean>} 신규 방문자 여부
 */
const registerSiteVisitor = async (sql, day, visitorHash) => {
  const rows = await sql`
    INSERT INTO analytics_daily_visitors (day, scope, visitor_hash)
    VALUES (${day}, 'site', ${visitorHash})
    ON CONFLICT DO NOTHING
    RETURNING id
  `

  return Boolean(rows[0])
}

/**
 * 게시물 방문자를 등록하고 신규 방문자면 true를 반환한다.
 * @param {import('postgres').Sql} sql - DB 클라이언트
 * @param {string} day - YYYY-MM-DD
 * @param {string} postId - 게시물 ID
 * @param {string} visitorHash - 방문자 해시
 * @returns {Promise<boolean>} 신규 방문자 여부
 */
const registerPostVisitor = async (sql, day, postId, visitorHash) => {
  const rows = await sql`
    INSERT INTO analytics_daily_visitors (day, scope, post_id, visitor_hash)
    VALUES (${day}, 'post', ${postId}, ${visitorHash})
    ON CONFLICT DO NOTHING
    RETURNING id
  `

  return Boolean(rows[0])
}

/**
 * 페이지뷰·읽음 이벤트를 기록한다.
 * @param {{ visitorHash: string, postId?: string | null, recordSite?: boolean, recordView?: boolean, recordRead?: boolean }} input - 기록 입력
 * @returns {Promise<{ ok: true }>}
 */
export const recordAnalyticsPageview = async (input) => {
  const sql = getPostgresClient()

  if (!sql) {
    return { ok: true }
  }

  const day = getAnalyticsDayKey()
  const visitorHash = input.visitorHash
  const postId = input.postId || null
  const recordSite = input.recordSite !== false
  const recordView = Boolean(input.recordView)
  const recordRead = Boolean(input.recordRead)

  if (recordSite) {
    await ensureSiteDailyRow(sql, day)

    const isNewSiteVisitor = await registerSiteVisitor(sql, day, visitorHash)

    await sql`
      UPDATE site_analytics_daily
      SET
        page_views = page_views + 1,
        visitors = visitors + ${isNewSiteVisitor ? 1 : 0}
      WHERE day = ${day}
    `
  }

  if (!postId) {
    return { ok: true }
  }

  await ensurePostDailyRow(sql, day, postId)

  if (recordView) {
    const isNewPostVisitor = await registerPostVisitor(sql, day, postId, visitorHash)

    await sql`
      UPDATE post_analytics_daily
      SET
        views = views + 1,
        visitors = visitors + ${isNewPostVisitor ? 1 : 0}
      WHERE day = ${day}
        AND post_id = ${postId}
    `
  }

  if (recordRead) {
    await sql`
      UPDATE post_analytics_daily
      SET reads = reads + 1
      WHERE day = ${day}
        AND post_id = ${postId}
    `
  }

  return { ok: true }
}

/**
 * 요청에서 일 단위 방문자 해시를 만든다.
 * @param {import('h3').H3Event} event - H3 이벤트
 * @returns {string} visitor hash
 */
export const createVisitorHashFromEvent = (event) => {
  const day = getAnalyticsDayKey()
  const ip = String(getRequestIP(event, { xForwardedFor: true }) || '')
  const userAgent = String(getRequestHeader(event, 'user-agent') || '')

  return createDailyVisitorHash({
    day,
    ip,
    userAgent,
    secret: getAnalyticsHashSecret()
  })
}

/**
 * 통계 요약을 조회한다.
 * @param {{ days?: number }} [options] - 조회 옵션
 * @returns {Promise<Object>} 요약 통계
 */
export const getAnalyticsSummary = async (options = {}) => {
  const sql = getPostgresClient()
  const days = Math.min(Math.max(Number(options.days) || 30, 1), 365)

  if (!sql) {
    return {
      todayVisitors: 0,
      visitorsLast7Days: 0,
      pageViewsLast30Days: 0,
      days
    }
  }

  const today = getAnalyticsDayKey()

  const todayRows = await sql`
    SELECT visitors, page_views
    FROM site_analytics_daily
    WHERE day = ${today}::date
    LIMIT 1
  `

  const last7Rows = await sql`
    SELECT COALESCE(SUM(visitors), 0)::int AS visitors
    FROM site_analytics_daily
    WHERE day >= (${today}::date - 6)
  `

  const pageViewRows = await sql`
    SELECT COALESCE(SUM(page_views), 0)::int AS page_views
    FROM site_analytics_daily
    WHERE day >= (${today}::date - 29)
  `

  return {
    todayVisitors: Number(todayRows[0]?.visitors || 0),
    visitorsLast7Days: Number(last7Rows[0]?.visitors || 0),
    pageViewsLast30Days: Number(pageViewRows[0]?.page_views || 0),
    days
  }
}

/**
 * 인기 게시물 통계를 조회한다.
 * @param {{ days?: number, limit?: number }} [options] - 조회 옵션
 * @returns {Promise<Array<Object>>} 인기 게시물 목록
 */
export const getAnalyticsTopPosts = async (options = {}) => {
  const sql = getPostgresClient()
  const days = Math.min(Math.max(Number(options.days) || 30, 1), 365)
  const limit = Math.min(Math.max(Number(options.limit) || 5, 1), 20)

  if (!sql) {
    return []
  }

  const today = getAnalyticsDayKey()

  const rows = await sql`
    SELECT
      posts.id,
      posts.title,
      posts.slug,
      COALESCE(SUM(post_analytics_daily.views), 0)::int AS views,
      COALESCE(SUM(post_analytics_daily.reads), 0)::int AS reads,
      COALESCE(SUM(post_analytics_daily.visitors), 0)::int AS visitors
    FROM post_analytics_daily
    INNER JOIN posts ON posts.id = post_analytics_daily.post_id
    WHERE post_analytics_daily.day >= (${today}::date - ${days - 1})
    GROUP BY posts.id, posts.title, posts.slug
    ORDER BY views DESC, reads DESC, posts.published_at DESC NULLS LAST
    LIMIT ${limit}
  `

  return rows.map((row) => ({
    id: row.id,
    title: row.title,
    slug: row.slug,
    views: Number(row.views || 0),
    reads: Number(row.reads || 0),
    visitors: Number(row.visitors || 0)
  }))
}