# frozen_string_literal: true

require "uri"

Dir["#{Rails.root.join("lib/onebox/engine/*_onebox.rb")}"].sort.each { |f| require f }

module Oneboxer
  ONEBOX_CSS_CLASS = "onebox"
  AUDIO_REGEX = /\A\.(mp3|og[ga]|opus|wav|m4[abpr]|aac|flac)\z/i
  VIDEO_REGEX = /\A\.(mov|mp4|webm|m4v|3gp|ogv|avi|mpeg|ogv)\z/i

  # keep reloaders happy
  unless defined?(Oneboxer::Result)
    Result =
      Struct.new(:doc, :changed) do
        def to_html
          doc.to_html
        end

        def changed?
          changed
        end
      end
  end

  def self.ignore_redirects
    @ignore_redirects ||= [
      "http://www.dropbox.com",
      "http://store.steampowered.com",
      "http://vimeo.com",
      "https://reddit.com",
      "https://www.reddit.com",
      "https://old.reddit.com",
      "https://np.reddit.com",
      "https://new.reddit.com",
      "https://www.youtube.com",
      "https://youtu.be",
      "https://meet.google.com",
      "https://twitter.com",
      "https://x.com",
      Discourse.base_url,
    ]
  end

  def self.amazon_domains
    amazon_suffixes = %w[
      com
      com.br
      ca
      cn
      fr
      de
      in
      it
      co.jp
      com.mx
      nl
      pl
      sa
      sg
      es
      se
      com.tr
      ae
      co.uk
    ]
    amazon_suffixes.collect { |suffix| "https://www.amazon.#{suffix}" }
  end

  def self.force_get_hosts
    hosts = []
    hosts += SiteSetting.force_get_hosts.split("|").collect { |domain| "https://#{domain}" }
    hosts += amazon_domains

    hosts.uniq
  end

  def self.force_custom_user_agent_hosts
    SiteSetting.force_custom_user_agent_hosts.split("|")
  end

  def self.allowed_post_types
    @allowed_post_types ||= [Post.types[:regular], Post.types[:moderator_action]]
  end

  def self.local_handlers
    @local_handlers ||= {}
  end

  def self.register_local_handler(controller, &handler)
    local_handlers[controller] = handler
  end

  def self.preview(url, options = nil)
    options ||= {}
    invalidate(url) if options[:invalidate_oneboxes]
    onebox_raw(url, options)[:preview]
  end

  def self.onebox(url, options = nil)
    options ||= {}
    invalidate(url) if options[:invalidate_oneboxes]
    onebox_raw(url, options)[:onebox]
  end

  def self.cached_onebox(url)
    if c = Discourse.cache.read(onebox_cache_key(url))
      c[:onebox]
    end
  rescue => e
    invalidate(url)
    Rails.logger.warn("invalid cached onebox for #{url} #{e}")
    ""
  end

  def self.cached_preview(url)
    if c = Discourse.cache.read(onebox_cache_key(url))
      c[:preview]
    end
  rescue => e
    invalidate(url)
    Rails.logger.warn("invalid cached preview for #{url} #{e}")
    ""
  end

  def self.invalidate(url)
    Discourse.cache.delete(onebox_cache_key(url))
    Discourse.cache.delete(onebox_failed_cache_key(url))
  end

  def self.inline_data_for(url)
    engine_class = engine(url)
    return if engine_class.nil? || !engine_class.method_defined?(:inline_data)

    engine_class.new(url).inline_data
  end

  # Parse URLs out of HTML, returning the document when finished.
  def self.each_onebox_link(doc, extra_paths: [])
    onebox_links = doc.css("a.#{ONEBOX_CSS_CLASS}", *extra_paths)
    if onebox_links.present?
      onebox_links.each { |link| yield(link["href"], link) if link["href"].present? }
    end

    doc
  end

  HTML5_BLOCK_ELEMENTS = %w[
    address
    article
    aside
    blockquote
    canvas
    center
    dd
    div
    dl
    dt
    fieldset
    figcaption
    figure
    footer
    form
    h1
    h2
    h3
    h4
    h5
    h6
    header
    hgroup
    hr
    li
    main
    nav
    noscript
    ol
    output
    p
    pre
    section
    table
    tfoot
    ul
    video
  ]

  def self.apply(string_or_doc, extra_paths: nil)
    doc = string_or_doc
    doc = Loofah.html5_fragment(doc) if doc.is_a?(String)
    changed = false

    each_onebox_link(doc, extra_paths: extra_paths) do |url, element|
      onebox, _ = yield(url, element)
      next if onebox.blank?

