dudeswave2/dudeswave/src/dudeswave_auth.erl

%
% Copyright (c) 2024 Andrea Biscuola <a@abiscuola.com>
%
% Permission to use, copy, modify, and distribute this software for any
% purpose with or without fee is hereby granted, provided that the above
% copyright notice and this permission notice appear in all copies.
%
% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
%
-module(dudeswave_auth).
-moduledoc """
Dudes users management module.

Here lives all the functions needed to create, update and delete users
from the dudeswave database.
""".

-include_lib("dudeswave/include/defines.hrl").
-include_lib("storage/include/storage.hrl").

-export([authenticate/2, details/1, new/3,
    update/4, delete/1, logout/2, auth_cookies/1]).

-doc """
Verify a session with an existing cookie.

Spec:

```
-spec authenticate(User, Auth) -> true | false | {true, Cookie, Validity} | {error, Reason} when
	User :: binary(),
	Auth :: {cookie, binary()} | {password, binary()},
	Reason :: term().
```

Authenticate a user with either an existing `Cookie` or by issuing a new one
after authenticating with `Password`.

If `Cookie` is valid, the function returns `true`. If the authentication is denied
returns `false`
""".
-spec authenticate(User, Auth) -> true | false | {true, Cookie, Validity} | {error, Reason} when
	User :: binary(),
	Auth :: {cookie, binary()} | {password, binary()},
	Cookie :: binary(),
	Validity :: pos_integer(),
	Reason :: term().

authenticate(User, {cookie, Cookie}) ->
	case storage:read(?COOKIESBUCK, Cookie) of
		{ok, [R]} ->
			CurTime = calendar:now_to_universal_time(erlang:timestamp()),
			CookieTime = R#object.value,
			CookieUser = lists:keyfind(user, 1, R#object.metadata),

			if
				CookieTime >= CurTime ->
					if
						User =:= CookieUser -> true;
						true -> false
					end;
				true -> false
			end;
		{ok, []} -> false;
		{error, _} -> {error, service_unavailable}
	end;

authenticate(User, {password, Password}) ->
	case storage:read(?USERSBUCK, User) of
		{ok, [R]} ->
			Validity = case application:get_env(cookie_validity) of
				{ok, Value} ->
				    erlang:system_time(seconds) + Value * 86400;
				undefined ->
				    erlang:system_time(seconds) + ?DEFVALIDITY * 86400
			end,

			{ok, Hash} = lists:keyfind(hash, 1, R#object.metadata),
			{ok, Salt} = lists:keyfind(salt, 1, R#object.metadata),
			Auth = crypto:hash(sha256, <<Password/binary, Salt/binary>>),

			if
				Auth =:= Hash ->
					Cookie = base64:encode(rand:bytes(64)),
					case storage:write(?COOKIESBUCK, <<Cookie/binary>>,
					    Validity, [{user, User}]) of
						ok -> {true, Cookie, Validity};
						{error, Reason} -> {error, Reason}
					end;
				true -> false
			end;
		{ok, []} -> false;
		{error, Reason} -> {error, Reason}
	end.

-doc """
Close an existing session

Spec:

```
-spec logout(User, Cookie) -> ok | {error, Reason} when
	User :: binary(),
	Cookie :: binary(),
	Reason :: term().
```

Invalidate and delete `Cookie` associated with `User` from the system.
""".
-spec logout(User, Cookie) -> ok | {error, Reason} when
	User :: binary(),
	Cookie :: binary(),
	Reason :: term().

logout(User, Cookie) ->
	case storage:read(?COOKIESBUCK, Cookie) of
		{ok, [R]} ->
			{user, User} = lists:keyfind(user, 1, R#object.metadata),
			storage:delete(?COOKIESBUCK, Cookie);
		{ok, []} ->
			{error, not_found};
		{error, Reason} ->
			{error, Reason}
	end.

-doc """
Return user details.

Spec:

```
-spec details(User) -> Value | {error, Reason} when
	User :: binary(),
	Value :: term(),
	Reason :: term().
```
""".
-spec details(User) -> Value | {error, Reason} when
	User :: binary(),
	Value :: term(),
	Reason :: term().

details(User) ->
	case storage:read(?USERSBUCK, User) of
		{ok, [R]} -> R#object.value;
		{error, Reason} -> {error, Reason};
		{ok, []} -> {error, not_found}
	end.

-doc """
Create a new user.

Spec:

```
-spec new(User, Password, Email) -> ok | {error, Reason} when
	User :: binary(),
	Password :: binary(),
	Email :: binary(),
	Reason :: term().
```

The `User` is created, and stored in the application's users bucket
`Password` is salted and hashed with SHA256 before being stored.

The new user is saved with a metadata `status` of `waiting_confirmation`,
based on the application settings, the confirmation method may vary.
""".
-spec new(User, Password, Email) -> ok | {error, Reason} when
	User :: binary(),
	Password :: binary(),
	Email :: binary(),
	Reason :: term().

new(User, Password, Email) ->
	Salt = rand:bytes(?RANDBYTES),
	Hash = crypto:hash(sha256, <<Password/binary, Salt/binary>>),

	Data = #{<<"email">> => Email},
	Metadata = [{salt, Salt}, {hash, Hash}, {status, waiting_confirmation}],

	storage:write(?USERSBUCK, User, Data, Metadata).

-doc """
Update user's details

Spec:

```
-spec update(User, Name, Email, Desc) -> ok | {error, Reason} when
	User :: binary(),
	Name :: binary(),
	Email :: binary(),
	Desc :: binary(),
	Reason :: term().
```

The details apart from `User` are updated. The username itself is immutable
and cannot be modified. All the other fields, excluding the e-mail, are the
ones that can be seen in the public page.
""".
-spec update(User, Name, Email, Desc) -> ok | {error, Reason} when
	User :: binary(),
	Name :: binary(),
	Email :: binary(),
	Desc :: binary(),
	Reason :: term().

update(User, Name, Email, Desc) ->
	{ok, CurData, Metadata} = case storage:read(?USERSBUCK, User) of
		{ok, [R]} ->
			{ok, R#object.value, R#object.metadata};
		{error, Reason} -> {error, Reason}
	end,

	Data = CurData#{<<"email">> => Email, <<"name">> => Name,
	    <<"description">> => Desc},

	storage:write(?USERSBUCK, User, Data, Metadata).

-doc """
Delete an existing user from the database.

```
-spec delete(User) -> ok | {error, Reason} when
	User :: binary(),
	Reason :: term().
```
""".
-spec delete(User) -> ok | {error, Reason} when
	User :: binary(),
	Reason :: term().

delete(User) ->
	% We are missing the cleanup of the cookies
	% here. For that, we need to add at least another
	% API to the storage layer.
	storage:delete(?USERSBUCK, User).

-doc """
Get the authentication cookies from a cowboy request.

Spec:

```
-spec auth_cookies(Req) -> {User, Cookie} when
	Req :: cowboy_req:req(),
	User :: binary(),
	Cookie :: binary().
```
""".
-spec auth_cookies(Req) -> {User, Cookie} when
	Req :: cowboy_req:req(),
	User :: binary(),
	Cookie :: binary().

auth_cookies(Req) ->
	#{dudeauth := Cookie, dudename := User} = cowboy_req:match_cookies([dudeauth,
	    dudename], Req),

	{User, Cookie}.