module Nexmo
  module OAS
    module Renderer
      module Filters
        class CodeSnippets < Banzai::Filter
          def call(input)
            input.gsub(/^(\s*)```code_snippets(.+?)```/m) do |_s|
              @indentation = $1
              @config = YAML.safe_load($2)
              validate_config
              html
            end
          end

          private

          def create_tabs(content)
            tab = Nokogiri::XML::Element.new 'li', @document
            tab['class'] = 'Vlt-tabs__link'
            tab['class'] += ' Vlt-tabs__link_active' if content[:active]
            tab['aria-selected'] = 'true' if content[:active]

            if content['language']
              tab['data-language'] = content['language']
              tab['data-language-type'] = content['language_type']
              tab['data-language-linkable'] = true
            end

            tab_link = Nokogiri::XML::Element.new 'a', @document
            tab_link.inner_html = "<svg><use xlink:href=\"/assets/images/brands/#{content['icon']}.svg##{content['icon']}\" /></svg><span>" + content['title'] + '</span>'
            tab_link['class'] = 'tab-link'

            tab.add_child(tab_link)
            @tabs.add_child(tab)
          end

          def create_content(content)
            element = Nokogiri::XML::Element.new 'div', @document
            element['id'] = content['id']
            element['class'] = 'Vlt-tabs__panel'
            element['class'] += ' Vlt-tabs__panel_active' if content[:active]
            element.inner_html = content[:body]

            @tabs_content.add_child(element)
          end

          def html
            html = <<~HEREDOC
              <div class="Vlt-tabs">
                <div class="Vlt-tabs__header--bordered"></div>
                <div class="Vlt-tabs__content"></div>
              </div>
            HEREDOC

            @document = Nokogiri::HTML::DocumentFragment.parse(html)
            @tabs = @document.at_css('.Vlt-tabs__header--bordered')
            @tabs_content = @document.at_css('.Vlt-tabs__content')

            contents.each do |content|
              create_tabs(content)
              create_content(content)
            end

            source = @document.to_html

            "#{@indentation}FREEZESTART#{Base64.urlsafe_encode64(source)}FREEZEEND"
          end

          def contents
            list = content_from_source
            list ||= []

            return list unless list.any?

            list = sort_contents(list)
            resolve_active_tab(list)

            list
          end

          def validate_config
            return if @config && @config['source']
            raise 'A source key must be present in this building_blocks config'
          end

          def content_from_source
            source_path = "#{@config['source']}/*.yml"

            files = Dir[source_path]
            raise "No .yml files found for #{@config['source']} code snippets" if files.empty?

            files.map do |content_path|
              source = File.read(content_path)

              # Load the defaults for this language
              filename = File.basename(content_path, '.yml')
              defaults = CodeLanguageAPI.find(filename)

              content = YAML.safe_load(source)
              content['source'] = source
              content['id'] = SecureRandom.hex
              content['title'] ||= defaults.label
              content['language'] ||= defaults.key
              content['language_type'] ||= defaults.type
              content['dependencies'] ||= defaults.dependencies
              content['icon'] = defaults.icon
              content['weight'] ||= defaults.weight
              content['run_command'] ||= defaults.run_command
              content['unindent'] = defaults.unindent || false

              # If we don't have a file_name in config, use the one in the repo
              content['file_name'] ||= File.basename(content['code']['source'])

              parent_config = { 'code_only' => @config['code_only'], 'source' => @config['source'].gsub('_examples/', '') }
              if @config['application']
                parent_config = parent_config.merge({ 'application' => @config['application'] })
              end

              parent_config = parent_config.to_yaml.lines[1..-1].join

              source = <<~HEREDOC
                ```single_code_snippet
                #{content.to_yaml}\n#{parent_config}
                ```
              HEREDOC

              content[:body] = MarkdownPipeline.new(options).call(source)

              content
            end
          end

          def sort_contents(contents)
            contents.sort_by do |content|
              content['weight']
            end
          end

          def resolve_active_tab(contents)
            active_index = nil

            if options[:code_language]
              contents.each_with_index do |content, index|
                active_index = index if content['language'] == options[:code_language].key
              end
            end

            @tabs['data-has-initial-tab'] = active_index.present?
            @tabs['class'] += ' skip-pushstate' if @tabs['data-has-initial-tab']
            active_index ||= 0

            contents[active_index][:active] = true
          end
        end
      end
    end
  end
end