telega

-module(telega@deep_link).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/telega/deep_link.gleam").
-export([validate_payload/1, encode_payload/1, decode_payload/1, start_link/2, start_group_link/2, start_app_link/3, encoded_start_link/2, encoded_start_group_link/2, start_link_for_bot/2, start_group_link_for_bot/2, start_app_link_for_bot/3, encoded_start_link_for_bot/2, encoded_start_group_link_for_bot/2, payload_from_command/1, decoded_payload_from_command/1]).
-export_type([deep_link_error/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.

?MODULEDOC(
    " Deep-linking helpers: build `t.me` links that open the bot with a\n"
    " `/start` payload and read that payload back in the command handler.\n"
    "\n"
    " Telegram restricts start payloads to `A-Za-z0-9_-`, at most 64\n"
    " characters. To carry arbitrary data (user ids, referral codes with\n"
    " separators, unicode), pair `encode_payload`/`decode_payload` — they wrap\n"
    " the data in URL-safe base64, which fits the allowed alphabet.\n"
    "\n"
    " ```gleam\n"
    " // Somewhere a link is generated:\n"
    " let assert Ok(link) = deep_link.encoded_start_link_for_bot(ctx.bot_info, \"ref:42\")\n"
    " // -> \"https://t.me/my_bot?start=cmVmOjQy\"\n"
    "\n"
    " // In the /start handler:\n"
    " fn start_handler(ctx, command: update.Command) {\n"
    "   case deep_link.decoded_payload_from_command(command) {\n"
    "     Ok(Some(data)) -> reply.with_text(ctx, \"Referred by: \" <> data)\n"
    "     _ -> reply.with_text(ctx, \"Hello!\")\n"
    "   }\n"
    " }\n"
    " ```\n"
).

-type deep_link_error() :: {payload_too_long, integer()} |
    {invalid_payload_characters, binary()} |
    missing_bot_username.

-file("src/telega/deep_link.gleam", 245).
-spec is_allowed_codepoint(integer()) -> boolean().
is_allowed_codepoint(Codepoint) ->
    Code = gleam_stdlib:identity(Codepoint),
    (((((Code >= 16#41) andalso (Code =< 16#5A)) orelse ((Code >= 16#61) andalso (Code
    =< 16#7A)))
    orelse ((Code >= 16#30) andalso (Code =< 16#39)))
    orelse (Code =:= 16#5F))
    orelse (Code =:= 16#2D).

-file("src/telega/deep_link.gleam", 52).
?DOC(
    " Checks that a payload matches the Telegram deep-linking rules:\n"
    " 1 to 64 characters from `A-Za-z0-9_-`. Returns the payload unchanged.\n"
).
-spec validate_payload(binary()) -> {ok, binary()} | {error, deep_link_error()}.
validate_payload(Payload) ->
    Length = string:length(Payload),
    case Length of
        0 ->
            {error, {invalid_payload_characters, Payload}};

        _ when Length > 64 ->
            {error, {payload_too_long, Length}};

        _ ->
            case begin
                _pipe = Payload,
                _pipe@1 = gleam@string:to_utf_codepoints(_pipe),
                gleam@list:all(_pipe@1, fun is_allowed_codepoint/1)
            end of
                true ->
                    {ok, Payload};

                false ->
                    {error, {invalid_payload_characters, Payload}}
            end
    end.

-file("src/telega/deep_link.gleam", 74).
?DOC(
    " Encodes arbitrary data into a payload that fits the Telegram alphabet\n"
    " (URL-safe base64 without padding). Data must be at most 48 bytes,\n"
    " otherwise the encoded payload would not fit into 64 characters.\n"
).
-spec encode_payload(binary()) -> {ok, binary()} | {error, deep_link_error()}.
encode_payload(Data) ->
    Bytes = gleam_stdlib:identity(Data),
    Size = erlang:byte_size(Bytes),
    case Size of
        0 ->
            {error, {invalid_payload_characters, Data}};

        _ when Size > 48 ->
            {error, {payload_too_long, Size}};

        _ ->
            {ok, gleam@bit_array:base64_url_encode(Bytes, false)}
    end.

