# frozen_string_literal: true

require_relative './detector'

module Fusuma
  module Plugin
    module Detectors
      # Detect Hold gesture
      class HoldDetector < Detector
        SOURCES = %w[gesture timer].freeze
        BUFFER_TYPE = 'gesture'
        GESTURE_RECORD_TYPE = 'hold'

        BASE_THERESHOLD = 0.7

        # @param buffers [Array<Buffers::Buffer>]
        # @return [Events::Event] if event is detected
        # @return [Array<Events::Event>] if hold end event is detected
        # @return [NilClass] if event is NOT detected
        def detect(buffers)
          hold_buffer = find_hold_buffer(buffers)
          return if hold_buffer.empty?

          hold_events = hold_buffer.events

          timer_buffer = buffers.find { |b| b.type == 'timer' }
          timer_events = timer_buffer.events

          finger = hold_buffer.finger
          holding_time = calc_holding_time(hold_events: hold_events, timer_events: timer_events)

          @timeout ||= nil
          status = case hold_events.last.record.status
                   when 'begin'
                     if holding_time.zero?
                       'begin'
                     else
                       'timer'
                     end
                   when 'cancelled'
                     'cancelled'
                   when 'end'
                     'end'
                   else
                     last_record = hold_events.last.record.status
                     raise "Unexpected Status:#{last_record.status} in #{last_record}"
                   end

          repeat_index = create_repeat_index(finger: finger, status: status)
          oneshot_index = create_oneshot_index(finger: finger)

          @timeout = nil if status == 'begin'

          if status == 'timer'
            return if @timeout

            return unless enough?(index: oneshot_index, holding_time: holding_time)

            @timeout = holding_time
            return create_event(record: Events::Records::IndexRecord.new(
              index: oneshot_index, trigger: :oneshot
            ))
          end

          create_event(record: Events::Records::IndexRecord.new(
            index: repeat_index, trigger: :repeat
          ))
        end

        # @param [Integer] finger
        # @return [Config::Index]
        def create_oneshot_index(finger:)
          Config::Index.new(
            [
              Config::Index::Key.new(type),
              Config::Index::Key.new(finger.to_i)
            ]
          )
        end

        # @param [Integer] finger
        # @return [Config::Index]
        def create_repeat_index(finger:, status:)
          Config::Index.new(
            [
              Config::Index::Key.new(type),
              Config::Index::Key.new(finger.to_i),
              Config::Index::Key.new(status)
            ]
          )
        end

        private

        # @param buffers [Array<Buffers::Buffer>]
        # @return [Buffers::GestureBuffer]
        def find_hold_buffer(buffers)
          buffers.find { |b| b.type == BUFFER_TYPE }
                 .select_from_last_begin
                 .select_by_events { |e| e.record.gesture == GESTURE_RECORD_TYPE }
        end

        def calc_holding_time(hold_events:, timer_events:)
          last_time = if !timer_events.empty? && (hold_events.last.time < timer_events.last.time)
                        timer_events.last.time
                      else
                        hold_events.last.time
                      end
          last_time - hold_events.first.time
        end

        def enough?(index:, holding_time:)
          holding_time > threshold(index: index)
        end

        def threshold(index:)
          @threshold ||= {}
          @threshold[index.cache_key] ||= begin
            keys_specific = Config::Index.new [*index.keys, 'threshold']
            keys_global = Config::Index.new ['threshold', type]
            config_value = Config.search(keys_specific) ||
                           Config.search(keys_global) || 1
            BASE_THERESHOLD * config_value
          end
        end
      end
    end
  end
end