# frozen_string_literal: true

require 'tacview_client/base_processor'
require 'time'
require_relative 'datastore'

module TacScribe
  # Processes the events emitted by the Ruby Tacview Client
  class EventProcessor
    def initialize(datastore:, event_queue:)
      @datastore = datastore
      @event_queue = event_queue
    end

    def start
      loop do
        wrapped_event = @event_queue.events.shift
        process_event(wrapped_event)
      rescue StandardError => e
        puts wrapped_event
        puts e.inspect
        next
      end
    end

    def process_event(wrapped_event)
      case wrapped_event[:type]
      when :update_object
        update_object(wrapped_event[:event], wrapped_event[:time])
      when :delete_object
        delete_object(wrapped_event[:object_id])
      end
    end

    private

    # Process an update event for an object
    #
    # On the first appearance of the object there are usually more fields
    # including pilot names, object type etc.
    #
    # For existing objects these events are almost always lat/lon/alt updates
    # only
    #
    # @param event [Hash] A parsed ACMI line. This hash will always include
    #   the fields listed below but may also include others depending on the
    #   source line.
    # @option event [String] :object_id The hexadecimal format object ID.
    # @option event [BigDecimal] :latitude The object latitude in WGS 84 format.
    # @option event [BigDecimal] :longitude The object latitude in WGS 84
    #   format.
    # @option event [BigDecimal] :altitude The object altitude above sea level
    #   in meters to 1 decimal place.
    def update_object(event, time)
      if @event_queue.reference_latitude || @event_queue.reference_longitude
        localize_position(event)
      end

      @datastore.write_object(event, time)
    end

    # Process a delete event for an object
    #
    # @param object_id [String] A hexadecimal number representing the object
    #   ID
    def delete_object(object_id)
      @datastore.delete_object(object_id)
    end

    # If we have reference lat/long then use that as a base and update the event
    # position
    def localize_position(event)
      # There is no combination of layouts for these lines that doesn' trip
      # at least one rubocop cop so just ignore the guard clause. The best
      # one is using an inline if but that breaks the line length.
      # rubocop:disable Style/GuardClause
      if event[:latitude]
        event[:latitude] = @event_queue.reference_latitude + event[:latitude]
      end
      if event[:longitude]
        event[:longitude] = @event_queue.reference_longitude + event[:longitude]
      end
      # rubocop:enable Style/GuardClause
    end
  end
end