-module(caffeine_lang@codegen@relay).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/caffeine_lang/codegen/relay.gleam").
-export([generate_langfuse_to_datadog/1]).
-export_type([relay_file/0, scorer_data_type/0, scorer/0, langfuse_datadog_relay/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(
    " Codegen for the Relay artifact.\n"
    "\n"
    " A relay is a GitHub Action that pulls metrics from a source vendor and\n"
    " pushes them to a destination vendor. The compiler emits a self-contained\n"
    " set of files that a target repository drops in to start relaying.\n"
    "\n"
    " Today the only supported pairing is Langfuse → Datadog, producing four\n"
    " files:\n"
    "   - `.github/workflows/<name>.yml` — workflow that runs the runner on a\n"
    "     schedule, manages a cursor in a repo Variable, and dispatches manually.\n"
    "   - `relay/gleam.toml` — runner project manifest.\n"
    "   - `relay/src/relay.gleam` — runner that queries Langfuse v2 metrics\n"
    "     for `[from, to)` and submits one Datadog metric per scorer.\n"
    "   - `relay/src/manifest.gleam` — static declaration of which metrics the\n"
    "     relay emits. The runner imports it for its scorer allowlist; later\n"
    "     language tooling will import it to type-check measurement references.\n"
    "\n"
    " File contents come from templates under `priv/templates/relay/<pairing>/`.\n"
    " Each template is a real `.yml` / `.toml` / `.gleam` file with\n"
    " `{{PLACEHOLDER}}` tokens — so editors and reviewers get the right syntax\n"
    " highlighting and the diffs read naturally.\n"
).

-type relay_file() :: {relay_file, binary(), binary()}.

-type scorer_data_type() :: numeric | boolean | categorical.

-type scorer() :: {scorer, binary(), scorer_data_type()}.

-type langfuse_datadog_relay() :: {langfuse_datadog_relay,
        binary(),
        binary(),
        binary(),
        list(scorer())}.

-file("src/caffeine_lang/codegen/relay.gleam", 146).
-spec data_type_string(scorer_data_type()) -> binary().
data_type_string(Dt) ->
    case Dt of
        numeric ->
            <<"numeric"/utf8>>;

        boolean ->
            <<"boolean"/utf8>>;

        categorical ->
            <<"categorical"/utf8>>
    end.

-file("src/caffeine_lang/codegen/relay.gleam", 131).
-spec render_scorer_entry(scorer(), binary()) -> binary().
render_scorer_entry(Scorer, Metric_prefix) ->
    Data_type_str = data_type_string(erlang:element(3, Scorer)),
    Value_metric = case erlang:element(3, Scorer) of
        categorical ->
            <<"option.None"/utf8>>;

        numeric ->
            <<<<"option.Some(\""/utf8, Metric_prefix/binary>>/binary,
                ".value\")"/utf8>>;

        boolean ->
            <<<<"option.Some(\""/utf8, Metric_prefix/binary>>/binary,
                ".value\")"/utf8>>
    end,
    <<<<<<<<<<<<<<<<<<<<<<<<<<"    ScorerInfo(\n"/utf8, "      name: \""/utf8>>/binary,
                                                    (erlang:element(2, Scorer))/binary>>/binary,
                                                "\",\n"/utf8>>/binary,
                                            "      data_type: \""/utf8>>/binary,
                                        Data_type_str/binary>>/binary,
                                    "\",\n"/utf8>>/binary,
                                "      count_metric: \""/utf8>>/binary,
                            Metric_prefix/binary>>/binary,
                        ".count\",\n"/utf8>>/binary,
                    "      value_metric: "/utf8>>/binary,
                Value_metric/binary>>/binary,
            ",\n"/utf8>>/binary,
        "    ),\n"/utf8>>.

-file("src/caffeine_lang/codegen/relay.gleam", 125).
-spec scorer_entries(langfuse_datadog_relay()) -> binary().
scorer_entries(Relay) ->
    _pipe = erlang:element(5, Relay),
    _pipe@1 = gleam@list:map(
        _pipe,
        fun(_capture) ->
            render_scorer_entry(_capture, erlang:element(3, Relay))
        end
    ),
    erlang:list_to_binary(_pipe@1).

-file("src/caffeine_lang/codegen/relay.gleam", 119).
-spec cursor_var_name(langfuse_datadog_relay()) -> binary().
cursor_var_name(Relay) ->
    <<"RELAY_CURSOR_"/utf8,
        (string:uppercase(erlang:element(2, Relay)))/binary>>.

-file("src/caffeine_lang/codegen/relay.gleam", 109).
-spec substitutions(langfuse_datadog_relay()) -> list({binary(), binary()}).
substitutions(Relay) ->
    [{<<"{{RELAY_NAME}}"/utf8>>, erlang:element(2, Relay)},
        {<<"{{METRIC_PREFIX}}"/utf8>>, erlang:element(3, Relay)},
        {<<"{{SCHEDULE_CRON}}"/utf8>>, erlang:element(4, Relay)},
        {<<"{{CURSOR_VAR}}"/utf8>>, cursor_var_name(Relay)},
        {<<"{{SCORER_ENTRIES}}"/utf8>>, scorer_entries(Relay)}].

-file("src/caffeine_lang/codegen/relay.gleam", 101).
?DOC(
    " Read a template from `priv/templates/relay/langfuse_to_datadog/` and\n"
    " substitute the relay's fields into the `{{PLACEHOLDER}}` tokens. A\n"
    " missing template file means the package was shipped broken — assert so\n"
    " it fails loudly.\n"
).
-spec render(langfuse_datadog_relay(), binary()) -> binary().
render(Relay, Template_name) ->
    Template@1 = case simplifile:read(
        <<"priv/templates/relay/langfuse_to_datadog/"/utf8,
            Template_name/binary>>
    ) of
        {ok, Template} -> Template;
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Pattern match failed, no pattern matched the value."/utf8>>,
                        file => <<?FILEPATH/utf8>>,
                        module => <<"caffeine_lang/codegen/relay"/utf8>>,
                        function => <<"render"/utf8>>,
                        line => 102,
                        value => _assert_fail,
                        start => 4166,
                        'end' => 4238,
                        pattern_start => 4177,
                        pattern_end => 4189})
    end,
    gleam@list:fold(
        substitutions(Relay),
        Template@1,
        fun(Acc, Sub) ->
            {Placeholder, Value} = Sub,
            gleam@string:replace(Acc, Placeholder, Value)
        end
    ).

-file("src/caffeine_lang/codegen/relay.gleam", 75).
?DOC(" Generate the file set for a Langfuse → Datadog relay.\n").
-spec generate_langfuse_to_datadog(langfuse_datadog_relay()) -> list(relay_file()).
generate_langfuse_to_datadog(Relay) ->
    [{relay_file,
            <<<<".github/workflows/"/utf8, (erlang:element(2, Relay))/binary>>/binary,
                ".yml"/utf8>>,
            render(Relay, <<"workflow.yml"/utf8>>)},
        {relay_file,
            <<"relay/gleam.toml"/utf8>>,
            render(Relay, <<"gleam.toml"/utf8>>)},
        {relay_file,
            <<"relay/src/relay.gleam"/utf8>>,
            render(Relay, <<"runner.gleam"/utf8>>)},
        {relay_file,
            <<"relay/src/manifest.gleam"/utf8>>,
            render(Relay, <<"manifest.gleam"/utf8>>)}].