Add users/authentication with phx.gen.auth

lib/outlook/accounts.ex

@@ -0,0 +1,353 @@
+defmodule Outlook.Accounts do
+  @moduledoc """
+  The Accounts context.
+  """
+
+  import Ecto.Query, warn: false
+  alias Outlook.Repo
+
+  alias Outlook.Accounts.{User, UserToken, UserNotifier}
+
+  ## Database getters
+
+  @doc """
+  Gets a user by email.
+
+  ## Examples
+
+      iex> get_user_by_email("foo@example.com")
+      %User{}
+
+      iex> get_user_by_email("unknown@example.com")
+      nil
+
+  """
+  def get_user_by_email(email) when is_binary(email) do
+    Repo.get_by(User, email: email)
+  end
+
+  @doc """
+  Gets a user by email and password.
+
+  ## Examples
+
+      iex> get_user_by_email_and_password("foo@example.com", "correct_password")
+      %User{}
+
+      iex> get_user_by_email_and_password("foo@example.com", "invalid_password")
+      nil
+
+  """
+  def get_user_by_email_and_password(email, password)
+      when is_binary(email) and is_binary(password) do
+    user = Repo.get_by(User, email: email)
+    if User.valid_password?(user, password), do: 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)
+
+  ## User registration
+
+  @doc """
+  Registers a user.
+
+  ## Examples
+
+      iex> register_user(%{field: value})
+      {:ok, %User{}}
+
+      iex> register_user(%{field: bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def register_user(attrs) do
+    %User{}
+    |> User.registration_changeset(attrs)
+    |> Repo.insert()
+  end
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for tracking user changes.
+
+  ## Examples
+
+      iex> change_user_registration(user)
+      %Ecto.Changeset{data: %User{}}
+
+  """
+  def change_user_registration(%User{} = user, attrs \\ %{}) do
+    User.registration_changeset(user, attrs, hash_password: false, validate_email: false)
+  end
+
+  ## Settings
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for changing the user email.
+
+  ## Examples
+
+      iex> change_user_email(user)
+      %Ecto.Changeset{data: %User{}}
+
+  """
+  def change_user_email(user, attrs \\ %{}) do
+    User.email_changeset(user, attrs, validate_email: false)
+  end
+
+  @doc """
+  Emulates that the email will change without actually changing
+  it in the database.
+
+  ## Examples
+
+      iex> apply_user_email(user, "valid password", %{email: ...})
+      {:ok, %User{}}
+
+      iex> apply_user_email(user, "invalid password", %{email: ...})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def apply_user_email(user, password, attrs) do
+    user
+    |> User.email_changeset(attrs)
+    |> User.validate_current_password(password)
+    |> Ecto.Changeset.apply_action(:update)
+  end
+
+  @doc """
+  Updates the user email using the given token.
+
+  If the token matches, the user email is updated and the token is deleted.
+  The confirmed_at date is also updated to the current time.
+  """
+  def update_user_email(user, token) do
+    context = "change:#{user.email}"
+
+    with {:ok, query} <- UserToken.verify_change_email_token_query(token, context),
+         %UserToken{sent_to: email} <- Repo.one(query),
+         {:ok, _} <- Repo.transaction(user_email_multi(user, email, context)) do
+      :ok
+    else
+      _ -> :error
+    end
+  end
+
+  defp user_email_multi(user, email, context) do
+    changeset =
+      user
+      |> User.email_changeset(%{email: email})
+      |> User.confirm_changeset()
+
+    Ecto.Multi.new()
+    |> Ecto.Multi.update(:user, changeset)
+    |> Ecto.Multi.delete_all(:tokens, UserToken.user_and_contexts_query(user, [context]))
+  end
+
+  @doc ~S"""
+  Delivers the update email instructions to the given user.
+
+  ## Examples
+
+      iex> deliver_user_update_email_instructions(user, current_email, &url(~p"/users/settings/confirm_email/#{&1})")
+      {:ok, %{to: ..., body: ...}}
+
+  """
+  def deliver_user_update_email_instructions(%User{} = user, current_email, update_email_url_fun)
+      when is_function(update_email_url_fun, 1) do
+    {encoded_token, user_token} = UserToken.build_email_token(user, "change:#{current_email}")
+
+    Repo.insert!(user_token)
+    UserNotifier.deliver_update_email_instructions(user, update_email_url_fun.(encoded_token))
+  end
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for changing the user password.
+
+  ## Examples
+
+      iex> change_user_password(user)
+      %Ecto.Changeset{data: %User{}}
+
+  """
+  def change_user_password(user, attrs \\ %{}) do
+    User.password_changeset(user, attrs, hash_password: false)
+  end
+
+  @doc """
+  Updates the user password.
+
+  ## Examples
+
+      iex> update_user_password(user, "valid password", %{password: ...})
+      {:ok, %User{}}
+
+      iex> update_user_password(user, "invalid password", %{password: ...})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def update_user_password(user, password, attrs) do
+    changeset =
+      user
+      |> User.password_changeset(attrs)
+      |> User.validate_current_password(password)
+
+    Ecto.Multi.new()
+    |> Ecto.Multi.update(:user, changeset)
+    |> Ecto.Multi.delete_all(:tokens, UserToken.user_and_contexts_query(user, :all))
+    |> Repo.transaction()
+    |> case do
+      {:ok, %{user: user}} -> {:ok, user}
+      {:error, :user, changeset, _} -> {:error, changeset}
+    end
+  end
+
+  ## Session
+
+  @doc """
+  Generates a session token.
+  """
+  def generate_user_session_token(user) do
+    {token, user_token} = UserToken.build_session_token(user)
+    Repo.insert!(user_token)
+    token
+  end
+
+  @doc """
+  Gets the user with the given signed token.
+  """
+  def get_user_by_session_token(token) do
+    {:ok, query} = UserToken.verify_session_token_query(token)
+    Repo.one(query)
+  end
+
+  @doc """
+  Deletes the signed token with the given context.
+  """
+  def delete_user_session_token(token) do
+    Repo.delete_all(UserToken.token_and_context_query(token, "session"))
+    :ok
+  end
+
+  ## Confirmation
+
+  @doc ~S"""
+  Delivers the confirmation email instructions to the given user.
+
+  ## Examples
+
+      iex> deliver_user_confirmation_instructions(user, &url(~p"/users/confirm/#{&1}"))
+      {:ok, %{to: ..., body: ...}}
+
+      iex> deliver_user_confirmation_instructions(confirmed_user, &url(~p"/users/confirm/#{&1}"))
+      {:error, :already_confirmed}
+
+  """
+  def deliver_user_confirmation_instructions(%User{} = user, confirmation_url_fun)
+      when is_function(confirmation_url_fun, 1) do
+    if user.confirmed_at do
+      {:error, :already_confirmed}
+    else
+      {encoded_token, user_token} = UserToken.build_email_token(user, "confirm")
+      Repo.insert!(user_token)
+      UserNotifier.deliver_confirmation_instructions(user, confirmation_url_fun.(encoded_token))
+    end
+  end
+
+  @doc """
+  Confirms a user by the given token.
+
+  If the token matches, the user account is marked as confirmed
+  and the token is deleted.
+  """
+  def confirm_user(token) do
+    with {:ok, query} <- UserToken.verify_email_token_query(token, "confirm"),
+         %User{} = user <- Repo.one(query),
+         {:ok, %{user: user}} <- Repo.transaction(confirm_user_multi(user)) do
+      {:ok, user}
+    else
+      _ -> :error
+    end
+  end
+
+  defp confirm_user_multi(user) do
+    Ecto.Multi.new()
+    |> Ecto.Multi.update(:user, User.confirm_changeset(user))
+    |> Ecto.Multi.delete_all(:tokens, UserToken.user_and_contexts_query(user, ["confirm"]))
+  end
+
+  ## Reset password
+
+  @doc ~S"""
+  Delivers the reset password email to the given user.
+
+  ## Examples
+
+      iex> deliver_user_reset_password_instructions(user, &url(~p"/users/reset_password/#{&1}"))
+      {:ok, %{to: ..., body: ...}}
+
+  """
+  def deliver_user_reset_password_instructions(%User{} = user, reset_password_url_fun)
+      when is_function(reset_password_url_fun, 1) do
+    {encoded_token, user_token} = UserToken.build_email_token(user, "reset_password")
+    Repo.insert!(user_token)
+    UserNotifier.deliver_reset_password_instructions(user, reset_password_url_fun.(encoded_token))
+  end
+
+  @doc """
+  Gets the user by reset password token.
+
+  ## Examples
+
+      iex> get_user_by_reset_password_token("validtoken")
+      %User{}
+
+      iex> get_user_by_reset_password_token("invalidtoken")
+      nil
+
+  """
+  def get_user_by_reset_password_token(token) do
+    with {:ok, query} <- UserToken.verify_email_token_query(token, "reset_password"),
+         %User{} = user <- Repo.one(query) do
+      user
+    else
+      _ -> nil
+    end
+  end
+
+  @doc """
+  Resets the user password.
+
+  ## Examples
+
+      iex> reset_user_password(user, %{password: "new long password", password_confirmation: "new long password"})
+      {:ok, %User{}}
+
+      iex> reset_user_password(user, %{password: "valid", password_confirmation: "not the same"})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def reset_user_password(user, attrs) do
+    Ecto.Multi.new()
+    |> Ecto.Multi.update(:user, User.password_changeset(user, attrs))
+    |> Ecto.Multi.delete_all(:tokens, UserToken.user_and_contexts_query(user, :all))
+    |> Repo.transaction()
+    |> case do
+      {:ok, %{user: user}} -> {:ok, user}
+      {:error, :user, changeset, _} -> {:error, changeset}
+    end
+  end
+end

