BURs: rename AliasAndImplicationImporter to BulkUpdateRequestProcessor.

The name AliasAndImplicationImporter is a holdover from the time before
bulk update requests existed. This was a bad name because it doesn't do
any actual importing, instead it's used for parsing and executing bulk
update requests.

app/logical/bulk_update_request_processor.rb

@@ -0,0 +1,136 @@
+class BulkUpdateRequestProcessor
+  extend Memoist
+
+  class Error < StandardError; end
+  attr_accessor :text, :forum_topic_id, :skip_secondary_validations
+
+  def initialize(text, forum_topic_id: nil, skip_secondary_validations: true)
+    @forum_topic_id = forum_topic_id
+    @text = text
+    @skip_secondary_validations = skip_secondary_validations
+  end
+
+  def tokens
+    text.split(/\r\n|\r|\n/).reject(&:blank?).map do |line|
+      line = line.gsub(/[[:space:]]+/, " ").strip
+
+      if line =~ /^(?:create alias|aliasing|alias) (\S+) -> (\S+)$/i
+        [:create_alias, $1, $2]
+      elsif line =~ /^(?:create implication|implicating|implicate|imply) (\S+) -> (\S+)$/i
+        [:create_implication, $1, $2]
+      elsif line =~ /^(?:remove alias|unaliasing|unalias) (\S+) -> (\S+)$/i
+        [:remove_alias, $1, $2]
+      elsif line =~ /^(?:remove implication|unimplicating|unimplicate|unimply) (\S+) -> (\S+)$/i
+        [:remove_implication, $1, $2]
+      elsif line =~ /^(?:mass update|updating|update|change) (.+?) -> (.*)$/i
+        [:mass_update, $1, $2]
+      elsif line =~ /^category (\S+) -> (#{Tag.categories.regexp})/
+        [:change_category, $1, $2]
+      elsif line.strip.empty?
+        # do nothing
+      else
+        raise Error, "Unparseable line: #{line}"
+      end
+    end
+  end
+
+  def validate!
+    tokens.map do |token|
+      case token[0]
+      when :create_alias
+        tag_alias = TagAlias.new(creator: User.system, forum_topic_id: forum_topic_id, status: "pending", antecedent_name: token[1], consequent_name: token[2], skip_secondary_validations: skip_secondary_validations)
+        unless tag_alias.valid?
+          raise Error, "Error: #{tag_alias.errors.full_messages.join("; ")} (create alias #{tag_alias.antecedent_name} -> #{tag_alias.consequent_name})"
+        end
+
+      when :create_implication
+        tag_implication = TagImplication.new(creator: User.system, forum_topic_id: forum_topic_id, status: "pending", antecedent_name: token[1], consequent_name: token[2], skip_secondary_validations: skip_secondary_validations)
+        unless tag_implication.valid?
+          raise Error, "Error: #{tag_implication.errors.full_messages.join("; ")} (create implication #{tag_implication.antecedent_name} -> #{tag_implication.consequent_name})"
+        end
+
+      when :remove_alias, :remove_implication, :mass_update, :change_category
+        # okay
+
+      else
+        raise NotImplementedError, "Unknown token: #{token[0]}" # should never happen
+      end
+    end
+  end
+
+  def process!(approver)
+    ActiveRecord::Base.transaction do
+      tokens.map do |token|
+        case token[0]
+        when :create_alias
+          tag_alias = TagAlias.create(creator: approver, forum_topic_id: forum_topic_id, status: "pending", antecedent_name: token[1], consequent_name: token[2], skip_secondary_validations: skip_secondary_validations)
+          unless tag_alias.valid?
+            raise Error, "Error: #{tag_alias.errors.full_messages.join("; ")} (create alias #{tag_alias.antecedent_name} -> #{tag_alias.consequent_name})"
+          end
+          tag_alias.approve!(approver: approver)
+
+        when :create_implication
+          tag_implication = TagImplication.create(creator: approver, forum_topic_id: forum_topic_id, status: "pending", antecedent_name: token[1], consequent_name: token[2], skip_secondary_validations: skip_secondary_validations)
+          unless tag_implication.valid?
+            raise Error, "Error: #{tag_implication.errors.full_messages.join("; ")} (create implication #{tag_implication.antecedent_name} -> #{tag_implication.consequent_name})"
+          end
+          tag_implication.approve!(approver: approver)
+
+        when :remove_alias
+          tag_alias = TagAlias.active.find_by(antecedent_name: token[1], consequent_name: token[2])
+          raise Error, "Alias for #{token[1]} not found" if tag_alias.nil?
+          tag_alias.reject!
+
+        when :remove_implication
+          tag_implication = TagImplication.active.find_by(antecedent_name: token[1], consequent_name: token[2])
+          raise Error, "Implication for #{token[1]} not found" if tag_implication.nil?
+          tag_implication.reject!
+
+        when :mass_update
+          TagBatchChangeJob.perform_later(token[1], token[2], User.system, "127.0.0.1")
+
+        when :change_category
+          tag = Tag.find_or_create_by_name(token[1])
+          tag.category = Tag.categories.value_for(token[2])
+          tag.save
+
+        else
+          raise Error, "Unknown token: #{token[0]}"
+        end
+      end
+    end
+  end
+
+  def affected_tags
+    tokens.flat_map do |type, *args|
+      case type
+      when :create_alias, :remove_alias, :create_implication, :remove_implication
+        [args[0], args[1]]
+      when :mass_update
+        tags = PostQueryBuilder.new(args[0]).tags + PostQueryBuilder.new(args[1]).tags
+        tags.reject(&:negated).reject(&:optional).reject(&:wildcard).map(&:name)
+      when :change_category
+        args[0]
+      end
+    end.sort.uniq
+  rescue Error
+    []
+  end
+
+  def to_dtext
+    tokens.map do |token|
+      case token[0]
+      when :create_alias, :create_implication, :remove_alias, :remove_implication
+        "#{token[0].to_s.tr("_", " ")} [[#{token[1]}]] -> [[#{token[2]}]]"
+      when :mass_update
+        "mass update {{#{token[1]}}} -> #{token[2]}"
+      when :change_category
+        "category [[#{token[1]}]] -> #{token[2]}"
+      else
+        raise "Unknown token: #{token[0]}"
+      end
+    end.join("\n")
+  end
+
+  memoize :tokens
+end