viva_telemetry

-module(viva_telemetry@examples@metrics_example).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/viva_telemetry/examples/metrics_example.gleam").
-export([main/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(
    " Example: Using viva_telemetry/metrics\n"
    "\n"
    " Run: gleam run -m viva_telemetry/examples/metrics_example\n"
).

-file("src/viva_telemetry/examples/metrics_example.gleam", 87).
-spec format_bytes(integer()) -> binary().
format_bytes(Bytes) ->
    case Bytes >= 1048576 of
        true ->
            <<(gleam_stdlib:float_to_string(erlang:float(Bytes) / 1048576.0))/binary,
                " MB"/utf8>>;

        false ->
            case Bytes >= 1024 of
                true ->
                    <<(gleam_stdlib:float_to_string(
                            erlang:float(Bytes) / 1024.0
                        ))/binary,
                        " KB"/utf8>>;

                false ->
                    <<(erlang:integer_to_binary(Bytes))/binary, " B"/utf8>>
            end
    end.

-file("src/viva_telemetry/examples/metrics_example.gleam", 11).
-spec main() -> nil.
main() ->
    gleam_stdlib:println(<<"=== viva_telemetry/metrics Demo ===\n"/utf8>>),
    gleam_stdlib:println(<<"--- Counter ---"/utf8>>),
    Requests = viva_telemetry@metrics:counter(<<"http_requests_total"/utf8>>),
    viva_telemetry@metrics:inc(Requests),
    viva_telemetry@metrics:inc(Requests),
    viva_telemetry@metrics:inc_by(Requests, 10),
    gleam_stdlib:println(
        <<"http_requests_total: "/utf8,
            (erlang:integer_to_binary(
                viva_telemetry@metrics:get_counter(Requests)
            ))/binary>>
    ),
    Errors = viva_telemetry@metrics:counter_with_labels(
        <<"http_errors_total"/utf8>>,
        [{<<"method"/utf8>>, <<"GET"/utf8>>},
            {<<"status"/utf8>>, <<"500"/utf8>>}]
    ),
    viva_telemetry@metrics:inc(Errors),
    viva_telemetry@metrics:inc(Errors),
    gleam_stdlib:println(
        <<"http_errors_total: "/utf8,
            (erlang:integer_to_binary(
                viva_telemetry@metrics:get_counter(Errors)
            ))/binary>>
    ),
    gleam_stdlib:println(<<"\n--- Gauge ---"/utf8>>),
    Connections = viva_telemetry@metrics:gauge(<<"active_connections"/utf8>>),
    viva_telemetry@metrics:set(Connections, 10.0),
    viva_telemetry@metrics:gauge_inc(Connections),
    viva_telemetry@metrics:gauge_inc(Connections),
    viva_telemetry@metrics:gauge_dec(Connections),
    gleam_stdlib:println(
        <<"active_connections: "/utf8,
            (gleam_stdlib:float_to_string(
                viva_telemetry@metrics:get_gauge(Connections)
            ))/binary>>
    ),
    Temperature = viva_telemetry@metrics:gauge(<<"cpu_temperature"/utf8>>),
    viva_telemetry@metrics:set(Temperature, 65.5),
    gleam_stdlib:println(
        <<"cpu_temperature: "/utf8,
            (gleam_stdlib:float_to_string(
                viva_telemetry@metrics:get_gauge(Temperature)
            ))/binary>>
    ),
    gleam_stdlib:println(<<"\n--- Histogram ---"/utf8>>),
    Latency = viva_telemetry@metrics:histogram(
        <<"request_latency_ms"/utf8>>,
        viva_telemetry@metrics:default_latency_buckets()
    ),
    gleam@list:each(
        [5.2, 12.5, 48.0, 150.0, 520.0, 23.0, 8.0, 95.0],
        fun(V) -> viva_telemetry@metrics:observe(Latency, V) end
    ),
    {Count, Sum} = viva_telemetry@metrics:get_histogram_stats(Latency),
    gleam_stdlib:println(
        <<"request_latency_ms count: "/utf8,
            (erlang:integer_to_binary(Count))/binary>>
    ),
    gleam_stdlib:println(
        <<"request_latency_ms sum: "/utf8,
            (gleam_stdlib:float_to_string(Sum))/binary>>
    ),
    gleam_stdlib:println(
        <<"request_latency_ms avg: "/utf8,
            (gleam_stdlib:float_to_string(case erlang:float(Count) of
                    +0.0 -> +0.0;
                    -0.0 -> -0.0;
                    Gleam@denominator -> Sum / Gleam@denominator
                end))/binary>>
    ),
    gleam_stdlib:println(<<"\n--- BEAM Memory ---"/utf8>>),
    Mem = viva_telemetry@metrics:beam_memory(),
    gleam_stdlib:println(
        <<"Total: "/utf8, (format_bytes(erlang:element(2, Mem)))/binary>>
    ),
    gleam_stdlib:println(
        <<"Processes: "/utf8, (format_bytes(erlang:element(3, Mem)))/binary>>
    ),
    gleam_stdlib:println(
        <<"System: "/utf8, (format_bytes(erlang:element(5, Mem)))/binary>>
    ),
    gleam_stdlib:println(
        <<"Binary: "/utf8, (format_bytes(erlang:element(8, Mem)))/binary>>
    ),
    gleam_stdlib:println(
        <<"ETS: "/utf8, (format_bytes(erlang:element(10, Mem)))/binary>>
    ),
    gleam_stdlib:println(<<"\n--- Prometheus Export ---"/utf8>>),
    Prom = viva_telemetry@metrics:to_prometheus(),
    gleam_stdlib:println(Prom),
    gleam_stdlib:println(<<"\n=== Demo completed! ==="/utf8>>).