require 'active_support/core_ext/object/blank'
require 'active_support/core_ext/string/filters'
require 'active_support/core_ext/array/extract_options'

module ActionView
  # = Action View Text Helpers
  module Helpers #:nodoc:
    # The TextHelper module provides a set of methods for filtering, formatting
    # and transforming strings, which can reduce the amount of inline Ruby code in
    # your views. These helper methods extend Action View making them callable
    # within your template files.
    #
    # ==== Sanitization
    #
    # Most text helpers by default sanitize the given content, but do not escape it.
    # This means HTML tags will appear in the page but all malicious code will be removed.
    # Let's look at some examples using the +simple_format+ method:
    #
    #   simple_format('<a href="http://example.com/">Example</a>')
    #   # => "<p><a href=\"http://example.com/\">Example</a></p>"
    #
    #   simple_format('<a href="javascript:alert(\'no!\')">Example</a>')
    #   # => "<p><a>Example</a></p>"
    #
    # If you want to escape all content, you should invoke the +h+ method before
    # calling the text helper.
    #
    #   simple_format h('<a href="http://example.com/">Example</a>')
    #   # => "<p>&lt;a href=\"http://example.com/\"&gt;Example&lt;/a&gt;</p>"
    module TextHelper
      extend ActiveSupport::Concern

      include SanitizeHelper
      include TagHelper
      # The preferred method of outputting text in your views is to use the
      # <%= "text" %> eRuby syntax. The regular _puts_ and _print_ methods
      # do not operate as expected in an eRuby code block. If you absolutely must
      # output text within a non-output code block (i.e., <% %>), you can use the concat method.
      #
      #   <%
      #       concat "hello"
      #       # is the equivalent of <%= "hello" %>
      #
      #       if logged_in
      #         concat "Logged in!"
      #       else
      #         concat link_to('login', :action => :login)
      #       end
      #       # will either display "Logged in!" or a login link
      #   %>
      def concat(string)
        output_buffer << string
      end

      def safe_concat(string)
        output_buffer.respond_to?(:safe_concat) ? output_buffer.safe_concat(string) : concat(string)
      end

      # Truncates a given +text+ after a given <tt>:length</tt> if +text+ is longer than <tt>:length</tt>
      # (defaults to 30). The last characters will be replaced with the <tt>:omission</tt> (defaults to "...")
      # for a total length not exceeding <tt>:length</tt>.
      #
      # Pass a <tt>:separator</tt> to truncate +text+ at a natural break.
      #
      # The result is not marked as HTML-safe, so will be subject to the default escaping when
      # used in views, unless wrapped by <tt>raw()</tt>. Care should be taken if +text+ contains HTML tags
      # or entities, because truncation may produce invalid HTML (such as unbalanced or incomplete tags).
      #
      #   truncate("Once upon a time in a world far far away")
      #   # => "Once upon a time in a world..."
      #
      #   truncate("Once upon a time in a world far far away", :length => 17)
      #   # => "Once upon a ti..."
      #
      #   truncate("Once upon a time in a world far far away", :length => 17, :separator => ' ')
      #   # => "Once upon a..."
      #
      #   truncate("And they found that many people were sleeping better.", :length => 25, :omission => '... (continued)')
      #   # => "And they f... (continued)"
      #
      #   truncate("<p>Once upon a time in a world far far away</p>")
      #   # => "<p>Once upon a time in a wo..."
      def truncate(text, options = {})
        options.reverse_merge!(:length => 30)
        text.truncate(options.delete(:length), options) if text
      end

