gistfile1.rb

# This class represents a todo item and its associated
# data: name and description. There's also a "done"
# flag to show whether this todo item is done.

class Todo
  DONE_MARKER = 'X'
  UNDONE_MARKER = ' '

  attr_accessor :title, :description, :done

  def initialize(title, description='')
    @title = title
    @description = description
    @done = false
  end

  def done!
    self.done = true
  end

  def done?
    done
  end

  def undone!
    self.done = false
  end

  def to_s
    "[#{done? ? DONE_MARKER : UNDONE_MARKER}] #{title}"
  end
end

# This class represents a collection of Todo objects.
# You can perform typical collection-oriented actions
# on a TodoList object, including iteration and selection.

class TodoList
  attr_accessor :title

  def initialize(title)
    @title = title
    @todos = []
  end

  def add(todo)
    if todo.instance_of? Todo 
      @todos << todo
      return @todos
    else
      raise TypeError, 'can only add Todo objects'
    end
  end
  alias_method :<<, :add

  def size
    @todos.size
  end

  def first
    @todos.first
  end

  def last
    @todos.last
  end

  def shift
    @todos.shift
  end

  def pop
    @todos.pop
  end

  def item_at(key)
    @todos.fetch(key)
  end

  def mark_done_at(key)
    item_at(key).done!
  end

  def mark_undone_at(key)
    item_at(key).undone!
  end

  def done!
    @todos.each_index do |idx|
      mark_done_at(idx)
    end
  end

  def done?
    @todos.all? {|todo| todo.done?}
  end

  def remove_at(key)
    @todos.delete(item_at(key))
  end

  def to_s
    text = "#{title} \n"
    text << @todos.map(&:to_s).join("\n")
    text
  end

  def to_a
    @todos
  end

  def each
    @todos.each do |todo|
      yield(todo)
    end
    self
  end

  def select
    list = Todolist.new(title)
    each do |todo|
      list.add(todo) if yield(todo)
    end
    list
  end

  def find_by_title(str)
    select {|todo| todo.title == str}.first
  end

  def all_done
    select{|todo| todo.done?}
  end

  def all_not_done
    select{|todo| !todo.done?}
  end

  def mark_done(str)
    find_by_title(str) && find_by_title(str).done!
  end

  def mark_all_done
    each {|todo| todo.done!}
  end

  def mark_all_undone
    each {|todo| todo.undone!}
  end
end