gpop

-module(gpop).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/gpop.gleam").
-export([generate_key/0, with_proof/3, with_authorization/4]).
-export_type([key/0, p256_keypair/0]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

-opaque key() :: {key, p256_keypair(), bitstring(), bitstring()}.

-type p256_keypair() :: any().

-file("src/gpop.gleam", 99).
-spec append_optional_string(
    list({binary(), gleam@json:json()}),
    binary(),
    gleam@option:option(binary())
) -> list({binary(), gleam@json:json()}).
append_optional_string(Claims, Name, Value) ->
    case Value of
        none ->
            Claims;

        {some, V} ->
            lists:append([Claims, [{Name, gleam@json:string(V)}]])
    end.

-file("src/gpop.gleam", 122).
-spec encode_segment(binary()) -> binary().
encode_segment(Value) ->
    gleam@bit_array:base64_url_encode(<<Value/binary>>, false).

-file("src/gpop.gleam", 126).
-spec encode_coordinate(bitstring()) -> binary().
encode_coordinate(Coordinate) ->
    gleam@bit_array:base64_url_encode(Coordinate, false).

-file("src/gpop.gleam", 70).
-spec jwk_json(key()) -> gleam@json:json().
jwk_json(Key) ->
    gleam@json:object(
        [{<<"kty"/utf8>>, gleam@json:string(<<"EC"/utf8>>)},
            {<<"crv"/utf8>>, gleam@json:string(<<"P-256"/utf8>>)},
            {<<"x"/utf8>>,
                gleam@json:string(encode_coordinate(erlang:element(3, Key)))},
            {<<"y"/utf8>>,
                gleam@json:string(encode_coordinate(erlang:element(4, Key)))}]
    ).

-file("src/gpop.gleam", 62).
-spec header_json(key()) -> gleam@json:json().
header_json(Key) ->
    gleam@json:object(
        [{<<"typ"/utf8>>, gleam@json:string(<<"dpop+jwt"/utf8>>)},
            {<<"alg"/utf8>>, gleam@json:string(<<"ES256"/utf8>>)},
            {<<"jwk"/utf8>>, jwk_json(Key)}]
    ).

-file("src/gpop.gleam", 130).
-spec hash_access_token(binary()) -> binary().
hash_access_token(Access_token) ->
    _pipe = gleam@crypto:hash(sha256, <<Access_token/binary>>),
    gleam@bit_array:base64_url_encode(_pipe, false).

-file("src/gpop.gleam", 135).
-spec current_epoch_seconds() -> integer().
current_epoch_seconds() ->
    _pipe = gleam@time@timestamp:system_time(),
    _pipe@1 = gleam@time@timestamp:to_unix_seconds_and_nanoseconds(_pipe),
    gleam@pair:first(_pipe@1).

-file("src/gpop.gleam", 79).
-spec payload_json(
    gleam@http@request:request(any()),
    gleam@option:option(binary()),
    gleam@option:option(binary())
) -> gleam@json:json().
payload_json(Request, Nonce, Ath) ->
    Htm = gleam@http:method_to_string(erlang:element(2, Request)),
    Htu = begin
        _record = gleam@http@request:to_uri(Request),
        {uri,
            erlang:element(2, _record),
            erlang:element(3, _record),
            erlang:element(4, _record),
            erlang:element(5, _record),
            erlang:element(6, _record),
            none,
            none}
    end,
    Claims = begin
        _pipe = [{<<"htm"/utf8>>, gleam@json:string(Htm)},
            {<<"htu"/utf8>>, gleam@json:string(gleam@uri:to_string(Htu))},
            {<<"jti"/utf8>>, gleam@json:string(youid@uuid:v4_string())},
            {<<"iat"/utf8>>, gleam@json:int(current_epoch_seconds())}],
        _pipe@1 = append_optional_string(_pipe, <<"nonce"/utf8>>, Nonce),
        append_optional_string(_pipe@1, <<"ath"/utf8>>, Ath)
    end,
    gleam@json:object(Claims).

-file("src/gpop.gleam", 19).
?DOC(" Generate a new ES256 key pair suitable for DPoP proofs.\n").
-spec generate_key() -> key().
generate_key() ->
    {Pair, Public_key} = gpop_ffi:generate_p256_keypair(),
    {X@1, Y@1} = case Public_key of
        <<4, X:256/bitstring, Y:256/bitstring>> -> {X, Y};
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Pattern match failed, no pattern matched the value."/utf8>>,
                        file => <<?FILEPATH/utf8>>,
                        module => <<"gpop"/utf8>>,
                        function => <<"generate_key"/utf8>>,
                        line => 21,
                        value => _assert_fail,
                        start => 552,
                        'end' => 617,
                        pattern_start => 563,
                        pattern_end => 604})
    end,
    {key, Pair, X@1, Y@1}.

-file("src/gpop.gleam", 110).
-spec sign_jwt(gleam@json:json(), gleam@json:json(), key()) -> binary().
sign_jwt(Header, Payload, Key) ->
    Header_segment = begin
        _pipe = Header,
        _pipe@1 = gleam@json:to_string(_pipe),
        encode_segment(_pipe@1)
    end,
    Payload_segment = begin
        _pipe@2 = Payload,
        _pipe@3 = gleam@json:to_string(_pipe@2),
        encode_segment(_pipe@3)
    end,
    Signing_input = <<<<Header_segment/binary, "."/utf8>>/binary,
        Payload_segment/binary>>,
    Signature = begin
        _pipe@4 = <<Signing_input/binary>>,
        _pipe@5 = gpop_ffi:sign_es256(_pipe@4, erlang:element(2, Key)),
        gleam@bit_array:base64_url_encode(_pipe@5, false)
    end,
    <<<<Signing_input/binary, "."/utf8>>/binary, Signature/binary>>.

-file("src/gpop.gleam", 51).
-spec build_proof(
    gleam@http@request:request(any()),
    key(),
    gleam@option:option(binary()),
    gleam@option:option(binary())
) -> binary().
build_proof(Request, Key, Nonce, Ath) ->
    Header = header_json(Key),
    Payload = payload_json(Request, Nonce, Ath),
    sign_jwt(Header, Payload, Key).

-file("src/gpop.gleam", 26).
?DOC(" Attach a standalone DPoP proof header to the request.\n").
-spec with_proof(
    gleam@http@request:request(FQS),
    key(),
    gleam@option:option(binary())
) -> gleam@http@request:request(FQS).
with_proof(Req, Key, Nonce) ->
    Proof = build_proof(Req, Key, Nonce, none),
    gleam@http@request:set_header(Req, <<"dpop"/utf8>>, Proof).

-file("src/gpop.gleam", 37).
?DOC(
    " Attach an Authorization header using the DPoP scheme together with the\n"
    " accompanying proof bound to the access token.\n"
).
-spec with_authorization(
    gleam@http@request:request(FQW),
    key(),
    binary(),
    gleam@option:option(binary())
) -> gleam@http@request:request(FQW).
with_authorization(Req, Key, Access_token, Nonce) ->
    Proof = build_proof(
        Req,
        Key,
        Nonce,
        {some, hash_access_token(Access_token)}
    ),
    _pipe = Req,
    _pipe@1 = gleam@http@request:set_header(
        _pipe,
        <<"authorization"/utf8>>,
        <<"DPoP "/utf8, Access_token/binary>>
    ),
    gleam@http@request:set_header(_pipe@1, <<"dpop"/utf8>>, Proof).