class HTMLProofer::Check::Links

def allow_hash_href?
  @runner.options[:allow_hash_href]
end

def allow_missing_href?
  @runner.options[:allow_missing_href]
end

def anchor_tag?
node.name == "a"

def check_schemes
  case @link.url.scheme
  when "mailto"
    handle_mailto
  when "tel"
    handle_tel
  when "http"
    return unless @runner.options[:enforce_https]
    add_failure("#{@link.url.raw_attribute} is not an HTTPS link", element: @link)
  end
end

def check_sri
  return unless SRI_REL_TYPES.include?(@link.node["rel"])
  if blank?(@link.node["integrity"]) && blank?(@link.node["crossorigin"])
    add_failure(
      "SRI and CORS not provided in: #{@link.url.raw_attribute}",
      element: @link,
    )
  elsif blank?(@link.node["integrity"])
    add_failure("Integrity is missing in: #{@link.url.raw_attribute}", element: @link)
  elsif blank?(@link.node["crossorigin"])
    add_failure(
      "CORS not provided for external resource in: #{@link.link.url.raw_attribute}",
      element: @link,
    )
  end
end

def handle_mailto
  if @link.url.path.empty?
    add_failure(
      "#{@link.url.raw_attribute} contains no email address",
      element: @link,
    ) unless ignore_empty_mailto?
  # eg., if any do not match a valid URL
  elsif @link.url.path.split(",").any? { |email| !/#{URI::MailTo::EMAIL_REGEXP}/o.match?(email) }
    add_failure(
      "#{@link.url.raw_attribute} contains an invalid email address",
      element: @link,
    )
  end
end

def handle_tel
  add_failure(
    "#{@link.url.raw_attribute} contains no phone number",
    element: @link,
  ) if @link.url.path.empty?
end

def ignore_empty_mailto?
  @runner.options[:ignore_empty_mailto]
end

def run
  @html.css("a, link").each do |node|
    @link = create_element(node)
    next if @link.ignore?
    if !allow_hash_href? && @link.node["href"] == "#"
      add_failure("linking to internal hash #, which points to nowhere", element: @link)
      next
    end
    # is there even an href?
    if blank?(@link.url.raw_attribute)
      next if allow_missing_href?
      add_failure("'#{@link.node.name}' tag is missing a reference", element: @link)
      next
    end
    # is it even a valid URL?
    unless @link.url.valid?
      add_failure("#{@link.href} is an invalid URL", element: @link)
      next
    end
    if @link.url.protocol_relative?
      add_failure(
        "#{@link.url} is a protocol-relative URL, use explicit https:// instead",
        element: @link,
      )
      next
    end
    check_schemes
    # intentionally down here because we still want valid? & missing_href? to execute
    next if @link.url.non_http_remote?
    if !@link.url.internal? && @link.url.remote?
      check_sri if @runner.check_sri? && @link.link_tag?
      # we need to skip these for now; although the domain main be valid,
      # curl/Typheous inaccurately return 404s for some links. cc https://git.io/vyCFx
      next if @link.node["rel"] == "dns-prefetch"
      unless @link.url.path?
        add_failure("#{@link.url.raw_attribute} is an invalid URL", element: @link)
        next
      end
      add_to_external_urls(@link.url, @link.line)
    elsif @link.url.internal?
      # does the local directory have a trailing slash?
      if @link.url.unslashed_directory?(@link.url.absolute_path)
        add_failure(
          "internally linking to a directory #{@link.url.raw_attribute} without trailing slash",
          element: @link,
        )
        next
      end
      add_to_internal_urls(@link.url, @link.line)
    end
  end
end

def source_tag?
node.name == "source"