import { Router, Response } from 'express'
import pool from '../db/connection'
import { AuthRequest } from '../middleware/auth'
import { getCurrentMonth, getMonthRange } from '../utils/date'

const router = Router()
const VALID_TYPES = ['expense', 'income']

/** 根据 group_id 参数构建 WHERE 条件（含成员验证） */
async function buildWhereClause(
  userId: number | undefined,
  groupId: string | undefined,
  extraConditions: string[] = []
): Promise<{ where: string; params: any[] } | null> {
  const params: any[] = []

  if (groupId && groupId !== 'null') {
    // 验证用户是群组成员
    const [memberCheck] = await pool.query(
      'SELECT id FROM group_members WHERE group_id = ? AND user_id = ?',
      [groupId, userId]
    )
    if ((memberCheck as any[]).length === 0) return null

    // 群组视图：统计所有群组成员的个人账单
    params.push(groupId)
    let where = `WHERE t.user_id IN (SELECT user_id FROM group_members WHERE group_id = ?)`
    if (extraConditions.length > 0) where += ' AND ' + extraConditions.join(' AND ')
    return { where, params }
  }

  params.push(userId)
  let where = `WHERE t.user_id = ?`
  if (extraConditions.length > 0) where += ' AND ' + extraConditions.join(' AND ')
  return { where, params }
}

router.get('/overview', async (req: AuthRequest, res: Response) => {
  try {
    const { month, startDate: qStart, endDate: qEnd, group_id } = req.query

    let startDate: string
    let endDate: string
    let elapsedDays = 1

    if (qStart && qEnd) {
      startDate = qStart as string
      endDate = qEnd as string
      // 计算日期范围天数
      const start = new Date(startDate)
      const end = new Date(endDate)
      elapsedDays = Math.max(1, Math.ceil((end.getTime() - start.getTime()) / 86400000) + 1)
    } else {
      const m = (month as string) || getCurrentMonth()
      const range = getMonthRange(m)
      if (!range) return res.status(400).json({ code: 40001, message: '月份格式无效' })
      startDate = range.startDate
      endDate = range.endDate
      const now = new Date()
      const [year, mon] = m.split('-').map(Number)
      const isCurrentMonth = year === now.getFullYear() && mon === now.getMonth() + 1
      elapsedDays = isCurrentMonth ? now.getDate() : new Date(year, mon, 0).getDate()
    }

    const result = await buildWhereClause(
      req.userId,
      group_id as string | undefined,
      ['t.date >= ?', 't.date <= ?']
    )
    if (!result) return res.status(403).json({ code: 40300, message: '无权访问此群组' })

    const [rows] = await pool.query(
      `SELECT
        COALESCE(SUM(CASE WHEN t.type = 'expense' THEN t.amount ELSE 0 END), 0) as expense,
        COALESCE(SUM(CASE WHEN t.type = 'income' THEN t.amount ELSE 0 END), 0) as income,
        COUNT(*) as count,
        SUM(CASE WHEN t.type = 'expense' THEN 1 ELSE 0 END) as expenseCount,
        SUM(CASE WHEN t.type = 'income' THEN 1 ELSE 0 END) as incomeCount
       FROM transactions t ${result.where}`,
      [...result.params, startDate, endDate]
    )
    const row = (rows as any[])[0]
    const daily = elapsedDays > 0 ? Math.round(row.expense / elapsedDays) : 0
    const dailyIncome = elapsedDays > 0 ? Math.round(row.income / elapsedDays) : 0

    res.json({
      code: 0,
      data: {
        expense: row.expense,
        income: row.income,
        count: row.count,
        daily,
        dailyIncome,
        expenseCount: row.expenseCount,
        incomeCount: row.incomeCount
      }
    })
  } catch (err) {
    console.error('[Stats] overview error:', err)
    res.status(500).json({ code: 50000, message: '服务器错误' })
  }
})

router.get('/category', async (req: AuthRequest, res: Response) => {
  try {
    const { month, type = 'expense', group_id } = req.query
    if (!VALID_TYPES.includes(type as string)) {
      return res.status(400).json({ code: 40002, message: '类型无效' })
    }
    const m = (month as string) || getCurrentMonth()
    const range = getMonthRange(m)
    if (!range) return res.status(400).json({ code: 40001, message: '月份格式无效' })
    const { startDate, endDate } = range

    const result = await buildWhereClause(
      req.userId,
      group_id as string | undefined,
      ['t.type = ?', 't.date >= ?', 't.date <= ?']
    )
    if (!result) return res.status(403).json({ code: 40300, message: '无权访问此群组' })

    const [rows] = await pool.query(
      `SELECT c.id, COALESCE(c.name, '未分类') as name, COALESCE(c.icon, '?') as icon, COALESCE(c.color, '#BFB3B3') as color, SUM(t.amount) as amount, COUNT(t.id) as count
       FROM transactions t
       LEFT JOIN categories c ON t.category_id = c.id
       ${result.where}
       GROUP BY c.id, c.name, c.icon, c.color
       ORDER BY amount DESC`,
      [...result.params, type, startDate, endDate]
    )

