module StandardTags

  include Radiant::Taggable
  include LocalTime

  require "will_paginate/view_helpers"
  include WillPaginate::ViewHelpers

  class TagError < StandardError; end
  class RequiredAttributeError < StandardError; end

  desc %{
    Causes the tags referring to a page's attributes to refer to the current page.

    *Usage:*
    
    <pre><code><r:page>...</r:page></code></pre>
  }
  tag 'page' do |tag|
    tag.locals.page = tag.globals.page
    tag.expand
  end

  [:breadcrumb, :slug, :title].each do |method|
    desc %{
      Renders the @#{method}@ attribute of the current page.
    }
    tag method.to_s do |tag|
      tag.locals.page.send(method)
    end
  end

  desc %{
    Renders the @path@ attribute of the current page.
  }
  tag 'path' do |tag|
    relative_url_for(tag.locals.page.path, tag.globals.page.request)
  end
  deprecated_tag 'url', :substitute => 'path', :deadline => '1.2'

  desc %{
    Gives access to a page's children.

    *Usage:*
    
    <pre><code><r:children>...</r:children></code></pre>
  }
  tag 'children' do |tag|
    tag.locals.children = tag.locals.page.children
    tag.expand
  end

  desc %{
    Renders the total number of children.
  }
  tag 'children:count' do |tag|
    options = children_find_options(tag)
    options.delete(:order) # Order is irrelevant
    tag.locals.children.count(options)
  end

  desc %{
    Returns the first child. Inside this tag all page attribute tags are mapped to
    the first child. Takes the same ordering options as @<r:children:each>@.

    *Usage:*
    
    <pre><code><r:children:first>...</r:children:first></code></pre>
  }
  tag 'children:first' do |tag|
    options = children_find_options(tag)
    children = tag.locals.children.find(:all, options)
    if first = children.first
      tag.locals.page = first
      tag.expand
    end
  end

  desc %{
    Returns the last child. Inside this tag all page attribute tags are mapped to
    the last child. Takes the same ordering options as @<r:children:each>@.

    *Usage:*
    
    <pre><code><r:children:last>...</r:children:last></code></pre>
  }
  tag 'children:last' do |tag|
    options = children_find_options(tag)
    children = tag.locals.children.find(:all, options)
    if last = children.last
      tag.locals.page = last
      tag.expand
    end
  end

  desc %{
    Cycles through each of the children. Inside this tag all page attribute tags
    are mapped to the current child page.
    
    Supply @paginated="true"@ to paginate the displayed list. will_paginate view helper
    options can also be specified, including @per_page@, @previous_label@, @next_label@,
    @class@, @separator@, @inner_window@ and @outer_window@.

    *Usage:*
    
    <pre><code><r:children:each [offset="number"] [limit="number"]
     [by="published_at|updated_at|created_at|slug|title|keywords|description"]
     [order="asc|desc"] 
     [status="draft|reviewed|published|hidden|all"]
     [paginated="true"]
     [per_page="number"]
     >
     ...
    </r:children:each>
    </code></pre>
  }
  tag 'children:each' do |tag|
    render_children_with_pagination(tag)
  end

  desc %{
    The pagination tag is not usually called directly. Supply paginated="true" when you display a list and it will
    be automatically display only the current page of results, with pagination controls at the bottom.

    *Usage:*
    
    <pre><code><r:children:each paginated="true" per_page="50" container="false" previous_label="foo" next_label="bar">
      <r:child>...</r:child>
    </r:children:each>
    </code></pre>
  }
  tag 'pagination' do |tag|
    if tag.locals.paginated_list
      will_paginate(tag.locals.paginated_list, will_paginate_options(tag))
    end
  end

  desc %{
    Page attribute tags inside of this tag refer to the current child. This is occasionally
    useful if you are inside of another tag (like &lt;r:find&gt;) and need to refer back to the
    current child.

    *Usage:*
    
    <pre><code><r:children:each>
      <r:child>...</r:child>
    </r:children:each>
    </code></pre>
  }
  tag 'children:each:child' do |tag|
    tag.locals.page = tag.locals.child
    tag.expand
  end
  
  desc %{
    Renders the tag contents only if the current page is the first child in the context of
    a children:each tag
    
    *Usage:*
    
    <pre><code><r:children:each>
      <r:if_first >
        ...
      </r:if_first>
    </r:children:each>
    </code></pre>
    
  }
  tag 'children:each:if_first' do |tag|
    tag.expand if tag.locals.first_child
  end

  
  desc %{
    Renders the tag contents unless the current page is the first child in the context of
    a children:each tag
    
    *Usage:*
    
    <pre><code><r:children:each>
      <r:unless_first >
        ...
      </r:unless_first>
    </r:children:each>
    </code></pre>
    
  }
  tag 'children:each:unless_first' do |tag|
    tag.expand unless tag.locals.first_child
  end
  
  desc %{
    Renders the tag contents only if the current page is the last child in the context of
    a children:each tag
    
    *Usage:*
    
    <pre><code><r:children:each>
      <r:if_last >
        ...
      </r:if_last>
    </r:children:each>
    </code></pre>
    
  }
  tag 'children:each:if_last' do |tag|
    tag.expand if tag.locals.last_child
  end

  
  desc %{
    Renders the tag contents unless the current page is the last child in the context of
    a children:each tag
    
    *Usage:*
    
    <pre><code><r:children:each>
      <r:unless_last >
        ...
      </r:unless_last>
    </r:children:each>
    </code></pre>
    
  }
  tag 'children:each:unless_last' do |tag|
    tag.expand unless tag.locals.last_child
  end
  
  desc %{
    Renders the tag contents only if the contents do not match the previous header. This
    is extremely useful for rendering date headers for a list of child pages.

