url_helper.rb

require 'action_view/helpers/javascript_helper'

module ActionView
  module Helpers #:nodoc:
    # Provides a set of methods for making easy links and getting urls that 
    # depend on the controller and action. This means that you can use the 
    # same format for links in the views that you do in the controller.
    module UrlHelper
      include JavaScriptHelper
      
      # Returns the URL for the set of +options+ provided. This takes the 
      # same options as url_for in action controller. For a list, see the 
      # documentation for ActionController::Base#url_for. Note that it'll 
      # set :only_path => true so you'll get the relative /controller/action 
      # instead of the fully qualified http://example.com/controller/action.
      #  
      # When called from a view, url_for returns an HTML escaped url. If you 
      # need an unescaped url, pass :escape => false in the +options+.
      def url_for(options = {}, *parameters_for_method_reference)
        if options.kind_of? Hash
          options = { :only_path => true }.update(options.symbolize_keys)
          escape = options.key?(:escape) ? options.delete(:escape) : true
        else
          escape = true
        end

        url = @controller.send(:url_for, options, *parameters_for_method_reference)
        escape ? html_escape(url) : url
      end

      # Creates a link tag of the given +name+ using a URL created by the set 
      # of +options+. See the valid options in the documentation for 
      # ActionController::Base#url_for. It's also possible to pass a string instead 
      # of an options hash to get a link tag that uses the value of the string as the 
      # href for the link. If nil is passed as a name, the link itself will become 
      # the name.
      #
      # The +html_options+ will accept a hash of html attributes for the link tag.
      # It also accepts 3 modifiers that specialize the link behavior. 
      #
      # * <tt>:confirm => 'question?'</tt>: This will add a JavaScript confirm 
      #   prompt with the question specified. If the user accepts, the link is 
      #   processed normally, otherwise no action is taken.
      # * <tt>:popup => true || array of window options</tt>: This will force the 
      #   link to open in a popup window. By passing true, a default browser window 
      #   will be opened with the URL. You can also specify an array of options 
      #   that are passed-thru to JavaScripts window.open method.
      # * <tt>:method => symbol of HTTP verb</tt>: This modifier will dynamically
      #   create an HTML form and immediately submit the form for processing using 
      #   the HTTP verb specified. Useful for having links perform a POST operation
      #   in dangerous actions like deleting a record (which search bots can follow
      #   while spidering your site). Supported verbs are :post, :delete and :put.
      #   Note that if the user has JavaScript disabled, the request will fall back 
      #   to using GET. If you are relying on the POST behavior, your should check
      #   for it in your controllers action by using the request objects methods
      #   for post?, delete? or put?.
      #
      # You can mix and match the +html_options+ with the exception of
      # :popup and :method which will raise an ActionView::ActionViewError
      # exception.
      #
      #   link_to "Visit Other Site", "http://www.rubyonrails.org/", :confirm => "Are you sure?"
      #   link_to "Help", { :action => "help" }, :popup => true
      #   link_to "View Image", { :action => "view" }, :popup => ['new_window_name', 'height=300,width=600']
      #   link_to "Delete Image", { :action => "delete", :id => @image.id }, :confirm => "Are you sure?", :method => :delete
      def link_to(name, options = {}, html_options = nil, *parameters_for_method_reference)
        if html_options
          html_options = html_options.stringify_keys
          convert_options_to_javascript!(html_options)
          tag_options = tag_options(html_options)
        else
          tag_options = nil
        end

        url = options.is_a?(String) ? options : self.url_for(options, *parameters_for_method_reference)
        "<a href=\"#{url}\"#{tag_options}>#{name || url}</a>"
      end

