# frozen_string_literal: true

require 'cgi'
require 'stringio'

module Ruby2html
  class Render
    HTML5_TAGS = %w[
      a abbr address area article aside audio b base bdi bdo blockquote body br button canvas caption
      cite code col colgroup data datalist dd del details dfn dialog div dl dt em embed fieldset
      figcaption figure footer form h1 h2 h3 h4 h5 h6 head header hr html i iframe img input ins
      kbd label legend li link main map mark meta meter nav noscript object ol optgroup option
      output p param picture pre progress q rp rt ruby s samp script section select small source
      span strong style sub summary sup table tbody td template textarea tfoot th thead time title
      tr track u ul var video wbr
    ].freeze

    VOID_ELEMENTS = %w[area base br col embed hr img input link meta param source track wbr].freeze

    COMMON_RAILS_METHOD_HELPERS = %w[content_tag link_to image_tag form_tag form_for form_with form_with_model button_to].freeze

    attr_reader :output

    def initialize(context, &root)
      @context = context
      @root = root
      @output = StringIO.new
      @current_output = @output
    end

    def render(*args, **options, &block)
      set_instance_variables

      if !args.empty? || !options.empty? || block_given?
        return plain @context.render(*args, **options, &block)
      end
      instance_exec(&@root)
      result = @output.string
      if defined?(ActiveSupport)
        result = ActiveSupport::SafeBuffer.new(result)
      end

      result
    end

    HTML5_TAGS.each do |tag|
      define_method(tag) do |*args, **options, &block|
        html!(tag, *args, **options, &block)
      end
    end

    def respond_to?(method_name, include_private = false)
      HTML5_TAGS.include?(method_name) || super
    end

    def html!(name, *args, **options, &block)
      content = args.first.is_a?(String) ? args.shift : nil
      attributes = options

      tag_content = StringIO.new
      tag_content << '<'
      tag_content << name
      tag_content << attributes_to_s(attributes)

      if VOID_ELEMENTS.include?(name)
        tag_content << ' />'
      else
        tag_content << '>'

        if block_given?
          prev_output = @current_output
          nested_content = StringIO.new
          @current_output = nested_content
          block_result = yield
          @current_output = prev_output
          tag_content << (block_result.is_a?(String) ? escape_html(block_result) : nested_content.string)
        elsif content
          tag_content << escape_html(content)
        end

        tag_content << '</'
        tag_content << name
        tag_content << '>'
      end

      @current_output << tag_content.string
    end

    def plain(text)
      if defined?(ActiveSupport) && (text.is_a?(ActiveSupport::SafeBuffer) || text.html_safe?)
        @current_output << text
      else
        @current_output << escape_html(text.to_s)
      end
    end

    def component(component_output)
      @current_output << component_output
    end

    private
      def method_missing(method_name, *args, **options, &block)
        if @context.respond_to?(method_name)
          @context.send(method_name, *args, **options, &block)
        else
          super
        end
      end

      def respond_to_missing?(method_name, include_private = false)
        @context.respond_to?(method_name) || super
      end

      COMMON_RAILS_METHOD_HELPERS.each do |method|
        define_method(method) do |*args, &block|
          plain @context.send(method, *args, &block)
        end
      end if defined?(ActionView)

      def attributes_to_s(attributes)
        return '' if attributes.empty?

        result = StringIO.new
        attributes.each do |k, v|
          result << ' '
          result << k.to_s
          result << '="'
          result << escape_html(v)
          result << '"'
        end
        result.string
      end

      def escape_html(text)
        CGI.escapeHTML(text.to_s)
      end

      def set_instance_variables
        @context.instance_variables.each do |name|
          instance_variable_set(name, @context.instance_variable_get(name))
        end
      end
  end
end