    If you would like to use several header blocks you may use the @name@ attribute to
    name the header. When a header is named it will not restart until another header of
    the same name is different.

    Using the @restart@ attribute you can cause other named headers to restart when the
    present header changes. Simply specify the names of the other headers in a semicolon
    separated list.

    *Usage:*
    
    <pre><code><r:children:each>
      <r:header [name="header_name"] [restart="name1[;name2;...]"]>
        ...
      </r:header>
    </r:children:each>
    </code></pre>
  }
  tag 'children:each:header' do |tag|
    previous_headers = tag.locals.previous_headers
    name = tag.attr['name'] || :unnamed
    restart = (tag.attr['restart'] || '').split(';')
    header = tag.expand
    unless header == previous_headers[name]
      previous_headers[name] = header
      unless restart.empty?
        restart.each do |n|
          previous_headers[n] = nil
        end
      end
      header
    end
  end

  desc %{
    Page attribute tags inside this tag refer to the parent of the current page.

    *Usage:*
    
    <pre><code><r:parent>...</r:parent></code></pre>
  }
  tag "parent" do |tag|
    parent = tag.locals.page.parent
    tag.locals.page = parent
    tag.expand if parent
  end

  desc %{
    Renders the contained elements only if the current contextual page has a parent, i.e.
    is not the root page.

    *Usage:*
    
    <pre><code><r:if_parent>...</r:if_parent></code></pre>
  }
  tag "if_parent" do |tag|
    parent = tag.locals.page.parent
    tag.expand if parent
  end

  desc %{
    Renders the contained elements only if the current contextual page has no parent, i.e.
    is the root page.

    *Usage:*
    
    <pre><code><r:unless_parent>...</r:unless_parent></code></pre>
  }
  tag "unless_parent" do |tag|
    parent = tag.locals.page.parent
    tag.expand unless parent
  end

  desc %{
    Renders the contained elements only if the current contextual page has one or
    more child pages.  The @status@ attribute limits the status of found child pages
    to the given status, the default is @"published"@. @status="all"@ includes all
    non-virtual pages regardless of status.

    *Usage:*
    
    <pre><code><r:if_children [status="published"]>...</r:if_children></code></pre>
  }
  tag "if_children" do |tag|
    children = tag.locals.page.children.count(:conditions => children_find_options(tag)[:conditions])
    tag.expand if children > 0
  end

  desc %{
    Renders the contained elements only if the current contextual page has no children.
    The @status@ attribute limits the status of found child pages to the given status,
    the default is @"published"@. @status="all"@ includes all non-virtual pages
    regardless of status.

    *Usage:*
    
    <pre><code><r:unless_children [status="published"]>...</r:unless_children></code></pre>
  }
  tag "unless_children" do |tag|
    children = tag.locals.page.children.count(:conditions => children_find_options(tag)[:conditions])
    tag.expand unless children > 0
  end
  
    desc %{
    Aggregates the children of multiple paths using the @paths@ attribute.
    Useful for combining many different sections/categories into a single
    feed or listing.
    
    *Usage*:
    
    <pre><code><r:aggregate paths="/section1; /section2; /section3"> ... </r:aggregate></code></pre>
  }
  tag "aggregate" do |tag|
    required_attr(tag, 'paths', 'urls')
    paths = (tag.attr['paths']||tag.attr["urls"]).split(";").map(&:strip).reject(&:blank?).map { |u| clean_path u }
    parent_ids = paths.map {|u| Page.find_by_path(u) }.map(&:id)
    tag.locals.parent_ids = parent_ids
    tag.expand
  end
  
  desc %{
    Sets the scope to the individual aggregated page allowing you to
    iterate through each of the listed paths.
    
    *Usage*:
    
    <pre><code><r:aggregate:each paths="/section1; /section2; /section3"> ... </r:aggregate:each></code></pre>
  }
  tag "aggregate:each" do |tag|
    aggregates = []
    tag.locals.aggregated_pages = tag.locals.parent_ids.map {|p| Page.find(p)}
    tag.locals.aggregated_pages.each do |aggregate_page|
      tag.locals.page = aggregate_page
      aggregates << tag.expand
    end
    aggregates.flatten.join('')
  end
  
  tag "aggregate:each:children" do |tag|
    tag.locals.children = tag.locals.page.children
    tag.expand
  end
  
  tag "aggregate:each:children:each" do |tag|
    options = children_find_options(tag)
    result = []
    children = tag.locals.children
    tag.locals.previous_headers = {}
    children.find(:all, options).each do |item|
      tag.locals.child = item
      tag.locals.page = item
      result << tag.expand
    end
    result.flatten.join('')
  end
  
  tag "aggregate:children" do |tag|
    tag.expand
  end
  
  desc %{
    Renders the total count of children of the aggregated pages.  Accepts the
    same options as @<r:children:each />@.