      # Generates a form containing a single button that submits to the URL created
      # by the set of +options+. This is the safest method to ensure links that
      # cause changes to your data are not triggered by search bots or accelerators.
      # If the HTML button does not work with your layout, you can also consider
      # using the link_to method with the <tt>:method</tt> modifier as described in
      # the link_to documentation.
      #
      # The generated FORM element has a class name of <tt>button-to</tt>
      # to allow styling of the form itself and its children. You can control
      # the form submission and input element behavior using +html_options+.
      # This method accepts the <tt>:method</tt> and <tt>:confirm</tt> modifiers
      # described in the link_to documentation. If no <tt>:method</tt> modifier
      # is given, it will default to performing a POST operation. You can also 
      # disable the button by passing <tt>:disabled => true</tt> in +html_options+.
      #
      #   button_to "New", :action => "new"
      #
      # Generates the following HTML:
      #
      #   <form method="post" action="/controller/new" class="button-to">
      #     <div><input value="New" type="submit" /></div>
      #   </form>
      #
      # If you are using RESTful routes, you can pass the <tt>:method</tt>
      # to change the HTTP verb used to submit the form.
      #
      #   button_to "Delete Image", { :action => "delete", :id => @image.id },
      #             :confirm => "Are you sure?", :method => :delete
      #
      # Which generates the following HTML:
      #
      #   <form method="post" action="/images/delete/1" class="button-to">
      #     <div>
      #       <input type="hidden" name="_method" value="delete" />
      #       <input onclick="return confirm('Are you sure?');"
      #                 value="Delete" type="submit" />
      #     </div>
      #   </form>
      def button_to(name, options = {}, html_options = {})
        html_options = html_options.stringify_keys
        convert_boolean_attributes!(html_options, %w( disabled ))

        method_tag = ''
        if (method = html_options.delete('method')) && %w{put delete}.include?(method.to_s)
          method_tag = tag('input', :type => 'hidden', :name => '_method', :value => method.to_s)
        end

        form_method = method.to_s == 'get' ? 'get' : 'post'

        if confirm = html_options.delete("confirm")
          html_options["onclick"] = "return #{confirm_javascript_function(confirm)};"
        end

        url = options.is_a?(String) ? options : self.url_for(options)
        name ||= url

        html_options.merge!("type" => "submit", "value" => name)
        
        "<form method=\"#{form_method}\" action=\"#{escape_once url}\" class=\"button-to\"><div>" + 
          method_tag + tag("input", html_options) + "</div></form>"
      end


      # DEPRECATED. It is reccommended to use the AssetTagHelper::image_tag within
      # a link_to method to generate a linked image.
      # 
      #   link_to(image_tag("rss", :size => "30x45", :border => 0), "http://www.example.com")
      def link_image_to(src, options = {}, html_options = {}, *parameters_for_method_reference)
        image_options = { "src" => src.include?("/") ? src : "/images/#{src}" }
        image_options["src"] += ".png" unless image_options["src"].include?(".")

        html_options = html_options.stringify_keys
        if html_options["alt"]
          image_options["alt"] = html_options["alt"]
          html_options.delete "alt"
        else
          image_options["alt"] = src.split("/").last.split(".").first.capitalize
        end

        if html_options["size"]
          image_options["width"], image_options["height"] = html_options["size"].split("x")
          html_options.delete "size"
        end

        if html_options["border"]
          image_options["border"] = html_options["border"]
          html_options.delete "border"
        end

        if html_options["align"]
          image_options["align"] = html_options["align"]
          html_options.delete "align"
        end

        link_to(tag("img", image_options), options, html_options, *parameters_for_method_reference)
      end

      alias_method :link_to_image, :link_image_to
      deprecate :link_to_image => "use link_to(image_tag(...), url)",
        :link_image_to => "use link_to(image_tag(...), url)"

      # Creates a link tag of the given +name+ using a URL created by the set of
      # +options+ unless the current request uri is the same as the links, in 
      # which case only the name is returned (or the given block is yielded, if
      # one exists). Refer to the documentation for link_to_unless for block usage.
      #
      #   <ul id="navbar">
      #     <li><%= link_to_unless_current("Home", { :action => "index" }) %></li>
      #     <li><%= link_to_unless_current("About Us", { :action => "about" }) %></li>
      #   </ul>
      #
      # This will render the following HTML when on the about us page:
      #
      #   <ul id="navbar">
      #     <li><a href="/controller/index">Home</a></li>
      #     <li>About Us</li>
      #   </ul>
      def link_to_unless_current(name, options = {}, html_options = {}, *parameters_for_method_reference, &block)
        link_to_unless current_page?(options), name, options, html_options, *parameters_for_method_reference, &block
      end

      # Creates a link tag of the given +name+ using a URL created by the set of
      # +options+ unless +condition+ is true, in which case only the name is 
      # returned. To specialize the default behavior, you can pass a block that
      # accepts the name or the full argument list for link_to_unless (see the example).
      #
      #   <%= link_to_unless(@current_user.nil?, "Reply", { :action => "reply" }) %>
      #
      # This example uses a block to modify the link if the condition isn't met.
      #
      #   <%= link_to_unless(@current_user.nil?, "Reply", { :action => "reply" }) do |name|
      #      link_to(name, { :controller => "accounts", :action => "signup" })
      #    end %>     
      def link_to_unless(condition, name, options = {}, html_options = {}, *parameters_for_method_reference, &block)
        if condition
          if block_given?
            block.arity <= 1 ? yield(name) : yield(name, options, html_options, *parameters_for_method_reference)
          else
            name
          end
        else
          link_to(name, options, html_options, *parameters_for_method_reference)
        end  
      end
      
