module PreviewHelper

def find_template_data(lookup_context:, template_identifier:)
  template = lookup_context.find_template(template_identifier)
  if Rails.version.to_f >= 6.1 || template.source.present?
    {
      source: template.source,
      prism_language_name: prism_language_name_by_template(template: template)
    }
  # :nocov:
  else
    # Fetch template source via finding it through preview paths
    # to accomodate source view when exclusively using templates
    # for previews for Rails < 6.1.
    all_template_paths = ViewComponent::Base.config.preview_paths.map do |preview_path|
      Dir.glob("#{preview_path}/**/*")
    end.flatten
    # Search for templates the contain `html`.
    matching_templates = all_template_paths.find_all do |path|
      path =~ /#{template_identifier}*.(html)/
    end
    raise ViewComponent::NoMatchingTemplatesForPreviewError.new(template_identifier) if matching_templates.empty?
    raise ViewComponent::MultipleMatchingTemplatesForPreviewError.new(template_identifier) if matching_templates.size > 1
    template_file_path = matching_templates.first
    template_source = File.read(template_file_path)
    prism_language_name = prism_language_name_by_template_path(template_file_path: template_file_path)
    {
      source: template_source,
      prism_language_name: prism_language_name
    }
  end
  # :nocov:
end

def preview_source
  return if @render_args.nil?
  render "preview_source"
end

def prism_css_source_url
  serve_static_preview_assets? ? asset_path("prism.css", skip_pipeline: true) : "https://cdn.jsdelivr.net/npm/prismjs@1.28.0/themes/prism.min.css"
end

def prism_js_source_url
  serve_static_preview_assets? ? asset_path("prism.min.js", skip_pipeline: true) : "https://cdn.jsdelivr.net/npm/prismjs@1.28.0/prism.min.js"
end

def prism_language_name_by_template(template:)
  language = template.identifier.split(".").last
  return FALLBACK_LANGUAGE unless AVAILABLE_PRISM_LANGUAGES.include? language
  language
end

def prism_language_name_by_template_path(template_file_path:)
  language = template_file_path.gsub(".html", "").split(".").last
  return FALLBACK_LANGUAGE unless AVAILABLE_PRISM_LANGUAGES.include? language
  language
end

def serve_static_preview_assets?
  ViewComponent::Base.config.show_previews && Rails.application.config.public_file_server.enabled
end