    *Usage*:
    
    <pre><code><r:aggregate paths="/section1; /section2; /section3">
      <r:children:count />
    </r:aggregate></code></pre>
  }  
  tag "aggregate:children:count" do |tag|
    options = aggregate_children(tag)
    if ActiveRecord::Base.connection.adapter_name.downcase == 'postgresql'
      options[:group] = Page.columns.map {|c| c.name}.join(', ')
      Page.find(:all, options).size
    else
      Page.count(options)
    end
  end
  desc %{
    Renders the contained block for each child of the aggregated pages.  Accepts the
    same options as the plain @<r:children:each />@.

    *Usage*:
    
    <pre><code><r:aggregate paths="/section1; /section2; /section3">
      <r:children:each>
        ...
      </r:children:each>
    </r:aggregate></code></pre>
  }
  tag "aggregate:children:each" do |tag|
    render_children_with_pagination(tag, :aggregate => true)
  end
  
  desc %{
    Renders the first child of the aggregated pages.  Accepts the
    same options as @<r:children:each />@.

    *Usage*:
    
    <pre><code><r:aggregate paths="/section1; /section2; /section3">
      <r:children:first>
        ...
      </r:children:first>
    </r:aggregate></code></pre>
  }
  tag "aggregate:children:first" do |tag|
    options = aggregate_children(tag)
    children = Page.find(:all, options)
    if first = children.first
      tag.locals.page = first
      tag.expand
    end
  end
  
  desc %{
    Renders the last child of the aggregated pages.  Accepts the
    same options as @<r:children:each />@.

    *Usage*:
    
    <pre><code><r:aggregate paths="/section1; /section2; /section3">
      <r:children:last>
        ...
      </r:children:last>
    </r:aggregate></code></pre>
  }
  tag "aggregate:children:last" do |tag|
    options = aggregate_children(tag)
    children = Page.find(:all, options)
    if last = children.last
      tag.locals.page = last
      tag.expand
    end
  end

  desc %{
    Renders a counter value or one of the values given based on a global cycle counter. 
    
    To get a numeric counter just use the tag, or specify a start value with @start@.
    Use the @reset@ attribute to reset the cycle to the beginning. Using @reset@ on a
    numbered cycle will begin at 0. Use the @name@  attribute to track multiple cycles; 
    the default is @cycle@.

    *Usage:*
    
    <pre><code><r:cycle [values="first, second, third"] [reset="true|false"] [name="cycle"] [start="second"] /></code></pre>
    <pre><code><r:cycle start="3" /></code></pre>
  }
  tag 'cycle' do |tag|
    cycle = (tag.globals.cycle ||= {})
    if tag.attr['values']
      values = tag.attr['values'].split(",").collect(&:strip)
    end
    start = tag.attr['start']
    cycle_name = tag.attr['name'] || 'cycle'
    if values
      if start
        current_index = (cycle[cycle_name] ||= values.index(start))
      else
        current_index = (cycle[cycle_name] ||=  0)
      end
      current_index = 0 if tag.attr['reset'] == 'true'
      cycle[cycle_name] = (current_index + 1) % values.size
      values[current_index]
    else
      cycle[cycle_name] ||= (start.presence || 0).to_i
      output = cycle[cycle_name]
      cycle[cycle_name] += 1
      if tag.attr['reset'] == 'true'
        cycle[cycle_name] = 0
        output = cycle[cycle_name]
      end
      output
    end
  end

  desc %{
    Renders the main content of a page. Use the @part@ attribute to select a specific
    page part. By default the @part@ attribute is set to body. Use the @inherit@
    attribute to specify that if a page does not have a content part by that name that
    the tag should render the parent's content part. By default @inherit@ is set to
    @false@. Use the @contextual@ attribute to force a part inherited from a parent
    part to be evaluated in the context of the child page. By default 'contextual'
    is set to true.

    *Usage:*
    
    <pre><code><r:content [part="part_name"] [inherit="true|false"] [contextual="true|false"] /></code></pre>
  }
  tag 'content' do |tag|
    page = tag.locals.page
    part_name = tag_part_name(tag)
    # Prevent simple and deep recursive rendering of the same page part
    rendering_parts = (tag.locals.rendering_parts ||= Hash.new {|h,k| h[k] = []})
    if rendering_parts[page.id].include?(part_name)
      raise TagError.new(%{Recursion error: already rendering the `#{part_name}' part.})
    else
      rendering_parts[page.id] << part_name
    end
    inherit = boolean_attr_or_error(tag,'inherit',false)
    part_page = page
    if inherit
      while (part_page.part(part_name).nil? and (not part_page.parent.nil?)) do
        part_page = part_page.parent
      end
    end
    contextual = boolean_attr_or_error(tag,'contextual', true)
    part = part_page.part(part_name)
    tag.locals.page = part_page unless contextual
    result = tag.globals.page.render_snippet(part) unless part.nil?
    rendering_parts[page.id].delete(part_name)
    result
  end

  desc %{
    Renders the containing elements if all of the listed parts exist on a page.
    By default the @part@ attribute is set to @body@, but you may list more than one
    part by separating them with a comma. Setting the optional @inherit@ to true will
    search ancestors independently for each part. By default @inherit@ is set to @false@.