lib/outlook/accounts/user.ex

@@ -0,0 +1,155 @@
+defmodule Outlook.Accounts.User do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  schema "users" do
+    field :email, :string
+    field :password, :string, virtual: true, redact: true
+    field :hashed_password, :string, redact: true
+    field :confirmed_at, :naive_datetime
+
+    timestamps()
+  end
+
+  @doc """
+  A user changeset for registration.
+
+  It is important to validate the length of both email and password.
+  Otherwise databases may truncate the email without warnings, which
+  could lead to unpredictable or insecure behaviour. Long passwords may
+  also be very expensive to hash for certain algorithms.
+
+  ## Options
+
+    * `:hash_password` - Hashes the password so it can be stored securely
+      in the database and ensures the password field is cleared to prevent
+      leaks in the logs. If password hashing is not needed and clearing the
+      password field is not desired (like when using this changeset for
+      validations on a LiveView form), this option can be set to `false`.
+      Defaults to `true`.
+
+    * `:validate_email` - Validates the uniqueness of the email, in case
+      you don't want to validate the uniqueness of the email (like when
+      using this changeset for validations on a LiveView form before
+      submitting the form), this option can be set to `false`.
+      Defaults to `true`.
+  """
+  def registration_changeset(user, attrs, opts \\ []) do
+    user
+    |> cast(attrs, [:email, :password])
+    |> validate_email(opts)
+    |> validate_password(opts)
+  end
+
+  defp validate_email(changeset, opts) do
+    changeset
+    |> validate_required([:email])
+    |> validate_format(:email, ~r/^[^\s]+@[^\s]+$/, message: "must have the @ sign and no spaces")
+    |> validate_length(:email, max: 160)
+    |> maybe_validate_unique_email(opts)
+  end
+
+  defp validate_password(changeset, opts) do
+    changeset
+    |> validate_required([:password])
+    |> validate_length(:password, min: 12, max: 72)
+    # |> validate_format(:password, ~r/[a-z]/, message: "at least one lower case character")
+    # |> validate_format(:password, ~r/[A-Z]/, message: "at least one upper case character")
+    # |> validate_format(:password, ~r/[!?@#$%^&*_0-9]/, message: "at least one digit or punctuation character")
+    |> maybe_hash_password(opts)
+  end
+
+  defp maybe_hash_password(changeset, opts) do
+    hash_password? = Keyword.get(opts, :hash_password, true)
+    password = get_change(changeset, :password)
+
+    if hash_password? && password && changeset.valid? do
+      changeset
+      # If using Bcrypt, then further validate it is at most 72 bytes long
+      |> validate_length(:password, max: 72, count: :bytes)
+      |> put_change(:hashed_password, Bcrypt.hash_pwd_salt(password))
+      |> delete_change(:password)
+    else
+      changeset
+    end
+  end
+
+  defp maybe_validate_unique_email(changeset, opts) do
+    if Keyword.get(opts, :validate_email, true) do
+      changeset
+      |> unsafe_validate_unique(:email, Outlook.Repo)
+      |> unique_constraint(:email)
+    else
+      changeset
+    end
+  end
+
+  @doc """
+  A user changeset for changing the email.
+
+  It requires the email to change otherwise an error is added.
+  """
+  def email_changeset(user, attrs, opts \\ []) do
+    user
+    |> cast(attrs, [:email])
+    |> validate_email(opts)
+    |> case do
+      %{changes: %{email: _}} = changeset -> changeset
+      %{} = changeset -> add_error(changeset, :email, "did not change")
+    end
+  end
+
+  @doc """
+  A user changeset for changing the password.
+
+  ## Options
+
+    * `:hash_password` - Hashes the password so it can be stored securely
+      in the database and ensures the password field is cleared to prevent
+      leaks in the logs. If password hashing is not needed and clearing the
+      password field is not desired (like when using this changeset for
+      validations on a LiveView form), this option can be set to `false`.
+      Defaults to `true`.
+  """
+  def password_changeset(user, attrs, opts \\ []) do
+    user
+    |> cast(attrs, [:password])
+    |> validate_confirmation(:password, message: "does not match password")
+    |> validate_password(opts)
+  end
+
+  @doc """
+  Confirms the account by setting `confirmed_at`.
+  """
+  def confirm_changeset(user) do
+    now = NaiveDateTime.utc_now() |> NaiveDateTime.truncate(:second)
+    change(user, confirmed_at: now)
+  end
+
+  @doc """
+  Verifies the password.
+
+  If there is no user or the user doesn't have a password, we call
+  `Bcrypt.no_user_verify/0` to avoid timing attacks.
+  """
+  def valid_password?(%Outlook.Accounts.User{hashed_password: hashed_password}, password)
+      when is_binary(hashed_password) and byte_size(password) > 0 do
+    Bcrypt.verify_pass(password, hashed_password)
+  end
+
+  def valid_password?(_, _) do
+    Bcrypt.no_user_verify()
+    false
+  end
+
+  @doc """
+  Validates the current password otherwise adds an error to the changeset.
+  """
+  def validate_current_password(changeset, password) do
+    if valid_password?(changeset.data, password) do
+      changeset
+    else
+      add_error(changeset, :current_password, "is not valid")
+    end
+  end
+end

