const http = require('http')
const mysql = require('mysql2/promise')

const PORT = 3007
const TWO_DAYS_MS = 2 * 24 * 60 * 60 * 1000

const pool = mysql.createPool({
  host: '56b4c23f6853c.gz.cdb.myqcloud.com',
  port: 14413,
  user: 'cdb_outerroot',
  password: 'Zhiqun1984',
  database: 'soul_miniprogram',
  charset: 'utf8mb4',
  waitForConnections: true,
  connectionLimit: 5,
  queueLimit: 0
})

function isExcluded(id, partTitle) {
  const lid = String(id || '').toLowerCase()
  if (lid === 'preface' || lid === 'epilogue') return true
  if (lid.startsWith('appendix-') || lid.startsWith('appendix_')) return true
  const pt = String(partTitle || '')
  if (/序言|尾声|附录/.test(pt)) return true
  return false
}

function cleanPartTitle(pt) {
  return (pt || '真实的行业').replace(/^第[一二三四五六七八九十]+篇[｜|]?/, '').trim() || '真实的行业'
}

async function getFeaturedSections() {
  const tags = [
    { tag: '热门', tagClass: 'tag-pink' },
    { tag: '推荐', tagClass: 'tag-purple' },
    { tag: '精选', tagClass: 'tag-free' }
  ]
  try {
    const [rows] = await pool.query(`
      SELECT c.id, c.section_title, c.part_title, c.is_free,
             COALESCE(t.cnt, 0) as view_count
      FROM chapters c
      LEFT JOIN (
        SELECT chapter_id, COUNT(*) as cnt
        FROM user_tracks
        WHERE action = 'view_chapter' AND chapter_id IS NOT NULL
        GROUP BY chapter_id
      ) t ON c.id = t.chapter_id
      WHERE c.id NOT IN ('preface','epilogue')
        AND c.id NOT LIKE 'appendix-%' AND c.id NOT LIKE 'appendix\\_%'
        AND c.part_title NOT LIKE '%序言%' AND c.part_title NOT LIKE '%尾声%'
        AND c.part_title NOT LIKE '%附录%'
      ORDER BY view_count DESC, c.updated_at DESC
      LIMIT 6
    `)
    if (rows && rows.length > 0) {
      return rows.slice(0, 3).map((r, i) => ({
        id: r.id,
        title: r.section_title || '',
        part: cleanPartTitle(r.part_title),
        tag: tags[i]?.tag || '推荐',
        tagClass: tags[i]?.tagClass || 'tag-purple'
      }))
    }
  } catch (e) {
    console.error('[featured] query error:', e.message)
  }
  try {
    const [fallback] = await pool.query(`
      SELECT id, section_title, part_title, is_free
      FROM chapters
      WHERE id NOT IN ('preface','epilogue')
        AND id NOT LIKE 'appendix-%' AND id NOT LIKE 'appendix\\_%'
        AND part_title NOT LIKE '%序言%' AND part_title NOT LIKE '%尾声%'
        AND part_title NOT LIKE '%附录%'
      ORDER BY updated_at DESC
      LIMIT 3
    `)
    if (fallback?.length > 0) {
      return fallback.map((r, i) => ({
        id: r.id,
        title: r.section_title || '',
        part: cleanPartTitle(r.part_title),
        tag: tags[i]?.tag || '推荐',
        tagClass: tags[i]?.tagClass || 'tag-purple'
      }))
    }
  } catch (_) {}
  return [
    { id: '1.1', title: '荷包：电动车出租的被动收入模式', tag: '免费', tagClass: 'tag-free', part: '真实的人' },
    { id: '3.1', title: '3000万流水如何跑出来', tag: '热门', tagClass: 'tag-pink', part: '真实的行业' },
    { id: '8.1', title: '流量杠杆:抖音、Soul、飞书', tag: '推荐', tagClass: 'tag-purple', part: '真实的赚钱' }
  ]
}

async function handleLatestChapters(res) {
  try {
    const [rows] = await pool.query(`
      SELECT id, part_title, section_title, is_free, price, created_at, updated_at
      FROM chapters
      ORDER BY sort_order ASC, id ASC
    `)
    let chapters = (rows || [])
      .map(r => ({
        id: r.id,
        title: r.section_title || '',
        part: cleanPartTitle(r.part_title),
        isFree: !!r.is_free,
        price: r.price || 0,
        updatedAt: r.updated_at || r.created_at,
        createdAt: r.created_at
      }))
      .filter(c => !isExcluded(c.id, c.part))

