# frozen_string_literal: true
require "nokogiri"
require "forwardable"

module ThemeCheck
  class HtmlVisitor
    include RegexHelpers
    attr_reader :checks

    def initialize(checks)
      @checks = checks
      @placeholder_values = []
    end

    def visit_template(template)
      doc = parse(template)
      visit(HtmlNode.new(doc, template, @placeholder_values))
    rescue ArgumentError => e
      call_checks(:on_parse_error, e, template)
    end

    private

    def parse(template)
      parseable_source = +template.source.clone

      # Replace all liquid tags with {%#{i}######%} to prevent the HTML
      # parser from freaking out. We transparently replace those placeholders in
      # HtmlNode.
      matches(parseable_source, LIQUID_TAG_OR_VARIABLE).each do |m|
        value = m[0]
        @placeholder_values.push(value)
        key = (@placeholder_values.size - 1).to_s
        parseable_source[m.begin(0)...m.end(0)] = "{%#{key.ljust(m.end(0) - m.begin(0) - 4, '#')}%}"
      end

      Nokogiri::HTML5.fragment(parseable_source, max_tree_depth: 400, max_attributes: 400)
    end

    def visit(node)
      call_checks(:on_element, node) if node.element?
      call_checks(:"on_#{node.name}", node)
      node.children.each { |child| visit(child) }
      unless node.literal?
        call_checks(:"after_#{node.name}", node)
        call_checks(:after_element, node) if node.element?
      end
    end

    def call_checks(method, *args)
      checks.call(method, *args)
    end
  end
end