    When listing more than one part, you may optionally set the @find@ attribute to @any@
    so that it will render the containing elements if any of the listed parts are found.
    By default the @find@ attribute is set to @all@.

    *Usage:*
    
    <pre><code><r:if_content [part="part_name, other_part"] [inherit="true"] [find="any"]>...</r:if_content></code></pre>
  }
  tag 'if_content' do |tag|
    part_name = tag_part_name(tag)
    parts_arr = part_name.split(',')
    inherit = boolean_attr_or_error(tag, 'inherit', 'false')
    find = attr_or_error(tag, :attribute_name => 'find', :default => 'all', :values => 'any, all')
    expandable = true
    one_found = false
    parts_arr.each do |name|
      part_page = tag.locals.page
      name.strip!
      if inherit
        while (part_page.part(name).nil? and (not part_page.parent.nil?)) do
          part_page = part_page.parent
        end
      end
      expandable = false if part_page.part(name).nil?
      one_found ||= true if !part_page.part(name).nil?
    end
    expandable = true if (find == 'any' and one_found)
    tag.expand if expandable
  end

  desc %{
    The opposite of the @if_content@ tag. It renders the contained elements if all of the
    specified parts do not exist. Setting the optional @inherit@ to true will search
    ancestors independently for each part. By default @inherit@ is set to @false@.

    When listing more than one part, you may optionally set the @find@ attribute to @any@
    so that it will not render the containing elements if any of the listed parts are found.
    By default the @find@ attribute is set to @all@.

    *Usage:*
    
    <pre><code><r:unless_content [part="part_name, other_part"] [inherit="false"] [find="any"]>...</r:unless_content></code></pre>
  }
  tag 'unless_content' do |tag|
    part_name = tag_part_name(tag)
    parts_arr = part_name.split(',')
    inherit = boolean_attr_or_error(tag, 'inherit', false)
    find = attr_or_error(tag, :attribute_name => 'find', :default => 'all', :values => 'any, all')
    expandable, all_found = true, true
    parts_arr.each do |name|
      part_page = tag.locals.page
      name.strip!
      if inherit
        while (part_page.part(name).nil? and (not part_page.parent.nil?)) do
          part_page = part_page.parent
        end
      end
      expandable = false if !part_page.part(name).nil?
      all_found = false if part_page.part(name).nil?
    end
    if all_found == false and find == 'all'
      expandable = true
    end
    tag.expand if expandable
  end

  desc %{
    Renders the containing elements only if the page's path matches the regular expression
    given in the @matches@ attribute. If the @ignore_case@ attribute is set to false, the
    match is case sensitive. By default, @ignore_case@ is set to true.

    *Usage:*
    
    <pre><code><r:if_path matches="regexp" [ignore_case="true|false"]>...</r:if_path></code></pre>
  }
  tag 'if_path' do |tag|
    required_attr(tag,'matches')
    regexp = build_regexp_for(tag, 'matches')
    unless tag.locals.page.path.match(regexp).nil?
       tag.expand
    end
  end
  deprecated_tag 'if_url', :substitute => 'if_path', :deadline => '1.2'

  desc %{
    The opposite of the @if_path@ tag.

    *Usage:*
    
    <pre><code><r:unless_path matches="regexp" [ignore_case="true|false"]>...</r:unless_path></code></pre>
  }
  tag 'unless_path' do |tag|
    required_attr(tag, 'matches')
    regexp = build_regexp_for(tag, 'matches')
    if tag.locals.page.path.match(regexp).nil?
        tag.expand
    end
  end
  deprecated_tag 'unless_url', :substitute => 'unless_path', :deadline => '1.2'

  desc %{
    Renders the contained elements if the current contextual page is either the actual page or one of its parents.

    This is typically used inside another tag (like &lt;r:children:each&gt;) to add conditional mark-up if the child element is or descends from the current page.

    *Usage:*
    
    <pre><code><r:if_ancestor_or_self>...</r:if_ancestor_or_self></code></pre>
  }
  tag "if_ancestor_or_self" do |tag|
    tag.expand if (tag.globals.page.ancestors + [tag.globals.page]).include?(tag.locals.page)
  end

  desc %{
    Renders the contained elements unless the current contextual page is either the actual page or one of its parents.

    This is typically used inside another tag (like &lt;r:children:each&gt;) to add conditional mark-up unless the child element is or descends from the current page.