      # Highlights one or more +phrases+ everywhere in +text+ by inserting it into
      # a <tt>:highlighter</tt> string. The highlighter can be specialized by passing <tt>:highlighter</tt>
      # as a single-quoted string with <tt>\1</tt> where the phrase is to be inserted (defaults to
      # '<mark>\1</mark>')
      #
      #   highlight('You searched for: rails', 'rails')
      #   # => You searched for: <mark>rails</mark>
      #
      #   highlight('You searched for: ruby, rails, dhh', 'actionpack')
      #   # => You searched for: ruby, rails, dhh
      #
      #   highlight('You searched for: rails', ['for', 'rails'], :highlighter => '<em>\1</em>')
      #   # => You searched <em>for</em>: <em>rails</em>
      #
      #   highlight('You searched for: rails', 'rails', :highlighter => '<a href="search?q=\1">\1</a>')
      #   # => You searched for: <a href="search?q=rails">rails</a>
      #
      # You can still use <tt>highlight</tt> with the old API that accepts the
      # +highlighter+ as its optional third parameter:
      #
      #   highlight('You searched for: rails', 'rails', '<a href="search?q=\1">\1</a>')
      #   # => You searched for: <a href="search?q=rails">rails</a>
      def highlight(text, phrases, *args)
        options = args.extract_options!
        unless args.empty?
          options[:highlighter] = args[0]
        end
        options[:highlighter] ||= '<mark>\1</mark>'

        text = sanitize(text) unless options[:sanitize] == false
        if text.blank? || phrases.blank?
          text
        else
          match = Array(phrases).map { |p| Regexp.escape(p) }.join('|')
          text.gsub(/(#{match})(?![^<]*?>)/i, options[:highlighter])
        end.html_safe
      end

      # Extracts an excerpt from +text+ that matches the first instance of +phrase+.
      # The <tt>:radius</tt> option expands the excerpt on each side of the first occurrence of +phrase+ by the number of characters
      # defined in <tt>:radius</tt> (which defaults to 100). If the excerpt radius overflows the beginning or end of the +text+,
      # then the <tt>:omission</tt> option (which defaults to "...") will be prepended/appended accordingly. The resulting string
      # will be stripped in any case. If the +phrase+ isn't found, nil is returned.
      #
      #   excerpt('This is an example', 'an', :radius => 5)
      #   # => ...s is an exam...
      #
      #   excerpt('This is an example', 'is', :radius => 5)
      #   # => This is a...
      #
      #   excerpt('This is an example', 'is')
      #   # => This is an example
      #
      #   excerpt('This next thing is an example', 'ex', :radius => 2)
      #   # => ...next...
      #
      #   excerpt('This is also an example', 'an', :radius => 8, :omission => '<chop> ')
      #   # => <chop> is also an example
      #
      # You can still use <tt>excerpt</tt> with the old API that accepts the
      # +radius+ as its optional third and the +ellipsis+ as its
      # optional forth parameter:
      #   excerpt('This is an example', 'an', 5)                   # => ...s is an exam...
      #   excerpt('This is also an example', 'an', 8, '<chop> ')   # => <chop> is also an example
      def excerpt(text, phrase, *args)
        return unless text && phrase

        options = args.extract_options!
        unless args.empty?
          options[:radius]   = args[0]
          options[:omission] = args[1]
        end
        radius   = options[:radius]   || 100
        omission = options[:omission] || "..."

        phrase = Regexp.escape(phrase)
        return unless found_pos = text =~ /(#{phrase})/i

        start_pos = [ found_pos - radius, 0 ].max
        end_pos   = [ [ found_pos + phrase.length + radius - 1, 0].max, text.length ].min

        prefix  = start_pos > 0 ? omission : ""
        postfix = end_pos < text.length - 1 ? omission : ""

        prefix + text[start_pos..end_pos].strip + postfix
      end

      # Attempts to pluralize the +singular+ word unless +count+ is 1. If
      # +plural+ is supplied, it will use that when count is > 1, otherwise
      # it will use the Inflector to determine the plural form
      #
      #   pluralize(1, 'person')
      #   # => 1 person
      #
      #   pluralize(2, 'person')
      #   # => 2 people
      #
      #   pluralize(3, 'person', 'users')
      #   # => 3 users
      #
      #   pluralize(0, 'person')
      #   # => 0 people
      def pluralize(count, singular, plural = nil)
        "#{count || 0} " + ((count == 1 || count =~ /^1(\.0+)?$/) ? singular : (plural || singular.pluralize))
      end

