const find = (db, collectionName, conditions) => {
  const collection = db.collection(collectionName)
  const cursor = collection.find(conditions)
  const documents = []

  return new Promise((resolve, reject) => {
    cursor.forEach(
      (doc) => documents.push(doc),
      () => resolve(documents)
    )
  })
}

app.get('/operacoes', async (req, res) => {
  let conditions = {}
  let titulo = "Gerais"
  const { filtro } = req.query
  if (filtro) {
    switch (filtro) {
      case 'entradas':
        titulo = " de Entrada"
        conditions = {
          valor: { $gte: 0 }
        }
        break
      case 'saidas':
        titulo = " de Saída"
        conditions = {
          valor: { $lt: 0 }
        }
        break
      default:
        break
    }
  }
  const operacoes = await find(app.db, 'operacoes', conditions)
  res.render('operacoes', { titulo: titulo, operacoes })
})