require "active_support/core_ext/digest/uuid"

module Ahoy
  class Tracker
    UUID_NAMESPACE = "a82ae811-5011-45ab-a728-569df7499c5f"

    attr_reader :request, :controller

    def initialize(**options)
      @store = Ahoy::Store.new(options.merge(ahoy: self))
      @controller = options[:controller]
      @request = options[:request] || @controller.try(:request)
      @visit_token = options[:visit_token]
      @user = options[:user]
      @options = options
    end

    # can't use keyword arguments here
    def track(name, properties = {}, options = {})
      if exclude?
        debug "Event excluded"
      else
        data = {
          visit_token: visit_token,
          user_id: user.try(:id),
          name: name.to_s,
          properties: properties,
          time: trusted_time(options[:time]),
          event_id: options[:id] || generate_id
        }.select { |_, v| v }

        @store.track_event(data)
      end
      true
    rescue => e
      report_exception(e)
    end

    def track_visit(defer: false, started_at: nil)
      if exclude?
        debug "Visit excluded"
      else
        if defer
          set_cookie("ahoy_track", true, nil, false)
        else
          delete_cookie("ahoy_track")

          data = {
            visit_token: visit_token,
            visitor_token: visitor_token,
            user_id: user.try(:id),
            started_at: trusted_time(started_at),
          }.merge(visit_properties).select { |_, v| v }

          @store.track_visit(data)

          Ahoy::GeocodeV2Job.perform_later(visit_token, data[:ip]) if Ahoy.geocode && data[:ip]
        end
      end
      true
    rescue => e
      report_exception(e)
    end

    def geocode(data)
      data = {
        visit_token: visit_token
      }.merge(data).select { |_, v| v }

      @store.geocode(data)
      true
    rescue => e
      report_exception(e)
    end

    def authenticate(user)
      if exclude?
        debug "Authentication excluded"
      else
        @store.user = user

        data = {
          visit_token: visit_token,
          user_id: user.try(:id)
        }
        @store.authenticate(data)
      end
      true
    rescue => e
      report_exception(e)
    end

    def visit
      @visit ||= @store.visit
    end

    def visit_or_create
      @visit ||= @store.visit_or_create
    end

    def new_visit?
      Ahoy.cookies ? !existing_visit_token : visit.nil?
    end

    def new_visitor?
      !existing_visitor_token
    end

    def set_visit_cookie
      set_cookie("ahoy_visit", visit_token, Ahoy.visit_duration)
    end

    def set_visitor_cookie
      if new_visitor?
        set_cookie("ahoy_visitor", visitor_token, Ahoy.visitor_duration)
      end
    end

    def user
      @user ||= @store.user
    end

    def visit_properties
      @visit_properties ||= request ? Ahoy::VisitProperties.new(request, api: api?).generate : {}
    end

    def visit_token
      @visit_token ||= ensure_token(visit_token_helper)
    end
    alias_method :visit_id, :visit_token

    def visitor_token
      @visitor_token ||= ensure_token(visitor_token_helper)
    end
    alias_method :visitor_id, :visitor_token

    def reset
      reset_visit
      delete_cookie("ahoy_visitor")
    end

    def reset_visit
      delete_cookie("ahoy_visit")
      delete_cookie("ahoy_events")
      delete_cookie("ahoy_track")
    end

    protected

    def api?
      @options[:api]
    end

    # private, but used by API
    def missing_params?
      if Ahoy.cookies && api? && Ahoy.protect_from_forgery
        !(existing_visit_token && existing_visitor_token)
      else
        false
      end
    end

    def set_cookie(name, value, duration = nil, use_domain = true)
      # safety net
      return unless Ahoy.cookies && request

      cookie = Ahoy.cookie_options.merge(value: value)
      cookie[:expires] = duration.from_now if duration
      # prefer cookie_options[:domain] over cookie_domain
      cookie[:domain] ||= Ahoy.cookie_domain if Ahoy.cookie_domain
      cookie.delete(:domain) unless use_domain
      request.cookie_jar[name] = cookie
    end

    def delete_cookie(name)
      request.cookie_jar.delete(name) if request && request.cookie_jar[name]
    end

    def trusted_time(time = nil)
      if !time || (api? && !(1.minute.ago..Time.now).cover?(time))
        Time.current
      else
        time
      end
    end

    def exclude?
      unless defined?(@exclude)
        @exclude = @store.exclude?
      end
      @exclude
    end

    def report_exception(e)
      if defined?(ActionDispatch::RemoteIp::IpSpoofAttackError) && e.is_a?(ActionDispatch::RemoteIp::IpSpoofAttackError)
        debug "Tracking excluded due to IP spoofing"
      else
        raise e if !defined?(Rails) || Rails.env.development? || Rails.env.test?
        Safely.report_exception(e)
      end
    end

    def generate_id
      @store.generate_id
    end

    def visit_token_helper
      @visit_token_helper ||= begin
        token = existing_visit_token
        token ||= visit_anonymity_set unless Ahoy.cookies
        token ||= generate_id unless Ahoy.api_only
        token
      end
    end

    def visitor_token_helper
      @visitor_token_helper ||= begin
        token = existing_visitor_token
        token ||= visitor_anonymity_set unless Ahoy.cookies
        token ||= generate_id unless Ahoy.api_only
        token
      end
    end

    def existing_visit_token
      @existing_visit_token ||= begin
        token = visit_header
        token ||= visit_cookie if Ahoy.cookies && !(api? && Ahoy.protect_from_forgery)
        token ||= visit_param if api?
        token
      end
    end

    def existing_visitor_token
      @existing_visitor_token ||= begin
        token = visitor_header
        token ||= visitor_cookie if Ahoy.cookies && !(api? && Ahoy.protect_from_forgery)
        token ||= visitor_param if api?
        token
      end
    end

    def visit_anonymity_set
      @visit_anonymity_set ||= Digest::UUID.uuid_v5(UUID_NAMESPACE, ["visit", Ahoy.mask_ip(request.remote_ip), request.user_agent].join("/"))
    end

    def visitor_anonymity_set
      @visitor_anonymity_set ||= Digest::UUID.uuid_v5(UUID_NAMESPACE, ["visitor", Ahoy.mask_ip(request.remote_ip), request.user_agent].join("/"))
    end

    def visit_cookie
      @visit_cookie ||= request && request.cookies["ahoy_visit"]
    end

    def visitor_cookie
      @visitor_cookie ||= request && request.cookies["ahoy_visitor"]
    end

    def visit_header
      @visit_header ||= request && request.headers["Ahoy-Visit"]
    end

    def visitor_header
      @visitor_header ||= request && request.headers["Ahoy-Visitor"]
    end

    def visit_param
      @visit_param ||= request && request.params["visit_token"]
    end

    def visitor_param
      @visitor_param ||= request && request.params["visitor_token"]
    end

    def ensure_token(token)
      token = Ahoy::Utils.ensure_utf8(token)
      token.to_s.gsub(/[^a-z0-9\-]/i, "").first(64) if token
    end

    def debug(message)
      Ahoy.log message
    end
  end
end