      parsed_onebox = Loofah.html5_fragment(onebox)
      next if parsed_onebox.children.blank?

      changed = true

      parent = element.parent
      if parent&.node_name&.downcase == "p" &&
           parsed_onebox.children.any? { |child|
             HTML5_BLOCK_ELEMENTS.include?(child.node_name.downcase)
           }
        siblings = parent.children
        element_idx = siblings.find_index(element)
        before_idx = first_significant_element_index(siblings, element_idx - 1, -1)
        after_idx = first_significant_element_index(siblings, element_idx + 1, +1)

        if before_idx < 0 && after_idx >= siblings.size
          parent.replace parsed_onebox
        elsif before_idx < 0
          parent.children = siblings[after_idx..siblings.size]
          parent.add_previous_sibling(parsed_onebox)
        elsif after_idx >= siblings.size
          parent.children = siblings[0..before_idx]
          parent.add_next_sibling(parsed_onebox)
        else
          parent_rest = parent.dup

          parent.children = siblings[0..before_idx]
          parent_rest.children = siblings[after_idx..siblings.size]

          parent.add_next_sibling(parent_rest)
          parent.add_next_sibling(parsed_onebox)
        end
      else
        element.replace parsed_onebox
      end
    end

    Result.new(doc, changed)
  end

  def self.first_significant_element_index(elements, index, step)
    while index >= 0 && index < elements.size &&
            (
              elements[index].node_name.downcase == "br" ||
                (
                  elements[index].node_name.downcase == "text" &&
                    elements[index].to_html.strip.blank?
                )
            )
      index = index + step
    end

    index
  end

  def self.is_previewing?(user_id)
    Discourse.redis.get(preview_key(user_id)) == "1"
  end

  def self.preview_onebox!(user_id)
    Discourse.redis.setex(preview_key(user_id), 1.minute, "1")
  end

  def self.onebox_previewed!(user_id)
    Discourse.redis.del(preview_key(user_id))
  end

  def self.engine(url)
    Onebox::Matcher.new(
      url,
      { allowed_iframe_regexes: Onebox::Engine.origins_to_regexes(allowed_iframe_origins) },
    ).oneboxed
  end

  def self.recently_failed?(url)
    Discourse.cache.read(onebox_failed_cache_key(url)).present?
  end

  def self.cache_failed!(url)
    Discourse.cache.write(onebox_failed_cache_key(url), true, expires_in: 1.hour)
  end

  private

  def self.preview_key(user_id)
    "onebox:preview:#{user_id}"
  end

  def self.blank_onebox
    { preview: "", onebox: "" }
  end

  def self.onebox_cache_key(url)
    "onebox__#{url}"
  end

  def self.onebox_failed_cache_key(url)
    "onebox_failed__#{url}"
  end

  def self.onebox_raw(url, opts = {})
    url = UrlHelper.normalized_encode(url).to_s
    local_onebox(url, opts) || external_onebox(url)
  rescue => e
    # no point warning here, just cause we have an issue oneboxing a url
    # we can later hunt for failed oneboxes by searching logs if needed
    Rails.logger.info("Failed to onebox #{url} #{e} #{e.backtrace}")
    # return a blank hash, so rest of the code works
    blank_onebox
  end

  def self.local_onebox(url, opts = {})
    return unless route = Discourse.route_for(url)

    html =
      case route[:controller]
      when "uploads"
        local_upload_html(url)
      when "topics"
        local_topic_html(url, route, opts)
      when "users"
        local_user_html(url, route, opts)
      when "list"
        local_category_html(url, route)
      else
        if handler = local_handlers[route[:controller]]
          handler.call(url, route)
        end
      end

    normalized_url = ::Onebox::Helpers.normalize_url_for_output(URI(url).to_s)
    html = html.presence || "<a href='#{normalized_url}'>#{normalized_url}</a>"
    { onebox: html, preview: html }
  end

  def self.local_upload_html(url)
    additional_controls =
      if SiteSetting.disable_onebox_media_download_controls
        "controlslist='nodownload'"
      else
        ""
      end

