// Copyright 2021 EMQ Technologies Co., Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"fmt"

	"github.com/lf-edge/ekuiper/pkg/api"
)

type echo struct{}

func (f *echo) Validate(args []interface{}) error {
	if len(args) != 1 {
		return fmt.Errorf("echo function only supports 1 parameter but got %d", len(args))
	}
	return nil
}

func (f *echo) Exec(args []interface{}, _ api.FunctionContext) (interface{}, bool) {
	result := args[0]
	return result, true
}

func (f *echo) IsAggregate() bool {
	return false
}

var Echo echo