gistfile1.txt

# web/helpers/session.ex
defmodule MySercetApp.Session do
  alias MySercetApp.{Repo, User}

  def authenticate(%{"email" => email, "password" => password}) do
    user = Repo.get_by(User, email: String.downcase(email))

    case check_password(user, password) do
      true -> {:ok, user}
      _ -> :error
    end
  end


# web/models/user.ex

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

  @derive {Poison.Encoder, only: [:id, :username, :email]}

  schema "users" do
    field :username, :string, unique: true
    field :email, :string, unique: true
    field :encrypted_password, :string
    field :password, :string, virtual: true

    timestamps
  end

  @required_fields ~w(username email)
  @optional_fields ~w(encrypted_password)

  @doc """
  Creates a changeset based on the `model` and `params`.

  If no params are provided, an invalid changeset is returned
  with no validation performed.
  """
  def changeset(model, params \\ :empty) do
    model
    |> cast(params, @required_fields, @optional_fields)
    |> validate_format(:email, ~r/@/)
    |> validate_length(:password, min: 5)
    |> validate_confirmation(:password, message: "Password does not match")
    |> unique_constraint(:email, message: "Email already taken")
    |> unique_constraint(:username, message: "Username already taken")
    |> generate_encrypted_password
  end

  defp generate_encrypted_password(current_changeset) do
    case current_changeset do
      %Ecto.Changeset{valid?: true, changes: %{password: password}} ->
        put_change(current_changeset, :encrypted_password, Comeonin.Bcrypt.hashpwsalt(password))
      _ ->
        current_changeset
    end
  end
end

  defp check_password(user, password) do
    case user do
      nil -> Comeonin.Bcrypt.dummy_checkpw()
      _ -> Comeonin.Bcrypt.checkpw(password, user.encrypted_password)
    end
  end
end