class ERBLint::Linters::BlankslateApiMigration

def args_to_s(args)
  string_args = args.except(:__polymorphic_type).map { |k, v| "#{k}: #{v}" }.join(", ")
  string_args = ":#{args[:__polymorphic_type]}, #{string_args}" if args[:__polymorphic_type]
  return string_args if string_args.blank?
  "(#{string_args})"
end

def autocorrect(_, offense)
  return unless offense.context
  lambda do |corrector|
    corrector.replace(offense.source_range, offense.context)
  end
end

def build_blankslate_arguments(kwargs)
  new_blankslate = {
    arguments: {},
    slots: {
      visual_icon: {},
      visual_image: {},
      heading: {
        tag: ":h2"
      },
      description: {},
      primary_action: {},
      secondary_action: {}
    }
  }
  kwargs&.pairs&.each do |pair|
    source_value = pair.value.source
    case pair.key.value.to_sym
    when :title
      new_blankslate[:slots][:heading][:content] = extract_value(pair.value)
    when :title_tag
      new_blankslate[:slots][:heading][:tag] = source_value
    when :icon
      new_blankslate[:slots][:visual_icon][:icon] = source_value
    when :icon_size
      new_blankslate[:slots][:visual_icon][:size] = source_value
    when :image_src
      new_blankslate[:slots][:visual_image][:src] = source_value
    when :image_alt
      new_blankslate[:slots][:visual_image][:alt] = source_value
    when :description
      new_blankslate[:slots][:description][:content] = extract_value(pair.value)
    when :button_text
      new_blankslate[:slots][:primary_action][:content] = extract_value(pair.value)
    when :button_url
      new_blankslate[:slots][:primary_action][:href] = source_value
    when :button_classes
      new_blankslate[:slots][:primary_action][:classes] = source_value
    when :link_text
      new_blankslate[:slots][:secondary_action][:content] = extract_value(pair.value)
    when :link_url
      new_blankslate[:slots][:secondary_action][:href] = source_value
    when :large
      next # Large does not exist anymore
    else
      new_blankslate[:arguments][pair.key.source] = source_value
    end
  end
  new_blankslate
end

def build_replacement_blankslate(kwargs, indent)
  data = build_blankslate_arguments(kwargs)
  component_args = args_to_s(data[:arguments])
  # If Blankslate has no heading, we don't update it.
  return if data[:slots][:heading][:content].nil?
  # If Blankslate sets both image and icon. don't update it.
  return if data[:slots][:visual_icon].present? && data[:slots][:visual_image].present?
  slots = data[:slots].map do |slot, slot_data|
    next if slot_data.empty?
    slot_args = args_to_s(slot_data.except(:content))
    content = slot_data[:content]
    if content
      <<~HTML.indent(2)
        <% c.#{slot}#{slot_args} do %>
          #{content}
        <% end %>
      HTML
    else
      <<~HTML.indent(2)
        <% c.#{slot}#{slot_args} %>
      HTML
    end
  end.compact.join("\n").chomp
  # Body needs to match the file indentation.
  body = <<~HTML.indent(indent).chomp
    #{slots}
    <% end %>
  HTML
  # The render call will always be aligned.
  "<%= render Primer::Beta::Blankslate.new#{component_args} do |c| %>\n#{body}"
end

def extract_value(value)
  return value.value if value.type == :str
  "<%= #{value.source} %>"
end

def run(processed_source)
  processed_source.ast.descendants(:erb).each do |erb_node|
    _, _, code_node = *erb_node
    code = code_node.children.first.strip
    next unless code.include?("Primer::BlankslateComponent")
    # Don't fix custom blankslates
    next if code.end_with?("do", "|")
    line = erb_node.loc.source_line
    indent = line.split("<%=").first.size
    ast = erb_ast(code)
    kwargs = ast.arguments.first.arguments.last
    replacement = build_replacement_blankslate(kwargs, indent)
    add_offense(processed_source.to_source_range(erb_node.loc), "`Primer::BlankslateComponent` is deprecated. `Primer::Beta::Blankslate` should be used instead", replacement)
  end
end