    *Usage:*
    
    <pre><code><r:unless_ancestor_or_self>...</r:unless_ancestor_or_self></code></pre>
  }
  tag "unless_ancestor_or_self" do |tag|
    tag.expand unless (tag.globals.page.ancestors + [tag.globals.page]).include?(tag.locals.page)
  end

  desc %{
    Renders the contained elements if the current contextual page is also the actual page.

    This is typically used inside another tag (like &lt;r:children:each&gt;) to add conditional mark-up if the child element is the current page.

    *Usage:*
    
    <pre><code><r:if_self>...</r:if_self></code></pre>
  }
  tag "if_self" do |tag|
    tag.expand if tag.locals.page == tag.globals.page
  end

  desc %{
    Renders the contained elements unless the current contextual page is also the actual page.

    This is typically used inside another tag (like &lt;r:children:each&gt;) to add conditional mark-up unless the child element is the current page.

    *Usage:*

    <pre><code><r:unless_self>...</r:unless_self></code></pre>
  }
  tag "unless_self" do |tag|
    tag.expand unless tag.locals.page == tag.globals.page
  end

  desc %{
    Renders the name of the author of the current page.
  }
  tag 'author' do |tag|
    page = tag.locals.page
    if author = page.created_by
      author.name
    end
  end

  desc %{
    Renders the Gravatar of the author of the current page or the named user.

    *Usage:*

    <pre><code><r:gravatar /></code></pre>

    or

    <pre><code><r:gravatar [name="User Name"]
        [rating="G | PG | R | X"]
        [size="32px"] /></code></pre>
  }
  tag 'gravatar' do |tag|
    page = tag.locals.page
    name = (tag.attr['name'] || page.created_by.name)
    rating = (tag.attr['rating'] || 'G')
    size = (tag.attr['size'] || '32px')
    email = User.find_by_name(name).email
    default = "#{request.protocol}#{request.host_with_port}/images/admin/avatar_#{([size.to_i] * 2).join('x')}.png"
    unless email.blank?
      url = '//gravatar.com/avatar/'
      url << "#{Digest::MD5.new.update(email)}?"
      url << "rating=#{rating}"
      url << "&size=#{size.to_i}"
      url << "&default=#{default}"
      url
    else
      default
    end
  end

  desc %{
    Renders the date based on the current page (by default when it was published or created).
    The format attribute uses the same formating codes used by the Ruby @strftime@ function.
    By default it's set to @%A, %B %d, %Y@. You may also use the string @rfc1123@ as a shortcut
    for @%a, %d %b %Y %H:%M:%S GMT@ (non-localized). The @for@ attribute selects which date to
    render. Valid options are @published_at@, @created_at@, @updated_at@, and @now@. @now@ will
    render the current date/time, regardless of the page.

    *Usage:*

    <pre><code><r:date [format="%A, %B %d, %Y"] [for="published_at"]/></code></pre>
  }
  tag 'date' do |tag|
    page = tag.locals.page
    format = (tag.attr['format'] || '%A, %B %d, %Y')
    time_attr = tag.attr['for']
    date = if time_attr
      case
      when time_attr == 'now'
        Time.zone.now
      when Page.date_column_names.include?(time_attr)
        page[time_attr]
      else
        raise TagError, "Invalid value for 'for' attribute."
      end
    else
      page.published_at || page.created_at
    end
    case format
    when 'rfc1123'
      CGI.rfc1123_date(date.to_time)
    else
      @i18n_date_format_keys ||= (I18n.config.backend.send(:translations)[I18n.locale][:date][:formats].keys rescue [])
    format = @i18n_date_format_keys.include?(format.to_sym) ? format.to_sym : format
      I18n.l date, :format => format
    end
  end

  desc %{
    Renders a link to the page. When used as a single tag it uses the page's title
    for the link name. When used as a double tag the part in between both tags will
    be used as the link text. The link tag passes all attributes over to the HTML
    @a@ tag. This is very useful for passing attributes like the @class@ attribute
    or @id@ attribute. If the @anchor@ attribute is passed to the tag it will
    append a pound sign (<code>#</code>) followed by the value of the attribute to
    the @href@ attribute of the HTML @a@ tag--effectively making an HTML anchor.

    *Usage:*

    <pre><code><r:link [anchor="name"] [other attributes...] /></code></pre>
    
    or
    
    <pre><code><r:link [anchor="name"] [other attributes...]>link text here</r:link></code></pre>
  }
  tag 'link' do |tag|
    options = tag.attr.dup
    anchor = options['anchor'] ? "##{options.delete('anchor')}" : ''
    attributes = options.inject('') { |s, (k, v)| s << %{#{k.downcase}="#{v}" } }.strip
    attributes = " #{attributes}" unless attributes.empty?
    text = tag.double? ? tag.expand : tag.render('title')
    %{<a href="#{tag.render('path')}#{anchor}"#{attributes}>#{text}</a>}
  end

  desc %{
    Renders a trail of breadcrumbs to the current page. The separator attribute
    specifies the HTML fragment that is inserted between each of the breadcrumbs. By
    default it is set to @>@. The boolean @nolinks@ attribute can be specified to render
    breadcrumbs in plain text, without any links (useful when generating title tag). 
    Set the boolean @noself@ attribute to omit the present page (useful in page headers).

