# frozen_string_literal: true

if ActiveObject.configuration.autoload_enumerable
  module Enumerable
    CRITICAL_ZSCORE ||= {
      3 => 1.15,
      4 => 1.48,
      5 => 1.71,
      6 => 1.89,
      7 => 2.02,
      8 => 2.13,
      9 => 2.21,
      10 => 2.29,
      11 => 2.34,
      12 => 2.41,
      13 => 2.46,
      14 => 2.51,
      15 => 2.55,
      16 => 2.59,
      17 => 2.62,
      18 => 2.65,
      19 => 2.68,
      20 => 2.71,
      21 => 2.73,
      22 => 2.76,
      23 => 2.78,
      24 => 2.80,
      25 => 2.82,
      26 => 2.84,
      27 => 2.86,
      28 => 2.88,
      29 => 2.89,
      30 => 2.91,
      31 => 2.92,
      32 => 2.94,
      33 => 2.95,
      34 => 2.97,
      35 => 2.98,
      36 => 2.99,
      37 => 3.00,
      38 => 3.01,
      39 => 3.03,
      40 => 3.04,
      50 => 3.13,
      60 => 3.20,
      70 => 3.26,
      80 => 3.31,
      90 => 3.35,
      100 => 3.38,
      110 => 3.42,
      120 => 3.44,
      130 => 3.47,
      140 => 3.49
    }.freeze

    # rubocop:disable Lint/UnusedMethodArgument
    def cluster(&block)
      result = []
      each do |ele|
        last_res = result.last
        last_res && (yield(ele) == yield(last_res.last)) ? last_res << ele : result << [ele]
      end
      result
    end
    # rubocop:enable Lint/UnusedMethodArgument

    def critical_zscore(identity = nil)
      collection_length = length
      result = nil

      CRITICAL_ZSCORE.keys.sort.each do |key|
        break if key > collection_length
        result = CRITICAL_ZSCORE[key]
      end

      result || identity
    end

    def difference(identity = 0, &block)
      if block_given?
        map(&block).difference(identity)
      else
        inject { |key, val| key - val } || identity
      end
    end

    def divisible(identity = 0, &block)
      if block_given?
        map(&block).divisible(identity)
      else
        inject { |key, val| key / val } || identity
      end
    end

    def drop_last(num)
      collection_length = to_a.length
      return self if num > collection_length
      self[0...(collection_length - num)]
    end

    def drop_last_if
      return(to_enum(:drop_last_if)) unless block_given?

      result = []
      dropping = true
      reverse_each do |val|
        result.unshift(val) unless dropping &&= yield(val)
      end
      result
    end

    def exactly?(num)
      found_count = 0
      if block_given?
        each { |*opt| found_count += 1 if yield(*opt) }
      else
        each { |opt| found_count += 1 if opt }
      end
      found_count > num ? false : num == found_count
    end

    def exclude?(object)
      !include?(object)
    end

    def expand
      map { |val| val.is_a?(Enumerable) ? val.expand : val }
    end

    def exponential(identity = 0, &block)
      if block_given?
        map(&block).exponential(identity)
      else
        inject { |key, val| key**val } || identity
      end
    end

    def frequencies
      each_with_object(::Hash.new(0)) { |key, hsh| hsh[key] += 1 }
    end

    # rubocop:disable Style/CaseEquality
    def incase?(object)
      any? { |val| object === val }
    end
    # rubocop:enable Style/CaseEquality

    # rubocop:disable Metrics/MethodLength
    def interpose(sep, &block)
      enum = Enumerator.new do |val|
        items = each

        loop do
          begin
            val << items.next
          rescue StopIteration
            break
          end

          begin
            items.peek
          rescue StopIteration
            break
          else
            val << sep
          end
        end
      end

      block ? enum.each(&block) : enum
    end
    # rubocop:enable Metrics/MethodLength

    def many?
      found_count = 0
      if block_given?
        any? do |val|
          found_count += 1 if yield val
          found_count > 1
        end
      else
        any? { (found_count += 1) > 1 }
      end
    end

    def mean(identity = 0)
      return identity if empty?

      collection_length = length
      sum.to_f / collection_length.to_f
    end

    alias_method :average, :mean

    def median(identity = 0)
      collection_length = length.to_f
      collection_sorted = sort

      return(identity) unless collection_length > 0.0

      half_collection = collection_length / 2.0
      sorted_collection = collection_sorted[half_collection]

      if (collection_length % 2).zero?
        (collection_sorted[half_collection - 1.0] + sorted_collection) / 2.0
      else
        sorted_collection
      end
    end

    # rubocop:disable Metrics/AbcSize
    def mode(identity = 0)
      return identity unless length.positive?

      frequency_distribution = each_with_object(::Hash.new(0)) { |val, hsh| hsh[val] += 1 }
      frequency_top_two = frequency_distribution.sort_by { |_, val| -val }.take(2)
      top_two_first = frequency_top_two.first

      return if frequency_top_two.length != 1 && top_two_first.last == frequency_top_two.last.last
      top_two_first.first
    end
    # rubocop:enable Metrics/AbcSize

    def multiple(identity = 0, &block)
      if block_given?
        map(&block).multiple(identity)
      else
        inject { |key, val| key * val } || identity
      end
    end

    # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
    def percentile(num, identity = 0)
      return identity unless length.positive?

      collection_sorted = sort
      rank = (num.to_f / 100) * (length + 1)

      if rank.fraction?
        truncated_rank = rank.truncate
        sample_one = collection_sorted[truncated_rank - 1]
        sample_two = collection_sorted[truncated_rank]

        (rank.fraction * (sample_two - sample_one)) + sample_one
      else
        collection_sorted[rank - 1]
      end
    end
    # rubocop:enable Metrics/AbcSize, Metrics/MethodLength

    def range(identity = 0)
      return identity unless length.positive?

      collection_sorted = sort
      collection_sorted.last - collection_sorted.first
    end

    def reject_outliers
      cz = critical_zscore
      reject { |value| zscore(value) > cz }
    end

    def reject_outliers!
      replace(reject_outliers)
    end

    def select_outliers
      cz = critical_zscore
      select { |value| zscore(value) > cz }
    end

    def several?
      found_count = 0
      if block_given?
        each { |*opt| found_count += 1 if yield(*opt) }
      else
        each { |opt| found_count += 1 if opt }
      end
      found_count > 1
    end

    def standard_deviation(identity = 0)
      return identity if length < 2

      ::Math.sqrt(variance)
    end

    def sum(identity = 0, &block)
      if block_given?
        map(&block).sum(identity)
      else
        inject { |sum, val| sum + val } || identity
      end
    end

    def take_last(num)
      collection_length = to_a.length

      return self if num > collection_length

      self[(collection_length - num)..-1]
    end

    def take_last_if
      return(to_enum(:take_last_if)) unless block_given?

      result = []
      reverse_each { |val| yield(val) ? result.unshift(val) : break }
      result
    end

    def variance(identity = 0)
      collection_length = length

      return identity if collection_length <= 1

      total = inject(0.0) { |sum, val| sum + (val - mean)**2.0 }
      total.to_f / (collection_length.to_f - 1.0)
    end

    def zscore(value)
      sd = standard_deviation
      return 0 if sd.zero?

      (mean - value).abs / sd
    end

  end
end