    normalized_url = ::Onebox::Helpers.normalize_url_for_output(url)
    case File.extname(URI(url).path || "")
    when VIDEO_REGEX
      <<~HTML
        <div class="onebox video-onebox">
          <video #{additional_controls} width="100%" height="100%" controls="">
            <source src='#{normalized_url}'>
            <a href='#{normalized_url}'>
              #{normalized_url}
            </a>
          </video>
        </div>
      HTML
    when AUDIO_REGEX
      <<~HTML
        <audio #{additional_controls} controls>
          <source src='#{normalized_url}'>
          <a href='#{normalized_url}'>
            #{normalized_url}
          </a>
        </audio>
      HTML
    end
  end

  def self.local_topic(url, route, opts)
    if current_user = User.find_by(id: opts[:user_id])
      if current_category = Category.find_by(id: opts[:category_id])
        return unless Guardian.new(current_user).can_see_category?(current_category)
      end

      if current_topic = Topic.find_by(id: opts[:topic_id])
        return unless Guardian.new(current_user).can_see_topic?(current_topic)
      end
    end

    return unless topic = Topic.find_by(id: route[:id] || route[:topic_id])
    return if topic.private_message?

    if current_category.blank? || current_category.id != topic.category_id
      return unless Guardian.new.can_see_topic?(topic)
    else
      return unless Guardian.new(current_user).can_see_topic?(topic)
    end

    topic
  end

  def self.local_topic_html(url, route, opts)
    return unless topic = local_topic(url, route, opts)

    post_number = route[:post_number].to_i

    post =
      (
        if post_number > 1
          topic.posts.where(post_number: post_number).first
        else
          topic.ordered_posts.first
        end
      )

    return if !post || post.hidden || !allowed_post_types.include?(post.post_type)

    if post_number > 1 && opts[:topic_id] == topic.id
      excerpt = post.excerpt(SiteSetting.post_onebox_maxlength, keep_svg: true)
      excerpt.gsub!(/[\r\n]+/, " ")
      excerpt.gsub!("[/quote]", "[quote]") # don't break my quote

      quote =
        "[quote=\"#{post.user.username}, topic:#{topic.id}, post:#{post.post_number}\"]\n#{excerpt}\n[/quote]"

      PrettyText.cook(quote)
    else
      title, excerpt = localized_topic_onebox_content(topic, post, opts[:locale])

      args = {
        topic_id: topic.id,
        post_number: post.post_number,
        avatar: PrettyText.avatar_img(post.user.avatar_template_url, "tiny"),
        original_url: url,
        title: PrettyText.unescape_emoji(CGI.escapeHTML(title)),
        category_html: CategoryBadge.html_for(topic.category),
        quote: PrettyText.unescape_emoji(excerpt),
      }

      template = template("discourse_topic_onebox")
      Mustache.render(template, args)
    end
  end

  # Returns the [title, excerpt] for an internal topic onebox card, localized to
  # +locale+ when a translation exists. The title and excerpt fall back to the
  # original independently, so a translated title can sit above an untranslated
  # preview. Used while cooking a translated post (see LocalizedCookedPostProcessor).
  def self.localized_topic_onebox_content(topic, post, locale)
    title = topic.title
    excerpt = post.excerpt(SiteSetting.post_onebox_maxlength, keep_svg: true)

    return title, excerpt if locale.blank? || !SiteSetting.content_localization_enabled

    if (topic_localization = topic.get_localization(locale, fallback: false))
      title = topic_localization.title.presence || title
    end

    if (post_localization = post.get_localization(locale, fallback: false)) &&
         post_localization.cooked.present?
      excerpt =
        Post.excerpt(
          post_localization.cooked,
          SiteSetting.post_onebox_maxlength,
          keep_svg: true,
          post: post,
        )
    end

    [title, excerpt]
  end

  def self.local_user_html(url, route, opts)
    username = route[:username] || ""

    if user = User.find_by(username_lower: username.downcase)
      return if SiteSetting.allow_users_to_hide_profile && user.user_option&.hide_profile?
      return unless Guardian.new(User.find_by(id: opts[:user_id])).can_see_profile?(user)
      name = user.name if SiteSetting.enable_names

      args = {
        user_id: user.id,
        username: user.username,
        avatar: PrettyText.avatar_img(user.avatar_template, "huge"),
        name: name,
        bio: user.user_profile.bio_excerpt(230),
        location: Onebox::Helpers.sanitize(user.user_profile.location),
        joined:
          I18n.t(
            "onebox.discourse.user_joined_community",
            date: user.created_at.strftime(I18n.t("datetime_formats.formats.date_only")),
          ),
        website: user.user_profile.website,
        website_name: UserSerializer.new(user).website_name,
        original_url: url,
      }