lib/outlook/accounts/user_notifier.ex

@@ -0,0 +1,79 @@
+defmodule Outlook.Accounts.UserNotifier do
+  import Swoosh.Email
+
+  alias Outlook.Mailer
+
+  # Delivers the email using the application mailer.
+  defp deliver(recipient, subject, body) do
+    email =
+      new()
+      |> to(recipient)
+      |> from({"Outlook", "contact@example.com"})
+      |> subject(subject)
+      |> text_body(body)
+
+    with {:ok, _metadata} <- Mailer.deliver(email) do
+      {:ok, email}
+    end
+  end
+
+  @doc """
+  Deliver instructions to confirm account.
+  """
+  def deliver_confirmation_instructions(user, url) do
+    deliver(user.email, "Confirmation instructions", """
+
+    ==============================
+
+    Hi #{user.email},
+
+    You can confirm your account by visiting the URL below:
+
+    #{url}
+
+    If you didn't create an account with us, please ignore this.
+
+    ==============================
+    """)
+  end
+
+  @doc """
+  Deliver instructions to reset a user password.
+  """
+  def deliver_reset_password_instructions(user, url) do
+    deliver(user.email, "Reset password instructions", """
+
+    ==============================
+
+    Hi #{user.email},
+
+    You can reset your password by visiting the URL below:
+
+    #{url}
+
+    If you didn't request this change, please ignore this.
+
+    ==============================
+    """)
+  end
+
+  @doc """
+  Deliver instructions to update a user email.
+  """
+  def deliver_update_email_instructions(user, url) do
+    deliver(user.email, "Update email instructions", """
+
+    ==============================
+
+    Hi #{user.email},
+
+    You can change your email by visiting the URL below:
+
+    #{url}
+
+    If you didn't request this change, please ignore this.
+
+    ==============================
+    """)
+  end
+end

