-module(viva_tensor@core@error).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/viva_tensor/core/error.gleam").
-export([shape_to_string/1, to_string/1]).
-export_type([tensor_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(
    " Centralized error types for tensor operations.\n"
    "\n"
    " Philosophy: fail fast, fail loud, fail informatively.\n"
    "\n"
    " Each error variant carries enough context to debug the issue without\n"
    " printf-debugging. ShapeMismatch tells you both shapes. IndexOutOfBounds\n"
    " tells you the index AND the size. No more \"index out of bounds\" with no context.\n"
    "\n"
    " Why a single error type instead of operation-specific ones?\n"
    " - Simpler API (one Result type everywhere)\n"
    " - Easy to convert to user-facing messages\n"
    " - Pattern matching still works for specific handling\n"
).

-type tensor_error() :: {shape_mismatch, list(integer()), list(integer())} |
    {invalid_shape, binary()} |
    {dimension_error, binary()} |
    {broadcast_error, list(integer()), list(integer())} |
    {index_out_of_bounds, integer(), integer()} |
    {dtype_error, binary()}.

-file("src/viva_tensor/core/error.gleam", 90).
?DOC(" Pretty-print a shape like [2, 3, 4].\n").
-spec shape_to_string(list(integer())) -> binary().
shape_to_string(Shape) ->
    <<<<"["/utf8,
            (gleam@string:join(
                gleam@list:map(Shape, fun erlang:integer_to_binary/1),
                <<", "/utf8>>
            ))/binary>>/binary,
        "]"/utf8>>.

-file("src/viva_tensor/core/error.gleam", 61).
?DOC(" Human-readable error message. Useful for debugging.\n").
-spec to_string(tensor_error()) -> binary().
to_string(Error) ->
    case Error of
        {shape_mismatch, Expected, Got} ->
            <<<<<<"Shape mismatch: expected "/utf8,
                        (shape_to_string(Expected))/binary>>/binary,
                    ", got "/utf8>>/binary,
                (shape_to_string(Got))/binary>>;

        {invalid_shape, Reason} ->
            <<"Invalid shape: "/utf8, Reason/binary>>;

        {dimension_error, Reason@1} ->
            <<"Dimension error: "/utf8, Reason@1/binary>>;

        {broadcast_error, A, B} ->
            <<<<<<"Cannot broadcast shapes "/utf8, (shape_to_string(A))/binary>>/binary,
                    " and "/utf8>>/binary,
                (shape_to_string(B))/binary>>;

        {index_out_of_bounds, Index, Size} ->
            <<<<<<"Index "/utf8, (erlang:integer_to_binary(Index))/binary>>/binary,
                    " out of bounds for size "/utf8>>/binary,
                (erlang:integer_to_binary(Size))/binary>>;

        {dtype_error, Reason@2} ->
            <<"Dtype error: "/utf8, Reason@2/binary>>
    end.