# frozen_string_literal: true

require_relative "selector_assertions/html_selector"

module Rails
  module Dom
    module Testing
      module Assertions
        # Adds the +assert_dom+ method for use in Rails functional
        # test cases, which can be used to make assertions on the response HTML of a controller
        # action. You can also call +assert_dom+ within another +assert_dom+ to
        # make assertions on elements selected by the enclosing assertion.
        #
        # Use +css_select+ to select elements without making an assertions, either
        # from the response HTML or elements selected by the enclosing assertion.
        #
        # In addition to HTML responses, you can make the following assertions:
        #
        # * +assert_dom_encoded+ - Assertions on HTML encoded inside XML, for example for dealing with feed item descriptions.
        # * +assert_dom_email+ - Assertions on the HTML body of an e-mail.
        module SelectorAssertions
          # Select and return all matching elements.
          #
          # If called with a single argument, uses that argument as a selector.
          # Called without an element +css_select+ selects from
          # the element returned in +document_root_element+
          #
          # The default implementation of +document_root_element+ raises an exception explaining this.
          #
          # Returns an empty Nokogiri::XML::NodeSet if no match is found.
          #
          # If called with two arguments, uses the first argument as the root
          # element and the second argument as the selector. Attempts to match the
          # root element and any of its children.
          # Returns an empty Nokogiri::XML::NodeSet if no match is found.
          #
          # The selector may be a CSS selector expression (String).
          # css_select returns nil if called with an invalid css selector.
          #
          #   # Selects all div tags
          #   divs = css_select("div")
          #
          #   # Selects all paragraph tags and does something interesting
          #   pars = css_select("p")
          #   pars.each do |par|
          #     # Do something fun with paragraphs here...
          #   end
          #
          #   # Selects all list items in unordered lists
          #   items = css_select("ul>li")
          #
          #   # Selects all form tags and then all inputs inside the form
          #   forms = css_select("form")
          #   forms.each do |form|
          #     inputs = css_select(form, "input")
          #     ...
          #   end
          def css_select(*args)
            raise ArgumentError, "you at least need a selector argument" if args.empty?

