switch to mongodb, add drag&drop

frontend/src/components/home.js

@@ -0,0 +1,41 @@
+function getFilesDataTransferItems(dataTransferItems) {
+    function traverseFileTreePromise(item, path = "", folder) {
+        return new Promise(resolve => {
+            if (item.isFile) {
+                item.file(file => {
+                    file.filepath = path + "/" + file.name; //save full path
+                    folder.push(file);
+                    resolve(file);
+                });
+            } else if (item.isDirectory) {
+                let dirReader = item.createReader();
+                dirReader.readEntries(entries => {
+                    let entriesPromises = [];
+                    let subfolder = [];
+                    folder.push({ name: item.name, subfolder: subfolder });
+                    for (let entry of entries)
+                        entriesPromises.push(
+                            traverseFileTreePromise(entry, path + "/" + item.name, subfolder)
+                        );
+                    resolve(Promise.all(entriesPromises));
+                });
+            }
+        });
+    }
+
+    let files = [];
+    return new Promise((resolve, reject) => {
+        let entriesPromises = [];
+        for (let it of dataTransferItems)
+            entriesPromises.push(
+                traverseFileTreePromise(it.webkitGetAsEntry(), "", files)
+            );
+        Promise.all(entriesPromises).then(entries => {
+            resolve(files);
+        });
+    });
+}
+
+export function get_files_data_transfer_items(data_transfer_items) {
+    return getFilesDataTransferItems(data_transfer_items);
+}