class AddFollowUnfollowedAt < ActiveRecord::Migration[5.2]
  # We need up/down migrations because `remove_index` doesn’t allow `unique: true` and can’t be properly rolled back.
  def up
    add_column :follows, :unfollowed_at, :datetime

    remove_index :follows, [:gestionnaire_id, :dossier_id]
    add_index :follows, [:gestionnaire_id, :dossier_id, :unfollowed_at], unique: true,
      name: :uniqueness_index # We need a custom name because the autogenerated name would be too long
  end

  def down
    remove_column :follows, :unfollowed_at
    # We don’t need to remove the index: dropping the column automatically deletes it.

    add_index :follows, [:gestionnaire_id, :dossier_id], unique: true
  end
end