    res.json({ code: 0, data: rows })
  } catch (err) {
    console.error('[Stats] category error:', err)
    res.status(500).json({ code: 50000, message: '服务器错误' })
  }
})

router.get('/trend', async (req: AuthRequest, res: Response) => {
  try {
    const { month, type = 'expense', group_id } = req.query
    if (!VALID_TYPES.includes(type as string)) {
      return res.status(400).json({ code: 40002, message: '类型无效' })
    }
    const m = (month as string) || getCurrentMonth()
    const range = getMonthRange(m)
    if (!range) return res.status(400).json({ code: 40001, message: '月份格式无效' })
    const { startDate, endDate } = range

    const result = await buildWhereClause(
      req.userId,
      group_id as string | undefined,
      ['t.type = ?', 't.date >= ?', 't.date <= ?']
    )
    if (!result) return res.status(403).json({ code: 40300, message: '无权访问此群组' })

    const [rows] = await pool.query(
      `SELECT DATE_FORMAT(t.date, '%Y-%m-%d') as date, SUM(t.amount) as amount
       FROM transactions t
       ${result.where}
       GROUP BY t.date
       ORDER BY t.date`,
      [...result.params, type, startDate, endDate]
    )

    res.json({ code: 0, data: rows })
  } catch (err) {
    console.error('[Stats] trend error:', err)
    res.status(500).json({ code: 50000, message: '服务器错误' })
  }
})

/** 智能分类建议：根据历史记录的金额和备注推荐分类 */
router.get('/suggest-category', async (req: AuthRequest, res: Response) => {
  try {
    const userId = req.userId
    const { amount, type = 'expense', note = '' } = req.query

    if (!amount || !['expense', 'income'].includes(type as string)) {
      return res.status(400).json({ code: 40001, message: '参数错误' })
    }

    const amt = parseInt(amount as string)
    const noteStr = (note as string).trim()

    // 1. 关键词匹配：从备注中提取关键词，查找历史记录中最常用的分类
    let suggestedCategory: any = null
    let confidence = 0

    if (noteStr) {
      // 提取关键词（取前4个字符以上的词）
      const keywords = noteStr.replace(/[，,。.！!？?\s]+/g, ' ').split(' ').filter(w => w.length >= 1)
      if (keywords.length > 0) {
        const likeClauses = keywords.map(() => 't.note LIKE ?').join(' OR ')
        const likeParams = keywords.map(k => `%${k}%`)

        const [rows] = await pool.query(
          `SELECT t.category_id, c.name, c.color, COUNT(*) as cnt
           FROM transactions t
           LEFT JOIN categories c ON t.category_id = c.id
           WHERE t.user_id = ? AND t.type = ? AND (${likeClauses})
           GROUP BY t.category_id, c.name, c.color
           ORDER BY cnt DESC
           LIMIT 1`,
          [userId, type, ...likeParams]
        )
        const match = (rows as any[])[0]
        if (match) {
          suggestedCategory = { id: match.category_id, name: match.name, color: match.color }
          // 置信度基于匹配次数
          confidence = Math.min(90, 40 + match.cnt * 15)
        }
      }
    }

    // 2. 金额相近匹配（±30%）
    if (!suggestedCategory) {
      const minAmt = Math.floor(amt * 0.7)
      const maxAmt = Math.ceil(amt * 1.3)
      const [rows] = await pool.query(
        `SELECT t.category_id, c.name, c.color, COUNT(*) as cnt
         FROM transactions t
         LEFT JOIN categories c ON t.category_id = c.id
         WHERE t.user_id = ? AND t.type = ? AND t.amount BETWEEN ? AND ?
         GROUP BY t.category_id, c.name, c.color
         ORDER BY cnt DESC
         LIMIT 1`,
        [userId, type, minAmt, maxAmt]
      )
      const match = (rows as any[])[0]
      if (match) {
        suggestedCategory = { id: match.category_id, name: match.name, color: match.color }
        confidence = Math.min(70, 20 + match.cnt * 10)
      }
    }

    // 3. 最近使用的分类（兜底）
    if (!suggestedCategory) {
      const [rows] = await pool.query(
        `SELECT t.category_id, c.name, c.color
         FROM transactions t
         LEFT JOIN categories c ON t.category_id = c.id
         WHERE t.user_id = ? AND t.type = ?
         ORDER BY t.created_at DESC
         LIMIT 1`,
        [userId, type]
      )
      const match = (rows as any[])[0]
      if (match) {
        suggestedCategory = { id: match.category_id, name: match.name, color: match.color }
        confidence = 20
      }
    }

    res.json({
      code: 0,
      data: {
        category: suggestedCategory,
        confidence
      }
    })
  } catch (err) {
    console.error('[Stats] suggest-category error:', err)
    res.status(500).json({ code: 50000, message: '服务器错误' })
  }
})

export default router