      # Creates a link tag of the given +name+ using a URL created by the set of
      # +options+ if +condition+ is true, in which case only the name is 
      # returned. To specialize the default behavior, you can pass a block that
      # accepts the name or the full argument list for link_to_unless (see the examples
      # in link_to_unless).
      def link_to_if(condition, name, options = {}, html_options = {}, *parameters_for_method_reference, &block)
        link_to_unless !condition, name, options, html_options, *parameters_for_method_reference, &block
      end

      # Creates a mailto link tag to the specified +email_address+, which is
      # also used as the name of the link unless +name+ is specified. Additional
      # html attributes for the link can be passed in +html_options+.
      #
      # mail_to has several methods for hindering email harvestors and customizing
      # the email itself by passing special keys to +html_options+.
      #
      # Special HTML Options:
      #
      # * <tt>:encode</tt>  - This key will accept the strings "javascript" or "hex".
      #   Passing "javascript" will dynamically create and encode the mailto: link then
      #   eval it into the DOM of the page. This method will not show the link on
      #   the page if the user has JavaScript disabled. Passing "hex" will hex
      #   encode the +email_address+ before outputting the mailto: link.
      # * <tt>:replace_at</tt>  - When the link +name+ isn't provided, the
      #   +email_address+ is used for the link label. You can use this option to
      #   obfuscate the +email_address+ by substituting the @ sign with the string
      #   given as the value.
      # * <tt>:replace_dot</tt>  - When the link +name+ isn't provided, the
      #   +email_address+ is used for the link label. You can use this option to
      #   obfuscate the +email_address+ by substituting the . in the email with the
      #   string given as the value.
      # * <tt>:subject</tt>  - Preset the subject line of the email.
      # * <tt>:body</tt> - Preset the body of the email.
      # * <tt>:cc</tt>  - Carbon Copy addition recipients on the email.
      # * <tt>:bcc</tt>  - Blind Carbon Copy additional recipients on the email.
      #
      # Examples:
      #   mail_to "me@domain.com"  # => <a href="mailto:me@domain.com">me@domain.com</a>
      #   mail_to "me@domain.com", "My email", :encode => "javascript"  # =>
      #     <script type="text/javascript">eval(unescape('%64%6f%63...%6d%65%6e'))</script>
      #
      #   mail_to "me@domain.com", "My email", :encode => "hex"  # =>
      #     <a href="mailto:%6d%65@%64%6f%6d%61%69%6e.%63%6f%6d">My email</a>
      #
      #   mail_to "me@domain.com", nil, :replace_at => "_at_", :replace_dot => "_dot_", :class => "email"  # =>
      #     <a href="mailto:me@domain.com" class="email">me_at_domain_dot_com</a>
      #
      #   mail_to "me@domain.com", "My email", :cc => "ccaddress@domain.com", 
      #            :subject => "This is an example email"  # =>
      #     <a href="mailto:me@domain.com?cc=ccaddress@domain.com&subject=This%20is%20an%20example%20email">My email</a>
      def mail_to(email_address, name = nil, html_options = {})
        html_options = html_options.stringify_keys
        encode = html_options.delete("encode").to_s
        cc, bcc, subject, body = html_options.delete("cc"), html_options.delete("bcc"), html_options.delete("subject"), html_options.delete("body")

        string = ''
        extras = ''
        extras << "cc=#{CGI.escape(cc).gsub("+", "%20")}&" unless cc.nil?
        extras << "bcc=#{CGI.escape(bcc).gsub("+", "%20")}&" unless bcc.nil?
        extras << "body=#{CGI.escape(body).gsub("+", "%20")}&" unless body.nil?
        extras << "subject=#{CGI.escape(subject).gsub("+", "%20")}&" unless subject.nil?
        extras = "?" << extras.gsub!(/&?$/,"") unless extras.empty?

