Handle case sensitive file moves (#1427)

pkg/utils/file.go

@@ -306,3 +306,43 @@ func GetFunscriptPath(path string) string {
 	fn := strings.TrimSuffix(path, ext)
 	return fn + ".funscript"
 }
+
+// IsFsPathCaseSensitive checks the fs of the given path to see if it is case sensitive
+// if the case sensitivity can not be determined false and an error != nil are returned
+func IsFsPathCaseSensitive(path string) (bool, error) {
+	// The case sensitivity of the fs of "path" is determined by case flipping
+	// the first letter rune from the base string of the path
+	// If the resulting flipped path exists then the fs should not be case sensitive
+	// ( we check the file mod time to avoid matching an existing path )
+
+	fi, err := os.Stat(path)
+	if err != nil { // path cannot be stat'd
+		return false, err
+	}
+
+	base := filepath.Base(path)
+	fBase, err := FlipCaseSingle(base)
+	if err != nil { // cannot be case flipped
+		return false, err
+	}
+	i := strings.LastIndex(path, base)
+	if i < 0 { // shouldn't happen
+		return false, fmt.Errorf("could not case flip path %s", path)
+	}
+
+	flipped := []byte(path)
+	for _, c := range []byte(fBase) { // replace base of path with the flipped one ( we need to flip the base or last dir part )
+		flipped[i] = c
+		i++
+	}
+
+	fiCase, err := os.Stat(string(flipped))
+	if err != nil { // cannot stat the case flipped path
+		return true, nil // fs of path should be case sensitive
+	}
+
+	if fiCase.ModTime() == fi.ModTime() { // file path exists and is the same
+		return false, nil // fs of path is not case sensitive
+	}
+	return false, fmt.Errorf("can not determine case sensitivity of path %s", path)
+}

pkg/utils/strings.go

@@ -5,6 +5,7 @@ import (
 	"math/rand"
 	"strings"
 	"time"
+	"unicode"
 )
 
 var characters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890")
@@ -18,8 +19,37 @@ func RandomSequence(n int) string {
 	return string(b)
 }
 
+// FlipCaseSingle flips the case ( lower<->upper ) of a single char from the string s
+// If the string cannot be flipped, the original string value and an error are returned
+func FlipCaseSingle(s string) (string, error) {
+	rr := []rune(s)
+	for i, r := range rr {
+		if unicode.IsLetter(r) { // look for a letter  to flip
+			if unicode.IsUpper(r) {
+				rr[i] = unicode.ToLower(r)
+				return string(rr), nil
+			}
+			rr[i] = unicode.ToUpper(r)
+			return string(rr), nil
+		}
+
+	}
+	return s, fmt.Errorf("could not case flip string %s", s)
+}
+
 type StrFormatMap map[string]interface{}
 
+// StrFormat formats the provided format string, replacing placeholders
+// in the form of "{fieldName}" with the values in the provided
+// StrFormatMap.
+//
+// For example,
+// StrFormat("{foo} bar {baz}", StrFormatMap{
+//     "foo": "bar",
+//     "baz": "abc",
+// })
+//
+// would return: "bar bar abc"
 func StrFormat(format string, m StrFormatMap) string {
 	args := make([]string, len(m)*2)
 	i := 0