      Mustache.render(template("discourse_user_onebox"), args)
    else
      nil
    end
  end

  def self.local_category_html(url, route)
    return unless route[:category_slug_path_with_id]
    category = Category.find_by_slug_path_with_id(route[:category_slug_path_with_id])
    guardian = Guardian.new

    if guardian.can_see_category?(category)
      subcategories =
        category.subcategories.select { |subcategory| guardian.can_see_category?(subcategory) }

      args = {
        url: category.url,
        name: category.name,
        color: category.color,
        logo_url: category.uploaded_logo&.url,
        description: Onebox::Helpers.sanitize(category.description),
        has_subcategories: category.subcategories.present?,
        subcategories:
          subcategories.collect { |sc| { name: sc.name, color: sc.color, url: sc.url } },
      }

      Mustache.render(template("discourse_category_onebox"), args)
    end
  end

  def self.preserve_fragment_url_hosts
    @preserve_fragment_url_hosts ||= ["http://github.com"]
  end

  def self.allowed_iframe_origins
    allowed = SiteSetting.allowed_onebox_iframes.split("|")
    allowed = Onebox::Engine.all_iframe_origins if allowed.include?("*")
    allowed += SiteSetting.allowed_iframes.split("|")
  end

  def self.external_onebox(url, available_strategies = nil)
    key = onebox_cache_key(url)
    cached = Discourse.cache.read(key)
    return cached if cached

    result = compute_external_onebox(url, available_strategies)
    Discourse.cache.write(key, result, expires_in: external_onebox_ttl(result))
    result
  end

  def self.external_onebox_ttl(result)
    result[:onebox].blank? ? 1.minute : 1.day
  end

  def self.compute_external_onebox(url, available_strategies = nil)
    uri = URI(url)
    available_strategies ||= Oneboxer.ordered_strategies(uri.hostname)
    strategy = available_strategies.shift

    max_redirects = 0 if SiteSetting.block_onebox_on_redirect
    fd =
      FinalDestination.new(
        url,
        get_final_destination_options(url, strategy).merge(
          stop_at_blocked_pages: true,
          max_redirects: max_redirects,
          initial_https_redirect_ignore_limit: SiteSetting.block_onebox_on_redirect,
        ),
      )
    uri = fd.resolve

    return blank_onebox if fd.status == :blocked_page

    if fd.status != :resolved
      args = { link: url }
      if fd.status == :invalid_address
        args[:error_message] = I18n.t("errors.onebox.invalid_address", hostname: fd.hostname)
      elsif (fd.status_code || uri.nil?) && available_strategies.present?
        # Try a different oneboxing strategy, if we have any options left:
        return compute_external_onebox(url, available_strategies)
      elsif fd.bot_challenge?
        args[:error_message] = I18n.t("errors.onebox.bot_challenge")
      elsif fd.status_code
        args[:error_message] = I18n.t("errors.onebox.error_response", status_code: fd.status_code)
      end

      error_box = blank_onebox
      error_box[:preview] = preview_error_onebox(args)
      return error_box
    end

    return blank_onebox if uri.blank?

    onebox_options = {
      max_width: 695,
      sanitize_config: Onebox::SanitizeConfig::DISCOURSE_ONEBOX,
      allowed_iframe_origins: allowed_iframe_origins,
      hostname: GlobalSetting.hostname,
      facebook_app_access_token: SiteSetting.facebook_app_access_token,
      disable_media_download_controls: SiteSetting.disable_onebox_media_download_controls,
      content_type: fd.content_type,
    }

    onebox_options[:cookie] = fd.cookie if fd.cookie

    preview_result = Onebox.preview(uri.to_s, onebox_options)
    result = {
      onebox: WordWatcher.censor(preview_result.to_s),
      preview: WordWatcher.censor(preview_result.placeholder_html.to_s),
    }