        email_address = email_address.to_s

        email_address_obfuscated = email_address.dup
        email_address_obfuscated.gsub!(/@/, html_options.delete("replace_at")) if html_options.has_key?("replace_at")
        email_address_obfuscated.gsub!(/\./, html_options.delete("replace_dot")) if html_options.has_key?("replace_dot")

        if encode == "javascript"
          tmp = "document.write('#{content_tag("a", name || email_address, html_options.merge({ "href" => "mailto:"+email_address+extras }))}');"
          for i in 0...tmp.length
            string << sprintf("%%%x",tmp[i])
          end
          "<script type=\"#{Mime::JS}\">eval(unescape('#{string}'))</script>"
        elsif encode == "hex"
          email_address_encoded = ''
          email_address_obfuscated.each_byte do |c|
            email_address_encoded << sprintf("&#%d;", c)
          end

          protocol = 'mailto:'
          protocol.each_byte { |c| string << sprintf("&#%d;", c) }

          for i in 0...email_address.length
            if email_address[i,1] =~ /\w/
              string << sprintf("%%%x",email_address[i])
            else
              string << email_address[i,1]
            end
          end
          content_tag "a", name || email_address_encoded, html_options.merge({ "href" => "#{string}#{extras}" })
        else
          content_tag "a", name || email_address_obfuscated, html_options.merge({ "href" => "mailto:#{email_address}#{extras}" })
        end
      end

      # True if the current request uri was generated by the given +options+.
      def current_page?(options)
        url_string = CGI.escapeHTML(url_for(options))
        request = @controller.request
        if url_string =~ /^\w+:\/\//
          url_string == "#{request.protocol}#{request.host_with_port}#{request.request_uri}"
        else
          url_string == request.request_uri
        end
      end

      private
        def convert_options_to_javascript!(html_options)
          confirm, popup = html_options.delete("confirm"), html_options.delete("popup")

          # post is deprecated, but if its specified and method is not, assume that method = :post
          method, post   = html_options.delete("method"), html_options.delete("post")
          if !method && post
            ActiveSupport::Deprecation.warn(
              "Passing :post as a link modifier is deprecated. " +
              "Use :method => \"post\" instead. :post will be removed in Rails 2.0."
            )
            method = :post
          end
        
          html_options["onclick"] = case
            when popup && method
              raise ActionView::ActionViewError, "You can't use :popup and :post in the same link"
            when confirm && popup
              "if (#{confirm_javascript_function(confirm)}) { #{popup_javascript_function(popup)} };return false;"
            when confirm && method
              "if (#{confirm_javascript_function(confirm)}) { #{method_javascript_function(method)} };return false;"
            when confirm
              "return #{confirm_javascript_function(confirm)};"
            when method
              "#{method_javascript_function(method)}return false;"
            when popup
              popup_javascript_function(popup) + 'return false;'
            else
              html_options["onclick"]
          end
        end
        
        def confirm_javascript_function(confirm)
          "confirm('#{escape_javascript(confirm)}')"
        end
        
        def popup_javascript_function(popup)
          popup.is_a?(Array) ? "window.open(this.href,'#{popup.first}','#{popup.last}');" : "window.open(this.href);"
        end
        
        def method_javascript_function(method)
          submit_function = 
            "var f = document.createElement('form'); f.style.display = 'none'; " +
            "this.parentNode.appendChild(f); f.method = 'POST'; f.action = this.href;"
          
          unless method == :post
            submit_function << "var m = document.createElement('input'); m.setAttribute('type', 'hidden'); "
            submit_function << "m.setAttribute('name', '_method'); m.setAttribute('value', '#{method}'); f.appendChild(m);"
          end
          
          submit_function << "f.submit();"
        end

        # Processes the _html_options_ hash, converting the boolean
        # attributes from true/false form into the form required by
        # HTML/XHTML.  (An attribute is considered to be boolean if
        # its name is listed in the given _bool_attrs_ array.)
        #
        # More specifically, for each boolean attribute in _html_options_
        # given as:
        #
        #     "attr" => bool_value
        #
        # if the associated _bool_value_ evaluates to true, it is
        # replaced with the attribute's name; otherwise the attribute is
        # removed from the _html_options_ hash.  (See the XHTML 1.0 spec,
        # section 4.5 "Attribute Minimization" for more:
        # http://www.w3.org/TR/xhtml1/#h-4.5)
        #
        # Returns the updated _html_options_ hash, which is also modified
        # in place.
        #
        # Example:
        #
        #   convert_boolean_attributes!( html_options,
        #                                %w( checked disabled readonly ) )
        def convert_boolean_attributes!(html_options, bool_attrs)
          bool_attrs.each { |x| html_options[x] = x if html_options.delete(x) }
          html_options
        end
    end
  end
end