require 'active_model/naming'

module Scrivito
  # This class represents individual external or internal links Scrivito is able to identify and
  # to process. To format a link for rendering on an HTML page, use the +scrivito_path+ or
  # +scrivito_url+ methods.
  # @api public
  class Link

    extend ActiveModel::Naming

    # Parses a URL and returns a {Link} object. Determines internal URLs based on the given
    # +hostname+ and +port+.
    # @api public
    # @param [String] url
    # @param host [String] the hostname of internal urls
    # @param port [String] the port of internal urls
    def self.parse(url, host, port)
      LinkParser.new(host, port).parse(url)
    end

    # Create a new link object.
    # @example Set the 'current_campaign' link of an object:
    #   obj.update(current_campaign: Scrivito::Link.new(obj: Obj.find('55dd1ce50ecc41c8')))
    # @api public
    # @param [Hash] link_data
    # @option link_data [String] url
    # @option link_data [Obj] obj
    # @option link_data [String] title
    # @option link_data [String] query
    # @option link_data [String] target
    # @option link_data [String] fragment
    def initialize(link_data)
      @link_data = link_data.with_indifferent_access
    end

    # The external URL of the link. Returns +nil+ if the link is internal.
    # Warning: Do not output the URL directly unless you know what you are doing.
    # Normally, you want to use the +scrivito_path+ or +scrivito_url+ methods to format a link.
    # @api public
    def url
      @link_data[:url]
    end

    # Set the external URL of the link. This causes the link to become an external link.
    # @api public
    # @param value [String] the url of the link
    def url=(value)
      @link_data[:url] = value
    end

    # Returns the {BasicObj Obj} this link references. Returns +nil+ if the link is external.
    # @api public
    def obj
      @link_data[:obj]
    end

    # Set the {BasicObj Obj} this link should reference.
    # @api public
    # @param value [Obj] the obj this link should point to
    def obj=(value)
      @link_data[:obj] = value
    end

    # Returns the title of the link.
    # @api public
    def title
      @link_data[:title]
    end

    # Set the link title.
    # @api public
    # @param value [String] the title of the link
    def title=(value)
      @link_data[:title] = value
    end

    # Returns the query string of the link as in "index.html?query_string".
    # See RFC3986 for details (http://www.ietf.org/rfc/rfc3986.txt).
    # @api public
    def query
      @link_data[:query]
    end

    # Set the query string of the link as in "index.html?query_string".
    # See RFC3986 for details (http://www.ietf.org/rfc/rfc3986.txt).
    # @api public
    # @param value [String] the query string of the link
    def query=(value)
      @link_data[:query] = value
    end

    # Returns the anchor of the link as in "index.html#anchor".
    # See RFC3986 for details (http://www.ietf.org/rfc/rfc3986.txt).
    # @api public
    def fragment
      @link_data[:fragment]
    end

    # Set the anchor of the link as in "index.html#anchor".
    # See RFC3986 for details (http://www.ietf.org/rfc/rfc3986.txt).
    # @api public
    # @param value [String] the anchor or fragment of the link
    def fragment=(value)
      @link_data[:fragment] = value
    end

    # Returns the link target. "target" refers to the equally-named HTML attribute,
    # not the link destination.
    # @api public
    def target
      @link_data[:target]
    end

    # Set the link target. "target" refers to the equally-named HTML attribute,
    # not the link destination.
    # @api public
    # @param value [String] the target of the link
    def target=(value)
      @link_data[:target] = value
    end

    # Returns the file extension (e.g. zip, pdf) of the (internal or external) destination
    # of this link.
    # Returns an empty string if the file extension cannot be determined.
    # @api public
    def file_extension
      if internal?
        obj ? obj.file_extension : ""
      else
        path = URI.parse(url).path rescue nil
        path.blank? ? "" : File.extname(path)[1..-1] || ""
      end
    end

    # Returns the title of this Link if it is set. If not, the +display_title+ of the destination
    # object is returned for internal links, or the +url+ for external links.
    # @api public
    def display_title
      dt = title
      dt = obj.display_title if dt.blank? && !external?
      dt = url if dt.blank?
      dt
    end

    # The alt description of a +Link+, used by {ScrivitoHelper#scrivito_image_tag}.
    #
    # By default, this method returns the +title+ of this +Link+.
    # If +title+ is +nil+ and this +Link+ references an {BasicObj Obj}, the
    # +alt_description+ of that {BasicObj Obj} is used.
    #
    # @api public
    def alt_description
      return title if title
      obj.alt_description if internal?
    end

    # Returns true if this Link points to a CMS object.
    # @api public
    def internal?
      url.nil?
    end

    # Returns true if this Link points to an external location.
    # @api public
    def external?
      !internal?
    end

    def resolved?
      external? || !obj.nil?
    end

    def query_and_fragment
      str = ''
      str << "?#{query}" if query.present?
      str << "##{fragment}" if fragment.present?
      str
    end

    def internal_url
      raise 'Called #internal_url on an external link!' if external?
      "objid:#{obj.id}"
    end

    def to_cms_api_html_url
      if internal?
        "#{internal_url}#{query_and_fragment}"
      else
        url
      end
    end

    def to_cms_api_linklist_params
      params = {}

      if internal?
        params[:obj_id] = obj.id
        params[:title] = title if title
        params[:query] = query if query
        params[:fragment] = fragment if fragment
        params[:target] = target if target
      else
        params[:url] = url
        params[:title] = title if title
        params[:target] = target if target
      end

      params
    end

    def ==(other)
      return false unless other.is_a?(Link)

      to_cms_api_linklist_params == other.to_cms_api_linklist_params
    end
  end
end