require_dependency 'chunk'

class Revision < ActiveRecord::Base
  belongs_to :page
  belongs_to :web
  has_one :deconstructed, :dependent => true
  has_many :chunks, :dependent => true, :order => 'id ASC'

  validates_presence_of :author
  
  # utility to pick up the web affiliation from the page
  before_save :set_web
  def set_web() self.web ||= page.web end
  
  # after_save and not before as we need the chunks association collection to
  # exist. This is a two-stage save for the revisions: first the revision row
  # the the matching deconstructed content. Unfortunate, but I'd rather pre-cache
  # the deconstruction.
  after_save :deconstruct_markup

  PRE_ENGINE_ACTIONS  = [ NoWikiChunk, IncludeChunk, SyntacticHighlightChunk, ExplicitLinkChunk, BlikiLinkChunk, InterWebLinkChunk, GlossaryDefinition ]
  POST_ENGINE_ACTIONS = [ GlossaryUsage, WikiWordChunk, TodoChunk ] # LiteralTagsChunk, LiteralPreChunk, URIChunk,

  def deconstruct_markup
    chunks.clear
    @display_content = nil
    @pre_render_cache = nil
    
    @pre_render_cache = markup_content.dup
    [PRE_ENGINE_ACTIONS, page.web.markup_engine, POST_ENGINE_ACTIONS].flatten.each do |chunk|
      @pre_render_cache.gsub! chunk.pattern do |matched_string|
        matched_bit = chunk.create :revision => self, :match_data => $~
        matched_bit.mask_text
      end
    end

    chunks.reload
    if deconstructed
      deconstructed.content = @pre_render_cache
      deconstructed.save
    else
      deconstructed = Deconstructed.create :content => @pre_render_cache, :revision => self
    end
  end

  def display_content(view)
    chunks.reject do |chunk|
      chunk.is_a? MarkupEngine
    end.reverse.inject(deconstructed.content.dup) do |display_content, chunk|
      display_content.gsub chunk.mask_text, chunk.resolved_text(view)
    end
  end

  def pretty_created_at
    # Must use DateTime because Time doesn't support %e on at least some platforms
    DateTime.new(
      created_at.year, created_at.mon, created_at.day, created_at.hour, created_at.min
    ).strftime "%B %e, %Y %H:%M" 
  end

  # Finds all the current revisions for a particular web. This is required for
  # the extra conditions processing, which can't be done wrom the Web has_many
  # relationship.
  def self.current_for(web, options={})
    self.with_scope(:find => {:conditions => ['revisions.current = ? AND revisions.web_id = ?', true, web.id]}) do
      self.find(:all, options)
    end
  end

  # Should be called from within a transaction - see Page#revise
  def current!
    update_attribute :current, true
    Chunk.update_all ['current = ?', true], "revision_id = #{id}"
  end

  # Should be called from within a transaction - see Page#revise
  def not_current!
    update_attribute :current, false
    Chunk.update_all ['current = ?', false], "revision_id = #{id}"
  end
end