streamwatcher/stream.go

package main

import (
	"encoding/json"
	"image"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"sync"
	"time"

	"gocv.io/x/gocv"
)

// Stream Unexported
type Stream struct {
	URL      string `json:"url"`
	Base64   string `json:"base64"`
	Interval int    `json:"interval"`
	FileLock sync.Mutex
}

// NewStream creates a new Stream Object
func NewStream(URL string) Stream {
	base64 := URLToBase64(URL)

	stream := Stream{
		URL:      URL,
		Base64:   base64,
		Interval: 5000,
	}
	stream.WriteStreamJSON()
	return stream
}

// Update gets called by UpdateInterval Interval milliseconds to fetch the latest instant
func (s Stream) Update() {
	log.Print("Update:", s.URL)
	resp, err := http.Get(s.URL)
	if err != nil {
		log.Fatal(err)
	}
	img, err := ioutil.ReadAll(resp.Body)
	defer resp.Body.Close()

	mat, err := gocv.IMDecode(img, gocv.IMReadColor)
	if err != nil {
		log.Fatal("Could not IMDecode img")
	}
	go gocv.IMWrite(s.GetCurrentColorInstantPath(), mat)

	grey := gocv.NewMat()
	gocv.CvtColor(mat, &grey, gocv.ColorBGRAToBGR)
	gocv.GaussianBlur(mat, &mat, image.Point{X: 21, Y: 21}, 0, 0, gocv.BorderReflect)
	go s.SaveStreamInstant(grey)
}

// UpdateInterval calls Update() every interval
func (s Stream) UpdateInterval() {
	for {
		s.Update()
		time.Sleep(time.Duration(s.Interval) * time.Millisecond)
	}
}

// GetStreamInstant http.Get(URL) and returns the response
func (s Stream) GetStreamInstant() gocv.Mat {
	resp, err := http.Get(s.URL)
	if err != nil {
		log.Fatal(err)
	}
	img, err := ioutil.ReadAll(resp.Body)
	defer resp.Body.Close()

	mat, err := gocv.IMDecode(img, gocv.IMReadColor)
	if err != nil {
		log.Fatal("Could not IMDecode img")
	}

	return mat
}

// SaveStreamInstant writes the img to the CurrentStreamInstantPath, moves existing instant to PreviousStreamInstantPath
func (s Stream) SaveStreamInstant(mat gocv.Mat) {
	s.FileLock.Lock()
	streamStoreDir := s.GetStreamStoreDirPath()
	os.MkdirAll(streamStoreDir, os.ModePerm)

	currentStreamInstantPath := s.GetCurrentInstantPath()
	swap := FileExists(s.GetCurrentInstantPath())

	if swap {
		currentStreamInstantPath = s.GetNextInstantPath()
	}

	gocv.IMWrite(currentStreamInstantPath, mat)

	if swap {
		s.SwapInstants(s.GetPreviousInstantPath(), s.GetCurrentInstantPath(), s.GetNextInstantPath())
	}
	s.FileLock.Unlock()
}

// SwapInstants swaps the file location, first current -> previous and then next -> current
func (s Stream) SwapInstants(previous string, current string, next string) {
	err := os.Rename(current, previous)
	if err != nil {
		log.Fatal("Couldn't copy current image instant to previous image instant")
	}
	err = os.Rename(next, current)
	if err != nil {
		log.Fatal("Couldn't copy next image instant to current image instant")
	}
}

// GetStreamJSONPath returns filepath.Join(s.GetStreamStoreDirPath(), "stream.json")
func (s Stream) GetStreamJSONPath() string {
	return filepath.Join(s.GetStreamStoreDirPath(), "stream.json")
}

// WriteStreamJSON writes the Stream struct to GetStreamJSONPath()
func (s Stream) WriteStreamJSON() {
	if !FileExists(s.GetStreamStoreDirPath()) {
		os.MkdirAll(s.GetStreamStoreDirPath(), os.ModePerm)
	}
	file, _ := json.MarshalIndent(s, "", "")
	_ = ioutil.WriteFile(s.GetStreamJSONPath(), file, 0644)
}

// GetStreamStoreDirPath returns filepath.Join(s.GetStreamDirPath(), s.Base64)
func (s Stream) GetStreamStoreDirPath() string {
	return filepath.Join(GetStreamDirPath(), s.Base64)
}

// GetPreviousInstantPath returns filepath.Join(GetStreamDirPath(), s.Base64, "previous.jpg")
func (s Stream) GetPreviousInstantPath() string {
	return filepath.Join(s.GetStreamStoreDirPath(), "previous.jpg")
}

// PreviousInstantPathExists returns FileExists(GetPreviousInstantPath())
func (s Stream) PreviousInstantPathExists() bool {
	return FileExists(s.GetPreviousInstantPath())
}

// IMReadPrevious returns gocv.IMRead(GetPreviousInstantPath(), gocv.IMReadGrayScale)
func (s Stream) IMReadPrevious() gocv.Mat {
	return gocv.IMRead(s.GetPreviousInstantPath(), gocv.IMReadGrayScale)
}

// GetCurrentInstantPath returns filepath.Join(s.GetStreamDirPath(), s.Base64, "current.jpg")
func (s Stream) GetCurrentInstantPath() string {
	return filepath.Join(s.GetStreamStoreDirPath(), "current.jpg")
}

// CurrentInstantPathExists returns FileExists(GetCurrentInstantPath())
func (s Stream) CurrentInstantPathExists() bool {
	return FileExists(s.GetCurrentInstantPath())
}

// IMReadCurrent returns gocv.IMRead(GetCurrentInstantPath(), gocv.IMReadGrayScale)
func (s Stream) IMReadCurrent() gocv.Mat {
	return gocv.IMRead(s.GetCurrentInstantPath(), gocv.IMReadGrayScale)
}

// GetCurrentColorInstantPath returns filepath.Join(s.GetStreamDirPath(), s.Base64, "current_color.jpg")
func (s Stream) GetCurrentColorInstantPath() string {
	return filepath.Join(s.GetStreamStoreDirPath(), "current_color.jpg")
}

// CurrentColorInstantPathExists returns FileExists(GetCurrentColorInstantPath())
func (s Stream) CurrentColorInstantPathExists() bool {
	return FileExists(s.GetCurrentColorInstantPath())
}

// IMReadCurrentColor returns gocv.IMRead(GetCurrentColorInstantPath(), gocv.IMReadColor)
func (s Stream) IMReadCurrentColor() gocv.Mat {
	return gocv.IMRead(s.GetCurrentColorInstantPath(), gocv.IMReadColor)
}

// GetNextInstantPath returns filepath.Join(s.GetStreamDirPath(), s.Base64, "last.jpg")
func (s Stream) GetNextInstantPath() string {
	return filepath.Join(s.GetStreamStoreDirPath(), "last.jpg")
}

// NextInstantPathExists returns FileExists(GetNextInstantPath())
func (s Stream) NextInstantPathExists() bool {
	return FileExists(s.GetNextInstantPath())
}

// IMReadNext returns gocv.IMRead(GetNextInstantPath(), gocv.IMReadGrayScale)
func (s Stream) IMReadNext() gocv.Mat {
	return gocv.IMRead(s.GetNextInstantPath(), gocv.IMReadGrayScale)
}