refactored basic database parsing

app/builders/db_builder.rb

@@ -7,20 +7,33 @@ class DbBuilder
   end
 
   def update_db(schema:)
-    # split path into chunks
-    entries = schema.map do |entry|
-      entry[:chunks] = entry[:path][1..-1].split('/').reverse
-      entry
-    end
     # create the root folder if it doesn't exist
     @db.root_folder ||= DbFolder.create(name: 'root', path: '/')
     @root_folder = @db.root_folder
-    # add the folder entries
+
+    # create the entry array from the schema
+    entries = __create_entries(schema)
+
+    # parse the entries array
+    # Note: @root_folder gets linked in on
+    #       the first call to __build_folder
     __parse_folder_entries(parent: nil, entries: entries)
   end
 
   protected
 
+  # Adds :chunks to each schema element
+  # :chunks is an array of the entry's path elements
+  # this makes it easier to traverse the database structure.
+  def __create_entries(schema)
+    schema.map do |entry|
+      entry[:chunks] = entry[:path][1..-1].split('/').reverse
+      entry
+    end
+  end
+
+  # Creates or updates the folder defined by these entries.
+  # Then adds in any subfolders or subfiles
   def __parse_folder_entries(parent:, entries:, default_name: '')
     # find the info stream entry if it exists
     info = __read_info_entry(entries) || { name: default_name }
@@ -30,20 +43,14 @@ class DbBuilder
     folder = __build_folder(parent: parent, path: path, info: info)
     # group the folder entries
     groups = __group_entries(entries)
-    # convert the entries into subfolders and files
-    groups.each do |name, entry_group|
-      if entry_group.length == 1
-        folder.db_files << __build_file(folder: folder, entry: entry_group[0],
-                                        default_name: name)
-      elsif entry_group.length > 1
-        folder.subfolders << __parse_folder_entries(parent: folder,
-                                                    entries: entry_group,
-                                                    default_name: name)
-      end
-    end
+    # process the groups as subfolders or files
+    __process_folder_contents(folder, groups)
+
     folder
   end
 
+  # if this folder has an info stream, find that entry and
+  # use its metadata to update the folder's attributes
   def  __read_info_entry(entries)
     if entries[0][:chunks] == ['info']
       info_entry = entries.slice!(0)
@@ -51,32 +58,33 @@ class DbBuilder
     end
   end
 
-  def __build_folder(parent:, path:, info:)
-    return @root_folder if parent.nil?
-    folder = parent.subfolders.find_by_path(path)
-    folder ||= DbFolder.new(parent: parent, path: path)
-    folder.update_attributes(info)
-    folder.save!
-    folder
-  end
-
-  def __build_file(folder:, entry:, default_name:)
-    file = folder.db_files.find_by_path(entry[:path])
-    file ||= DbFile.new(name: default_name)
-    file.save!
-    file
-  end
-
-  def __build_path(entries)
   # all entries agree on a common path
   # up to the point where they still have
   # chunks. Get this common path by popping
   # the chunks off the first entry's path
+  def __build_path(entries)
     parts = entries[0][:path].split('/')
     parts.pop(entries[0][:chunks].length)
     parts.join('/') # stitch parts together to form a path
   end
 
+  # create or update a DbFolder object at the
+  # specified path. If the parent parameter is nil
+  # then the folder must be the Db's root folder
+  def __build_folder(parent:, path:, info:)
+    return @root_folder if parent.nil?
+    folder = parent.subfolders.find_by_path(path)
+    folder ||= DbFolder.new(parent: parent, path: path)
+    folder.update_attributes(info)
+    folder.save!
+    folder
+  end
+
+  # collect the folder's entries into a set groups
+  # based off the next item in their :chunk array
+  # returns entry_groups which is a Hash with
+  # :key = name of the common chunk
+  # :value = the entry, less the common chunk
   def __group_entries(entries)
     entry_groups = {}
     entries.map do |entry|
@@ -85,6 +93,8 @@ class DbBuilder
     entry_groups
   end
 
+  # helper function to __group_entries that handles
+  # sorting entries into the entry_groups Hash
   def __add_to_group(entry_groups, group_name, entry)
     entry_groups[group_name] ||= []
     if entry[:chunks] == ['info'] # put the info stream in front
@@ -93,4 +103,27 @@ class DbBuilder
       entry_groups[group_name].append(entry)
     end
   end
+
+  # convert the groups into subfolders and files
+  def __process_folder_contents(folder, groups)
+    groups.each do |name, entry_group|
+      if entry_group.length == 1
+        folder.db_files << __build_file(folder: folder, entry: entry_group[0],
+                                        default_name: name)
+      elsif entry_group.length > 1
+        folder.subfolders << __parse_folder_entries(parent: folder,
+                                                    entries: entry_group,
+                                                    default_name: name)
+      end
+    end
+  end
+
+  # create or update a DbFile object at the
+  # specified path.
+  def __build_file(folder:, entry:, default_name:)
+    file = folder.db_files.find_by_path(entry[:path])
+    file ||= DbFile.new(name: default_name)
+    file.save!
+    file
+  end
 end