module TemplateRenderer
  # This class is used to give ERB templates access to objects of our choosing.
  #
  #   TemplateContext.bind(:object => value)  # => <Binding>
  #
  # The binding returned here can then be passed into an ERB instance's #result method
  # giving it access to the values passed into the #bind method of TemplateContext.
  #
  # It uses method missing to expose the content of the hash, so it's not the most speedy
  # solutions, but it is reasonably OK.
  class TemplateContext
    def self.bind(locals)
      new(locals).send(:binding)
    end

    def initialize(locals)
      @locals = locals
    end

    def method_missing(method_name)
      @locals[method_name] || super
    end

    def partial(template_name)
      template = IO.read(File.join(PROPER_ROOT, "/app/views/#{template_name}.rhtml"))
      ERB.new(template).result(binding)
    end
  end

  # Renders the template at the given path. This path is calculated relative to the
  # rails default view directory.
  def render(template_name, locals = {})
    template = IO.read(File.join(PROPER_ROOT, "app/views/#{template_name}.rhtml"))
    ERB.new(template).result(TemplateContext.bind(locals))
  end
end