    *Usage:*

    <pre><code><r:breadcrumbs [separator="separator_string"] [nolinks="true"] [noself="true"]/></code></pre>
  }
  tag 'breadcrumbs' do |tag|
    page = tag.locals.page
    nolinks = (tag.attr['nolinks'] == 'true')
    noself = (tag.attr['noself'] == 'true')
    breadcrumbs = []
    breadcrumbs.unshift page.breadcrumb unless noself
    page.ancestors.each do |ancestor|
      tag.locals.page = ancestor
      if nolinks
        breadcrumbs.unshift tag.render('breadcrumb')
      else
        breadcrumbs.unshift %{<a href="#{tag.render('path')}">#{tag.render('breadcrumb')}</a>}
      end
    end
    separator = tag.attr['separator'] || ' &gt; '
    breadcrumbs.join(separator)
  end

  desc %{
    Inside this tag all page related tags refer to the page found at the @path@ attribute.
    @path@s may be relative or absolute paths.

    *Usage:*

    <pre><code><r:find path="value_to_find">...</r:find></code></pre>
  }
  tag 'find' do |tag|
    required_attr(tag,'path','url')
    path = tag.attr['path'] || tag.attr['url']

    found = Page.find_by_path(absolute_path_for(tag.locals.page.path, path))
    if page_found?(found)
      tag.locals.page = found
      tag.expand
    end
  end

  desc %{
    Randomly renders one of the options specified by the @option@ tags.

    *Usage:*

    <pre><code><r:random>
      <r:option>...</r:option>
      <r:option>...</r:option>
      ...
    <r:random>
    </code></pre>
  }
  tag 'random' do |tag|
    tag.locals.random = []
    tag.expand
    options = tag.locals.random
    option = options[rand(options.size)]
    option if option
  end
  tag 'random:option' do |tag|
    items = tag.locals.random
    items << tag.expand
  end

  desc %{
    Nothing inside a set of hide tags is rendered.

    *Usage:*

    <pre><code><r:hide>...</r:hide></code></pre>
  }
  tag 'hide' do |tag|
  end

  desc %{
    Escapes angle brackets, etc. for rendering in an HTML document.

    *Usage:*

    <pre><code><r:escape_html>...</r:escape_html></code></pre>
  }
  tag "escape_html" do |tag|
    CGI.escapeHTML(tag.expand)
  end

  desc %{
    Renders a list of links specified in the @paths@ attribute according to three
    states:

    * @normal@ specifies the normal state for the link
    * @here@ specifies the state of the link when the path matches the current
       page's PATH
    * @selected@ specifies the state of the link when the current page matches
       is a child of the specified path
    # @if_last@ renders its contents within a @normal@, @here@ or
      @selected@ tag if the item is the last in the navigation elements
    # @if_first@ renders its contents within a @normal@, @here@ or
      @selected@ tag if the item is the first in the navigation elements

    The @between@ tag specifies what should be inserted in between each of the links.

    *Usage:*

    <pre><code><r:navigation paths="[Title: path | Title: path | ...]">
      <r:normal><a href="<r:path />"><r:title /></a></r:normal>
      <r:here><strong><r:title /></strong></r:here>
      <r:selected><strong><a href="<r:path />"><r:title /></a></strong></r:selected>
      <r:between> | </r:between>
    </r:navigation>
    </code></pre>
  }
  tag 'navigation' do |tag|
    hash = tag.locals.navigation = {}
    tag.expand
    raise TagError.new("`navigation' tag must include a `normal' tag") unless hash.has_key? :normal
    ActiveSupport::Deprecation.warn("The 'urls' attribute of the r:navigation tag has been deprecated in favour of 'paths'. Please update your site.") if tag.attr['urls']
    result = []
    pairs = (tag.attr['paths']||tag.attr['urls']).to_s.split('|').map do |pair|
      parts = pair.split(':')
      value = parts.pop
      key = parts.join(':')
      [key.strip, value.strip]
    end
    pairs.each_with_index do |(title, path), i|
      compare_path = remove_trailing_slash(path)
      page_path = remove_trailing_slash(self.path)
      hash[:title] = title
      hash[:path] = path
      tag.locals.first_child = i == 0
      tag.locals.last_child = i == pairs.length - 1
      case page_path
      when compare_path
        result << (hash[:here] || hash[:selected] || hash[:normal]).call
      when Regexp.compile( '^' + Regexp.quote(path))
        result << (hash[:selected] || hash[:normal]).call
      else
        result << hash[:normal].call
      end
    end
    between = hash.has_key?(:between) ? hash[:between].call : ' '
    result.reject { |i| i.blank? }.join(between)
  end
  [:normal, :here, :selected, :between].each do |symbol|
    tag "navigation:#{symbol}" do |tag|
      hash = tag.locals.navigation
      hash[symbol] = tag.block
    end
  end
  [:title, :path].each do |symbol|
    tag "navigation:#{symbol}" do |tag|
      hash = tag.locals.navigation
      hash[symbol]
    end
  end
  tag "navigation:url" do |tag|
    hash = tag.locals.navigation
    ActiveSupport::Deprecation.warn("The 'r:navigation:url' tag has been deprecated in favour of 'r:navigation:path'. Please update your site.")
    hash[:path]
  end

  desc %{
    Renders the containing elements if the element is the first
    in the navigation list

