require 'addressable/uri'

module Scrivito
  class LinkParser
    EDITING_CONTEXT_PARAMS = [
      '_scrivito_display_mode'.freeze,
      '_scrivito_workspace_id'.freeze,
    ].freeze

    EDITING_CONTEXT_AND_ENCRYPTED_PARAMS = (
      EDITING_CONTEXT_PARAMS + [
        'encrypted_params'.freeze
      ]
    ).freeze

    ENCRYPTED_PARAMS = 'encrypted_params'.freeze
    SCRIVITO_BINARY_REDIRECT = 'scrivito/binary_redirect'.freeze
    SCRIVITO_CMS_DISPATCH = 'scrivito/cms_dispatch'.freeze
    SCRIVITO_UI_PATH = 'scrivito/ui'.freeze

    def initialize(host, port)
      @host = host
      @port = port
    end

    def parse(url)
      uri = Addressable::URI.parse(url)

      return Link.new(url: url) unless application_uri?(uri)

      uri.path = remove_ui_path(uri)

      route_params = recognize_path(uri.to_s)

      if obj = find_obj_via_id_or_permalink(route_params)
        Link.new(
          obj: obj,
          query: remove_params(uri.query_values, EDITING_CONTEXT_PARAMS),
          fragment: uri.fragment,
        )
      elsif obj = find_obj_via_binary(route_params, uri)
        Link.new(
          obj: obj,
          query: remove_params(uri.query_values, EDITING_CONTEXT_AND_ENCRYPTED_PARAMS),
          fragment: uri.fragment,
        )
      else
        uri.path = '/' if uri.path.blank?
        uri.port = nil
        uri.host = nil
        uri.scheme = nil

        Link.new(url: uri.to_s)
      end
    rescue Addressable::URI::InvalidURIError
      Link.new(url: url)
    end

    private

    def remove_ui_path(uri)
      if (params = recognize_precedence_path(uri.to_s)) && params[:controller] == SCRIVITO_UI_PATH
        params[:application_path]
      else
        uri.path
      end
    end

    def application_uri?(uri)
      absolute_uri?(uri) && internal_uri?(uri) || relative_uri?(uri) && uri.path.present?
    end

    def absolute_uri?(uri)
      # Ruby's URI parser assumes URLs without a scheme as relative, while a browser assumes a
      # schemeless "//scrivito.com" as absolute. Since the URLs are for the browser, we cannot use
      # Ruby's URI here.
      # See issue https://github.com/sporkmonger/addressable/issues/147 for details.
      uri.to_s =~ /\A([a-z][a-z\d\-+\.]*:|\/\/).*/i
    end

    def relative_uri?(uri)
      !absolute_uri?(uri)
    end

    def internal_uri?(uri)
      if uri.port.present?
        uri.host == @host && uri.port == Integer(@port)
      else
        uri.host == @host
      end
    end

    def find_obj_via_id_or_permalink(route_params)
      return unless route_params[:controller] == SCRIVITO_CMS_DISPATCH

      if id = route_params[:id]
        Obj.find(id)
      elsif permalink = route_params[:permalink]
        Obj.find_by_permalink(permalink)
      end
    rescue Scrivito::ResourceNotFound
    end

    def find_obj_via_binary(route_params, uri)
      return unless route_params[:controller] == SCRIVITO_BINARY_REDIRECT

      encrypted_params = uri.query_values[ENCRYPTED_PARAMS]
      binary = BinaryParamVerifier.verify_without_expire(encrypted_params)
      Obj.find(binary.obj_id)
    rescue Scrivito::ResourceNotFound, Scrivito::BinaryParamVerifier::InvalidSignature
    end

    def recognize_path(url)
      recognize_precedence_path(url) || recognize_app_path(url) || {}
    end

    def recognize_precedence_path(url)
      Scrivito::SdkEngine.routes.recognize_path(url, method: :get)
    rescue ActionController::RoutingError
    end

    def recognize_app_path(url)
      Rails.application.routes.recognize_path(url, method: :get)
    rescue ActionController::RoutingError
    end

    def remove_params(query_values, params_to_remove)
      if query_values
        filtered_query_values = query_values.except!(*params_to_remove)
        uri = Addressable::URI.new(query_values: filtered_query_values)
        uri.query.presence
      end
    end
  end
end