module MasterView

  class RenderLevel #contains render modes, each gen level
    attr_accessor :render_modes

    def initialize(render_modes = [])
      @render_modes = render_modes
    end

    def push(render_mode)
      @render_modes.push render_mode
    end
  end

  class RenderMode #contains tags and output, each output style
    attr_accessor :output, :tags, :mode_type
    def initialize(output = nil, mode_type = :normal)
      @output = output
      @tags = []
      @mode_type = mode_type
    end

    def tag
      @tags.last
    end

    def directives
      @tags.last.directives
    end

    def render_directives(method_name, context=tag.create_context)
      dcs = DirectiveCallStack.new
      tag_name = tag.tag_name.downcase
      depth = tags.size-1
      @tags.each do |tag|
        case depth
        when 0
          dcs << tag.directives.determine_dcs(method_name)
        when 1
          dcs << tag.directives.determine_dcs(determine_method(:child, tag_name, method_name))
          dcs << tag.directives.determine_dcs(determine_method(:child, :any, method_name))
          dcs << tag.directives.determine_dcs(determine_method(:descendant, tag_name, method_name))
          dcs << tag.directives.determine_dcs(determine_method(:descendant, :any, method_name))
        else
          dcs << tag.directives.determine_dcs(determine_method(:descendant, tag_name, method_name))
          dcs << tag.directives.determine_dcs(determine_method(:descendant, :any, method_name))
        end
        depth -= 1
      end
      dcs.context = context
      dcs.render
    end

    def determine_method(modifier, tag_name, base)
      type = "#{modifier.to_s}_#{tag_name.to_s}_#{base.to_s}"
    end
  end

  class DirectiveCallStack
    attr_reader :directives_to_call
    attr_accessor :context

    def initialize
      @directives_to_call = []
    end

    def <<(directive_calls)
      if directive_calls.is_a? DirectiveCallStack
        @directives_to_call << directive_calls.directives_to_call
      else
        @directives_to_call << directive_calls
      end
      @directives_to_call.flatten!
      self
    end

    def render
      return [] if @directives_to_call.empty?
      directive_proc = @directives_to_call.shift
      directive_proc.call(self)
    end
  end

  class DirectiveSet
    attr_accessor :directives
    def initialize
      @directives = []
    end

    def <<(directive)
      @directives << directive
      @directives.flatten!
      self  
    end

    def determine_dcs(method_name)
      method_name_sym = method_name.to_sym
      dcs = DirectiveCallStack.new
      @directives.each do |directive|
        if directive.respond_to? method_name_sym
          dcs << create_call_proc(directive, method_name_sym)
        end
      end
      dcs
    end

    def create_call_proc(directive, method_name_sym)
      lambda do |dcs|
        directive.save_directive_call_stack(dcs) if directive.respond_to? :save_directive_call_stack
        directive.send(method_name_sym, dcs)
      end
    end
    
  end


  class SimpleRenderHandler
    def description
      'SimpleRenderHandler is the default renderer for nodes, it should be invoked as the last directive and will output node normally'
    end

    def stag(dcs)
      context = dcs.context
      ret = []
      ret << "<#{context[:tag].tag_name}" 
      context[:tag].attributes.sort.each do |name, value| 
        ret << " #{name}=\"#{value}\""
      end
      ret << '>' #must output as separate string so simplify_empty_elements can find it
    end

    def characters(dcs)
      context = dcs.context
      [] << context[:content_part]
    end

    def comment(dcs)
      context = dcs.context
      [] << '<!-- ' << context[:content_part] << ' -->'
    end
    
    def cdata(dcs)
      context = dcs.context
      [] << '<![CDATA[' << context[:content_part] << ']]>'
    end

    def etag(dcs)
      context = dcs.context
      [] << '</' << "#{context[:tag].tag_name}>" #must output </ as separate string so simplify_empty_elements can find it
    end
    
  end

  class Tag 
    attr_accessor :directives, :tag_name, :attributes, :mode_type, :stag, :content, :etag, :parent
    def initialize(directives, tag_name, attributes, mode_type, parent)
      @tag_name = tag_name
      @attributes = attributes
      @mode_type = mode_type
      @directives = directives
      @stag = []
      @content = []
      @etag = []
      @parent = parent
    end

