multipartkit

-module(multipartkit@infer).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/multipartkit/infer.gleam").
-export([default_inferer/0, content_type_from_filename/1, content_type_from_bytes/1]).
-export_type([inferer/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.

-type inferer() :: {inferer,
        fun((binary()) -> gleam@option:option(binary())),
        fun((bitstring()) -> gleam@option:option(binary()))}.

-file("src/multipartkit/infer.gleam", 58).
-spec noop_filename(binary()) -> gleam@option:option(binary()).
noop_filename(_) ->
    none.

-file("src/multipartkit/infer.gleam", 62).
-spec noop_bytes(bitstring()) -> gleam@option:option(binary()).
noop_bytes(_) ->
    none.

-file("src/multipartkit/infer.gleam", 54).
?DOC(
    " Inferer that always returns `None`.\n"
    "\n"
    " `add_file_auto` uses this and therefore always emits\n"
    " `application/octet-stream` unless the host swaps in a real inferer via\n"
    " `add_file_auto_with`.\n"
).
-spec default_inferer() -> inferer().
default_inferer() ->
    {inferer, fun noop_filename/1, fun noop_bytes/1}.

-file("src/multipartkit/infer.gleam", 107).
?DOC(
    " Optional content-type inference from a filename.\n"
    "\n"
    " This is the default no-op of multipartkit's pluggable inference\n"
    " interface: it **always returns `None`** for every input, including\n"
    " well-known extensions like `\"photo.png\"` or `\"doc.pdf\"`. multipartkit\n"
    " deliberately ships no built-in extension table so the library has zero\n"
    " inference dependencies; callers who want real inference wire one in via\n"
    " `form.add_file_auto_with` (the function this helper exists to compose\n"
    " with). Calling this function directly is rarely what you want — it\n"
    " exists mainly so the `Inferer` shape stays uniform whether or not a\n"
    " real inferer is wired in.\n"
    "\n"
    " To get actual inference, build an `Inferer` from `nao1215/mimetype`\n"
    " (or any other inference library) and pass it to\n"
    " `form.add_file_auto_with`:\n"
    "\n"
    " ```gleam\n"
    " import gleam/option.{type Option, None, Some}\n"
    " import mimetype\n"
    " import multipartkit/form\n"
    " import multipartkit/infer.{type Inferer, Inferer}\n"
    "\n"
    " let inferer =\n"
    "   Inferer(\n"
    "     from_filename: fn(name) {\n"
    "       case mimetype.filename_to_mime_type_strict(name) {\n"
    "         Ok(value) -> Some(value)\n"
    "         Error(_) -> None\n"
    "       }\n"
    "     },\n"
    "     from_bytes: fn(body) {\n"
    "       case mimetype.detect_strict(body) {\n"
    "         Ok(value) -> Some(value)\n"
    "         Error(_) -> None\n"
    "       }\n"
    "     },\n"
    "   )\n"
    " form.add_file_auto_with(my_form, \"upload\", \"photo.png\", bytes, inferer)\n"
    " ```\n"
    "\n"
    " See also `examples/mimetype_inference` for a runnable wiring.\n"
).
-spec content_type_from_filename(binary()) -> gleam@option:option(binary()).
content_type_from_filename(Filename) ->
    (erlang:element(2, default_inferer()))(Filename).

-file("src/multipartkit/infer.gleam", 119).
?DOC(
    " Optional content-type inference from a body byte sequence.\n"
    "\n"
    " Same documented default-no-op policy as `content_type_from_filename`:\n"
    " this **always returns `None`** for every input, including well-known\n"
    " magic-byte signatures like the 8-byte PNG header. Wire `nao1215/mimetype`\n"
    " (or another inferer) in via `form.add_file_auto_with` for actual\n"
    " inference — see the docstring on `content_type_from_filename` for a\n"
    " worked example.\n"
).
-spec content_type_from_bytes(bitstring()) -> gleam@option:option(binary()).
content_type_from_bytes(Body) ->
    (erlang:element(3, default_inferer()))(Body).