const { query, transaction } = require('../config/database')
const { paginate } = require('../utils/pagination')
const orderService = require('../services/orderService')
const { requireAuth } = require('./users')

const ORDER_UPDATEABLE_FIELDS = ['status', 'total_price', 'totalPrice', 'cart']

function allowedUpdateFields(body) {
  const result = {}
  for (const key of ORDER_UPDATEABLE_FIELDS) {
    if (key in body) {
      result[key] = body[key]
    }
  }
  return result
}

async function getOrders(ctx) {
  const operator = await requireAuth(ctx)
  if (!operator) return

  const { page, pageSize, status } = ctx.query
  let sql = `
    SELECT 
      o.*,
      JSON_ARRAYAGG(
        JSON_OBJECT(
          'id', oi.id,
          'order_id', oi.order_id,
          'goods_id', oi.goods_id,
          'goods_name', oi.goods_name,
          'price', oi.price,
          'quantity', oi.quantity,
          'weight', oi.weight,
          'subtotal', oi.subtotal,
          'unit', oi.unit
        )
      ) as items_json
    FROM orders o
    LEFT JOIN order_items oi ON o.id = oi.order_id
    WHERE 1=1
  `
  const params = []

  if (operator.role !== 1) {
    sql += ' AND o.user_id = ?'
    params.push(operator.id)
  }

  if (status) {
    sql += ' AND o.status = ?'
    params.push(status)
  }
  sql += ' GROUP BY o.id ORDER BY o.created_at DESC'
  
  const result = await paginate(query, sql, params, page, pageSize)

  const rows = (result.data || []).map(row => {
    let items = []
    try {
      const itemsJson = row.items_json
      if (itemsJson) {
        items = typeof itemsJson === 'string' ? JSON.parse(itemsJson) : itemsJson
        if (items.length === 1 && items[0].id === null) {
          items = []
        }
      }
    } catch {}
    
    const { items_json, ...order } = row
    return { ...order, items }
  })
  result.data = rows

  ctx.body = {
    code: 200,
    ...result
  }
}

async function getOrderById(ctx) {
  const operator = await requireAuth(ctx)
  if (!operator) return

  const orderId = ctx.params.id
  const orders = await query('SELECT * FROM orders WHERE id = ?', [orderId])

  if (orders.length > 0) {
    const order = orders[0]

    if (operator.role !== 1 && order.user_id !== operator.id) {
      ctx.body = { code: 403, message: '无权查看此订单' }
      return
    }

    order.items = await orderService.getOrderItems(orderId)
    ctx.body = {
      code: 200,
      data: order
    }
  } else {
    ctx.body = {
      code: 404,
      message: '订单不存在'
    }
  }
}

async function createOrder(ctx) {
  const operator = await requireAuth(ctx)
  if (!operator) return

  const { totalPrice, cart, remark, customerName, customerPhone, orderType, status } = ctx.request.body
  const userId = ctx.request.body.userId || operator.id

  if (operator.role !== 1 && userId !== operator.id) {
    ctx.body = { code: 403, message: '无权为他人创建订单' }
    return
  }

  if (!cart || (Array.isArray(cart) && cart.length === 0)) {
    ctx.body = { code: 400, message: '购物车不能为空' }
    return
  }

  const items = typeof cart === 'string' ? JSON.parse(cart) : cart
  const calculatedTotalPrice = await orderService.recalculateTotalPrice(items)
  const orderId = `ORD${Date.now()}${Math.floor(Math.random() * 10000).toString().padStart(4, '0')}`
  const orderStatus = status || 'pending'

  const userInfo = JSON.stringify({
    remark: remark || '',
    customerName: customerName || '',
    customerPhone: customerPhone || '',
    orderType: orderType || 'customer'
  })

  await transaction(async (conn) => {
    for (const item of items) {
      const goodsId = item.id || item.goods_id || item.goodsId
      if (!goodsId) continue
      const qty = item.pricingType === 2 ? 1 : (item.quantity || 1)

      const [rows] = await conn.execute('SELECT id, name, stock FROM goods WHERE id = ? FOR UPDATE', [goodsId])
      if (rows.length === 0) {
        throw new Error('商品不存在')
      }
      if (rows[0].stock < qty) {
        throw new Error(`${rows[0].name} 库存不足（当前库存: ${rows[0].stock}，需要: ${qty}）`)
      }

