Sudoku...started

GAH!

class Sudoku
  def initialize(puzzle) # puzzle == String
    @puzzle = puzzle
    @cell = Cell.new(puzzle)
    @rows = Row.new(puzzle)
    @column = Column.new(puzzle)
    @three_by_three = ThreeByThree.new(puzzle)
  end
end

class Cell
  def initialize(puzzle)
    @puzzle = puzzle.index('0')
  end
end

class Row
  attr_accessor :row_num, :row, :index_of_row

  def initialize(puzzle, cell = '0')
    @row_num = puzzle.index(cell) / 9
    @row = puzzle[(0+(row_num*9)), 9].split('')
    @index_of_row = @row.index(cell) % 9
  end
end

class Column
  def initialize(puzzle, cell = '0')
    @col_num = puzzle.index(cell) % 9
    @col = @col_num.step(puzzle.size - 1, 9).map { |i| puzzle[i] }
    @index_of_col = @col.index(cell) % 9
  end
end

class ThreeByThree
  attr_accessor :grid
  def initialize(puzzle, cell = '0')
    @grid = []
  end

  def col_num(puzzle, cell)
    puzzle.index(cell) % 9
  end

  def row_num(puzzle, cell)
    puzzle.index(cell) / 9
  end

  def grid_pos(puzzle, cell)
    [row_num(puzzle, cell), col_num(puzzle, cell)] # Use 0 index for all locations of cell
  end

  # def find_grid(puzzle, cell)
  #   puzzle.split('').collect do |num_str|
  #     grid_pos(puzzle, num_str)
  #   end
  # end

  def grid_no(puzzle, cell)
    cell_index = puzzle.index(cell)

  end

  def subgrid_at(id)
    if id == 0
      id += 1
    end
    hash = {1 => 0, 2 => 3, 3 => 6, 4 => 27, 5 => 30, 6 => 33, 7 => 54, 8 => 57, 9 => 60}
    [hash[id],hash[id]+9,hash[id]+18].inject([]) do |array, offset|
      array + puzzle[offset..offset+2]
    end
  end

  def list_indexices(puzzle, cell)
    puzzle.split('').each_with_index do |num_str, index|
      puts index if num_str == cell
    end
  end
end

puzzle = '619030040270061008000047621486302079000014580031009060005720806320106057160400030'
cell = '0'
grid = ThreeByThree.new(puzzle, cell)
# p grid.find_grid(puzzle,cell)
# p grid.list_indexices(puzzle,cell)
# p grid.grid_pos(puzzle,cell)

def subgrid_at(id)
  if id == 0
    id += 1
  end
  hash = {1 => 0, 2 => 3, 3 => 6, 4 => 27, 5 => 30, 6 => 33, 7 => 54, 8 => 57, 9 => 60}
  [hash[id],hash[id]+9,hash[id]+18].inject([]) do |array, offset|
    array + puzzle[offset..offset+2]
  end
end