-module(viva_tensor@examples@backend).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/viva_tensor/examples/backend.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(
    " Backend Demo - Demonstrating pluggable backends\n"
    "\n"
    " Shows how to:\n"
    " 1. Auto-select the best available backend\n"
    " 2. Explicitly choose a specific backend\n"
    " 3. Compare performance across backends\n"
    "\n"
    " Execute: gleam run -m examples/backend_demo\n"
).

-file("src/viva_tensor/examples/backend.gleam", 208).
-spec benchmark_backend(
    viva_tensor@backend@protocol:backend(),
    list(float()),
    list(float()),
    integer(),
    integer(),
    integer()
) -> {float(), boolean()}.
benchmark_backend(B, A, B_data, M, N, K) ->
    Start = viva_tensor@core@ffi:now_microseconds(),
    Result = viva_tensor@backend@protocol:matmul(B, A, B_data, M, N, K),
    End = viva_tensor@core@ffi:now_microseconds(),
    Time = erlang:float(End - Start) / 1000.0,
    {Time, gleam@result:is_ok(Result)}.

-file("src/viva_tensor/examples/backend.gleam", 244).
-spec random_floats(integer()) -> list(float()).
random_floats(N) ->
    _pipe = gleam@list:range(0, N - 1),
    gleam@list:map(_pipe, fun(_) -> viva_tensor@core@ffi:random_uniform() end).

-file("src/viva_tensor/examples/backend.gleam", 261).
-spec float_to_str(float()) -> binary().
float_to_str(F) ->
    Rounded = begin
        _pipe = erlang:round(F * 100.0),
        erlang:float(_pipe)
    end,
    Result = Rounded / 100.0,
    gleam_stdlib:float_to_string(Result).

-file("src/viva_tensor/examples/backend.gleam", 249).
-spec format_time(float()) -> binary().
format_time(Ms) ->
    case Ms < 1.0 of
        true ->
            <<(float_to_str(Ms * 1000.0))/binary, " μs"/utf8>>;

        false ->
            case Ms < 1000.0 of
                true ->
                    <<(float_to_str(Ms))/binary, " ms"/utf8>>;

                false ->
                    <<(float_to_str(Ms / 1000.0))/binary, " s"/utf8>>
            end
    end.

-file("src/viva_tensor/examples/backend.gleam", 276).
-spec repeat_string(binary(), integer()) -> binary().
repeat_string(S, N) ->
    case N =< 0 of
        true ->
            <<""/utf8>>;

        false ->
            <<S/binary, (repeat_string(S, N - 1))/binary>>
    end.

-file("src/viva_tensor/examples/backend.gleam", 267).
-spec pad_right(binary(), integer()) -> binary().
pad_right(S, Width) ->
    Len = string:length(S),
    Padding = Width - Len,
    case Padding > 0 of
        true ->
            <<S/binary, (repeat_string(<<" "/utf8>>, Padding))/binary>>;

        false ->
            S
    end.

-file("src/viva_tensor/examples/backend.gleam", 224).
-spec print_backend_row(binary(), float(), boolean()) -> nil.
print_backend_row(Name, Time, Ok) ->
    Time_str = case Time > +0.0 of
        true ->
            format_time(Time);

        false ->
            <<"N/A"/utf8>>
    end,
    Result_str = case Ok of
        true ->
            <<"✓ OK"/utf8>>;

        false ->
            <<"✗ Error/N/A"/utf8>>
    end,
    gleam_stdlib:println(
        <<<<<<<<<<<<"  │ "/utf8, (pad_right(Name, 18))/binary>>/binary,
                            " │ "/utf8>>/binary,
                        (pad_right(Time_str, 12))/binary>>/binary,
                    " │ "/utf8>>/binary,
                (pad_right(Result_str, 12))/binary>>/binary,
            " │"/utf8>>
    ).