            root = args.size == 1 ? document_root_element : args.shift

            nodeset(root).css(args.first)
          end

          # An assertion that selects elements and makes one or more equality tests.
          #
          # If the first argument is an element, selects all matching elements
          # starting from (and including) that element and all its children in
          # depth-first order.
          #
          # If no element is specified +assert_dom+ selects from
          # the element returned in +document_root_element+
          # unless +assert_dom+ is called from within an +assert_dom+ block.
          # Override +document_root_element+ to tell +assert_dom+ what to select from.
          # The default implementation raises an exception explaining this.
          #
          # When called with a block +assert_dom+ passes an array of selected elements
          # to the block. Calling +assert_dom+ from the block, with no element specified,
          # runs the assertion on the complete set of elements selected by the enclosing assertion.
          # Alternatively the array may be iterated through so that +assert_dom+ can be called
          # separately for each element.
          #
          #
          # ==== Example
          # If the response contains two ordered lists, each with four list elements then:
          #   assert_dom "ol" do |elements|
          #     elements.each do |element|
          #       assert_dom element, "li", 4
          #     end
          #   end
          #
          # will pass, as will:
          #   assert_dom "ol" do
          #     assert_dom "li", 8
          #   end
          #
          # The selector may be a CSS selector expression (String, Symbol, or Numeric) or an expression
          # with substitution values (Array).
          # Substitution uses a custom pseudo class match. Pass in whatever attribute you want to match (enclosed in quotes) and a ? for the substitution.
          # assert_dom returns nil if called with an invalid css selector.
          #
          # assert_dom "div:match('id', ?)", "id_string"
          # assert_dom "div:match('id', ?)", :id_string
          # assert_dom "div:match('id', ?)", 1
          # assert_dom "div:match('id', ?)", /\d+/
          #
          # === Equality Tests
          #
          # The equality test may be one of the following:
          # * <tt>true</tt> - Assertion is true if at least one element selected.
          # * <tt>false</tt> - Assertion is true if no element selected.
          # * <tt>String/Regexp</tt> - Assertion is true if the text value of at least
          #   one element matches the string or regular expression.
          # * <tt>Integer</tt> - Assertion is true if exactly that number of
          #   elements are selected.
          # * <tt>Range</tt> - Assertion is true if the number of selected
          #   elements fit the range.
          # If no equality test specified, the assertion is true if at least one
          # element selected.
          #
          # To perform more than one equality tests, use a hash with the following keys:
          # * <tt>:text</tt> - Narrow the selection to elements that have this text
          #   value (string or regexp).
          # * <tt>:html</tt> - Narrow the selection to elements that have this HTML
          #   content (string or regexp).
          # * <tt>:count</tt> - Assertion is true if the number of selected elements
          #   is equal to this value.
          # * <tt>:minimum</tt> - Assertion is true if the number of selected
          #   elements is at least this value.
          # * <tt>:maximum</tt> - Assertion is true if the number of selected
          #   elements is at most this value.
          #
          # If the method is called with a block, once all equality tests are
          # evaluated the block is called with an array of all matched elements.
          #
          #   # At least one form element
          #   assert_dom "form"
          #
          #   # Form element includes four input fields
          #   assert_dom "form input", 4
          #
          #   # Page title is "Welcome"
          #   assert_dom "title", "Welcome"
          #
          #   # Page title is "Welcome" and there is only one title element
          #   assert_dom "title", {count: 1, text: "Welcome"},
          #       "Wrong title or more than one title element"
          #
          #   # Page contains no forms
          #   assert_dom "form", false, "This page must contain no forms"
          #
          #   # Test the content and style
          #   assert_dom "body div.header ul.menu"
          #
          #   # Use substitution values
          #   assert_dom "ol>li:match('id', ?)", /item-\d+/
          #
          #   # All input fields in the form have a name
          #   assert_dom "form input" do
          #     assert_dom ":match('name', ?)", /.+/  # Not empty
          #   end
          def assert_dom(*args, &block)
            @selected ||= nil

            selector = HTMLSelector.new(args, @selected) { nodeset document_root_element }

            if selector.selecting_no_body?
              assert true
              return
            end

            selector.select.tap do |matches|
              assert_size_match!(matches.size, selector.tests,
                selector.css_selector, selector.message)

              nest_selection(matches, &block) if block_given? && !matches.empty?
            end
          end
          alias_method :assert_select, :assert_dom

          # Extracts the content of an element, treats it as encoded HTML and runs
          # nested assertion on it.
          #
          # You typically call this method within another assertion to operate on
          # all currently selected elements. You can also pass an element or array
          # of elements.
          #
          # The content of each element is un-encoded, and wrapped in the root
          # element +encoded+. It then calls the block with all un-encoded elements.
          #
          #   # Selects all bold tags from within the title of an Atom feed's entries (perhaps to nab a section name prefix)
          #   assert_dom "feed[xmlns='http://www.w3.org/2005/Atom']" do
          #     # Select each entry item and then the title item
          #     assert_dom "entry>title" do
          #       # Run assertions on the encoded title elements
          #       assert_dom_encoded do
          #         assert_dom "b"
          #       end
          #     end
          #   end
          #
          #
          #   # Selects all paragraph tags from within the description of an RSS feed
          #   assert_dom "rss[version=2.0]" do
          #     # Select description element of each feed item.
          #     assert_dom "channel>item>description" do
          #       # Run assertions on the encoded elements.
          #       assert_dom_encoded do
          #         assert_dom "p"
          #       end
          #     end
          #   end
          #
          # The DOM is created using an HTML parser specified by
          # Rails::Dom::Testing.default_html_version (either :html4 or :html5).
          #
          # When testing in a Rails application, the parser default can also be set by setting
          # +Rails.application.config.dom_testing_default_html_version+.
          #
          # If you want to specify the HTML parser just for a particular assertion, pass
          # <tt>html_version: :html4</tt> or <tt>html_version: :html5</tt> keyword arguments:
          #
          #   assert_dom "feed[xmlns='http://www.w3.org/2005/Atom']" do
          #     assert_dom "entry>title" do
          #       assert_dom_encoded(html_version: :html5) do
          #         assert_dom "b"
          #       end
          #     end
          #   end
          #
          def assert_dom_encoded(element = nil, html_version: nil, &block)
            if !element && !@selected
              raise ArgumentError, "Element is required when called from a nonnested assert_dom"
            end

