Add the API Authentication.

CHANGELOG.org

@@ -49,3 +49,7 @@
     Update Links.create_one to use a function.
 ** 0.5.2 <2023-08-05 Sat>
     Add dependencies for API Authentication.
+** 0.6.0 <2023-08-05 Sat>
+    Add User model.
+** 0.7.0 <2023-08-05 Sat>
+    Add the API Authentication.

config/config.exs

@@ -47,6 +47,10 @@ config :logger, :console,
 # Use Jason for JSON parsing in Phoenix
 config :phoenix, :json_library, Jason
 
+config :link_shortener, LinkShortenerWeb.Auth.Guardian,
+  issuer: "link_shortener",
+  secret_key: System.get_env("SECRET_KEY_BASE")
+
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.
 import_config "#{config_env()}.exs"

lib/link_shortener/accounts/accounts.ex

@@ -0,0 +1,104 @@
+defmodule LinkShortener.Accounts do
+  @moduledoc """
+  The Accounts context.
+  """
+
+  import Ecto.Query, warn: false
+  alias LinkShortener.Repo
+
+  alias LinkShortener.Accounts.User
+
+  @doc """
+  Returns the list of users.
+
+  ## Examples
+
+      iex> list_users()
+      [%User{}, ...]
+
+  """
+  def list_users do
+    Repo.all(User)
+  end
+
+  @doc """
+  Gets a single user.
+
+  Raises `Ecto.NoResultsError` if the User does not exist.
+
+  ## Examples
+
+      iex> get_user!(123)
+      %User{}
+
+      iex> get_user!(456)
+      ** (Ecto.NoResultsError)
+
+  """
+  def get_user!(id), do: Repo.get!(User, id)
+
+  @doc """
+  Creates a user.
+
+  ## Examples
+
+      iex> create_user(%{field: value})
+      {:ok, %User{}}
+
+      iex> create_user(%{field: bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def create_user(attrs \\ %{}) do
+    %User{}
+    |> User.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  @doc """
+  Updates a user.
+
+  ## Examples
+
+      iex> update_user(user, %{field: new_value})
+      {:ok, %User{}}
+
+      iex> update_user(user, %{field: bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def update_user(%User{} = user, attrs) do
+    user
+    |> User.changeset(attrs)
+    |> Repo.update()
+  end
+
+  @doc """
+  Deletes a user.
+
+  ## Examples
+
+      iex> delete_user(user)
+      {:ok, %User{}}
+
+      iex> delete_user(user)
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def delete_user(%User{} = user) do
+    Repo.delete(user)
+  end
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for tracking user changes.
+
+  ## Examples
+
+      iex> change_user(user)
+      %Ecto.Changeset{data: %User{}}
+
+  """
+  def change_user(%User{} = user, attrs \\ %{}) do
+    User.changeset(user, attrs)
+  end
+end

lib/link_shortener/accounts/user.ex

@@ -0,0 +1,31 @@
+defmodule LinkShortener.Accounts.User do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  schema "users" do
+    field :email, :string
+    field :encrypted_password, :string
+    field :password, :string, virtual: true
+
+    timestamps()
+  end
+
+  @doc false
+  def changeset(user, attrs) do
+    user
+    |> cast(attrs, [:email, :password])
+    |> validate_required([:email, :password])
+    |> unique_constraint(:email)
+    |> put_hashed_password()
+  end
+
+  defp put_hashed_password(changeset) do
+    case changeset do
+      %Ecto.Changeset{valid?: true, changes: %{password: password}}
+        ->
+          put_change(changeset, :encrypted_password, Comeonin.Bcrypt.hashpwsalt(password))
+      _ ->
+          changeset
+    end
+  end
+end

lib/link_shortener_web/auth/guardian.ex

@@ -0,0 +1,16 @@
+defmodule LinkShortenerWeb.Auth.Guardian do
+  use Guardian, otp_app: :link_shortener
+
+  alias LinkShortener.Accounts
+
+  def subject_for_token(user, _claims) do
+    sub = to_string(user.id)
+    {:ok, sub}
+  end
+
+  def resource_from_claims(claims) do
+    id = claims["sub"]
+    resource = Accounts.get_user!(id)
+    {:ok,  resource}
+  end
+end

lib/link_shortener_web/controllers/api/v1/user_controller.ex

@@ -0,0 +1,26 @@
+defmodule LinkShortenerWeb.Api.V1.UserController do
+  use LinkShortenerWeb, :controller
+
+  alias LinkShortener.Accounts
+  alias LinkShortener.Accounts.User
+  alias LinkShortenerWeb.Auth.Guardian
+
+  action_fallback LinkShortenerWeb.FallbackController
+
+  def create(conn, %{"user" => user_params}) do
+    with {:ok, %User{} = user} <- Accounts.create_user(user_params),
+	 {:ok, token, _claims} <- Guardian.encode_and_sign(user) do
+      conn
+      |> put_status(:created)
+      |> render("user.json", %{user: user, token: token})
+    end
+  end
+
+  def signin(conn, %{"email" => email, "password" => password}) do
+    with {:ok, user, token} <- Guardian.authenticate(email, password) do
+      conn
+      |> put_status(:created)
+      |> render("user.json", %{user: user, token: token})
+    end
+  end
+end

lib/link_shortener_web/router.ex

@@ -27,6 +27,8 @@ defmodule LinkShortenerWeb.Router do
 
     scope "/v1", Api.V1, as: :v1 do
       resources "/links", LinkController
+      post "/users/signup", UserController, :create
+      post "/users/signin", UserController, :signin
     end
   end
 

lib/link_shortener_web/views/api/v1/user_view.ex

@@ -0,0 +1,12 @@
+defmodule LinkShortenerWeb.Api.V1.UserView do
+  use LinkShortenerWeb, :view
+
+  alias LinkShortenerWeb.Api.V1.UserView
+
+  def render("user.json", %{user: user, token: token}) do
+    %{
+      email: user.email,
+      token: token
+    }
+  end
+end

priv/repo/migrations/20230805173950_create_users.exs

@@ -0,0 +1,14 @@
+defmodule LinkShortener.Repo.Migrations.CreateUsers do
+  use Ecto.Migration
+
+  def change do
+    create table(:users) do
+      add :email, :string
+      add :encrypted_password, :string
+
+      timestamps()
+    end
+
+    create unique_index(:users, [:email])
+  end
+end