class Rubycritic::SourceControlSystem

def self.create
  supported_system = systems.detect(&:supported?)
  if supported_system
    supported_system.new
  else
    raise "Rubycritic requires a #{system_names} repository."
  end
end

def self.register_system
  @@systems << self
end

def self.supported?
  raise NotImplementedError.new("The #{self.class} class must implement the #{__method__} method.")
end

def self.system_names
  systems.join(", ")
end

def self.systems
  @@systems
end

def has_revision?
  raise NotImplementedError.new("The #{self.class} class must implement the #{__method__} method.")
end

def head_reference
  raise NotImplementedError.new("The #{self.class} class must implement the #{__method__} method.")
end

def revisions_count(file)
  raise NotImplementedError.new("The #{self.class} class must implement the #{__method__} method.")
end

def travel_to_head
  raise NotImplementedError.new("The #{self.class} class must implement the #{__method__} method.")
end