# Redmine - project management software
# Copyright (C) 2006-2008  Jean-Philippe Lang
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

module Redmine
  module WikiFormatting
    @@formatters = {}

    class << self
      def map
        yield self
      end
      
      def register(name, formatter, helper)
        raise ArgumentError, "format name '#{name}' is already taken" if @@formatters[name.to_sym]
        @@formatters[name.to_sym] = {:formatter => formatter, :helper => helper}
      end
      
      def formatter_for(name)
        entry = @@formatters[name.to_sym]
        (entry && entry[:formatter]) || Redmine::WikiFormatting::NullFormatter::Formatter
      end
      
      def helper_for(name)
        entry = @@formatters[name.to_sym]
        (entry && entry[:helper]) || Redmine::WikiFormatting::NullFormatter::Helper
      end
      
      def format_names
        @@formatters.keys.map
      end
      
      def to_html(format, text, options = {}, &block)
        text = if Setting.cache_formatted_text? && text.size > 2.kilobyte && cache_store && cache_key = cache_key_for(format, options[:object], options[:attribute])
          # Text retrieved from the cache store may be frozen
          # We need to dup it so we can do in-place substitutions with gsub!
          cache_store.fetch cache_key do
            formatter_for(format).new(text).to_html
          end.dup
        else
          formatter_for(format).new(text).to_html
        end
        if block_given?
          execute_macros(text, block)
        end
        text
      end

      # Returns a cache key for the given text +format+, +object+ and +attribute+ or nil if no caching should be done
      def cache_key_for(format, object, attribute)
        if object && attribute && !object.new_record? && object.respond_to?(:updated_on) && !format.blank?
          "formatted_text/#{format}/#{object.class.model_name.cache_key}/#{object.id}-#{attribute}-#{object.updated_on.to_s(:number)}"
        end
      end
      
      # Returns the cache store used to cache HTML output
      def cache_store
        ActionController::Base.cache_store
      end
      
      MACROS_RE = /
                    (!)?                        # escaping
                    (
                    \{\{                        # opening tag
                    ([\w]+)                     # macro name
                    (\(([^\}]*)\))?             # optional arguments
                    \}\}                        # closing tag
                    )
                  /x unless const_defined?(:MACROS_RE)
      
      # Macros substitution
      def execute_macros(text, macros_runner)
        text.gsub!(MACROS_RE) do
          esc, all, macro = $1, $2, $3.downcase
          args = ($5 || '').split(',').each(&:strip)
          if esc.nil?
            begin
              macros_runner.call(macro, args)
            rescue => e
              "<div class=\"flash error\">Error executing the <strong>#{macro}</strong> macro (#{e})</div>"
            end || all
          else
            all
          end
        end
      end
    end
    
    # Default formatter module
    module NullFormatter
      class Formatter
        include ActionView::Helpers::TagHelper
        include ActionView::Helpers::TextHelper
        include ActionView::Helpers::UrlHelper
        
        def initialize(text)
          @text = text
        end
        
        def to_html(*args)
          simple_format(auto_link(CGI::escapeHTML(@text)))
        end
      end
      
      module Helper
        def wikitoolbar_for(field_id)
        end
      
        def heads_for_wiki_formatter
        end
      
        def initial_page_content(page)
          page.pretty_title.to_s
        end
      end
    end
  end
end