    # NOTE: Call preview_result.errors after calling placeholder_html
    if preview_result.errors.any?
      error_keys = preview_result.errors.keys
      skip_if_only_error = [:image]
      unless error_keys.length == 1 && skip_if_only_error.include?(error_keys.first)
        missing_attributes = error_keys.map(&:to_s).sort.join(I18n.t("word_connector.comma"))
        error_message =
          I18n.t(
            "errors.onebox.missing_data",
            missing_attributes: missing_attributes,
            count: error_keys.size,
          )
        args = preview_result.verified_data.merge(error_message: error_message)

        if result[:preview].blank?
          result[:preview] = preview_error_onebox(args)
        else
          doc = Nokogiri::HTML5.fragment(result[:preview])
          aside = doc.at("aside")

          if aside
            # Add an error message to the preview that was returned
            error_fragment = preview_error_onebox_fragment(args)
            aside.add_child(error_fragment)
            result[:preview] = doc.to_html
          end
        end
      end
    end

    Oneboxer.cache_preferred_strategy(uri.hostname, strategy)

    result
  end

  def self.preview_error_onebox(args, is_fragment = false)
    args[:title] ||= args[:link] if args[:link]
    args[:error_message] = PrettyText.unescape_emoji(args[:error_message]) if args[:error_message]

    template_name = is_fragment ? "preview_error_fragment_onebox" : "preview_error_onebox"
    Mustache.render(template(template_name), args)
  end

  def self.preview_error_onebox_fragment(args)
    preview_error_onebox(args, true)
  end

  def self.template(template_name)
    @template_cache ||= {}
    @template_cache[template_name] ||= begin
      full_path = "#{Rails.root.join("lib/onebox/templates/#{template_name}.mustache")}"
      File.read(full_path)
    end
  end

  def self.ordered_strategies(hostname)
    all = strategies.keys
    preferred = Oneboxer.preferred_strategy(hostname)

    all.insert(0, all.delete(preferred)) if all.include?(preferred)

    all
  end

  def self.strategies
    {
      default: {
      }, # don't override anything by default
      force_get_and_ua: {
        force_get_host: true,
        force_custom_user_agent_host: true,
      },
    }
  end

  def self.cache_preferred_strategy(hostname, strategy)
    return if strategy == :default

    key = redis_oneboxer_strategy_key(hostname)
    Discourse.redis.without_namespace.setex(key, 2.weeks.to_i, strategy.to_s)
  end

  def self.clear_preferred_strategy!(hostname)
    key = redis_oneboxer_strategy_key(hostname)
    Discourse.redis.without_namespace.del(key)
  end

  def self.preferred_strategy(hostname)
    key = redis_oneboxer_strategy_key(hostname)
    Discourse.redis.without_namespace.get(key)&.to_sym
  end

  def self.redis_oneboxer_strategy_key(hostname)
    "ONEBOXER_STRATEGY_#{hostname}"
  end

  def self.get_final_destination_options(url, strategy = nil)
    fd_options = {
      ignore_redirects: ignore_redirects,
      force_get_hosts: force_get_hosts,
      force_custom_user_agent_hosts: force_custom_user_agent_hosts,
      preserve_fragment_url_hosts: preserve_fragment_url_hosts,
      timeout: 5,
      headers: {
        "Accept-Language" => accept_language,
      },
    }

    uri = URI(url)

    # For private GitHub repos, we get a 404 when trying to use
    # FinalDestination to request the final URL because no auth headers
    # are sent. In this case we can ignore redirects and go straight to
    # using Onebox.preview
    if SiteSetting.github_onebox_access_tokens.present? && uri.hostname == "github.com"
      fd_options[:ignore_redirects] << "https://github.com"
    end

    strategy = Oneboxer.ordered_strategies(uri.hostname).shift if strategy.blank?

    if strategy && Oneboxer.strategies[strategy][:force_get_host]
      fd_options[:force_get_hosts] = ["https://#{uri.hostname}"]
    end
    if strategy && Oneboxer.strategies[strategy][:force_custom_user_agent_host]
      fd_options[:force_custom_user_agent_hosts] = ["https://#{uri.hostname}"]
    end

    fd_options
  end

  def self.onebox_locale
    SiteSetting.onebox_locale.presence || SiteSetting.default_locale
  end

  def self.accept_language
    if onebox_locale == "en"
      "en;q=0.9, *;q=0.5"
    else
      "#{onebox_locale.gsub(/_/, "-")};q=0.9, en;q=0.8, *;q=0.5"
    end
  end
end