Refactor conversion of files JSON for download

Tries fixing CODEOCEAN-RQ

app/controllers/concerns/file_conversion.rb

@@ -7,26 +7,33 @@ module FileConversion
     # Return an empty list of files and directories if the files_json is nil
     return [[], []] if files_json.blank?
 
-    all_file_types = FileType.all
     directories = []
     files = files_json['files'].filter_map do |file|
       # entryType: `-` describes a regular file, `d` a directory. See `info ls` for others
       directories.push(file['name']) if file['entryType'] == 'd'
       next unless file['entryType'] == '-'
 
-      extension = File.extname(file['name'])
-      name = File.basename(file['name'], extension)
-      path = File.dirname(file['name']).sub(%r{^(?>\./|\.)}, '').presence
-      file_type = all_file_types.detect {|ft| ft.file_extension == extension } || FileType.new(file_extension: extension)
+      file['extension'] = File.extname(file['name'])
+      file
+    end
+
+    # Optimize SQL queries: We are first fetching all required file types from the database.
+    # Then, we store them in a hash, so that we can access them by using their file extension.
+    file_types = {}
+    FileType.where(file_extension: files.pluck('extension')).each do |file_type|
+      file_types[file_type.file_extension] = file_type
+    end
+
+    files.map! do |file|
       CodeOcean::File.new(
-        name:,
-        path:,
+        name: File.basename(file['name'], file['extension']),
+        path: File.dirname(file['name']).sub(%r{^(?>\./|\.)}, '').presence,
         size: file['size'],
         owner: file['owner'],
         group: file['group'],
         permissions: file['permissions'],
         updated_at: file['modificationTime'],
-        file_type:
+        file_type: file_types[file['extension']] || FileType.new(file_extension: file['extension'])
       )
     end
     [augment_files_for_download(files), directories]