gardner.rb: Rubocop fixes and refactor changes

- Fix several rubocop problems
- Update module to more fully encapsulate all dialogue tree handling
    - Add Plot class for storing all tree data
    - Add Digiplot class for (eventual) tree editing

lib/sapling/gardner.rb

@@ -2,47 +2,95 @@ require 'yaml'
 
 # Gardner is the module for working with a dialogue tree file
 module Gardner
+  # The Plot class handles a specific tree file. It provides functionality for
+  # parsing trunks and branches, and provides these as class attributes.
+  class Plot
+    # The trunk and branches instance variables
+    attr_reader :branches, :tree, :trunk
 
-  # Parse the tree array into an array of numbered branches, and ordered leaves.
+    # Initialize a new Plot from a tree file
     #
-  # @param tree [Array] The dialogue tree
-  # @return [Array] An array of numbered branches, with numbered leaves
-  def self.prune_branches(tree)
-    branches = { 0 => { "desc" => "Thanks for using Sapling!" } }
-    tree.each do |b|
-      branches[b["branch"]["number"]] = {
-        "desc" => b["branch"]["text"],
-        "options" => prune_leaves(b["branch"]["leaf"]) }
+    # @param tree [File] The dialogue tree file
+    def initialize(file)
+      @tree = file
+      prune_trunk
+      prune_branches
     end
 
-    return branches
+    # Parse the tree array into an array of numbered branches, and ordered
+    # leaves.
+    #
+    # @param tree [File] The dialogue tree
+    # @return [Array] An array of numbered branches, with numbered leaves
+    def prune_branches
+      @branches = { 0 => { 'desc' => 'Thanks for using Sapling!' } }
+      @tree.each do |b|
+        @branches[b['branch']['number']] = {
+          'desc' => b['branch']['text'],
+          'options' => prune_leaves(b['branch']['leaf'])
+        }
+      end
     end
 
     # Parse the leaves of a branch into a numbered hash of options.
     #
     # @param leaves [Array] The option of leaf hashes
     # @return [Hash] A numbered hash of options
-  def self.prune_leaves(leaves)
+    def prune_leaves(leaves)
       x = 1
       options = {}
 
       return options if leaves.nil?
 
       leaves.each do |l|
-      options[x] = { l["text"] => l["branch"] }
+        options[x] = { l['text'] => l['branch'] }
         x += 1
       end
 
-    return options
+      options
     end
 
     # Parse the trunk of the tree.
     #
-  # @param tree [Hash] The entire tree
     # @return [Array] The trunk, and the remainder of the tree
-  def self.prune_trunk(tree)
-    trunk = tree.shift
+    def prune_trunk
+      @trunk = @tree.shift
+    end
+  end
 
-    return [trunk,tree]
+  # Digiplot represents a Plot used for editing. The Digiplot functions exactly
+  # like a Plot, except with additional functionality for over-writing existing
+  # branches, leaves, and the trunk.
+  class Digiplot < Plot
+    # Duplicate the "old" trunk and branches, for restoration purposes
+    attr_reader :old_branches, :old_trunk
+
+    # Enable editing for the trunk
+    attr_writer :trunk
+
+    # Initialize a Digiplot just like a Plot, but also copy the trunk and
+    # branches to "old" instance variables.
+    def initialize
+      super
+      @old_trunk = @trunk
+      @old_branches = @branches
+    end
+
+    # Change a branch
+    #
+    # @param branch [Integer] the number of the branch to be edited
+    def branch=(branch, text)
+      @branches[branch]['desc'] = text
+    end
+
+    # Change a leaf on a branch, grasshopper
+    #
+    # @param branch [Integer] the number of the branch to be edited
+    # @param leaf [Integer] the number of the leaf to be edited
+    # @param text [String] the new text for the leaf
+    # @param target [Integer] the branch number target for the leaf option
+    def leaf=(branch, leaf, text, target)
+      @branches[branch]['options'][leaf] = { text => target }
+    end
   end
 end