module Padrino
  module Helpers
    ##
    # Helpers related to producing html tags within templates.
    ##
    module TagHelpers
      ##
      # Tag values escaped to html entities
      ##
      ESCAPE_VALUES = {
        "<" => "&lt;",
        ">" => "&gt;",
        '"' => "&quot;"
      }

      BOOLEAN_ATTRIBUTES = [
        :autoplay,
        :autofocus,
        :formnovalidate,
        :checked,
        :disabled,
        :hidden,
        :loop,
        :multiple,
        :muted,
        :readonly,
        :required,
        :selected
      ]

      ##
      # Creates an HTML tag with given name, content, and options
      #
      # @overload content_tag(name, content, options = nil)
      #   @param [Symbol] name
      #     The name of the HTML tag to create.
      #   @param [String] content
      #     The content inside of the the tag.
      #   @param [Hash] options
      #     The HTML options to include in this tag.
      #
      # @overload content_tag(name, options = nil, &block)
      #   @param [Symbol] name
      #     The name of the HTML tag to create.
      #   @param [Hash] options
      #     The HTML options to include in this tag.
      #   @param [Proc] block
      #     The block returning HTML content.
      #
      # @macro [new] global_html_attributes
      #   @option options [String] :id
      #     Specifies a unique identifier for the element.
      #   @option options [String] :class
      #     Specifies the stylesheet class of the element.
      #   @option options [String] :title
      #     Specifies the title for the element.
      #   @option options [String] :accesskey
      #     Specifies a shortcut key to access the element.
      #   @option options [Symbol] :dropzone
      #     Specifies what happens when dragged items are dropped on the element. (:copy, :link, :move)
      #   @option options [Boolean] :hidden
      #     Specifies whether or not the element is hidden from view.
      #   @option options [Boolean] :draggable
      #     Specifies whether or not the element is draggable. (true, false, :auto)
      #   @option options [Boolean] :contenteditable
      #     Specifies whether or not the element is editable.
      #
      # @return [String]
      #   Generated HTML with specified +options+
      #
      # @example
      #   content_tag(:p, 'Hello World', :class => 'light')
      #
      #   # => <p class="light">
      #   # =>   Hello World
      #   # => </p>
      #
      #   content_tag(:p, :class => 'dark') do
      #     link_to 'Padrino', 'http://www.padrinorb.com'
      #   end
      #
      #   # => <p class="dark">
      #   # =>   <a href="http://www.padrinorb.com">Padrino</a>
      #   # => </p>
      #
      # @api public
      def content_tag(name, content = nil, options = nil, &block)
        if block_given?
          options = content if content.is_a?(Hash)
          content = capture_html(&block)
        end

        content = content.join("\n") if content.respond_to?(:join)

        output = "<#{name}#{tag_options(options) if options}>#{content}</#{name}>"
        block_is_template?(block) ? concat_content(output) : output
      end

      ##
      # Creates an HTML input field with the given type and options
      #
      # @param [Symbol] type
      #   The type of input to create.
      # @param [Hash] options
      #   The HTML options to include in this input.
      #
      # @option options [String] :id
      #   Specifies a unique identifier for the input.
      # @option options [String] :class
      #   Specifies the stylesheet class of the input.
      # @option options [String] :name
      #   Specifies the name of the input.
      # @option options [String] :accesskey
      #   Specifies a shortcut key to access the input.
      # @option options [Integer] :tabindex
      #   Specifies the tab order of the input.
      # @option options [Boolean] :hidden
      #   Specifies whether or not the input is hidden from view.
      # @option options [Boolean] :spellcheck
      #   Specifies whether or not the input should have it's spelling and grammar checked for errors.
      # @option options [Boolean] :draggable
      #   Specifies whether or not the input is draggable. (true, false, :auto)
      # @option options [String] :pattern
      #   Specifies the regular expression pattern that the input's value is checked against.
      # @option options [Symbol] :autocomplete
      #   Specifies whether or not the input should have autocomplete enabled. (:on, :off)
      # @option options [Boolean] :autofocus
      #   Specifies whether or not the input should automatically get focus when the page loads.
      # @option options [Boolean] :required
      #   Specifies whether or not the input is required to be completeled before the form is submitted.
      # @option options [Boolean] :readonly
      #   Specifies whether or not the input is read only.
      # @option options [Boolean] :disabled
      #   Specifies whether or not the input is disabled.
      #
      # @return [String]
      #   Generated HTML with specified +options+
      #
      # @example
      #   input_tag :text, :name => 'handle'
      #   # => <input type="test" name="handle">
      #
      #   input_tag :password, :name => 'password', :size => 20
      #   # => <input type="password" name="password" size="20">
      #
      #   input_tag :text, :name => 'username', :required => true, :autofocus => true
      #   # => <input type="text" name="username" required autofocus>
      #
      #   input_tag :number, :name => 'credit_card', :autocomplete => :off
      #   # => <input type="number" autocomplete="off">
      #
      # @api semipublic
      def input_tag(type, options = {})
        tag(:input, options.reverse_merge!(:type => type))
      end

      ##
      # Creates an HTML tag with the given name and options
      #
      # @param [Symbol] name
      #  The name of the HTML tag to create.
      # @param [Hash] options
      #  The HTML options to include in this tag.
      #
      # @macro global_html_attributes
      #
      # @return [String]
      #   Generated HTML with specified +options+
      #
      # @example
      #   tag :hr, :class => 'dotted'
      #   # => <hr class="dotted">
      #
      #   tag :input, :name => 'username', :type => :text
      #   # => <input name="username" type="text">
      #
      #   tag :img, :src => 'images/pony.jpg', :alt => 'My Little Pony'
      #   # => <img src="images/pony.jpg" alt="My Little Pony">
      #
      #   tag :img, :src => 'sinatra.jpg, :data => { :nsfw => false, :geo => [34.087, -118.407] }
      #   # => <img src="sinatra.jpg" data-nsfw="false" data-geo="34.087 -118.407">
      #
      # @api public
      def tag(name, options = nil)
        "<#{name}#{tag_options(options) if options}>"
      end

      private
        ##
        # Returns a compiled list of HTML attributes
        ##
        def tag_options(options)
          return if options.blank?
          attributes = []
          options.each do |attribute, value|
            next if value.nil? || value == false
            if attribute == :data && value.is_a?(Hash)
              value.each { |k, v| attributes << %[data-#{k.to_s.dasherize}="#{escape_value(v)}"] }
            elsif BOOLEAN_ATTRIBUTES.include?(attribute)
              attributes << attribute.to_s
            else
              attributes << %[#{attribute}="#{escape_value(value)}"]
            end
          end
          " #{attributes.join(' ')}"
        end

        ##
        # Escape tag values to their HTML/XML entities.
        ##
        def escape_value(string)
          string.to_s.gsub(Regexp.union(*ESCAPE_VALUES.keys)){|c| ESCAPE_VALUES[c] }
        end
    end # TagHelpers
  end # Helpers
end # Padrino