lib/outlook/accounts/user_token.ex

@@ -0,0 +1,179 @@
+defmodule Outlook.Accounts.UserToken do
+  use Ecto.Schema
+  import Ecto.Query
+  alias Outlook.Accounts.UserToken
+
+  @hash_algorithm :sha256
+  @rand_size 32
+
+  # It is very important to keep the reset password token expiry short,
+  # since someone with access to the email may take over the account.
+  @reset_password_validity_in_days 1
+  @confirm_validity_in_days 7
+  @change_email_validity_in_days 7
+  @session_validity_in_days 60
+
+  schema "users_tokens" do
+    field :token, :binary
+    field :context, :string
+    field :sent_to, :string
+    belongs_to :user, Outlook.Accounts.User
+
+    timestamps(updated_at: false)
+  end
+
+  @doc """
+  Generates a token that will be stored in a signed place,
+  such as session or cookie. As they are signed, those
+  tokens do not need to be hashed.
+
+  The reason why we store session tokens in the database, even
+  though Phoenix already provides a session cookie, is because
+  Phoenix' default session cookies are not persisted, they are
+  simply signed and potentially encrypted. This means they are
+  valid indefinitely, unless you change the signing/encryption
+  salt.
+
+  Therefore, storing them allows individual user
+  sessions to be expired. The token system can also be extended
+  to store additional data, such as the device used for logging in.
+  You could then use this information to display all valid sessions
+  and devices in the UI and allow users to explicitly expire any
+  session they deem invalid.
+  """
+  def build_session_token(user) do
+    token = :crypto.strong_rand_bytes(@rand_size)
+    {token, %UserToken{token: token, context: "session", user_id: user.id}}
+  end
+
+  @doc """
+  Checks if the token is valid and returns its underlying lookup query.
+
+  The query returns the user found by the token, if any.
+
+  The token is valid if it matches the value in the database and it has
+  not expired (after @session_validity_in_days).
+  """
+  def verify_session_token_query(token) do
+    query =
+      from token in token_and_context_query(token, "session"),
+        join: user in assoc(token, :user),
+        where: token.inserted_at > ago(@session_validity_in_days, "day"),
+        select: user
+
+    {:ok, query}
+  end
+
+  @doc """
+  Builds a token and its hash to be delivered to the user's email.
+
+  The non-hashed token is sent to the user email while the
+  hashed part is stored in the database. The original token cannot be reconstructed,
+  which means anyone with read-only access to the database cannot directly use
+  the token in the application to gain access. Furthermore, if the user changes
+  their email in the system, the tokens sent to the previous email are no longer
+  valid.
+
+  Users can easily adapt the existing code to provide other types of delivery methods,
+  for example, by phone numbers.
+  """
+  def build_email_token(user, context) do
+    build_hashed_token(user, context, user.email)
+  end
+
+  defp build_hashed_token(user, context, sent_to) do
+    token = :crypto.strong_rand_bytes(@rand_size)
+    hashed_token = :crypto.hash(@hash_algorithm, token)
+
+    {Base.url_encode64(token, padding: false),
+     %UserToken{
+       token: hashed_token,
+       context: context,
+       sent_to: sent_to,
+       user_id: user.id
+     }}
+  end
+
+  @doc """
+  Checks if the token is valid and returns its underlying lookup query.
+
+  The query returns the user found by the token, if any.
+
+  The given token is valid if it matches its hashed counterpart in the
+  database and the user email has not changed. This function also checks
+  if the token is being used within a certain period, depending on the
+  context. The default contexts supported by this function are either
+  "confirm", for account confirmation emails, and "reset_password",
+  for resetting the password. For verifying requests to change the email,
+  see `verify_change_email_token_query/2`.
+  """
+  def verify_email_token_query(token, context) do
+    case Base.url_decode64(token, padding: false) do
+      {:ok, decoded_token} ->
+        hashed_token = :crypto.hash(@hash_algorithm, decoded_token)
+        days = days_for_context(context)
+
+        query =
+          from token in token_and_context_query(hashed_token, context),
+            join: user in assoc(token, :user),
+            where: token.inserted_at > ago(^days, "day") and token.sent_to == user.email,
+            select: user
+
+        {:ok, query}
+
+      :error ->
+        :error
+    end
+  end
+
+  defp days_for_context("confirm"), do: @confirm_validity_in_days
+  defp days_for_context("reset_password"), do: @reset_password_validity_in_days
+
+  @doc """
+  Checks if the token is valid and returns its underlying lookup query.
+
+  The query returns the user found by the token, if any.
+
+  This is used to validate requests to change the user
+  email. It is different from `verify_email_token_query/2` precisely because
+  `verify_email_token_query/2` validates the email has not changed, which is
+  the starting point by this function.
+
+  The given token is valid if it matches its hashed counterpart in the
+  database and if it has not expired (after @change_email_validity_in_days).
+  The context must always start with "change:".
+  """
+  def verify_change_email_token_query(token, "change:" <> _ = context) do
+    case Base.url_decode64(token, padding: false) do
+      {:ok, decoded_token} ->
+        hashed_token = :crypto.hash(@hash_algorithm, decoded_token)
+
+        query =
+          from token in token_and_context_query(hashed_token, context),
+            where: token.inserted_at > ago(@change_email_validity_in_days, "day")
+
+        {:ok, query}
+
+      :error ->
+        :error
+    end
+  end
+
+  @doc """
+  Returns the token struct for the given token value and context.
+  """
+  def token_and_context_query(token, context) do
+    from UserToken, where: [token: ^token, context: ^context]
+  end
+
+  @doc """
+  Gets all tokens for the given user for the given contexts.
+  """
+  def user_and_contexts_query(user, :all) do
+    from t in UserToken, where: t.user_id == ^user.id
+  end
+
+  def user_and_contexts_query(user, [_ | _] = contexts) do
+    from t in UserToken, where: t.user_id == ^user.id and t.context in ^contexts
+  end
+end

lib/outlook_web/components/layouts/root.html.heex

@@ -12,6 +12,26 @@
     </script>
   </head>
   <body class="bg-white antialiased">
+    <ul>
+      <%= if @current_user do %>
+        <li>
+          <%= @current_user.email %>
+        </li>
+        <li>
+          <.link href={~p"/users/settings"}>Settings</.link>
+        </li>
+        <li>
+          <.link href={~p"/users/log_out"} method="delete">Log out</.link>
+        </li>
+      <% else %>
+        <li>
+          <.link href={~p"/users/register"}>Register</.link>
+        </li>
+        <li>
+          <.link href={~p"/users/log_in"}>Log in</.link>
+        </li>
+      <% end %>
+    </ul>
     <%= @inner_content %>
   </body>
 </html>

lib/outlook_web/controllers/user_session_controller.ex

@@ -0,0 +1,42 @@
+defmodule OutlookWeb.UserSessionController do
+  use OutlookWeb, :controller
+
+  alias Outlook.Accounts
+  alias OutlookWeb.UserAuth
+
+  def create(conn, %{"_action" => "registered"} = params) do
+    create(conn, params, "Account created successfully!")
+  end
+
+  def create(conn, %{"_action" => "password_updated"} = params) do
+    conn
+    |> put_session(:user_return_to, ~p"/users/settings")
+    |> create(params, "Password updated successfully!")
+  end
+
+  def create(conn, params) do
+    create(conn, params, "Welcome back!")
+  end
+
+  defp create(conn, %{"user" => user_params}, info) do
+    %{"email" => email, "password" => password} = user_params
+
+    if user = Accounts.get_user_by_email_and_password(email, password) do
+      conn
+      |> put_flash(:info, info)
+      |> UserAuth.log_in_user(user, user_params)
+    else
+      # In order to prevent user enumeration attacks, don't disclose whether the email is registered.
+      conn
+      |> put_flash(:error, "Invalid email or password")
+      |> put_flash(:email, String.slice(email, 0, 160))
+      |> redirect(to: ~p"/users/log_in")
+    end
+  end
+
+  def delete(conn, _params) do
+    conn
+    |> put_flash(:info, "Logged out successfully.")
+    |> UserAuth.log_out_user()
+  end
+end

