pedrozath/coltrane

# frozen_string_literal: true

module Coltrane
  module Theory
    # It describes a sequence of intervals
    class IntervalSequence
      extend Forwardable
      attr_reader :intervals

      def_delegators :@intervals, :map, :each, :[], :size,
                     :reduce, :delete, :reject!, :delete_if, :detect, :to_a

      def initialize(*intervals, notes: nil, relative_intervals: nil)
        if intervals.any?
          @intervals = if intervals.first.is_a?(Interval)
                         intervals
                       else
                         intervals.map { |i| Interval[i] }
          end

        elsif notes
          notes = NoteSet[*notes] if notes.is_a?(Array)
          @intervals = intervals_from_notes(notes)
        elsif relative_intervals
          @relative_intervals = relative_intervals
          @intervals = intervals_from_relative_intervals(relative_intervals)
        else
          raise WrongKeywordsError,
                'Provide: [notes:] || [intervals:] || [relative_intervals:]'
        end
      end

      Interval.all_including_compound_and_altered.each do |interval|
        # Creates methods such as major_third, returning it if it finds
        define_method(interval.full_name.underscore.to_s) { find(interval) }
        # Creates methods such as has_major_third?, returning a boolean
        define_method("has_#{interval.full_name.underscore}?") { has?(interval) }
      end

      Interval.distances_names.map(&:underscore).each_with_index do |distance, i|
        # Creates methods such as has_third?, returning a boolean
        define_method("has_#{distance}?") { !!find_by_distance(i + 1) }
        # Creates methods such third, returning any third it finds
        define_method(distance.to_s) { find_by_distance(i + 1) }
        # Creates methods such third!, returning thirds that arent aug or dim
        define_method("#{distance}!") { find_by_distance(i + 1, false) }
      end

      instance_eval { alias [] new }

      def relative_intervals
        intervals_semitones[1..-1].each_with_index.map do |n, i|
          if i.zero?
            n
          elsif i < intervals_semitones.size
            n - intervals_semitones[i]
          end
        end + [12 - intervals_semitones.last]
      end

      def names
        intervals.map(&:name)
      end

      def find(interval)
        interval.clone if detect { |i| interval == i }
      end

      def has?(interval)
        !!find(interval)
      end

      def find_by_distance(n, accept_altered = true)
        strategy = (accept_altered ? :as : :as!)
        map { |interval| interval.send(strategy, n) }
          .compact
          .sort_by { |i| i.alteration.abs }
          .first
      end

      alias interval_names names

      def all
        intervals
      end

      def [](x)
        intervals[x]
      end

      def shift(amount)
        self.class.new(*intervals.map do |i|
          (i.semitones + amount) % 12
        end)
      end

      def zero_it
        shift(-intervals.first.semitones)
      end

      def inversion(index)
        self.class.new(*intervals.rotate(index)).zero_it
      end

      def next_inversion
        inversion(index + 1)
      end

      def previous_inversion
        inversion(index - 1)
      end

      def inversions
        Array.new(intervals.length) { |i| inversion(i) }
      end

      def intervals_semitones
        map(&:semitones)
      end

      def names
        map(&:name)
      end

      def full_names
        map(&:full_name)
      end

      def notes_for(root_note)
        NoteSet[
          *intervals.reduce([]) do |memo, interval|
            memo + [root_note + interval]
          end
        ]
      end

      def &(other)
        case other
        when Array then intervals & other
        when IntervalSequence then intervals & other.semitones
        end
      end

      private

      def intervals_from_relative_intervals(relative_intervals)
        relative_intervals[0..-2].reduce([Interval[0]]) do |memo, d|
          memo + [memo.last + d]
        end
      end

      def intervals_from_notes(notes)
        notes.map { |n| notes.root - n }.sort_by(&:semitones)
      end
    end
  end
end