minesweeper.rb

class Board
  def self.transform(board)
    @rows = []
    explode_rows(board)
    validate_rows
    process_rows
    reform_rows
  end

  def self.validate_rows
    raise ValueError unless rows_the_same_length?
    raise ValueError unless characters_valid?
    raise ValueError unless valid_borders?
  end

  def self.valid_borders?
    return false unless @rows.first.first == "+"
    return false unless @rows.first.last == "+"
    return false unless @rows.last.first == "+"
    return false unless @rows.last.last == "+"
    return false unless @rows.first[1..-2].all? { |character| character == "-" }
    return false unless @rows.last[1..-2].all? { |character| character == "-" }
    return false unless @rows[1..-2].first.first == "|"
    return false unless @rows[1..-2].first.last == "|"
    return false unless @rows[1..-2].last.first == "|"
    return false unless @rows[1..-2].last.last == "|"
    return true
  end

  def self.characters_valid?
    @rows.flatten.all? {|character| %w(+ * | - \ ).include? character }
  end

  def self.rows_the_same_length?
    @rows.all? {|row| row.length == @rows[0].length }
  end

  def self.explode_rows(board)
    board.each do |row|
      row_array = row.chars
      @rows << row_array
    end
  end

  def self.process_rows
    @rows.each_with_index do |row, row_key|
      row.each_with_index do |character, character_key|
        unless %w(+ - | *).include?(character)
          self.set_character_value(character, row_key, character_key)
        end
      end
    end
  end

  def self.set_character_value(location, row_key, character_key)
    above = row_key - 1
    below = row_key + 1
    right = character_key + 1
    left  = character_key - 1
    total = 0

    total += 1 if @rows[above][character_key] == "*"
    total += 1 if @rows[above][left] == "*"
    total += 1 if @rows[above][right] == "*"
    total += 1 if @rows[row_key][left] == "*"
    total += 1 if @rows[row_key][right] == "*"
    total += 1 if @rows[row_key][character_key] == "*"
    total += 1 if @rows[below][character_key] == "*"
    total += 1 if @rows[below][left] == "*"
    total += 1 if @rows[below][right] == "*"

    if total >= 1
      @rows[row_key][character_key] = total
    end
  end

  def self.reform_rows
    @rows.map! {|row| row.join("") }
  end
end

class ValueError < StandardError
end