    # creates a tag context using tag itself and mode type, also merge in any additional 
    # values passed in via values hash
    def create_context( values = {} )
      { 
        :tag => self,
        :mode_type => @mode_type
      }.merge!(values)
    end

    def data
      [] << @stag << @content << @etag
    end
  end



  class MIOSerializer
    def initialize(options)
      raise RequiredArgumentMissingError.new("Required argument is missing, specify the MasterViewIO object in options[:output_mio_tree]") unless options[:output_mio_tree]
      @options = options
      @mio_tree = options[:output_mio_tree]
    end

    def serialize(render_mode, tag)
      data_to_write = tag.data.join
      @mio_tree.path(render_mode.output).write(data_to_write, @options)
    end
  end

=begin
  # Serializer which simply serializes output to the console
  class ConsoleSerializer
    def serialize(render_mode, tag)
      puts "outputing mode=#{render_mode.mode_type} to file=#{render_mode.output}"
      puts tag.data.join
      puts ''
      true
    end
  end

  # Serializer which simply outputs each fragment to a hash with the key representing 
  # the path and the value the string contents.
  # You may specify this serializer as an option to the parser (:serializer => HashSerializer.new(output_hash)). 
  # It takes an empty hash as the single constructor parameter to which the contents will be output.
  class HashSerializer
    def initialize( output_hash )
      @output_hash = output_hash
    end

    def serialize(render_mode, tag)
      Log.debug { "adding to hash - outputing mode=#{render_mode.mode_type} to file=#{render_mode.output}" }
      @output_hash[ render_mode.output ] = tag.data.join
      true
    end
  end
=end

  class Renderer
    include DirectiveHelpers

    # Set of element names that can be simplified. Used in simplify_empty_elements.
    # Only simplify elements that are specified in the DTD as being empty, collapsing others can cause parsing
    # or rendering problems in browsers. 
    # http://www.w3.org/TR/xhtml1/dtds.html#a_dtd_XHTML-1.0-Strict
    # base, meta, link, hr, br, param, img, area, input, col 
    XHTMLEmptyElementNameSet = %w{ base meta link hr br param img area input col }.to_set

    attr_reader :directive_load_paths, :mv_ns, :keyword_expander, :default_extension
    attr_accessor :render_levels, :default_render_handler, :serializer, :template_pathname, :template_full_pathname
    attr_reader :directives_registry  #:nodoc:

    def self.last_renderer; @@last_renderer; end

    def initialize( options = {} )
      @@last_renderer = self; #save last renderer for convenient access
      @default_render_handler = SimpleRenderHandler.new
      @render_levels = [
        RenderLevel.new( [RenderMode.new] )
      ]

      serializer = options[:serializer] || DefaultSerializer
      self.serializer = serializer.is_a?(Class) ? serializer.new(options) : serializer #one can pass in Serializer class or an instance
      self.mv_ns = options[:namespace] || NamespacePrefix
      self.template_pathname = options[:template_pathname] 
      self.template_full_pathname = IOMgr.template.path(self.template_pathname).full_pathname if self.template_pathname
      @default_extension = (options[:output_mio_tree]) ? options[:output_mio_tree].default_extension : IOMgr.erb.default_extension
      @keyword_expander = KeywordExpander.new
      @keyword_expander.set_template_pathname(self.template_pathname, @default_extension)
      #ISSUE: if :additional_directive_paths then do cleaning and validity checks here and now
      # (then we don't need to keep re-checking in DirectiveRegistry or other processing)
      # [DJL 04-Jul-2006]
      self.directive_load_paths = ( DefaultDirectiveLoadPaths << options[:additional_directive_paths] ).flatten
    end

    def mv_ns=(namespace_prefix)
      @mv_ns = namespace_prefix
      Log.debug { 'namespace_prefix set to '+namespace_prefix }
    end

    # Sets directive_load_paths, re-requiring all the new load paths, however any directives that were
    # already required (and loaded) will still be in memory because these are not reset.
    def directive_load_paths=( directive_paths ) 

      @directives_registry = MasterView::DirectivesRegistry
      #ISSUE: can we optimize this if there aren't :additional_directive_paths?
      # Do we even need/want the notion of per-invocation :additional_directive_paths
      # given that the directives load path is configurable for the client app?
      # [DJL 04-Jul-2006]
      directives_registry.load_directives( directive_paths ) #?? if directive_load_paths != DefaultDirectiveLoadPaths ??