      # Wraps the +text+ into lines no longer than +line_width+ width. This method
      # breaks on the first whitespace character that does not exceed +line_width+
      # (which is 80 by default).
      #
      #   word_wrap('Once upon a time')
      #   # => Once upon a time
      #
      #   word_wrap('Once upon a time, in a kingdom called Far Far Away, a king fell ill, and finding a successor to the throne turned out to be more trouble than anyone could have imagined...')
      #   # => Once upon a time, in a kingdom called Far Far Away, a king fell ill, and finding\na successor to the throne turned out to be more trouble than anyone could have\nimagined...
      #
      #   word_wrap('Once upon a time', :line_width => 8)
      #   # => Once\nupon a\ntime
      #
      #   word_wrap('Once upon a time', :line_width => 1)
      #   # => Once\nupon\na\ntime
      #
      # You can still use <tt>word_wrap</tt> with the old API that accepts the
      # +line_width+ as its optional second parameter:
      #
      #   word_wrap('Once upon a time', 8)
      #   # => Once\nupon a\ntime
      def word_wrap(text, *args)
        options = args.extract_options!
        unless args.blank?
          options[:line_width] = args[0]
        end
        line_width = options[:line_width] || 80

        text.split("\n").collect do |line|
          line.length > line_width ? line.gsub(/(.{1,#{line_width}})(\s+|$)/, "\\1\n").strip : line
        end * "\n"
      end

      # Returns +text+ transformed into HTML using simple formatting rules.
      # Two or more consecutive newlines(<tt>\n\n</tt>) are considered as a
      # paragraph and wrapped in <tt><p></tt> tags. One newline (<tt>\n</tt>) is
      # considered as a linebreak and a <tt><br /></tt> tag is appended. This
      # method does not remove the newlines from the +text+.
      #
      # You can pass any HTML attributes into <tt>html_options</tt>. These
      # will be added to all created paragraphs.
      #
      # ==== Options
      # * <tt>:sanitize</tt> - If +false+, does not sanitize +text+.
      # * <tt>:wrapper_tag</tt> - String representing the tag wrapper, defaults to <tt>"p"</tt>
      #
      # ==== Examples
      #   my_text = "Here is some basic text...\n...with a line break."
      #
      #   simple_format(my_text)
      #   # => "<p>Here is some basic text...\n<br />...with a line break.</p>"
      #
      #   more_text = "We want to put a paragraph...\n\n...right there."
      #
      #   simple_format(more_text)
      #   # => "<p>We want to put a paragraph...</p>\n\n<p>...right there.</p>"
      #
      #   simple_format("Look ma! A class!", :class => 'description')
      #   # => "<p class='description'>Look ma! A class!</p>"
      #
      #   simple_format("<span>I'm allowed!</span> It's true.", {}, :sanitize => false)
      #   # => "<p><span>I'm allowed!</span> It's true.</p>"
      def simple_format(text, html_options={}, options={})
        text = sanitize(text) unless options[:sanitize] == false
        wrapper_tag = options.fetch(:wrapper_tag, :p)
        paragraphs = split_paragraphs(text)

        if paragraphs.empty?
          content_tag(wrapper_tag, nil, html_options)
        else
          paragraphs.map { |paragraph|
            content_tag(wrapper_tag, paragraph, html_options, options[:sanitize])
          }.join("\n\n").html_safe
        end
      end

