// app/api/book/chapters/route.ts
// 章节管理API - 支持列表查询、新增、编辑
// 开发: 卡若
// 日期: 2026-01-25

import { NextRequest, NextResponse } from 'next/server'
import { query } from '@/lib/db'

/**
 * GET - 获取章节列表
 * 支持参数:
 * - partId: 按篇筛选
 * - status: 按状态筛选 (draft/published/archived)
 * - page: 页码
 * - pageSize: 每页数量
 */
export async function GET(req: NextRequest) {
  try {
    const { searchParams } = new URL(req.url)
    const partId = searchParams.get('partId')
    const status = searchParams.get('status') || 'published'
    const page = parseInt(searchParams.get('page') || '1')
    const pageSize = parseInt(searchParams.get('pageSize') || '100')
    
    let sql = `
      SELECT id, part_id, part_title, chapter_id, chapter_title, section_title, 
             word_count, is_free, price, sort_order, status, created_at, updated_at
      FROM chapters
      WHERE 1=1
    `
    const params: any[] = []
    
    if (partId) {
      sql += ' AND part_id = ?'
      params.push(partId)
    }
    
    if (status && status !== 'all') {
      sql += ' AND status = ?'
      params.push(status)
    }
    
    sql += ' ORDER BY sort_order ASC'
    sql += ' LIMIT ? OFFSET ?'
    params.push(pageSize, (page - 1) * pageSize)
    
    const results = await query(sql, params) as any[]
    
    // 获取总数
    let countSql = 'SELECT COUNT(*) as total FROM chapters WHERE 1=1'
    const countParams: any[] = []
    if (partId) {
      countSql += ' AND part_id = ?'
      countParams.push(partId)
    }
    if (status && status !== 'all') {
      countSql += ' AND status = ?'
      countParams.push(status)
    }
    const countResult = await query(countSql, countParams) as any[]
    const total = countResult[0]?.total || 0
    
    return NextResponse.json({
      success: true,
      data: {
        list: results,
        total,
        page,
        pageSize,
        totalPages: Math.ceil(total / pageSize)
      }
    })
  } catch (error) {
    console.error('[Chapters API] 获取列表失败:', error)
    return NextResponse.json(
      { success: false, error: '获取章节列表失败' },
      { status: 500 }
    )
  }
}

/**
 * POST - 新增章节
 */
export async function POST(req: NextRequest) {
  try {
    const body = await req.json()
    const {
      id,
      partId,
      partTitle,
      chapterId,
      chapterTitle,
      sectionTitle,
      content,
      isFree = false,
      price = 1,
      sortOrder,
      status = 'published'
    } = body
    
    // 验证必填字段
    if (!id || !partId || !partTitle || !chapterId || !chapterTitle || !sectionTitle || !content) {
      return NextResponse.json(
        { success: false, error: '缺少必填字段' },
        { status: 400 }
      )
    }
    
    // 检查ID是否已存在
    const existing = await query('SELECT id FROM chapters WHERE id = ?', [id]) as any[]
    if (existing.length > 0) {
      return NextResponse.json(
        { success: false, error: '章节ID已存在' },
        { status: 400 }
      )
    }
    
    // 计算字数
    const wordCount = content.replace(/\s/g, '').length
    
    // 计算排序顺序（如果未提供）
    let order = sortOrder
    if (order === undefined || order === null) {
      const maxOrder = await query(
        'SELECT MAX(sort_order) as maxOrder FROM chapters WHERE part_id = ?',
        [partId]
      ) as any[]
      order = (maxOrder[0]?.maxOrder || 0) + 1
    }
    
    await query(`
      INSERT INTO chapters (id, part_id, part_title, chapter_id, chapter_title, section_title, content, word_count, is_free, price, sort_order, status)
      VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
    `, [id, partId, partTitle, chapterId, chapterTitle, sectionTitle, content, wordCount, isFree, isFree ? 0 : price, order, status])
    
    console.log('[Chapters API] 新增章节成功:', id)
    
    return NextResponse.json({
      success: true,
      message: '章节创建成功',
      data: { id, wordCount, sortOrder: order }
    })
  } catch (error) {
    console.error('[Chapters API] 新增章节失败:', error)
    return NextResponse.json(
      { success: false, error: '新增章节失败' },
      { status: 500 }
    )
  }
}

/**
 * PUT - 编辑章节
 */
export async function PUT(req: NextRequest) {
  try {
    const body = await req.json()
    const { id, ...updates } = body
    
    if (!id) {
      return NextResponse.json(
        { success: false, error: '缺少章节ID' },
        { status: 400 }
      )
    }
    
    // 检查章节是否存在
    const existing = await query('SELECT id FROM chapters WHERE id = ?', [id]) as any[]
    if (existing.length === 0) {
      return NextResponse.json(
        { success: false, error: '章节不存在' },
        { status: 404 }
      )
    }
    
    // 构建更新语句
    const allowedFields = ['part_id', 'part_title', 'chapter_id', 'chapter_title', 'section_title', 'content', 'is_free', 'price', 'sort_order', 'status']
    const fieldMapping: Record<string, string> = {
      partId: 'part_id',
      partTitle: 'part_title',
      chapterId: 'chapter_id',
      chapterTitle: 'chapter_title',
      sectionTitle: 'section_title',
      isFree: 'is_free',
      sortOrder: 'sort_order'
    }
    
    const setClauses: string[] = []
    const params: any[] = []
    
    for (const [key, value] of Object.entries(updates)) {
      const dbField = fieldMapping[key] || key
      if (allowedFields.includes(dbField) && value !== undefined) {
        setClauses.push(`${dbField} = ?`)
        params.push(value)
      }
    }
    
    // 如果更新了content，重新计算字数
    if (updates.content) {
      const wordCount = updates.content.replace(/\s/g, '').length
      setClauses.push('word_count = ?')
      params.push(wordCount)
    }
    
    if (setClauses.length === 0) {
      return NextResponse.json(
        { success: false, error: '没有可更新的字段' },
        { status: 400 }
      )
    }
    
    params.push(id)
    await query(`UPDATE chapters SET ${setClauses.join(', ')} WHERE id = ?`, params)
    
    console.log('[Chapters API] 更新章节成功:', id)
    
    return NextResponse.json({
      success: true,
      message: '章节更新成功'
    })
  } catch (error) {
    console.error('[Chapters API] 更新章节失败:', error)
    return NextResponse.json(
      { success: false, error: '更新章节失败' },
      { status: 500 }
    )
  }
}

/**
 * DELETE - 删除章节（软删除，改状态为archived）
 */
export async function DELETE(req: NextRequest) {
  try {
    const { searchParams } = new URL(req.url)
    const id = searchParams.get('id')
    
    if (!id) {
      return NextResponse.json(
        { success: false, error: '缺少章节ID' },
        { status: 400 }
      )
    }
    
    // 软删除：改状态为archived
    await query("UPDATE chapters SET status = 'archived' WHERE id = ?", [id])
    
    console.log('[Chapters API] 删除章节成功:', id)
    
    return NextResponse.json({
      success: true,
      message: '章节已删除'
    })
  } catch (error) {
    console.error('[Chapters API] 删除章节失败:', error)
    return NextResponse.json(
      { success: false, error: '删除章节失败' },
      { status: 500 }
    )
  }
}