Add a cache for gallery thumbnails (#496)

pkg/utils/file.go

@@ -1,10 +1,12 @@
 package utils
 
 import (
+	"archive/zip"
 	"fmt"
 	"github.com/h2non/filetype"
 	"github.com/h2non/filetype/types"
 	"io/ioutil"
+	"math"
 	"os"
 	"os/user"
 	"path/filepath"
@@ -66,7 +68,12 @@ func EnsureDir(path string) error {
 	return err
 }
 
-// RemoveDir removes the given file path along with all of its contents
+// EnsureDirAll will create a directory at the given path along with any necessary parents if they don't already exist
+func EnsureDirAll(path string) error {
+	return os.MkdirAll(path, 0755)
+}
+
+// RemoveDir removes the given dir (if it exists) along with all of its contents
 func RemoveDir(path string) error {
 	return os.RemoveAll(path)
 }
@@ -125,6 +132,75 @@ func GetHomeDirectory() string {
 	return currentUser.HomeDir
 }
 
+// IsZipFileUnmcompressed returns true if zip file in path is using 0 compression level
+func IsZipFileUncompressed(path string) (bool, error) {
+	r, err := zip.OpenReader(path)
+	if err != nil {
+		fmt.Printf("Error reading zip file %s: %s\n", path, err)
+		return false, err
+	} else {
+		defer r.Close()
+		for _, f := range r.File {
+			if f.FileInfo().IsDir() { // skip dirs, they always get store level compression
+				continue
+			}
+			return f.Method == 0, nil // check compression level of first actual  file
+		}
+	}
+	return false, nil
+}
+
+// humanize code taken from https://github.com/dustin/go-humanize and adjusted
+
+func logn(n, b float64) float64 {
+	return math.Log(n) / math.Log(b)
+}
+
+// HumanizeBytes returns a human readable bytes string of a uint
+func HumanizeBytes(s uint64) string {
+	sizes := []string{"B", "KB", "MB", "GB", "TB", "PB", "EB"}
+	if s < 10 {
+		return fmt.Sprintf("%d B", s)
+	}
+	e := math.Floor(logn(float64(s), 1024))
+	suffix := sizes[int(e)]
+	val := math.Floor(float64(s)/math.Pow(1024, e)*10+0.5) / 10
+	f := "%.0f %s"
+	if val < 10 {
+		f = "%.1f %s"
+	}
+
+	return fmt.Sprintf(f, val, suffix)
+}
+
+// WriteFile writes file to path creating parent directories if needed
+func WriteFile(path string, file []byte) error {
+	pathErr := EnsureDirAll(filepath.Dir(path))
+	if pathErr != nil {
+		return fmt.Errorf("Cannot ensure path %s", pathErr)
+	}
+
+	err := ioutil.WriteFile(path, file, 0755)
+	if err != nil {
+		return fmt.Errorf("Write error for thumbnail %s: %s ", path, err)
+	}
+	return nil
+}
+
+// GetIntraDir returns a string that can be added to filepath.Join to implement directory depth, "" on error
+//eg given a pattern of 0af63ce3c99162e9df23a997f62621c5 and a depth of 2 length of 3
+//returns 0af/63c or 0af\63c ( dependin on os)  that can be later used like this  filepath.Join(directory, intradir, basename)
+func GetIntraDir(pattern string, depth, length int) string {
+	if depth < 1 || length < 1 || (depth*length > len(pattern)) {
+		return ""
+	}
+	intraDir := pattern[0:length] // depth 1 , get length number of characters from pattern
+	for i := 1; i < depth; i++ {  // for every extra depth: move to the right of the pattern length positions, get length number of chars
+		intraDir = filepath.Join(intraDir, pattern[length*i:length*(i+1)]) //  adding each time to intradir the extra characters with a filepath join
+	}
+	return intraDir
+}
+
 func GetDir(path string) string {
 	if path == "" {
 		path = GetHomeDirectory()