      # Creates a Cycle object whose _to_s_ method cycles through elements of an
      # array every time it is called. This can be used for example, to alternate
      # classes for table rows. You can use named cycles to allow nesting in loops.
      # Passing a Hash as the last parameter with a <tt>:name</tt> key will create a
      # named cycle. The default name for a cycle without a +:name+ key is
      # <tt>"default"</tt>. You can manually reset a cycle by calling reset_cycle
      # and passing the name of the cycle. The current cycle string can be obtained
      # anytime using the current_cycle method.
      #
      #   # Alternate CSS classes for even and odd numbers...
      #   @items = [1,2,3,4]
      #   <table>
      #   <% @items.each do |item| %>
      #     <tr class="<%= cycle("odd", "even") -%>">
      #       <td>item</td>
      #     </tr>
      #   <% end %>
      #   </table>
      #
      #
      #   # Cycle CSS classes for rows, and text colors for values within each row
      #   @items = x = [{:first => 'Robert', :middle => 'Daniel', :last => 'James'},
      #                {:first => 'Emily', :middle => 'Shannon', :maiden => 'Pike', :last => 'Hicks'},
      #               {:first => 'June', :middle => 'Dae', :last => 'Jones'}]
      #   <% @items.each do |item| %>
      #     <tr class="<%= cycle("odd", "even", :name => "row_class") -%>">
      #       <td>
      #         <% item.values.each do |value| %>
      #           <%# Create a named cycle "colors" %>
      #           <span style="color:<%= cycle("red", "green", "blue", :name => "colors") -%>">
      #             <%= value %>
      #           </span>
      #         <% end %>
      #         <% reset_cycle("colors") %>
      #       </td>
      #    </tr>
      #  <% end %>
      def cycle(first_value, *values)
        options = values.extract_options!
        name = options.fetch(:name, "default")

        values.unshift(first_value)

        cycle = get_cycle(name)
        unless cycle && cycle.values == values
          cycle = set_cycle(name, Cycle.new(*values))
        end
        cycle.to_s
      end

      # Returns the current cycle string after a cycle has been started. Useful
      # for complex table highlighting or any other design need which requires
      # the current cycle string in more than one place.
      #
      #   # Alternate background colors
      #   @items = [1,2,3,4]
      #   <% @items.each do |item| %>
      #     <div style="background-color:<%= cycle("red","white","blue") %>">
      #       <span style="background-color:<%= current_cycle %>"><%= item %></span>
      #     </div>
      #   <% end %>
      def current_cycle(name = "default")
        cycle = get_cycle(name)
        cycle.current_value if cycle
      end

      # Resets a cycle so that it starts from the first element the next time
      # it is called. Pass in +name+ to reset a named cycle.
      #
      #   # Alternate CSS classes for even and odd numbers...
      #   @items = [[1,2,3,4], [5,6,3], [3,4,5,6,7,4]]
      #   <table>
      #   <% @items.each do |item| %>
      #     <tr class="<%= cycle("even", "odd") -%>">
      #         <% item.each do |value| %>
      #           <span style="color:<%= cycle("#333", "#666", "#999", :name => "colors") -%>">
      #             <%= value %>
      #           </span>
      #         <% end %>
      #
      #         <% reset_cycle("colors") %>
      #     </tr>
      #   <% end %>
      #   </table>
      def reset_cycle(name = "default")
        cycle = get_cycle(name)
        cycle.reset if cycle
      end

      class Cycle #:nodoc:
        attr_reader :values

        def initialize(first_value, *values)
          @values = values.unshift(first_value)
          reset
        end

        def reset
          @index = 0
        end

        def current_value
          @values[previous_index].to_s
        end

        def to_s
          value = @values[@index].to_s
          @index = next_index
          return value
        end

        private

        def next_index
          step_index(1)
        end

        def previous_index
          step_index(-1)
        end

        def step_index(n)
          (@index + n) % @values.size
        end
      end

      private
        # The cycle helpers need to store the cycles in a place that is
        # guaranteed to be reset every time a page is rendered, so it
        # uses an instance variable of ActionView::Base.
        def get_cycle(name)
          @_cycles = Hash.new unless defined?(@_cycles)
          return @_cycles[name]
        end

        def set_cycle(name, cycle_object)
          @_cycles = Hash.new unless defined?(@_cycles)
          @_cycles[name] = cycle_object
        end

        def split_paragraphs(text)
          return [] if text.blank?

          text.to_str.gsub(/\r\n?/, "\n").split(/\n\n+/).map! do |t|
            t.gsub!(/([^\n]\n)(?=[^\n])/, '\1<br />') || t
          end
        end
    end
  end
end