require "diff/diff"

require "wiki_content"
require "chunks/wiki"

require "date"
require "author"
require "page"

class Revision
  attr_accessor :page, :number, :content, :created_at, :author

  def initialize(page, number, content, created_at, author)
    @page, @number, @created_at, @author = page, number, created_at, author
    self.content = content
  end

  # Ensure that the wiki content is parsed when ever it is updated.
  def content=(content)
    @content = content
  end

  def created_on
    Date.new(@created_at.year, @created_at.mon, @created_at.day)
  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

  def next_revision
    page.revisions[number + 1]
  end

  def previous_revision
    number - 1 >= 0 && page.revisions[number - 1]
  end

  # Returns an array of all the WikiWords present in the content of this revision.
  def wiki_words
    unless @wiki_words_cache 
      wiki_chunks = display_content.find_chunks(WikiChunk::WikiLink)
      @wiki_words_cache = wiki_chunks.map { |c| ( c.escaped_text ? nil : c.page_name ) }.compact.uniq
    end
    @wiki_words_cache
  end  

  # Returns an array of all the WikiWords present in the content of this revision.
  # that already exists as a page in the web.
  def existing_pages
    wiki_words.select { |wiki_word| page.web.pages[wiki_word] }
  end

  # Returns an array of all the WikiWords present in the content of this revision
  # that *doesn't* already exists as a page in the web.
  def unexisting_pages
    wiki_words - existing_pages
  end  

	# Explicit check for new type of display cache with find_chunks method.
	# Ensures new version works with older snapshots.
  def display_content
    unless @display_cache && @display_cache.respond_to?(:find_chunks)
      @display_cache = WikiContent.new(self)
    end
    @display_cache
  end

  def display_diff
    previous_revision ? HTMLDiff.diff(previous_revision.display_content, display_content) : display_content
  end

  def clear_display_cache
    @display_cache = @published_cache = @wiki_words_cache = nil
  end
  
  def display_published
    @published_cache = WikiContent.new(self, {:mode => :publish}) if @published_cache.nil?
    @published_cache
  end

  def display_content_for_export
    WikiContent.new(self, {:mode => :export} )
  end

end