    *Usage:*

    <pre><code><r:normal><r:if_first>...</r:if_first></r:normal></code></pre>
  }
  tag 'navigation:if_first' do |tag|
    tag.expand if tag.locals.first_child
  end

  desc %{
    Renders the containing elements unless the element is the first
    in the navigation list

    *Usage:*

    <pre><code><r:normal><r:unless_first>...</r:unless_first></r:normal></code></pre>
  }
  tag 'navigation:unless_first' do |tag|
    tag.expand unless tag.locals.first_child
  end

  desc %{
    Renders the containing elements unless the element is the last
    in the navigation list

    *Usage:*

    <pre><code><r:normal><r:unless_last>...</r:unless_last></r:normal></code></pre>
  }
  tag 'navigation:unless_last' do |tag|
    tag.expand unless tag.locals.last_child
  end

  desc %{
    Renders the containing elements if the element is the last
    in the navigation list

    *Usage:*

    <pre><code><r:normal><r:if_last>...</r:if_last></r:normal></code></pre>
  }
  tag 'navigation:if_last' do |tag|
    tag.expand if tag.locals.last_child
  end

  desc %{
    Renders the containing elements only if Radiant in is development mode.

    *Usage:*

    <pre><code><r:if_dev>...</r:if_dev></code></pre>
  }
  tag 'if_dev' do |tag|
    tag.expand if dev?(tag.globals.page.request)
  end

  desc %{
    The opposite of the @if_dev@ tag.

    *Usage:*

    <pre><code><r:unless_dev>...</r:unless_dev></code></pre>
  }
  tag 'unless_dev' do |tag|
    tag.expand unless dev?(tag.globals.page.request)
  end

  desc %{
    Prints the page's status as a string.  Optional attribute 'downcase'
    will cause the status to be all lowercase.

    *Usage:*

    <pre><code><r:status [downcase='true'] /></code></pre>
  }
  tag 'status' do |tag|
    status = tag.globals.page.status.name
    return status.downcase if tag.attr['downcase']
    status
  end

  desc %(
    Renders the content of the field given in the @name@ attribute.

    *Usage:*

    <pre><code><r:field name="Keywords" /></code></pre>
  )
  tag 'field' do |tag|
    required_attr(tag,'name')
    tag.locals.page.field(tag.attr['name']).try(:content)
  end

  desc %(
    Renders the contained elements if the field given in the @name@ attribute
    exists. The tag also takes an optional @equals@ or @matches@ attribute;
    these will expand the tag if the field's content equals or matches the
    given string or regex.

    *Usage:*

    <pre><code><r:if_field name="author" [equals|matches="John"] [ignore_case="true|false"]>...</r:if_field></code></pre>
  )
  tag 'if_field' do |tag|
    required_attr(tag,'name')
    field = tag.locals.page.field(tag.attr['name'])
    return '' if field.nil?
    tag.expand if case
      when (tag.attr['equals'] and tag.attr['ignore_case'] == 'false') then field.content == tag.attr['equals']
      when tag.attr['equals'] then field.content.downcase == tag.attr['equals'].downcase
      when tag.attr['matches'] then field.content =~ build_regexp_for(tag, 'matches')
      else field
    end
  end

  desc %(
    The opposite of @if_field@. Renders the contained elements unless the field
    given in the @name@ attribute exists. The tag also takes an optional
    @equals@ or @matches@ attribute; these will expand the tag unless the
    field's content equals or matches the given string or regex.

    *Usage:*

    <pre><code><r:unless_field name="author" [equals|matches="John"] [ignore_case="true|false"]>...</r:unless_field></code></pre>
  )
  tag 'unless_field' do |tag|
    required_attr(tag,'name')
    field = tag.locals.page.field(tag.attr['name'])
    tag.expand unless case
      when (field and (tag.attr['equals'] and tag.attr['ignore_case'] == 'false')) then field.content == tag.attr['equals']
      when (field and tag.attr['equals']) then field.content.downcase == tag.attr['equals'].downcase
      when (field and tag.attr['matches']) then field.content =~ build_regexp_for(tag, 'matches')
      else field
    end
  end
  
  tag 'site' do |tag|
    tag.expand
  end
  desc %{
    Returns Radiant::Config['site.title'] as configured under the Settings tab.
  }
  tag "site:title" do |tag|
    Radiant::Config["site.title"]
  end
  desc %{
    Returns Radiant::Config['site.host'] as configured under the Settings tab.
  }
  tag "site:host" do |tag|
    Radiant::Config["site.host"]
  end
  desc %{
    Returns Radiant::Config['dev.host'] as configured under the Settings tab.
  }
  tag "site:dev_host" do |tag|
    Radiant::Config["dev.host"]
  end
  
