fermentord/pkg/tilt/scanner.go

// MIT License
//
// Copyright (c) 2020 Alex Howarth
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package tilt

import (
	"context"
	"log"
	"time"

	"github.com/JuulLabs-OSS/ble"
	"github.com/JuulLabs-OSS/ble/examples/lib/dev"
	"github.com/pkg/errors"
)

// Scanner for Tilt devices
type Scanner struct {
	devices Devices
}

// Devices stores discovered devices
type Devices map[Color]Tilt

// NewScanner returns a Scanner
func NewScanner() *Scanner {
	return &Scanner{}
}

// Scan finds Tilt devices and times out after a duration
func (s *Scanner) Scan(ctx context.Context, timeout time.Duration) error {
	s.devices = make(map[Color]Tilt)

	d, err := dev.NewDevice("hci0")
	if err != nil {
		return err
	}
	ble.SetDefaultDevice(d)
	defer ble.Stop()

	ctx2 := ble.WithSigHandler(context.WithTimeout(ctx, timeout))
	err = ble.Scan(ctx2, false, s.advHandler, advFilter)
	if err != nil {
		switch errors.Cause(err) {
		case nil:
		case context.DeadlineExceeded:
			// Finished scanning
			break

		case context.Canceled:
			break

		default:
			return err
		}
	}

	return err
}

func advFilter(a ble.Advertisement) bool {
	return IsTilt(a.ManufacturerData())
}

func (s *Scanner) advHandler(a ble.Advertisement) {
	// create iBeacon
	b, err := NewIBeacon(a.ManufacturerData())
	if err != nil {
		log.Println(err)
		return
	}

	// create Tilt from iBeacon
	t, err := NewTilt(b)
	if err != nil {
		log.Println(err)
		return
	}

	s.HandleTilt(t)
}

// HandleTilt adds a discovered Tilt to a map
func (s *Scanner) HandleTilt(t Tilt) {
	s.devices[t.col] = t
}

// Tilts contains the found devices
func (s *Scanner) Tilts() Devices {
	return s.devices
}