voltrb/volt

require 'volt/page/targets/helpers/comment_searchers'

module Volt
  # A dom template is used to optimize going from a template name to
  # dom nodes and bindings.  It stores a copy of the template's parsed
  # dom nodes, then when a new instance is requested, it updates the
  # dom markers (comments) for new binding numbers and returns a cloneNode'd
  # version of the dom nodes and the bindings.
  class DomTemplate
    include CommentSearchers

    def initialize(volt_app, template_name)
      template = volt_app.templates[template_name]

      if template
        html      = template['html']
        @bindings = template['bindings']
      else
        html      = "<div>-- &lt; missing view or tag at #{template_name.inspect}, make sure it's component is included in dependencies.rb &gt; --</div>"
        @bindings = {}
      end

      @nodes = build_from_html(html)

      track_binding_anchors
    end

    # Returns the dom nodes and bindings
    def make_new
      bindings = update_binding_anchors!(`self.nodes`)

      new_nodes = `self.nodes.cloneNode(true)`

      [new_nodes, bindings]
    end

    # Finds each of the binding anchors in the temp dom, then stores a reference
    # to them so they can be quickly updated without using xpath to find them again.
    def track_binding_anchors
      @binding_anchors = {}

      # Loop through the bindings, find in nodes.
      @bindings.each_pair do |name, binding|
        if name.is_a?(String)
          # Find the dom node for an attribute anchor
          node = nil
          `
            node = self.nodes.querySelector('#' + name);
          `
          @binding_anchors[name] = node
        else
          # Find the dom node for a comment anchor
          start_comment = find_by_comment("$#{name}", @nodes)
          end_comment   = find_by_comment("$/#{name}", @nodes)

          @binding_anchors[name] = [start_comment, end_comment]
        end
      end
    end

    # Takes the binding_anchors and updates them with new numbers (comments and id's)
    # then returns the bindings updated to the new numbers.
    def update_binding_anchors!(nodes)
      new_bindings = {}

      @binding_anchors.each_pair do |name, anchors|
        new_name         = @@binding_number
        @@binding_number += 1

        if name.is_a?(String)
          if name[0..1] == 'id'
            # A generated id
            # update the id
            `anchors.setAttribute('id', 'id' + new_name);`

            new_bindings["id#{new_name}"] = @bindings[name]
          else
            # Assume a fixed id, should not be updated
            # TODO: Might want to check the page to see if a node
            # with this id already exists and raise if it does.

            # Copy from existing binding
            new_bindings[name] = @bindings[name]
          end
        else
          start_comment, end_comment = anchors

          `
            if (start_comment.textContent) {
              // direct update
              start_comment.textContent = " $" + new_name + " ";
              end_comment.textContent = " $/" + new_name + " ";
            } else if (start_comment.innerText) {
              start_comment.innerText = " $" + new_name + " ";
              end_comment.innerText = " $/" + new_name + " ";
            } else {
              // phantomjs doesn't work with textContent, so we replace the nodes
              // and update the references
              start_comment.nodeValue = " $" + new_name + " ";
              end_comment.nodeValue = " $/" + new_name + " ";
            }
          `

          # %x{
          #   start_comment.innerText = " $" + new_name + " ";
          #   end_comment.innerText = " $/" + new_name + " ";
          # }

          new_bindings[new_name] = @bindings[name]
        end
      end

      new_bindings
    end
  end
end