require 'cgi'
require 'chunks/engines'
require 'chunks/category'
require 'chunks/include'
require 'chunks/todo'
require 'chunks/wiki'
require 'chunks/literal'
require 'chunks/uri'
require 'chunks/nowiki'

# Wiki content is just a string that can process itself with a chain of
# actions. The actions can modify wiki content so that certain parts of
# it are protected from being rendered by later actions.
#
# When wiki content is rendered, it can be interrogated to find out 
# which chunks were rendered. This means things like categories, wiki 
# links, can be determined.
#
# Exactly how wiki content is rendered is determined by a number of 
# settings that are optionally passed in to a constructor. The current
# options are:
#  * :engine 
#    => The structural markup engine to use (Textile, Markdown, RDoc)
#  * :engine_opts
#    => A list of options to pass to the markup engines (safe modes, etc)
#  * :pre_engine_actions
#    => A list of render actions or chunks to be processed before the
#       markup engine is applied. By default this is:    
#       Category, Include, URIChunk, WikiChunk::Link, WikiChunk::Word
#  * :post_engine_actions
#    => A list of render actions or chunks to apply after the markup 
#       engine. By default these are:    
#       Literal::Pre, Literal::Tags
#       ToDo items
#  * :mode
#    => How should the content be rendered? For normal display (:display), 
#       publishing (:publish) or export (:export)?
#
# AUTHOR: Mark Reid <mark @ threewordslong . com>
# CREATED: 15th May 2004
# UPDATED: 22nd May 2004
class WikiContent < String

  # Moved URIChunk from pre-engine to post-engine, as it clashed with the textile
  # markup of "link":URL.
  PRE_ENGINE_ACTIONS  = [ NoWiki, Category, Include, WikiChunk::BlikiLink, WikiChunk::Link, WikiChunk::Word ] 
  POST_ENGINE_ACTIONS = [ Literal::Pre, Literal::Tags, URIChunk, Todo ]
  

  DEFAULT_OPTS = {
    :pre_engine_actions  => PRE_ENGINE_ACTIONS,
    :post_engine_actions => POST_ENGINE_ACTIONS,
    :engine              => Engines::Textile,
    :engine_opts         => [],
    :mode                => [:display]
  }

  attr_reader :web, :options, :rendered

  # Create a new wiki content string from the given one.
  # The options are explained at the top of this file.
  def initialize(revision, options = {})
    @revision = revision
    @web = @revision.page.web

    # Deep copy of DEFAULT_OPTS to ensure that changes to PRE/POST_ENGINE_ACTIONS stay local
    @options = Marshal.load(Marshal.dump(DEFAULT_OPTS)).update(options)
    @options[:engine] = Engines::MAP[@web.markup] || Engines::Textile
    @options[:engine_opts] = (@web.safe_mode ? [:filter_html, :filter_styles] : [])

    @options[:pre_engine_actions].delete(WikiChunk::Word) if @web.brackets_only

    super(@revision.content)

    begin
      render!(@options[:pre_engine_actions] + [@options[:engine]] + @options[:post_engine_actions])
    rescue => e
      @rendered = "<strong>#{e.message}</strong><br/><br/>#{e.backtrace.join('<br/>')}"
    end
  end

  # Call @web.page_link using current options.
  def page_link(name, text) 
    @web.make_link(name, text, @options) 
  end

  # Find all the chunks of the given types
  def find_chunks(chunk_type)
    rendered.select { |chunk| chunk.kind_of?(chunk_type) }
  end

  # Render this content using the specified actions.
  def render!(chunk_types)
    @chunks = []
    chunk_types.each { |chunk_type| self.apply_type!(chunk_type) }
    
    # unmasking order is reversed to allow chuncks that encapsulate other chunks,
    # e.g. a ToDo item with a WikiWork link.
    @rendered = @chunks.reverse.map { |chunk| chunk.unmask(self) }.compact
    (@chunks - @rendered).each { |chunk| chunk.revert(self) }
  end
  
  # Find all the chunks of the given type in this content
  # Each time the type's pattern is matched, create a new
  # chunk for it, and replace the occurance of the chunk
  # in this content with its mask.
  def apply_type!(chunk_type)
    self.gsub!( chunk_type.pattern ) do |match|
      @chunks << chunk_type.new($~, @revision)
      @chunks.last.mask(self)
    end
  end
end