-file("src/viva_tensor/examples/backend.gleam", 22).
-spec main() -> nil.
main() ->
    gleam_stdlib:println(<<""/utf8>>),
    gleam_stdlib:println(
        <<"╔═══════════════════════════════════════════════════════════════════════════╗"/utf8>>
    ),
    gleam_stdlib:println(
        <<"║              viva_tensor - BACKEND PROTOCOL DEMO                          ║"/utf8>>
    ),
    gleam_stdlib:println(
        <<"║          Pluggable computation backends for BEAM                          ║"/utf8>>
    ),
    gleam_stdlib:println(
        <<"╚═══════════════════════════════════════════════════════════════════════════╝"/utf8>>
    ),
    gleam_stdlib:println(<<""/utf8>>),
    gleam_stdlib:println(<<"━━━ AVAILABLE BACKENDS ━━━"/utf8>>),
    gleam_stdlib:println(<<""/utf8>>),
    Backends = [pure, accelerate, zig, {distributed, []}],
    gleam@list:each(
        Backends,
        fun(B) ->
            Status = case viva_tensor@backend@protocol:is_available(B) of
                true ->
                    <<"✓ Available"/utf8>>;

                false ->
                    <<"✗ Not available"/utf8>>
            end,
            gleam_stdlib:println(
                <<<<<<"  "/utf8, (viva_tensor@backend@protocol:name(B))/binary>>/binary,
                        ": "/utf8>>/binary,
                    Status/binary>>
            ),
            case viva_tensor@backend@protocol:is_available(B) of
                true ->
                    gleam_stdlib:println(
                        <<"    └─ "/utf8,
                            (viva_tensor@backend@protocol:info(B))/binary>>
                    );

                false ->
                    nil
            end
        end
    ),
    gleam_stdlib:println(<<""/utf8>>),
    Best = viva_tensor@backend@protocol:auto_select(),
    gleam_stdlib:println(<<"━━━ AUTO-SELECTED BACKEND ━━━"/utf8>>),
    gleam_stdlib:println(
        <<"  Best available: "/utf8,
            (viva_tensor@backend@protocol:name(Best))/binary>>
    ),
    gleam_stdlib:println(
        <<"  Info: "/utf8, (viva_tensor@backend@protocol:info(Best))/binary>>
    ),
    gleam_stdlib:println(<<""/utf8>>),
    gleam_stdlib:println(<<"━━━ MATRIX MULTIPLICATION DEMO ━━━"/utf8>>),
    gleam_stdlib:println(<<""/utf8>>),
    M = 64,
    N = 64,
    K = 64,
    Size_str = <<<<<<<<<<<<(erlang:integer_to_binary(M))/binary, "x"/utf8>>/binary,
                        (erlang:integer_to_binary(K))/binary>>/binary,
                    " @ "/utf8>>/binary,
                (erlang:integer_to_binary(K))/binary>>/binary,
            "x"/utf8>>/binary,
        (erlang:integer_to_binary(N))/binary>>,
    gleam_stdlib:println(<<"  Matrix size: "/utf8, Size_str/binary>>),
    gleam_stdlib:println(<<""/utf8>>),
    A = random_floats(M * K),
    B@1 = random_floats(K * N),
    gleam_stdlib:println(
        <<"  ┌────────────────────┬──────────────┬──────────────┐"/utf8>>
    ),
    gleam_stdlib:println(
        <<"  │ Backend            │ Time         │ Result       │"/utf8>>
    ),
    gleam_stdlib:println(
        <<"  ├────────────────────┼──────────────┼──────────────┤"/utf8>>
    ),
    {Pure_time, Pure_ok} = benchmark_backend(pure, A, B@1, M, N, K),
    print_backend_row(<<"Pure Erlang"/utf8>>, Pure_time, Pure_ok),
    case viva_tensor@backend@protocol:is_available(accelerate) of
        true ->
            {Acc_time, Acc_ok} = benchmark_backend(accelerate, A, B@1, M, N, K),
            print_backend_row(<<"Apple Accelerate"/utf8>>, Acc_time, Acc_ok);

        false ->
            print_backend_row(<<"Apple Accelerate"/utf8>>, +0.0, false)
    end,
    case viva_tensor@backend@protocol:is_available(zig) of
        true ->
            {Zig_time, Zig_ok} = benchmark_backend(zig, A, B@1, M, N, K),
            print_backend_row(<<"Zig SIMD"/utf8>>, Zig_time, Zig_ok);

