[Files Refactor] Import export fixup (#2763)

* Adjust json schema
* Remove mappings file from export
* Import file/folder support
* Update documentation
* Make gallery filenames unique

pkg/models/jsonschema/folder.go

@@ -0,0 +1,56 @@
+package jsonschema
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"strings"
+
+	jsoniter "github.com/json-iterator/go"
+	"github.com/stashapp/stash/pkg/hash/md5"
+	"github.com/stashapp/stash/pkg/models/json"
+)
+
+type Folder struct {
+	BaseDirEntry
+
+	Path string `json:"path,omitempty"`
+
+	CreatedAt json.JSONTime `json:"created_at,omitempty"`
+	UpdatedAt json.JSONTime `json:"updated_at,omitempty"`
+}
+
+func (f *Folder) Filename() string {
+	// prefix with the path depth so that we can import lower-level folders first
+	depth := strings.Count(f.Path, string("/"))
+
+	// hash the full path for a unique filename
+	hash := md5.FromString(f.Path)
+
+	basename := path.Base(f.Path)
+
+	return fmt.Sprintf("%2x.%s.%s.json", depth, basename, hash)
+}
+
+func LoadFolderFile(filePath string) (*Folder, error) {
+	var folder Folder
+	file, err := os.Open(filePath)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+	var json = jsoniter.ConfigCompatibleWithStandardLibrary
+	jsonParser := json.NewDecoder(file)
+	err = jsonParser.Decode(&folder)
+	if err != nil {
+		return nil, err
+	}
+	return &folder, nil
+}
+
+func SaveFolderFile(filePath string, folder *Folder) error {
+	if folder == nil {
+		return fmt.Errorf("folder must not be nil")
+	}
+	return marshalToFile(filePath, folder)
+}