      if (orderStatus === 'completed') {
        await conn.execute('UPDATE goods SET stock = stock - ?, sales = COALESCE(sales, 0) + ? WHERE id = ?', [qty, qty, goodsId])
        await conn.execute('UPDATE stock SET quantity = quantity - ? WHERE goods_id = ?', [qty, goodsId])
      }
    }

    await conn.execute(
      'INSERT INTO orders (id, user_id, status, total_price, cart, user_info) VALUES (?, ?, ?, ?, ?, ?)',
      [orderId, userId || null, orderStatus, calculatedTotalPrice, typeof cart === 'string' ? cart : JSON.stringify(cart), userInfo]
    )
    await orderService.insertOrderItems(conn, orderId, cart)
  })

  const orders = await query('SELECT * FROM orders WHERE id = ?', [orderId])
  const created = orders[0]
  created.items = await orderService.getOrderItems(orderId)

  if (created.status === 'completed') {
    setImmediate(() => orderService.processOrderComplete(created))
  }

  ctx.body = {
    code: 200,
    data: created
  }
}

async function updateOrder(ctx) {
  const operator = await requireAuth(ctx)
  if (!operator) return

  const orderId = ctx.params.id
  const body = allowedUpdateFields(ctx.request.body)

  const orders = await query('SELECT * FROM orders WHERE id = ?', [orderId])

  if (orders.length > 0) {
    const order = orders[0]

    if (operator.role !== 1 && order.user_id !== operator.id) {
      ctx.body = { code: 403, message: '无权修改此订单' }
      return
    }

    const prevStatus = order.status
    const updateFields = []
    const updateParams = []

    if (body.status !== undefined) {
      updateFields.push('status = ?')
      updateParams.push(body.status)
    }
    const totalPrice = body.total_price !== undefined ? body.total_price : body.totalPrice
    if (totalPrice !== undefined) {
      updateFields.push('total_price = ?')
      updateParams.push(totalPrice)
    }
    if (body.cart !== undefined) {
      const cartStr = typeof body.cart === 'string' ? body.cart : JSON.stringify(body.cart)
      updateFields.push('cart = ?')
      updateParams.push(cartStr)
    }

    if (updateFields.length === 0) {
      ctx.body = { code: 400, message: '没有需要更新的字段' }
      return
    }

    const newStatus = body.status !== undefined ? body.status : prevStatus

    await transaction(async (conn) => {
      if (newStatus === 'completed' && prevStatus !== 'completed') {
        const items = body.cart !== undefined
          ? (typeof body.cart === 'string' ? JSON.parse(body.cart) : body.cart)
          : JSON.parse(order.cart || '[]')

        for (const item of items) {
          const goodsId = item.id || item.goods_id || item.goodsId
          if (!goodsId) continue
          const qty = item.pricingType === 2 ? 1 : (item.quantity || 1)

          const [rows] = await conn.execute('SELECT stock FROM goods WHERE id = ? FOR UPDATE', [goodsId])
          if (rows.length > 0 && rows[0].stock >= qty) {
            await conn.execute('UPDATE goods SET stock = stock - ?, sales = COALESCE(sales, 0) + ? WHERE id = ?', [qty, qty, goodsId])
            await conn.execute('UPDATE stock SET quantity = quantity - ? WHERE goods_id = ?', [qty, goodsId])
          }
        }
      }

      updateParams.push(orderId)
      await conn.execute(`UPDATE orders SET ${updateFields.join(', ')} WHERE id = ?`, updateParams)

      if (body.cart !== undefined) {
        await conn.execute('DELETE FROM order_items WHERE order_id = ?', [orderId])
        await orderService.insertOrderItems(conn, orderId, body.cart)
      }
    })

    const updatedOrders = await query('SELECT * FROM orders WHERE id = ?', [orderId])
    const completed = updatedOrders[0]
    completed.items = await orderService.getOrderItems(orderId)

    if (completed.status === 'completed' && prevStatus !== 'completed') {
      setImmediate(() => orderService.processOrderComplete(completed))
    }

    // 订单状态变更时发送微信订阅消息通知
    if (newStatus !== prevStatus && completed.user_id) {
      setImmediate(() => orderService.sendWechatNotification(completed.user_id, completed.id, newStatus, completed.total_price))
    }

    ctx.body = {
      code: 200,
      data: completed
    }
  } else {
    ctx.body = {
      code: 404,
      message: '订单不存在'
    }
  }
}

module.exports = {
  getOrders,
  getOrderById,
  createOrder,
  updateOrder
}