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

async function getPurchases(ctx) {
  let sql = `
    SELECT p.*, 
      (SELECT COUNT(*) FROM purchase_items WHERE purchase_id = p.id) as items_count
    FROM purchases p
    WHERE 1=1`
  const params = []

  if (ctx.query.keyword) {
    sql += ' AND (p.supplier_name LIKE ?)'
    params.push(`%${ctx.query.keyword}%`)
  }

  sql += ' ORDER BY p.created_at DESC'
  const result = await paginate(query, sql, params, ctx.query.page, ctx.query.pageSize)

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

async function getPurchaseById(ctx) {
  const id = parseInt(ctx.params.id)
  const purchases = await query('SELECT * FROM purchases WHERE id = ?', [id])

  if (purchases.length === 0) {
    ctx.body = { code: 404, message: '采购单不存在' }
    return
  }

  const purchase = purchases[0]
  const items = await query(
    `SELECT pi.*, g.name as goods_name 
     FROM purchase_items pi 
     LEFT JOIN goods g ON pi.goods_id = g.id 
     WHERE pi.purchase_id = ?`,
    [id]
  )

  purchase.items = items
  purchase.items_count = items.length

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

async function createPurchase(ctx) {
  const { supplier_id, items, remarks } = ctx.request.body || {}

  if (!supplier_id || !Array.isArray(items) || items.length === 0) {
    ctx.body = { code: 400, message: '请选择供应商和采购商品' }
    return
  }

  const suppliers = await query('SELECT * FROM suppliers WHERE id = ?', [supplier_id])
  if (suppliers.length === 0) {
    ctx.body = { code: 404, message: '供应商不存在' }
    return
  }
  const supplier = suppliers[0]

  let total = 0
  for (const item of items) {
    const qty = parseInt(item.quantity) || 0
    const price = parseFloat(item.purchase_price) || 0
    if (qty <= 0 || price < 0) {
      ctx.body = { code: 400, message: '数量/单价不合法' }
      return
    }
    total += price * qty
  }

  const result = await transaction(async (conn) => {
    const [purchaseResult] = await conn.execute(
      'INSERT INTO purchases (supplier_id, supplier_name, total, remarks) VALUES (?, ?, ?, ?)',
      [supplier_id, supplier.name, total, remarks || '']
    )
    const purchaseId = purchaseResult.insertId

    for (const item of items) {
      const [goods] = await conn.execute('SELECT name FROM goods WHERE id = ?', [item.goods_id])
      const goodsName = goods.length > 0 ? goods[0].name : ''
      await conn.execute(
        'INSERT INTO purchase_items (purchase_id, goods_id, goods_name, quantity, purchase_price) VALUES (?, ?, ?, ?, ?)',
        [purchaseId, item.goods_id, goodsName, item.quantity || 0, item.purchase_price || 0]
      )
    }
    return purchaseId
  })

  ctx.body = {
    code: 200,
    message: '采购单创建成功',
    data: { id: result }
  }
}

async function inboundPurchase(ctx) {
  const operator = ctx.state.user
  if (!operator) {
    ctx.status = 401
    ctx.body = { code: 401, message: '未登录' }
    return
  }
  const id = parseInt(ctx.params.id)
  const purchases = await query('SELECT * FROM purchases WHERE id = ?', [id])

  if (purchases.length === 0) {
    ctx.body = { code: 404, message: '采购单不存在' }
    return
  }

  const purchase = purchases[0]
  if (purchase.status === 1) {
    ctx.body = { code: 400, message: '该采购单已入库' }
    return
  }

  const items = await query('SELECT * FROM purchase_items WHERE purchase_id = ?', [id])
  if (items.length === 0) {
    ctx.body = { code: 400, message: '采购单无明细' }
    return
  }

  await transaction(async (conn) => {
    for (const item of items) {
      const [goods] = await conn.execute('SELECT id, stock FROM goods WHERE id = ? FOR UPDATE', [item.goods_id])
      if (goods.length === 0) {
        throw new Error(`商品 ${item.goods_id} 不存在，无法入库`)
      }

      const [stockRows] = await conn.execute('SELECT quantity FROM stock WHERE goods_id = ? FOR UPDATE', [item.goods_id])
      if (stockRows.length > 0) {
        await conn.execute(
          'UPDATE stock SET quantity = quantity + ? WHERE goods_id = ?',
          [item.quantity, item.goods_id]
        )
      } else {
        await conn.execute(
          'INSERT INTO stock (goods_id, quantity, warehouse) VALUES (?, ?, ?)',
          [item.goods_id, item.quantity, '默认仓库']
        )
      }
      await conn.execute(
        'UPDATE goods SET stock = stock + ? WHERE id = ?',
        [item.quantity, item.goods_id]
      )

      try {
        await conn.execute(
          'INSERT INTO stock_logs (goods_id, change_type, delta, quantity_after, operator_id, remark) VALUES (?, ?, ?, ?, ?, ?)',
          [item.goods_id, 'purchase', item.quantity, (stockRows[0]?.quantity || 0) + item.quantity, operator.id, `采购入库 #${id}`]
        )
      } catch {}
    }
    await conn.execute('UPDATE purchases SET status = 1 WHERE id = ?', [id])
  })

  ctx.body = {
    code: 200,
    message: '入库成功'
  }
}

module.exports = {
  getPurchases,
  getPurchaseById,
  createPurchase,
  inboundPurchase
}