    if (chapters.length === 0) {
      return sendJSON(res, {
        success: true,
        banner: { id: '1.1', title: '开始阅读', part: '真实的人' },
        label: '为你推荐',
        chapters: [],
        hasNewUpdates: false
      })
    }

    const sorted = [...chapters].sort((a, b) => {
      const ta = a.updatedAt ? new Date(a.updatedAt).getTime() : 0
      const tb = b.updatedAt ? new Date(b.updatedAt).getTime() : 0
      return tb - ta
    })

    const mostRecentTime = sorted[0]?.updatedAt ? new Date(sorted[0].updatedAt).getTime() : 0
    const hasNewUpdates = Date.now() - mostRecentTime < TWO_DAYS_MS

    let banner, label, selected
    if (hasNewUpdates) {
      selected = sorted.slice(0, 3)
      banner = { id: selected[0].id, title: selected[0].title, part: selected[0].part }
      label = '最新更新'
    } else {
      const free = chapters.filter(c => c.isFree || c.price === 0)
      const candidates = free.length > 0 ? free : chapters
      const shuffled = [...candidates].sort(() => Math.random() - 0.5)
      selected = shuffled.slice(0, 3)
      banner = { id: selected[0].id, title: selected[0].title, part: selected[0].part }
      label = '为你推荐'
    }

    sendJSON(res, {
      success: true,
      banner,
      label,
      chapters: selected.map(c => ({ id: c.id, title: c.title, part: c.part, isFree: c.isFree })),
      hasNewUpdates
    })
  } catch (e) {
    console.error('[latest-chapters] error:', e.message)
    sendJSON(res, { success: false, error: '获取失败' }, 500)
  }
}

async function handleAllChapters(res) {
  const featuredSections = await getFeaturedSections()
  try {
    const [rows] = await pool.query(`
      SELECT id, part_id, part_title, chapter_id, chapter_title, section_title,
             content, is_free, price, word_count, sort_order, created_at, updated_at
      FROM chapters
      ORDER BY sort_order ASC, id ASC
    `)
    if (rows && rows.length > 0) {
      const seen = new Set()
      const data = rows
        .map(r => ({
          mid: r.mid || 0,
          id: r.id,
          partId: r.part_id || '',
          partTitle: r.part_title || '',
          chapterId: r.chapter_id || '',
          chapterTitle: r.chapter_title || '',
          sectionTitle: r.section_title || '',
          content: r.content || '',
          wordCount: r.word_count || 0,
          isFree: !!r.is_free,
          price: r.price || 0,
          sortOrder: r.sort_order || 0,
          status: 'published',
          createdAt: r.created_at,
          updatedAt: r.updated_at
        }))
        .filter(r => {
          if (seen.has(r.id)) return false
          seen.add(r.id)
          return true
        })

      return sendJSON(res, {
        success: true,
        data,
        total: data.length,
        featuredSections
      })
    }
  } catch (e) {
    console.error('[all-chapters] error:', e.message)
  }
  sendJSON(res, {
    success: true,
    data: [],
    total: 0,
    featuredSections
  })
}

function sendJSON(res, obj, code = 200) {
  res.writeHead(code, {
    'Content-Type': 'application/json; charset=utf-8',
    'Access-Control-Allow-Origin': '*',
    'Access-Control-Allow-Methods': 'GET, OPTIONS',
    'Access-Control-Allow-Headers': 'Content-Type, Authorization'
  })
  res.end(JSON.stringify(obj))
}

const server = http.createServer(async (req, res) => {
  if (req.method === 'OPTIONS') {
    return sendJSON(res, {})
  }
  const url = req.url.split('?')[0]
  if (url === '/api/book/latest-chapters') {
    return handleLatestChapters(res)
  }
  if (url === '/api/book/all-chapters') {
    return handleAllChapters(res)
  }
  if (url === '/health') {
    return sendJSON(res, { status: 'ok', time: new Date().toISOString() })
  }
  sendJSON(res, { error: 'not found' }, 404)
})

server.listen(PORT, '127.0.0.1', () => {
  console.log(`[soul-book-api] running on port ${PORT}`)
})