            content = nodeset(element || @selected).map do |elem|
              elem.children.select do |child|
                child.cdata? || (child.text? && !child.blank?)
              end.map(&:content)
            end.join

            selected = Rails::Dom::Testing.html_document_fragment(html_version: html_version).parse(content)
            nest_selection(selected) do
              if content.empty?
                yield selected
              else
                assert_dom ":root", &block
              end
            end
          end
          alias_method :assert_select_encoded, :assert_dom_encoded

          # Extracts the body of an email and runs nested assertions on it.
          #
          # You must enable deliveries for this assertion to work, use:
          #   ActionMailer::Base.perform_deliveries = true
          #
          # Example usage:
          #
          #   assert_dom_email do
          #     assert_dom "h1", "Email alert"
          #   end
          #
          #   assert_dom_email do
          #     items = assert_dom "ol>li"
          #     items.each do
          #        # Work with items here...
          #     end
          #   end
          #
          # The DOM is created using an HTML parser specified by
          # Rails::Dom::Testing.default_html_version (either :html4 or :html5).
          #
          # When testing in a Rails application, the parser default can also be set by setting
          # +Rails.application.config.dom_testing_default_html_version+.
          #
          # If you want to specify the HTML parser just for a particular assertion, pass
          # <tt>html_version: :html4</tt> or <tt>html_version: :html5</tt> keyword arguments:
          #
          #   assert_dom_email(html_version: :html5) do
          #     assert_dom "h1", "Email alert"
          #   end
          #
          def assert_dom_email(html_version: nil, &block)
            deliveries = ActionMailer::Base.deliveries
            assert !deliveries.empty?, "No e-mail in delivery list"

            deliveries.each do |delivery|
              (delivery.parts.empty? ? [delivery] : delivery.parts).each do |part|
                if /^text\/html\W/.match?(part["Content-Type"].to_s)
                  root = Rails::Dom::Testing.html_document_fragment(html_version: html_version).parse(part.body.to_s)
                  assert_dom root, ":root", &block
                end
              end
            end
          end
          alias_method :assert_select_email, :assert_dom_email

        private
          def document_root_element
            raise NotImplementedError, "Implementing document_root_element makes " \
              "assert_dom work without needing to specify an element to select from."
          end

          # +equals+ must contain :minimum, :maximum and :count keys
          def assert_size_match!(size, equals, css_selector, message = nil)
            min, max, count = equals[:minimum], equals[:maximum], equals[:count]

            message ||= %(Expected #{count_description(min, max, count)} matching #{css_selector.inspect}, found #{size})
            if count
              assert_equal count, size, message
            else
              assert_operator size, :>=, min, message if min
              assert_operator size, :<=, max, message if max
            end
          end

          def count_description(min, max, count)
            if min && max && (max != min)
              "between #{min} and #{max} elements"
            elsif min && max && max == min && count
              "exactly #{count} #{pluralize_element(min)}"
            elsif min && !(min == 1 && max == 1)
              "at least #{min} #{pluralize_element(min)}"
            elsif max
              "at most #{max} #{pluralize_element(max)}"
            end
          end

          def pluralize_element(quantity)
            quantity == 1 ? "element" : "elements"
          end

          def nest_selection(selection)
            # Set @selected to allow nested assert_dom.
            # Can be nested several levels deep.
            old_selected, @selected = @selected, selection
            yield @selected
          ensure
            @selected = old_selected
          end

          def nodeset(node)
            if node.is_a?(Nokogiri::XML::NodeSet)
              node
            else
              node ||= Nokogiri::HTML::Document.new
              Nokogiri::XML::NodeSet.new(node.document, [node])
            end
          end
        end
      end
    end
  end
end