        false ->
            print_backend_row(<<"Zig SIMD"/utf8>>, +0.0, false)
    end,
    gleam_stdlib:println(
        <<"  └────────────────────┴──────────────┴──────────────┘"/utf8>>
    ),
    gleam_stdlib:println(<<""/utf8>>),
    gleam_stdlib:println(<<"━━━ DOT PRODUCT DEMO ━━━"/utf8>>),
    gleam_stdlib:println(<<""/utf8>>),
    Vec_size = 10000,
    Vec_a = random_floats(Vec_size),
    Vec_b = random_floats(Vec_size),
    gleam_stdlib:println(
        <<"  Vector size: "/utf8, (erlang:integer_to_binary(Vec_size))/binary>>
    ),
    gleam_stdlib:println(<<""/utf8>>),
    Dot_start = viva_tensor@core@ffi:now_microseconds(),
    Dot_result = viva_tensor@backend@protocol:dot(Best, Vec_a, Vec_b),
    Dot_end = viva_tensor@core@ffi:now_microseconds(),
    Dot_time = erlang:float(Dot_end - Dot_start) / 1000.0,
    case Dot_result of
        {ok, Value} ->
            gleam_stdlib:println(
                <<<<<<<<<<<<"  Backend: "/utf8,
                                        (viva_tensor@backend@protocol:name(Best))/binary>>/binary,
                                    " → "/utf8>>/binary,
                                (float_to_str(Value))/binary>>/binary,
                            " ("/utf8>>/binary,
                        (format_time(Dot_time))/binary>>/binary,
                    ")"/utf8>>
            );

        {error, _} ->
            gleam_stdlib:println(<<"  Error computing dot product"/utf8>>)
    end,
    gleam_stdlib:println(<<""/utf8>>),
    gleam_stdlib:println(<<"━━━ REDUCTION OPERATIONS ━━━"/utf8>>),
    gleam_stdlib:println(<<""/utf8>>),
    Data = random_floats(100000),
    gleam_stdlib:println(<<"  Data size: 100,000 elements"/utf8>>),
    gleam_stdlib:println(<<""/utf8>>),
    Sum_start = viva_tensor@core@ffi:now_microseconds(),
    Sum_result = viva_tensor@backend@protocol:sum(Best, Data),
    Sum_end = viva_tensor@core@ffi:now_microseconds(),
    Sum_time = erlang:float(Sum_end - Sum_start) / 1000.0,
    case Sum_result of
        {ok, Value@1} ->
            gleam_stdlib:println(
                <<<<<<<<"  Sum: "/utf8, (float_to_str(Value@1))/binary>>/binary,
                            " ("/utf8>>/binary,
                        (format_time(Sum_time))/binary>>/binary,
                    ")"/utf8>>
            );

        {error, _} ->
            gleam_stdlib:println(<<"  Error computing sum"/utf8>>)
    end,
    Scale_start = viva_tensor@core@ffi:now_microseconds(),
    Scale_result = viva_tensor@backend@protocol:scale(
        Best,
        gleam@list:take(Data, 1000),
        2.0
    ),
    Scale_end = viva_tensor@core@ffi:now_microseconds(),
    Scale_time = erlang:float(Scale_end - Scale_start) / 1000.0,
    case Scale_result of
        {ok, _} ->
            gleam_stdlib:println(
                <<"  Scale (×2.0, 1000 elements): "/utf8,
                    (format_time(Scale_time))/binary>>
            );

        {error, _} ->
            gleam_stdlib:println(<<"  Error computing scale"/utf8>>)
    end,
    gleam_stdlib:println(<<""/utf8>>),
    gleam_stdlib:println(
        <<"═══════════════════════════════════════════════════════════════════════════"/utf8>>
    ),
    gleam_stdlib:println(<<"                         DEMO COMPLETE!"/utf8>>),
    gleam_stdlib:println(
        <<"═══════════════════════════════════════════════════════════════════════════"/utf8>>
    ).