lib/outlook_web/live/user_confirmation_instructions_live.ex

@@ -0,0 +1,45 @@
+defmodule OutlookWeb.UserConfirmationInstructionsLive do
+  use OutlookWeb, :live_view
+
+  alias Outlook.Accounts
+
+  def render(assigns) do
+    ~H"""
+    <.header>Resend confirmation instructions</.header>
+
+    <.simple_form :let={f} for={:user} id="resend_confirmation_form" phx-submit="send_instructions">
+      <.input field={{f, :email}} type="email" label="Email" required />
+      <:actions>
+        <.button phx-disable-with="Sending...">Resend confirmation instructions</.button>
+      </:actions>
+    </.simple_form>
+
+    <p>
+      <.link href={~p"/users/register"}>Register</.link>
+      |
+      <.link href={~p"/users/log_in"}>Log in</.link>
+    </p>
+    """
+  end
+
+  def mount(_params, _session, socket) do
+    {:ok, socket}
+  end
+
+  def handle_event("send_instructions", %{"user" => %{"email" => email}}, socket) do
+    if user = Accounts.get_user_by_email(email) do
+      Accounts.deliver_user_confirmation_instructions(
+        user,
+        &url(~p"/users/confirm/#{&1}")
+      )
+    end
+
+    info =
+      "If your email is in our system and it has not been confirmed yet, you will receive an email with instructions shortly."
+
+    {:noreply,
+     socket
+     |> put_flash(:info, info)
+     |> redirect(to: ~p"/")}
+  end
+end

lib/outlook_web/live/user_confirmation_live.ex

@@ -0,0 +1,56 @@
+defmodule OutlookWeb.UserConfirmationLive do
+  use OutlookWeb, :live_view
+
+  alias Outlook.Accounts
+
+  def render(%{live_action: :edit} = assigns) do
+    ~H"""
+    <.header>Confirm Account</.header>
+
+    <.simple_form :let={f} for={:user} id="confirmation_form" phx-submit="confirm_account">
+      <.input field={{f, :token}} type="hidden" value={@token} />
+      <:actions>
+        <.button phx-disable-with="Confirming...">Confirm my account</.button>
+      </:actions>
+    </.simple_form>
+
+    <p>
+      <.link href={~p"/users/register"}>Register</.link>
+      |
+      <.link href={~p"/users/log_in"}>Log in</.link>
+    </p>
+    """
+  end
+
+  def mount(params, _session, socket) do
+    {:ok, assign(socket, token: params["token"]), temporary_assigns: [token: nil]}
+  end
+
+  # Do not log in the user after confirmation to avoid a
+  # leaked token giving the user access to the account.
+  def handle_event("confirm_account", %{"user" => %{"token" => token}}, socket) do
+    case Accounts.confirm_user(token) do
+      {:ok, _} ->
+        {:noreply,
+         socket
+         |> put_flash(:info, "User confirmed successfully.")
+         |> redirect(to: ~p"/")}
+
+      :error ->
+        # If there is a current user and the account was already confirmed,
+        # then odds are that the confirmation link was already visited, either
+        # by some automation or by the user themselves, so we redirect without
+        # a warning message.
+        case socket.assigns do
+          %{current_user: %{confirmed_at: confirmed_at}} when not is_nil(confirmed_at) ->
+            {:noreply, redirect(socket, to: ~p"/")}
+
+          %{} ->
+            {:noreply,
+             socket
+             |> put_flash(:error, "User confirmation link is invalid or it has expired.")
+             |> redirect(to: ~p"/")}
+        end
+    end
+  end
+end

lib/outlook_web/live/user_forgot_password_live.ex

@@ -0,0 +1,46 @@
+defmodule OutlookWeb.UserForgotPasswordLive do
+  use OutlookWeb, :live_view
+
+  alias Outlook.Accounts
+
+  def render(assigns) do
+    ~H"""
+    <div class="mx-auto max-w-sm">
+      <.header class="text-center">
+        Forgot your password?
+        <:subtitle>We'll send a password reset link to your inbox</:subtitle>
+      </.header>
+
+      <.simple_form :let={f} id="reset_password_form" for={:user} phx-submit="send_email">
+        <.input field={{f, :email}} type="email" placeholder="Email" required />
+        <:actions>
+          <.button phx-disable-with="Sending..." class="w-full">
+            Send password reset instructions
+          </.button>
+        </:actions>
+      </.simple_form>
+    </div>
+    """
+  end
+
+  def mount(_params, _session, socket) do
+    {:ok, socket}
+  end
+
+  def handle_event("send_email", %{"user" => %{"email" => email}}, socket) do
+    if user = Accounts.get_user_by_email(email) do
+      Accounts.deliver_user_reset_password_instructions(
+        user,
+        &url(~p"/users/reset_password/#{&1}")
+      )
+    end
+
+    info =
+      "If your email is in our system, you will receive instructions to reset your password shortly."
+
+    {:noreply,
+     socket
+     |> put_flash(:info, info)
+     |> redirect(to: ~p"/")}
+  end
+end

lib/outlook_web/live/user_login_live.ex

@@ -0,0 +1,49 @@
+defmodule OutlookWeb.UserLoginLive do
+  use OutlookWeb, :live_view
+
+  def render(assigns) do
+    ~H"""
+    <div class="mx-auto max-w-sm">
+      <.header class="text-center">
+        Sign in to account
+        <:subtitle>
+          Don't have an account?
+          <.link navigate={~p"/users/register"} class="font-semibold text-brand hover:underline">
+            Sign up
+          </.link>
+          for an account now.
+        </:subtitle>
+      </.header>
+
+      <.simple_form
+        :let={f}
+        id="login_form"
+        for={:user}
+        action={~p"/users/log_in"}
+        as={:user}
+        phx-update="ignore"
+      >
+        <.input field={{f, :email}} type="email" label="Email" required />
+        <.input field={{f, :password}} type="password" label="Password" required />
+
+        <:actions :let={f}>
+          <.input field={{f, :remember_me}} type="checkbox" label="Keep me logged in" />
+          <.link href={~p"/users/reset_password"} class="text-sm font-semibold">
+            Forgot your password?
+          </.link>
+        </:actions>
+        <:actions>
+          <.button phx-disable-with="Sigining in..." class="w-full">
+            Sign in <span aria-hidden="true">→</span>
+          </.button>
+        </:actions>
+      </.simple_form>
+    </div>
+    """
+  end
+
+  def mount(_params, _session, socket) do
+    email = live_flash(socket.assigns.flash, :email)
+    {:ok, assign(socket, email: email), temporary_assigns: [email: nil]}
+  end
+end

