import { queryOne, execute } from '../../utils/db'
import { requireAuth } from '../../utils/session'

/**
 * 구글 그룹 메시지 조회
 * GET /api/google-group/messages
 * 
 * Gmail API로 그룹 이메일 조회
 * 
 * Query params:
 * - groupEmail: 그룹 이메일 주소 (예: dev-team@company.com)
 * - maxResults: 최대 결과 수 (기본 20)
 * - after: 이 날짜 이후 메시지 (YYYY-MM-DD)
 */
export default defineEventHandler(async (event) => {
  const session = await requireAuth(event)
  const query = getQuery(event)
  
  const groupEmail = query.groupEmail as string
  const maxResults = parseInt(query.maxResults as string) || 20
  const after = query.after as string
  
  if (!groupEmail) {
    throw createError({ statusCode: 400, message: '그룹 이메일이 필요합니다.' })
  }
  
  // 사용자의 Google 토큰 조회
  const employee = await queryOne<any>(`
    SELECT google_access_token, google_refresh_token, google_token_expires_at
    FROM wr_employee_info WHERE employee_id = $1
  `, [session.employeeId])
  
  if (!employee?.google_access_token) {
    throw createError({ 
      statusCode: 401, 
      message: 'Google 계정이 연결되지 않았습니다.' 
    })
  }
  
  let accessToken = employee.google_access_token
  
  // 토큰 만료 확인 및 갱신
  if (employee.google_token_expires_at && new Date(employee.google_token_expires_at) < new Date()) {
    accessToken = await refreshGoogleToken(session.employeeId, employee.google_refresh_token)
  }
  
  try {
    // Gmail API로 그룹 메일 검색
    let searchQuery = `list:${groupEmail}`
    if (after) {
      searchQuery += ` after:${after}`
    }
    
    const listResponse = await $fetch<any>('https://gmail.googleapis.com/gmail/v1/users/me/messages', {
      headers: { 'Authorization': `Bearer ${accessToken}` },
      query: {
        q: searchQuery,
        maxResults: maxResults
      }
    })
    
    if (!listResponse.messages || listResponse.messages.length === 0) {
      return { messages: [], total: 0 }
    }
    
    // 각 메시지의 상세 정보 조회
    const messages = await Promise.all(
      listResponse.messages.slice(0, maxResults).map(async (msg: any) => {
        const detail = await $fetch<any>(`https://gmail.googleapis.com/gmail/v1/users/me/messages/${msg.id}`, {
          headers: { 'Authorization': `Bearer ${accessToken}` },
          query: { format: 'metadata', metadataHeaders: ['Subject', 'From', 'Date', 'To'] }
        })
        
        const headers = detail.payload?.headers || []
        const getHeader = (name: string) => headers.find((h: any) => h.name === name)?.value || ''
        
        return {
          id: msg.id,
          threadId: msg.threadId,
          subject: getHeader('Subject'),
          from: getHeader('From'),
          to: getHeader('To'),
          date: getHeader('Date'),
          snippet: detail.snippet
        }
      })
    )
    
    return {
      messages,
      total: listResponse.resultSizeEstimate || messages.length
    }
  } catch (e: any) {
    console.error('Gmail API error:', e)
    
    if (e.status === 403) {
      throw createError({
        statusCode: 403,
        message: 'Gmail 접근 권한이 없습니다. Google 로그인 시 권한을 허용해주세요.'
      })
    }
    
    throw createError({
      statusCode: 500,
      message: '그룹 메시지를 가져오는데 실패했습니다.'
    })
  }
})

/**
 * Google 토큰 갱신
 */
async function refreshGoogleToken(employeeId: number, refreshToken: string): Promise<string> {
  const config = useRuntimeConfig()
  
  const response = await $fetch<any>('https://oauth2.googleapis.com/token', {
    method: 'POST',
    body: new URLSearchParams({
      client_id: config.googleClientId,
      client_secret: config.googleClientSecret,
      refresh_token: refreshToken,
      grant_type: 'refresh_token'
    }).toString(),
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' }
  })
  
  if (response.access_token) {
    await execute(`
      UPDATE wr_employee_info 
      SET google_access_token = $1, 
          google_token_expires_at = NOW() + INTERVAL '${response.expires_in} seconds'
      WHERE employee_id = $2
    `, [response.access_token, employeeId])
    
    return response.access_token
  }
  
  throw new Error('토큰 갱신 실패')
}