-file("src/telega/deep_link.gleam", 85).
?DOC(" Decodes a payload produced by `encode_payload` back to the original data.\n").
-spec decode_payload(binary()) -> {ok, binary()} | {error, deep_link_error()}.
decode_payload(Payload) ->
    _pipe = Payload,
    _pipe@1 = gleam@bit_array:base64_url_decode(_pipe),
    _pipe@2 = gleam@result:'try'(_pipe@1, fun gleam@bit_array:to_string/1),
    gleam@result:replace_error(_pipe@2, {invalid_payload_characters, Payload}).

-file("src/telega/deep_link.gleam", 234).
-spec normalize_username(binary()) -> {ok, binary()} |
    {error, deep_link_error()}.
normalize_username(Username) ->
    Username@1 = case Username of
        <<"@"/utf8, Rest/binary>> ->
            Rest;

        _ ->
            Username
    end,
    case Username@1 of
        <<""/utf8>> ->
            {error, missing_bot_username};

        _ ->
            {ok, Username@1}
    end.

-file("src/telega/deep_link.gleam", 97).
?DOC(
    " Builds `https://t.me/<username>?start=<payload>` — opens a private chat\n"
    " with the bot and suggests pressing Start; the payload arrives in the\n"
    " `/start` command. A leading `@` in the username is ignored.\n"
).
-spec start_link(binary(), binary()) -> {ok, binary()} |
    {error, deep_link_error()}.
start_link(Username, Payload) ->
    gleam@result:'try'(
        normalize_username(Username),
        fun(Username@1) ->
            gleam@result:'try'(
                validate_payload(Payload),
                fun(Payload@1) ->
                    {ok,
                        <<<<<<"https://t.me/"/utf8, Username@1/binary>>/binary,
                                "?start="/utf8>>/binary,
                            Payload@1/binary>>}
                end
            )
        end
    ).

-file("src/telega/deep_link.gleam", 108).
?DOC(
    " Builds `https://t.me/<username>?startgroup=<payload>` — prompts the user\n"
    " to pick a group to add the bot to; the payload arrives in `/start`.\n"
).
-spec start_group_link(binary(), binary()) -> {ok, binary()} |
    {error, deep_link_error()}.
start_group_link(Username, Payload) ->
    gleam@result:'try'(
        normalize_username(Username),
        fun(Username@1) ->
            gleam@result:'try'(
                validate_payload(Payload),
                fun(Payload@1) ->
                    {ok,
                        <<<<<<"https://t.me/"/utf8, Username@1/binary>>/binary,
                                "?startgroup="/utf8>>/binary,
                            Payload@1/binary>>}
                end
            )
        end
    ).

-file("src/telega/deep_link.gleam", 119).
?DOC(
    " Builds `https://t.me/<username>/<app_name>?startapp=<payload>` — opens a\n"
    " Mini App directly. Without a payload the `startapp` parameter is omitted.\n"
).
-spec start_app_link(binary(), binary(), gleam@option:option(binary())) -> {ok,
        binary()} |
    {error, deep_link_error()}.
start_app_link(Username, App_name, Payload) ->
    gleam@result:'try'(
        normalize_username(Username),
        fun(Username@1) ->
            Base = <<<<<<"https://t.me/"/utf8, Username@1/binary>>/binary,
                    "/"/utf8>>/binary,
                App_name/binary>>,
            case Payload of
                none ->
                    {ok, Base};

                {some, Payload@1} ->
                    gleam@result:'try'(
                        validate_payload(Payload@1),
                        fun(Payload@2) ->
                            {ok,
                                <<<<Base/binary, "?startapp="/utf8>>/binary,
                                    Payload@2/binary>>}
                        end
                    )
            end
        end
    ).

-file("src/telega/deep_link.gleam", 137).
?DOC(
    " Like `start_link`, but encodes arbitrary data with `encode_payload`\n"
    " first — one call instead of encode + link.\n"
).
-spec encoded_start_link(binary(), binary()) -> {ok, binary()} |
    {error, deep_link_error()}.
encoded_start_link(Username, Data) ->
    gleam@result:'try'(
        encode_payload(Data),
        fun(Payload) -> start_link(Username, Payload) end
    ).

-file("src/telega/deep_link.gleam", 147).
?DOC(
    " Like `start_group_link`, but encodes arbitrary data with\n"
    " `encode_payload` first.\n"
).
-spec encoded_start_group_link(binary(), binary()) -> {ok, binary()} |
    {error, deep_link_error()}.
encoded_start_group_link(Username, Data) ->
    gleam@result:'try'(
        encode_payload(Data),
        fun(Payload) -> start_group_link(Username, Payload) end
    ).