lib/outlook_web/live/user_registration_live.ex

@@ -0,0 +1,74 @@
+defmodule OutlookWeb.UserRegistrationLive do
+  use OutlookWeb, :live_view
+
+  alias Outlook.Accounts
+  alias Outlook.Accounts.User
+
+  def render(assigns) do
+    ~H"""
+    <div class="mx-auto max-w-sm">
+      <.header class="text-center">
+        Register for an account
+        <:subtitle>
+          Already registered?
+          <.link navigate={~p"/users/log_in"} class="font-semibold text-brand hover:underline">
+            Sign in
+          </.link>
+          to your account now.
+        </:subtitle>
+      </.header>
+
+      <.simple_form
+        :let={f}
+        id="registration_form"
+        for={@changeset}
+        phx-submit="save"
+        phx-change="validate"
+        phx-trigger-action={@trigger_submit}
+        action={~p"/users/log_in?_action=registered"}
+        method="post"
+        as={:user}
+      >
+        <.error :if={@changeset.action == :insert}>
+          Oops, something went wrong! Please check the errors below.
+        </.error>
+
+        <.input field={{f, :email}} type="email" label="Email" required />
+        <.input field={{f, :password}} type="password" label="Password" required />
+
+        <:actions>
+          <.button phx-disable-with="Creating account..." class="w-full">Create an account</.button>
+        </:actions>
+      </.simple_form>
+    </div>
+    """
+  end
+
+  def mount(_params, _session, socket) do
+    changeset = Accounts.change_user_registration(%User{})
+    socket = assign(socket, changeset: changeset, trigger_submit: false)
+    {:ok, socket, temporary_assigns: [changeset: nil]}
+  end
+
+  def handle_event("save", %{"user" => user_params}, socket) do
+    case Accounts.register_user(user_params) do
+      {:ok, user} ->
+        {:ok, _} =
+          Accounts.deliver_user_confirmation_instructions(
+            user,
+            &url(~p"/users/confirm/#{&1}")
+          )
+
+        changeset = Accounts.change_user_registration(user)
+        {:noreply, assign(socket, trigger_submit: true, changeset: changeset)}
+
+      {:error, %Ecto.Changeset{} = changeset} ->
+        {:noreply, assign(socket, :changeset, changeset)}
+    end
+  end
+
+  def handle_event("validate", %{"user" => user_params}, socket) do
+    changeset = Accounts.change_user_registration(%User{}, user_params)
+    {:noreply, assign(socket, changeset: Map.put(changeset, :action, :validate))}
+  end
+end

lib/outlook_web/live/user_reset_password_live.ex

@@ -0,0 +1,85 @@
+defmodule OutlookWeb.UserResetPasswordLive do
+  use OutlookWeb, :live_view
+
+  alias Outlook.Accounts
+
+  def render(assigns) do
+    ~H"""
+    <.header>Reset Password</.header>
+
+    <.simple_form
+      :let={f}
+      for={@changeset}
+      id="reset_password_form"
+      phx-submit="reset_password"
+      phx-change="validate"
+    >
+      <.error :if={@changeset.action == :insert}>
+        Oops, something went wrong! Please check the errors below.
+      </.error>
+
+      <.input field={{f, :password}} type="password" label="New password" required />
+      <.input
+        field={{f, :password_confirmation}}
+        type="password"
+        label="Confirm new password"
+        required
+      />
+      <:actions>
+        <.button phx-disable-with="Resetting...">Reset Password</.button>
+      </:actions>
+    </.simple_form>
+
+    <p>
+      <.link href={~p"/users/register"}>Register</.link>
+      |
+      <.link href={~p"/users/log_in"}>Log in</.link>
+    </p>
+    """
+  end
+
+  def mount(params, _session, socket) do
+    socket = assign_user_and_token(socket, params)
+
+    socket =
+      case socket.assigns do
+        %{user: user} ->
+          assign(socket, :changeset, Accounts.change_user_password(user))
+
+        _ ->
+          socket
+      end
+
+    {:ok, socket, temporary_assigns: [changeset: nil]}
+  end
+
+  # Do not log in the user after reset password to avoid a
+  # leaked token giving the user access to the account.
+  def handle_event("reset_password", %{"user" => user_params}, socket) do
+    case Accounts.reset_user_password(socket.assigns.user, user_params) do
+      {:ok, _} ->
+        {:noreply,
+         socket
+         |> put_flash(:info, "Password reset successfully.")
+         |> redirect(to: ~p"/users/log_in")}
+
+      {:error, changeset} ->
+        {:noreply, assign(socket, :changeset, Map.put(changeset, :action, :insert))}
+    end
+  end
+
+  def handle_event("validate", %{"user" => user_params}, socket) do
+    changeset = Accounts.change_user_password(socket.assigns.user, user_params)
+    {:noreply, assign(socket, changeset: Map.put(changeset, :action, :validate))}
+  end
+
+  defp assign_user_and_token(socket, %{"token" => token}) do
+    if user = Accounts.get_user_by_reset_password_token(token) do
+      assign(socket, user: user, token: token)
+    else
+      socket
+      |> put_flash(:error, "Reset password link is invalid or it has expired.")
+      |> redirect(to: ~p"/")
+    end
+  end
+end

