play_fair_matrix.rb

require_relative "Alphabet"

class PlayFairMatrix
  COLUMNS = 5
  attr_reader :matrix
  def initialize(options={})
    if options[:keyword]
      @matrix = build_matrix(keyword: options[:keyword])  
    else
      @matrix = build_matrix
    end
  end

  def char_from_index(options={})
    row = options[:row]
    column = options[:column]
    @matrix[row][column]
  end

  def chars_matrix_location(options={})
    char_array = options[:char_pair].split(//)
    char_location = { char1: {row: :p, index: 0, encrypted: '' }, char2:  {row: :p, index: 0, encrypted: '' }}
    @matrix.each do |key, val_array|
    index = 0
       val_array.each do |char|
	 if char_array[0] == char
           char_location[:char1][:row] = key
	   char_location[:char1][:index] = index 
	 end
	 if char_array[1] == char
           char_location[:char2][:row] = key
	   char_location[:char2][:index] = index 
	 end
	 index += 1
      end
    end
    char_location
  end
  
  def build_matrix(options = {})
   if options[:keyword]
             build_keyword_matrix(options[:keyword])
           else
              {A: ['P','L','A','Y','F'],
               B: ['R','I','E','X','M'],
               C: ['B','C','D','G','H'],
               D: ['K','N','O','Q','S'],
               E: ['T','U','V','W','Z']}
           end
  end

  def self.previous_row_symbol(options={})
    
    case options[:current_row]
    when :A
      :E
    when :B
      :A
    when :C
      :B
    when :D
      :C
    when :E
      :D
    end
  end
  def self.next_row_symbol(options={})
    
    case options[:current_row]
    when :A
      :B
    when :B
      :C
    when :C
      :D
    when :D
      :E
    when :E
      :A
    end
  end

  private

  def build_keyword_matrix(keyword)
    keys = keyword.upcase.gsub(/\s+/,"").split(//).uniq
    num_keys = keys.length
    current_index = 0

    alphabet = Alphabet.new(keyword: keyword)
    legal_letters = Alphabet.legal_letters
    matrix = {A: [], B: [], C: [], D: [], E: []}
    matrix.each do |key, row|
      for index in 0..COLUMNS - 1
        if current_index < num_keys
         matrix[key][index] = keys[current_index]
	  current_index += 1
	else
	  searching = true
          while searching
            legal_letters.each do |v_char|
              if alphabet.is_char_valid?(v_char)
                row[index] = v_char
		searching = false
                current_index += 1
		break
	      end
	    end
	  end
	end
      end
    end
    matrix
  end
end