-file("src/telega/deep_link.gleam", 227).
-spec bot_username(telega@model@types:user()) -> {ok, binary()} |
    {error, deep_link_error()}.
bot_username(Bot_info) ->
    case erlang:element(6, Bot_info) of
        {some, Username} ->
            {ok, Username};

        none ->
            {error, missing_bot_username}
    end.

-file("src/telega/deep_link.gleam", 157).
?DOC(
    " Like `start_link`, but takes the bot's `User` (e.g. `ctx.bot_info`) and\n"
    " fails with `MissingBotUsername` when the bot has no username.\n"
).
-spec start_link_for_bot(telega@model@types:user(), binary()) -> {ok, binary()} |
    {error, deep_link_error()}.
start_link_for_bot(Bot_info, Payload) ->
    gleam@result:'try'(
        bot_username(Bot_info),
        fun(Username) -> start_link(Username, Payload) end
    ).

-file("src/telega/deep_link.gleam", 166).
?DOC(" Like `start_group_link`, but takes the bot's `User` (e.g. `ctx.bot_info`).\n").
-spec start_group_link_for_bot(telega@model@types:user(), binary()) -> {ok,
        binary()} |
    {error, deep_link_error()}.
start_group_link_for_bot(Bot_info, Payload) ->
    gleam@result:'try'(
        bot_username(Bot_info),
        fun(Username) -> start_group_link(Username, Payload) end
    ).

-file("src/telega/deep_link.gleam", 175).
?DOC(" Like `start_app_link`, but takes the bot's `User` (e.g. `ctx.bot_info`).\n").
-spec start_app_link_for_bot(
    telega@model@types:user(),
    binary(),
    gleam@option:option(binary())
) -> {ok, binary()} | {error, deep_link_error()}.
start_app_link_for_bot(Bot_info, App_name, Payload) ->
    gleam@result:'try'(
        bot_username(Bot_info),
        fun(Username) -> start_app_link(Username, App_name, Payload) end
    ).

-file("src/telega/deep_link.gleam", 190).
?DOC(
    " Encodes arbitrary data and builds a start link for the bot — the closest\n"
    " analog of aiogram's `create_start_link(bot, data, encode=True)`:\n"
    "\n"
    " ```gleam\n"
    " let assert Ok(link) = deep_link.encoded_start_link_for_bot(ctx.bot_info, \"ref:42\")\n"
    " ```\n"
).
-spec encoded_start_link_for_bot(telega@model@types:user(), binary()) -> {ok,
        binary()} |
    {error, deep_link_error()}.
encoded_start_link_for_bot(Bot_info, Data) ->
    gleam@result:'try'(
        encode_payload(Data),
        fun(Payload) -> start_link_for_bot(Bot_info, Payload) end
    ).

-file("src/telega/deep_link.gleam", 199).
?DOC(" Encodes arbitrary data and builds a group start link for the bot.\n").
-spec encoded_start_group_link_for_bot(telega@model@types:user(), binary()) -> {ok,
        binary()} |
    {error, deep_link_error()}.
encoded_start_group_link_for_bot(Bot_info, Data) ->
    gleam@result:'try'(
        encode_payload(Data),
        fun(Payload) -> start_group_link_for_bot(Bot_info, Payload) end
    ).

-file("src/telega/deep_link.gleam", 209).
?DOC(
    " Extracts the raw `/start` payload from a command, normalizing the empty\n"
    " payload of a bare `/start` to `None`.\n"
).
-spec payload_from_command(telega@update:command()) -> gleam@option:option(binary()).
payload_from_command(Command) ->
    case erlang:element(4, Command) of
        {some, <<""/utf8>>} ->
            none;

        none ->
            none;

        {some, Payload} ->
            {some, Payload}
    end.

-file("src/telega/deep_link.gleam", 218).
?DOC(
    " Extracts and base64-decodes the payload of a command produced by an\n"
    " `encode_payload`-built link. `Ok(None)` means there was no payload.\n"
).
-spec decoded_payload_from_command(telega@update:command()) -> {ok,
        gleam@option:option(binary())} |
    {error, deep_link_error()}.
decoded_payload_from_command(Command) ->
    case payload_from_command(Command) of
        none ->
            {ok, none};

        {some, Payload} ->
            _pipe = decode_payload(Payload),
            gleam@result:map(_pipe, fun(Field@0) -> {some, Field@0} end)
    end.