lib/outlook_web/live/user_settings_live.ex

@@ -0,0 +1,161 @@
+defmodule OutlookWeb.UserSettingsLive do
+  use OutlookWeb, :live_view
+
+  alias Outlook.Accounts
+
+  def render(assigns) do
+    ~H"""
+    <.header>Change Email</.header>
+
+    <.simple_form
+      :let={f}
+      id="email_form"
+      for={@email_changeset}
+      phx-submit="update_email"
+      phx-change="validate_email"
+    >
+      <.error :if={@email_changeset.action == :insert}>
+        Oops, something went wrong! Please check the errors below.
+      </.error>
+
+      <.input field={{f, :email}} type="email" label="Email" required />
+
+      <.input
+        field={{f, :current_password}}
+        name="current_password"
+        id="current_password_for_email"
+        type="password"
+        label="Current password"
+        value={@email_form_current_password}
+        required
+      />
+      <:actions>
+        <.button phx-disable-with="Changing...">Change Email</.button>
+      </:actions>
+    </.simple_form>
+
+    <.header>Change Password</.header>
+
+    <.simple_form
+      :let={f}
+      id="password_form"
+      for={@password_changeset}
+      action={~p"/users/log_in?_action=password_updated"}
+      method="post"
+      phx-change="validate_password"
+      phx-submit="update_password"
+      phx-trigger-action={@trigger_submit}
+    >
+      <.error :if={@password_changeset.action == :insert}>
+        Oops, something went wrong! Please check the errors below.
+      </.error>
+
+      <.input field={{f, :email}} type="hidden" value={@current_email} />
+
+      <.input field={{f, :password}} type="password" label="New password" required />
+      <.input field={{f, :password_confirmation}} type="password" label="Confirm new password" />
+      <.input
+        field={{f, :current_password}}
+        name="current_password"
+        type="password"
+        label="Current password"
+        id="current_password_for_password"
+        value={@current_password}
+        required
+      />
+      <:actions>
+        <.button phx-disable-with="Changing...">Change Password</.button>
+      </:actions>
+    </.simple_form>
+    """
+  end
+
+  def mount(%{"token" => token}, _session, socket) do
+    socket =
+      case Accounts.update_user_email(socket.assigns.current_user, token) do
+        :ok ->
+          put_flash(socket, :info, "Email changed successfully.")
+
+        :error ->
+          put_flash(socket, :error, "Email change link is invalid or it has expired.")
+      end
+
+    {:ok, push_navigate(socket, to: ~p"/users/settings")}
+  end
+
+  def mount(_params, _session, socket) do
+    user = socket.assigns.current_user
+
+    socket =
+      socket
+      |> assign(:current_password, nil)
+      |> assign(:email_form_current_password, nil)
+      |> assign(:current_email, user.email)
+      |> assign(:email_changeset, Accounts.change_user_email(user))
+      |> assign(:password_changeset, Accounts.change_user_password(user))
+      |> assign(:trigger_submit, false)
+
+    {:ok, socket}
+  end
+
+  def handle_event("validate_email", params, socket) do
+    %{"current_password" => password, "user" => user_params} = params
+    email_changeset = Accounts.change_user_email(socket.assigns.current_user, user_params)
+
+    socket =
+      assign(socket,
+        email_changeset: Map.put(email_changeset, :action, :validate),
+        email_form_current_password: password
+      )
+
+    {:noreply, socket}
+  end
+
+  def handle_event("update_email", params, socket) do
+    %{"current_password" => password, "user" => user_params} = params
+    user = socket.assigns.current_user
+
+    case Accounts.apply_user_email(user, password, user_params) do
+      {:ok, applied_user} ->
+        Accounts.deliver_user_update_email_instructions(
+          applied_user,
+          user.email,
+          &url(~p"/users/settings/confirm_email/#{&1}")
+        )
+
+        info = "A link to confirm your email change has been sent to the new address."
+        {:noreply, put_flash(socket, :info, info)}
+
+      {:error, changeset} ->
+        {:noreply, assign(socket, :email_changeset, Map.put(changeset, :action, :insert))}
+    end
+  end
+
+  def handle_event("validate_password", params, socket) do
+    %{"current_password" => password, "user" => user_params} = params
+    password_changeset = Accounts.change_user_password(socket.assigns.current_user, user_params)
+
+    {:noreply,
+     socket
+     |> assign(:password_changeset, Map.put(password_changeset, :action, :validate))
+     |> assign(:current_password, password)}
+  end
+
+  def handle_event("update_password", params, socket) do
+    %{"current_password" => password, "user" => user_params} = params
+    user = socket.assigns.current_user
+
+    case Accounts.update_user_password(user, password, user_params) do
+      {:ok, user} ->
+        socket =
+          socket
+          |> assign(:trigger_submit, true)
+          |> assign(:password_changeset, Accounts.change_user_password(user, user_params))
+
+        {:noreply, socket}
+
+      {:error, changeset} ->
+        {:noreply, assign(socket, :password_changeset, changeset)}
+    end
+  end
+end

lib/outlook_web/router.ex

@@ -1,6 +1,8 @@
 defmodule OutlookWeb.Router do
   use OutlookWeb, :router
 
+  import OutlookWeb.UserAuth
+
   pipeline :browser do
     plug :accepts, ["html"]
     plug :fetch_session
@@ -8,6 +10,7 @@ defmodule OutlookWeb.Router do
     plug :put_root_layout, {OutlookWeb.Layouts, :root}
     plug :protect_from_forgery
     plug :put_secure_browser_headers
+    plug :fetch_current_user
   end
 
   pipeline :api do
@@ -41,4 +44,42 @@ defmodule OutlookWeb.Router do
       forward "/mailbox", Plug.Swoosh.MailboxPreview
     end
   end
+
+  ## Authentication routes
+
+  scope "/", OutlookWeb do
+    pipe_through [:browser, :redirect_if_user_is_authenticated]
+
+    live_session :redirect_if_user_is_authenticated,
+      on_mount: [{OutlookWeb.UserAuth, :redirect_if_user_is_authenticated}] do
+      live "/users/register", UserRegistrationLive, :new
+      live "/users/log_in", UserLoginLive, :new
+      live "/users/reset_password", UserForgotPasswordLive, :new
+      live "/users/reset_password/:token", UserResetPasswordLive, :edit
+    end
+
+    post "/users/log_in", UserSessionController, :create
+  end
+
+  scope "/", OutlookWeb do
+    pipe_through [:browser, :require_authenticated_user]
+
+    live_session :require_authenticated_user,
+      on_mount: [{OutlookWeb.UserAuth, :ensure_authenticated}] do
+      live "/users/settings", UserSettingsLive, :edit
+      live "/users/settings/confirm_email/:token", UserSettingsLive, :confirm_email
+    end
+  end
+
+  scope "/", OutlookWeb do
+    pipe_through [:browser]
+
+    delete "/users/log_out", UserSessionController, :delete
+
+    live_session :current_user,
+      on_mount: [{OutlookWeb.UserAuth, :mount_current_user}] do
+      live "/users/confirm/:token", UserConfirmationLive, :edit
+      live "/users/confirm", UserConfirmationInstructionsLive, :new
+    end
+  end
 end

