// Copyright 2017 Google Inc.
//
// 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 pipoint

import (
	"fmt"
	"os"

	"gobot.io/x/gobot/sysfs"
)

const (
	path = "/dev/servoblaster"
)

type ServoBlaster struct {
	Pin int
}

// SetDuty sets the servo period in ns.
func (s *ServoBlaster) SetDuty(period int) (err error) {
	file, err := sysfs.OpenFile(path, os.O_WRONLY, 0644)
	defer file.Close()
	if err != nil {
		return
	}

	_, err = file.Write([]byte(fmt.Sprintf("%d=%dus\n", s.Pin, period/1000)))
	return err
}