# frozen_string_literal: true

require 'georuby'
require 'sequel'
require 'sequel-postgis-georuby'
require 'singleton'
require 'concurrent-ruby'
require 'haversine'

module TacScribe
  # The in-memory cache that is updated by events in real-time before the data
  # is synced to the DB
  class Cache
    include Singleton
    include GeoRuby::SimpleFeatures

    @@cache = Concurrent::Hash.new

    attr_accessor :reference_latitude, :reference_longitude

    def data
      @@cache
    end

    def write_object(object)
      if reference_latitude != 0 || reference_longitude != 0
        localize_position(object)
      end

      id = object[:object_id]
      object[:id] = id

      cache_object = @@cache[id]

      object[:position] = set_position(object, cache_object)

      %i[object_id latitude longitude color country].each do |key|
        object.delete(key)
      end

      if object[:coalition]
        object[:coalition] = case object[:coalition]
                             when 'Allies'
                               0
                             when 'Enemies'
                               1
                             else
                               2
                             end
      end

      if cache_object
        object[:heading] = calculate_heading(cache_object, object)
        object[:speed] = calculate_speed(cache_object, object)
        cache_object.merge!(object)
      else
        object[:heading] = -1
        object[:speed] = 0
        cache_object = object
      end

      if !cache_object.key?(:altitude) || !cache_object[:altitude]
        cache_object[:altitude] = 0
      end
      if !cache_object.key?(:coalition) || !cache_object[:coalition]
        cache_object[:coalition] = 2
      end

      cache_object[:pilot] = nil unless cache_object.key?(:pilot)

      cache_object[:group] = nil unless cache_object.key?(:group)

      cache_object[:deleted] = false unless cache_object.key?(:deleted)

      cache_object[:updated_at] = Time.now

      @@cache[id] = cache_object
    end

    def delete_object(id)
      @@cache[id][:deleted] = true if @@cache[id]
    end

    def clear
      @@cache.clear
      self.reference_latitude = nil
      self.reference_longitude = nil
    end

    private

    def localize_position(object)
      if reference_latitude && object.key?(:latitude)
        object[:latitude] = reference_latitude + object[:latitude]
      end
      if reference_longitude && object.key?(:longitude)
        object[:longitude] = reference_longitude + object[:longitude]
      end
    end

    def set_position(object, cache_object)
      longitude = if object.key?(:longitude)
                    object[:longitude]
                  else
                    cache_object[:position].y
                  end

      latitude = if object.key?(:latitude)
                   object[:latitude]
                 else
                   cache_object[:position].x
                 end

      # This "Point" class is not lat/long aware which is why we are
      # flipping things up here because when it converts to SQL we need
      # the long to be first since that is what postgresql expects.
      Point.from_x_y(longitude, latitude)
    end

    def calculate_heading(cache_object, object)
      if cache_object[:position] == object[:position]
        return cache_object[:heading]
      end

      begin
        cache_object[:position].bearing_to(object[:position]).to_i
      rescue Math::DomainError => e
        puts 'Could not calculate heading: ' + e.message
        puts 'Old Position: ' + cache_object[:position].inspect
        puts 'New Position: ' + object[:position].inspect
      end
    end

    def calculate_speed(cache_object, object)
      time = object[:game_time] - cache_object[:game_time]

      start_point = cache_object[:position]
      end_point = object[:position]

      # Because of the above issues with Point and Lat/Lon
      # the values are reverse here :(
      distance = Haversine.distance(start_point.y, start_point.x,
                                    end_point.y, end_point.x).to_meters

      speed =  distance / time

      speed.to_i
    end
  end
end