lib/outlook_web/user_auth.ex

@@ -0,0 +1,231 @@
+defmodule OutlookWeb.UserAuth do
+  use OutlookWeb, :verified_routes
+
+  import Plug.Conn
+  import Phoenix.Controller
+
+  alias Outlook.Accounts
+
+  # Make the remember me cookie valid for 60 days.
+  # If you want bump or reduce this value, also change
+  # the token expiry itself in UserToken.
+  @max_age 60 * 60 * 24 * 60
+  @remember_me_cookie "_outlook_web_user_remember_me"
+  @remember_me_options [sign: true, max_age: @max_age, same_site: "Lax"]
+
+  @doc """
+  Logs the user in.
+
+  It renews the session ID and clears the whole session
+  to avoid fixation attacks. See the renew_session
+  function to customize this behaviour.
+
+  It also sets a `:live_socket_id` key in the session,
+  so LiveView sessions are identified and automatically
+  disconnected on log out. The line can be safely removed
+  if you are not using LiveView.
+  """
+  def log_in_user(conn, user, params \\ %{}) do
+    token = Accounts.generate_user_session_token(user)
+    user_return_to = get_session(conn, :user_return_to)
+
+    conn
+    |> renew_session()
+    |> put_token_in_session(token)
+    |> maybe_write_remember_me_cookie(token, params)
+    |> redirect(to: user_return_to || signed_in_path(conn))
+  end
+
+  defp maybe_write_remember_me_cookie(conn, token, %{"remember_me" => "true"}) do
+    put_resp_cookie(conn, @remember_me_cookie, token, @remember_me_options)
+  end
+
+  defp maybe_write_remember_me_cookie(conn, _token, _params) do
+    conn
+  end
+
+  # This function renews the session ID and erases the whole
+  # session to avoid fixation attacks. If there is any data
+  # in the session you may want to preserve after log in/log out,
+  # you must explicitly fetch the session data before clearing
+  # and then immediately set it after clearing, for example:
+  #
+  #     defp renew_session(conn) do
+  #       preferred_locale = get_session(conn, :preferred_locale)
+  #
+  #       conn
+  #       |> configure_session(renew: true)
+  #       |> clear_session()
+  #       |> put_session(:preferred_locale, preferred_locale)
+  #     end
+  #
+  defp renew_session(conn) do
+    conn
+    |> configure_session(renew: true)
+    |> clear_session()
+  end
+
+  @doc """
+  Logs the user out.
+
+  It clears all session data for safety. See renew_session.
+  """
+  def log_out_user(conn) do
+    user_token = get_session(conn, :user_token)
+    user_token && Accounts.delete_user_session_token(user_token)
+
+    if live_socket_id = get_session(conn, :live_socket_id) do
+      OutlookWeb.Endpoint.broadcast(live_socket_id, "disconnect", %{})
+    end
+
+    conn
+    |> renew_session()
+    |> delete_resp_cookie(@remember_me_cookie)
+    |> redirect(to: "/")
+  end
+
+  @doc """
+  Authenticates the user by looking into the session
+  and remember me token.
+  """
+  def fetch_current_user(conn, _opts) do
+    {user_token, conn} = ensure_user_token(conn)
+    user = user_token && Accounts.get_user_by_session_token(user_token)
+    assign(conn, :current_user, user)
+  end
+
+  defp ensure_user_token(conn) do
+    if token = get_session(conn, :user_token) do
+      {token, conn}
+    else
+      conn = fetch_cookies(conn, signed: [@remember_me_cookie])
+
+      if token = conn.cookies[@remember_me_cookie] do
+        {token, put_token_in_session(conn, token)}
+      else
+        {nil, conn}
+      end
+    end
+  end
+
+  @doc """
+  Handles mounting and authenticating the current_user in LiveViews.
+
+  ## `on_mount` arguments
+
+    * `:mount_current_user` - Assigns current_user
+      to socket assigns based on user_token, or nil if
+      there's no user_token or no matching user.
+
+    * `:ensure_authenticated` - Authenticates the user from the session,
+      and assigns the current_user to socket assigns based
+      on user_token.
+      Redirects to login page if there's no logged user.
+
+    * `:redirect_if_user_is_authenticated` - Authenticates the user from the session.
+      Redirects to signed_in_path if there's a logged user.
+
+  ## Examples
+
+  Use the `on_mount` lifecycle macro in LiveViews to mount or authenticate
+  the current_user:
+
+      defmodule OutlookWeb.PageLive do
+        use OutlookWeb, :live_view
+
+        on_mount {OutlookWeb.UserAuth, :mount_current_user}
+        ...
+      end
+
+  Or use the `live_session` of your router to invoke the on_mount callback:
+
+      live_session :authenticated, on_mount: [{OutlookWeb.UserAuth, :ensure_authenticated}] do
+        live "/profile", ProfileLive, :index
+      end
+  """
+  def on_mount(:mount_current_user, _params, session, socket) do
+    {:cont, mount_current_user(session, socket)}
+  end
+
+  def on_mount(:ensure_authenticated, _params, session, socket) do
+    socket = mount_current_user(session, socket)
+
+    if socket.assigns.current_user do
+      {:cont, socket}
+    else
+      socket =
+        socket
+        |> Phoenix.LiveView.put_flash(:error, "You must log in to access this page.")
+        |> Phoenix.LiveView.redirect(to: ~p"/users/log_in")
+
+      {:halt, socket}
+    end
+  end
+
+  def on_mount(:redirect_if_user_is_authenticated, _params, session, socket) do
+    socket = mount_current_user(session, socket)
+
+    if socket.assigns.current_user do
+      {:halt, Phoenix.LiveView.redirect(socket, to: signed_in_path(socket))}
+    else
+      {:cont, socket}
+    end
+  end
+
+  defp mount_current_user(session, socket) do
+    case session do
+      %{"user_token" => user_token} ->
+        Phoenix.Component.assign_new(socket, :current_user, fn ->
+          Accounts.get_user_by_session_token(user_token)
+        end)
+
+      %{} ->
+        Phoenix.Component.assign_new(socket, :current_user, fn -> nil end)
+    end
+  end
+
+  @doc """
+  Used for routes that require the user to not be authenticated.
+  """
+  def redirect_if_user_is_authenticated(conn, _opts) do
+    if conn.assigns[:current_user] do
+      conn
+      |> redirect(to: signed_in_path(conn))
+      |> halt()
+    else
+      conn
+    end
+  end
+
+  @doc """
+  Used for routes that require the user to be authenticated.
+
+  If you want to enforce the user email is confirmed before
+  they use the application at all, here would be a good place.
+  """
+  def require_authenticated_user(conn, _opts) do
+    if conn.assigns[:current_user] do
+      conn
+    else
+      conn
+      |> put_flash(:error, "You must log in to access this page.")
+      |> maybe_store_return_to()
+      |> redirect(to: ~p"/users/log_in")
+      |> halt()
+    end
+  end
+
+  defp put_token_in_session(conn, token) do
+    conn
+    |> put_session(:user_token, token)
+    |> put_session(:live_socket_id, "users_sessions:#{Base.url_encode64(token)}")
+  end
+
+  defp maybe_store_return_to(%{method: "GET"} = conn) do
+    put_session(conn, :user_return_to, current_path(conn))
+  end
+
+  defp maybe_store_return_to(conn), do: conn
+
+  defp signed_in_path(_conn), do: ~p"/"
+end