slideshow-api/internal/scanner.go

package internal

import (
	"errors"
	"io/fs"
	"math/rand"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"git.velvettear.de/velvettear/loggo"
	"git.velvettear.de/velvettear/slideshow-api/internal/config"
)

// slice of images
var images []string

// temporary slice of images
var tmpImages []string

// Scan the specified directory
func Scan() {
	timestamp := time.Now()
	directory := config.Directory
	loggo.Info("scanning directory for images and subdirectories...", "interval: "+strconv.FormatFloat(config.ScanInterval.Seconds(), 'f', 0, 64)+" seconds", "directory: "+directory)
	filepath.WalkDir(directory, checkDirectory)
	images = tmpImages
	tmpImages = nil
	loggo.InfoTimed("found "+strconv.Itoa(len(images))+" image(s)", timestamp.UnixMilli())
	go scheduleRescan()
}

// check if images has been found
func HasFoundImages() bool {
	return len(images) > 0
}

// get a random image
func GetRandomImage() (string, []byte, error) {
	var name string
	var data []byte
	var error error
	if len(images) == 0 {
		return name, data, errors.New("no images have been found")
	}
	image := images[rand.Intn(len(images))]
	if config.IsResolutionSet() {
		data, error = ScaleImage(image)
	} else {
		data, error = os.ReadFile(image)
	}
	return image, data, error
}

// sleep the specified interval and then trigger a rescan of the specified directory
func scheduleRescan() {
	loggo.Debug("sleeping for " + strconv.FormatInt(config.ScanInterval.Milliseconds(), 10) + "ms before next scan...")
	time.Sleep(config.ScanInterval)
	Scan()
}

// add image files to the slice of images and subdirectoies to the watcher
func checkDirectory(path string, dir fs.DirEntry, err error) error {
	if err != nil {
		return err
	}
	if dir.IsDir() || !isImage(path) {
		return nil
	}
	tmpImages = append(tmpImages, path)
	loggo.Debug("added image to temporary slice of images", path)
	return nil
}

// check if a file is an image
func isImage(file string) bool {
	return strings.HasSuffix(file, ".jpeg") || strings.HasSuffix(file, ".jpg") || strings.HasSuffix(file, ".png")
}