      # is this a good idea? no clear that we need/want to modify mv_ns after app initialization
      # If so, this could be simplifed.  Discuss with jeffb.
      # [DJL 04-Jul-2006]
      if @mv_ns != NamespacePrefix
        @directives_registry = directives_registry.clone
      end

      # only need to do the following if :additional_directive_paths or nonstd @mv_ns???
      directives_registry.build_directive_maps( @mv_ns )
      
    end

    def modes
      @render_levels.last.render_modes
    end
    def push_level(render_level)
      @render_levels.push render_level
    end

    def push_tag(tag_name, attributes)
      modes.each do |mode|
        attributes_copy = attributes.clone #these get changed in select_active_directives
        directives = select_active_directives(tag_name, attributes_copy, mode)
        parent = (mode.tags.empty?) ? nil : mode.tag
        mode.tags.push Tag.new(directives, tag_name, attributes_copy, mode.mode_type, parent)
        mode.tag.stag << mode.render_directives(:stag)
      end
    end

    def append_content(type, content)
      modes.each do |mode|
        if mode.tag
          mode.tag.content << mode.render_directives( type, mode.tag.create_context(:content_part => content) )
        end
      end
    end

    #does not call any directives, direct output
    def append_raw(raw_output) 
      modes.each do |mode|
        if mode.tag
          mode.tag.content << raw_output
        end
      end
    end

    def pop_level
      @render_levels.pop
    end

    def pop_tag
      need_to_pop_level = false
      modes.each do |mode|
        mode.tag.etag << mode.render_directives(:etag)
        content = []
        content << mode.tag.stag << mode.tag.content << mode.tag.etag
        content = simplify_empty_elements content
        last_tag = mode.tags.pop
        if mode.tags.empty?
          unless mode.output.nil?
            @serializer.serialize(mode, last_tag)
            need_to_pop_level = true
          end
        else #add it to the parent
          mode.tag.content << content
        end
      end
      pop_level if need_to_pop_level
    end


    # Simplify (collapse) empty elements so that <foo></foo> from rexml parsing ends up being <foo/> .
    # Only simplify elements that are specified in the DTD as being empty, collapsing others can cause parsing
    # or rendering problems in browsers. Uses constant XHTMLEmptyElementNameSet to find elements that should be
    # collapsed. 
    # http://www.w3.org/TR/xhtml1/dtds.html#a_dtd_XHTML-1.0-Strict
    # xhtml-1.0-Strict empty elements are:
    # base, meta, link, hr, br, param, img, area, input, col 
    def simplify_empty_elements(content) #relies on the fact that > and </ are individual strings and are back to back with nothing in between
      ret = []
      current_element_name = nil
      next_to_last = nil
      last = nil
      content.flatten!
      content.each do |item|
        if next_to_last == '>' && last == '</' && XHTMLEmptyElementNameSet.include?(current_element_name) 
          ret.pop #remove '>'
          ret.pop #remove '</'
          ret << ' />' # adding in a space to make xhtml more compatible with html editors and older browsers
        else
          ret << item
        end
        unless item.nil?
          if !item.starts_with?('</') && item.starts_with?('<')
            current_element_name = /^<(\S*)/.match(item)[1] # depending on what is after < this might be empty string
          elsif last && last.starts_with?('</')
            current_element_name = nil
          end
        end
        next_to_last = last
        last = item
      end
      ret
    end

    def capitalize_first_letter(string)
      string[0,1].upcase + string[1..-1]
    end

    def select_active_directives(tag_name, attributes, mode)
      selected = DirectiveSet.new
      directive_processors = directives_registry.construct_directive_processors( attributes )
      sorted_directives = directive_processors.sort do |x,y| 
        xval = (x.respond_to?(:priority)) ? x.priority : DirectivePriorities::Medium
        yval = (y.respond_to?(:priority)) ? y.priority : DirectivePriorities::Medium
        xval <=> yval
      end
      sorted_directives << @default_render_handler #insure this is last
      selected << sorted_directives
    end

  end


  class MasterViewListener
    include REXML::SAX2Listener
    include DirectiveHelpers

    def initialize( options = {} )
      @renderer = Renderer.new(options)
    end

    def xmldecl(version, encoding, standalone)
      #todo
    end

    def start_document
      #todo
    end

    def doctype(name, pub, sys, long_name, uri)
      #todo
    end

    def start_element(uri, localname, qname, attributes)
      unescape_attributes!(attributes)
      push_levels(attributes)
      @renderer.push_tag(qname, attributes)
    end

    def characters(text)
      @renderer.append_content(:characters, text)
    end

    def comment(comment)
      @renderer.append_content(:comment, comment)
    end

    def cdata(content)
      @renderer.append_content(:cdata, content)
    end

    def end_element(uri, localname, qname)
      @renderer.pop_tag
    end

    def end_document
      #todo
    end

    def unescape_attributes!(attributes)
      attributes.each do |name, value|
        value.replace CGI::unescapeHTML(value)
        value.gsub!('&apos;', '\'')
      end
    end

    def generate_replace(value)
      @renderer.append_raw ERB_EVAL+value+ERB_END
    end