  private
    def render_children_with_pagination(tag, opts={})
      if opts[:aggregate]
        findable = Page
        options = aggregate_children(tag)
      else
        findable = tag.locals.children
        options = children_find_options(tag)
      end
      paging = pagination_find_options(tag)
      result = []
      tag.locals.previous_headers = {}
      displayed_children = paging ? findable.paginate(options.merge(paging)) : findable.all(options)
      displayed_children.each_with_index do |item, i|
        tag.locals.child = item
        tag.locals.page = item
        tag.locals.first_child = i == 0
        tag.locals.last_child = i == displayed_children.length - 1
        result << tag.expand
      end
      if paging && displayed_children.total_pages > 1
        tag.locals.paginated_list = displayed_children
        result << tag.render('pagination', tag.attr.dup)
      end
      result.flatten.join('')
    end
    
    def children_find_options(tag)
      attr = tag.attr.symbolize_keys

      options = {}

      [:limit, :offset].each do |symbol|
        if number = attr[symbol]
          if number =~ /^\d+$/
            options[symbol] = number.to_i
          else
            raise TagError.new("`#{symbol}' attribute must be a positive number")
          end
        end
      end

      by = (attr[:by] || 'published_at').strip
      order = (attr[:order] || 'asc').strip
      order_string = ''
      if self.attributes.keys.include?(by)
        order_string << by
      else
        raise TagError.new("`by' attribute of `each' tag must be set to a valid field name")
      end
      if order =~ /^(asc|desc)$/i
        order_string << " #{$1.upcase}"
      else
        raise TagError.new(%{`order' attribute of `each' tag must be set to either "asc" or "desc"})
      end
      options[:order] = order_string

      status = (attr[:status] || ( dev?(tag.globals.page.request) ? 'all' : 'published')).downcase
      unless status == 'all'
        stat = Status[status]
        unless stat.nil?
          options[:conditions] = ["(virtual = ?) and (status_id = ?)", false, stat.id]
        else
          raise TagError.new(%{`status' attribute of `each' tag must be set to a valid status})
        end
      else
        options[:conditions] = ["virtual = ?", false]
      end
      options
    end
      
    def aggregate_children(tag)
      options = children_find_options(tag)
      parent_ids = tag.locals.parent_ids
    
      conditions = options[:conditions]
      conditions.first << " AND parent_id IN (?)"
      conditions << parent_ids
      options
    end
    
    def pagination_find_options(tag)
      attr = tag.attr.symbolize_keys
      if attr[:paginated] == 'true'
        pagination_parameters.merge(attr.slice(:per_page))
      else
        false
      end
    end
    
    def will_paginate_options(tag)
      attr = tag.attr.symbolize_keys
      if attr[:paginated] == 'true'
        attr.slice(:class, :previous_label, :next_label, :inner_window, :outer_window, :separator, :per_page).merge({:renderer => Radiant::Pagination::LinkRenderer.new(tag.globals.page.path)})
      else
        {}
      end
    end

    def remove_trailing_slash(string)
      (string =~ %r{^(.*?)/$}) ? $1 : string
    end

    def tag_part_name(tag)
      tag.attr['part'] || 'body'
    end

    def build_regexp_for(tag, attribute_name)
      ignore_case = tag.attr.has_key?('ignore_case') && tag.attr['ignore_case']=='false' ? nil : true
      begin
        regexp = Regexp.new(tag.attr['matches'], ignore_case)
      rescue RegexpError => e
        raise TagError.new("Malformed regular expression in `#{attribute_name}' argument of `#{tag.name}' tag: #{e.message}")
      end
      regexp
    end

    def relative_url_for(url, request)
      File.join(ActionController::Base.relative_url_root || '', url)
    end

    def absolute_path_for(base_path, new_path)
      if new_path.first == '/'
        new_path
      else
        File.expand_path(File.join(base_path, new_path))
      end
    end

    def page_found?(page)
      page && !(FileNotFoundPage === page)
    end

    def boolean_attr_or_error(tag, attribute_name, default)
      attribute = attr_or_error(tag, :attribute_name => attribute_name, :default => default.to_s, :values => 'true, false')
      (attribute.to_s.downcase == 'true') ? true : false
    end

    def attr_or_error(tag, options = {})
      attribute_name = options[:attribute_name].to_s
      default = options[:default]
      values = options[:values].split(',').map!(&:strip)

      attribute = (tag.attr[attribute_name] || default).to_s
      raise TagError.new(%{`#{attribute_name}' attribute of `#{tag.name}' tag must be one of: #{values.join(', ')}}) unless values.include?(attribute)
      return attribute
    end
    
    def required_attr(tag, *attribute_names)
      attr_collection = attribute_names.map{|a| "`#{a}'"}.join(' or ')
      raise TagError.new("`#{tag.name}' tag must contain a #{attr_collection} attribute.") if (tag.attr.keys & attribute_names).blank?
    end

    def dev?(request)
      return false if request.nil?
      if dev_host = Radiant::Config['dev.host']
        dev_host == request.host
      else
        request.host =~ /^dev\./
      end
    end
    
end