defmodule User do
  use Web, :model

  use EctoStateMachine,
    states: [:unconfirmed, :confirmed, :blocked, :admin],
    events: [
      [
        name:     :confirm,
        from:     [:unconfirmed],
        to:       :confirmed,
        callback: fn(model) -> Ecto.Changeset.change(model, confirmed_at: Ecto.DateTime.utc) end # yeah you can bring your own code to these functions.
      ], [
        name:     :block,
        from:     [:confirmed, :admin],
        to:       :blocked
      ], [
        name:     :make_admin,
        from:     [:confirmed],
        to:       :admin
      ]
    ]

  schema "users" do
    field :state, :string, default: "unconfirmed"
  end
end

user = Repo.get_by(User, id: 1)

# Create changeset transition user state to "confirmed". We can make him admin!
confirmed_user = User.confirm(user)     # =>

# We can validate ability to change user's state
User.can_confirm?(confirmed_user)       # => false
User.can_make_admin?(confirmed_user)    # => true

# Create changeset transition user state to "admin"
admin = User.make_admin(confirmed_user)

# Store changeset to the database
Repo.update(admin)                      


# List all possible states
# If column isn't `:state`, function name will be prefixed. IE,
# for column `:rules` function name will be `rules_states`
User.states # => [:unconfirmed, :confirmed, :blocked, :admin]

# List all possible events
# If column isn't `:state`, function name will be prefixed. IE,
# for column `:rules` function name will be `rules_events`
User.events # => [:confirm, :block, :make_admin]

defmodule Dummy.User do
  use Dummy.Web, :model

  use EctoStateMachine,
    column: :rules,
    # bla-bla-bla
end