    # handle a mv:gen_partial attribute, which calls generate and outputs a token
    # it takes an optional :dir => 'foo/bar' which is prepended to partial path,
    # otherwise it just uses what is in partial. 
    # This creates a generate attribute value which will be used later.
    # Parameters
    # value = attribute value for gen_partial
    # attributes = all remaining attributes hash
    def handle_gen_partial(attributes)
      value = @renderer.keyword_expander.resolveAttrAndDelete(attributes, @renderer.mv_ns+'gen_partial')
      if value 
        prepend_dir = find_string_val_in_string_hash(value, :dir) #only used for masterview
        partial = find_string_val_in_string_hash(value, :partial) 
        return if partial.nil?
        path = render_partial_name_to_file_name(partial, @renderer.default_extension)
        path = File.join(prepend_dir, path) if prepend_dir
        generate_attribute = attributes[@renderer.mv_ns+'generate'] || '' # check if we need to add to existing generate
        generate_attribute = path + (generate_attribute.blank? ? '' : ', '+generate_attribute)
        attributes[@renderer.mv_ns+'generate'] = generate_attribute 
        @renderer.append_raw( ERB_EVAL+'render( '+value+' )'+ERB_END ) 
      end
    end

    def push_levels(attributes)
      handle_gen_partial(attributes)
      
      gen_replace = @renderer.keyword_expander.resolveAttrAndDelete(attributes, @renderer.mv_ns+'gen_replace') #get and delete from map
      generate_replace( gen_replace ) unless gen_replace.nil?

      gen = @renderer.keyword_expander.resolveAttrAndDelete(attributes, @renderer.mv_ns+'generate') #get and delete from map
      if gen
        omit_comment = OmitGeneratedComments || File.extname(gen) != MasterView::IOMgr.erb.default_extension
        attributes[@renderer.mv_ns+'insert_generated_comment'] =  @renderer.template_full_pathname.to_s unless omit_comment #add the comment directive, so it will be written to each gen'd file
        render_level = nil
        gen_values = parse_eval_into_hash(gen, :normal)

        #Log.debug { 'generate_hash='+gen_values.inspect }

        gen_values.each do |key,value|
          mode_type = key.to_sym
          arr_values = (value.is_a?(Enumerable)) ? value : [value] #if not enumerable add it to array
          value.each do |path|
            path.strip!
            #Log.debug { ('pushing mode='+mode_type.to_s+' path='+path).indent(2*@renderer.render_levels.size) } 
            render_level ||= RenderLevel.new
            render_level.push RenderMode.new(path, mode_type)
          end
        end
        @renderer.push_level(render_level) unless render_level.nil?
      end

    end
    
  end

  class Parser
    def self.parse_mio( template_mio, output_mio_tree, options = {})
      options[:template_pathname]= template_mio.pathname
      options[:output_mio_tree] = output_mio_tree
      template = template_mio.read
      self.parse( template, options )
    end


    # parse a MasterView template and render output. 
    # template param is actual template source passed in as string or array.
    # options are the optional parameters which control the output (:output_mio_tree, :namespace, :serializer)
    def self.parse( template, options = DefaultParserOptions.clone)
      options[:listeners] ||= [MasterViewListener]
      options[:rescue_exceptions] = RescueExceptions unless options.include?(:rescue_exceptions)

      begin
      if options[:tidy]
        template = TidyHelper.tidy(template)
      elsif options[:escape_erb]
        template = EscapeErbHelper.escape_erb(template)
      end
      
      parser = REXML::Parsers::SAX2Parser.new( template )
      options[:listeners].each do |listener|
        if listener.is_a? Class
          parser.listen( listener.new(options) )
        else
          parser.listen(listener)
        end
      end
      parser.parse
      rescue Exception => e
        if options[:rescue_exceptions]
          Log.error { "Failure to parse template. Exception="+e }
          Log.debug { e.backtrace.join("\n") }
        else
          raise
        end
      end
    end

  end

end