-module(oaspec@openapi@diagnostic_format).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/oaspec/openapi/diagnostic_format.gleam").
-export([pointer_to_human/1]).

-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(
    " Human-readable rendering of diagnostic pointer strings. The machine\n"
    " layer — `Diagnostic.pointer` itself — is left untouched so future\n"
    " `--format json` output or any consumer that wants the raw\n"
    " JSON Pointer / dotted path can still read it verbatim. This module\n"
    " only owns the CLI presentation transform.\n"
    "\n"
    " The function is deliberately spec-context free: it never looks a\n"
    " path up in a parsed spec. That is a larger follow-up; here the goal\n"
    " is simply to turn `paths.~1pets.get.parameters.0` into\n"
    " `GET /pets, parameter #0` so a reader does not need to know about\n"
    " JSON Pointer escape rules.\n"
).

-file("src/oaspec/openapi/diagnostic_format.gleam", 56).
?DOC(
    " JSON Pointer unescaping per RFC 6901: `~1` → `/`, `~0` → `~`.\n"
    " Order matters: `~1` must be decoded first so `~01` ends up as `~1`,\n"
    " not `/`.\n"
).
-spec unescape_segment(binary()) -> binary().
unescape_segment(S) ->
    _pipe = S,
    _pipe@1 = gleam@string:replace(_pipe, <<"~1"/utf8>>, <<"/"/utf8>>),
    gleam@string:replace(_pipe@1, <<"~0"/utf8>>, <<"~"/utf8>>).

-file("src/oaspec/openapi/diagnostic_format.gleam", 39).
-spec split_pointer(binary()) -> list(binary()).
split_pointer(Pointer) ->
    _pipe = Pointer,
    _pipe@1 = gleam@string:replace(_pipe, <<"#/"/utf8>>, <<""/utf8>>),
    _pipe@2 = gleam@string:replace(_pipe@1, <<"/"/utf8>>, <<"."/utf8>>),
    _pipe@3 = gleam@string:split(_pipe@2, <<"."/utf8>>),
    _pipe@4 = gleam@list:filter(_pipe@3, fun(S) -> S /= <<""/utf8>> end),
    gleam@list:map(_pipe@4, fun unescape_segment/1).

-file("src/oaspec/openapi/diagnostic_format.gleam", 94).
-spec with_tail(binary(), list(binary())) -> binary().
with_tail(Base, Rest) ->
    case Rest of
        [] ->
            Base;

        _ ->
            <<<<<<Base/binary, " ("/utf8>>/binary,
                    (gleam@string:join(Rest, <<"."/utf8>>))/binary>>/binary,
                ")"/utf8>>
    end.

-file("src/oaspec/openapi/diagnostic_format.gleam", 101).
-spec default_format(list(binary()), binary()) -> binary().
default_format(Segments, Original) ->
    case Segments of
        [] ->
            Original;

        _ ->
            gleam@string:join(Segments, <<"."/utf8>>)
    end.

-file("src/oaspec/openapi/diagnostic_format.gleam", 62).
-spec format_segments(list(binary()), binary()) -> binary().
format_segments(Segments, Original) ->
    case Segments of
        [<<"paths"/utf8>>, Path, Method, <<"parameters"/utf8>>, Idx | Rest] ->
            with_tail(
                <<<<<<<<(string:uppercase(Method))/binary, " "/utf8>>/binary,
                            Path/binary>>/binary,
                        ", parameter #"/utf8>>/binary,
                    Idx/binary>>,
                Rest
            );

        [<<"paths"/utf8>>, Path@1, Method@1, <<"requestBody"/utf8>> | Rest@1] ->
            with_tail(
                <<<<<<(string:uppercase(Method@1))/binary, " "/utf8>>/binary,
                        Path@1/binary>>/binary,
                    ", requestBody"/utf8>>,
                Rest@1
            );

        [<<"paths"/utf8>>,
            Path@2,
            Method@2,
            <<"responses"/utf8>>,
            Status |
            Rest@2] ->
            with_tail(
                <<<<<<<<(string:uppercase(Method@2))/binary, " "/utf8>>/binary,
                            Path@2/binary>>/binary,
                        ", response "/utf8>>/binary,
                    Status/binary>>,
                Rest@2
            );

        [<<"paths"/utf8>>, Path@3, Method@3 | Rest@3] ->
            with_tail(
                <<<<(string:uppercase(Method@3))/binary, " "/utf8>>/binary,
                    Path@3/binary>>,
                Rest@3
            );

        [<<"components"/utf8>>, <<"schemas"/utf8>>, Name | Rest@4] ->
            with_tail(<<"schemas."/utf8, Name/binary>>, Rest@4);

        [<<"components"/utf8>>, <<"parameters"/utf8>>, Name@1 | Rest@5] ->
            with_tail(<<"parameters."/utf8, Name@1/binary>>, Rest@5);

        [<<"components"/utf8>>, <<"responses"/utf8>>, Name@2 | Rest@6] ->
            with_tail(<<"responses."/utf8, Name@2/binary>>, Rest@6);

        [<<"components"/utf8>>, <<"requestBodies"/utf8>>, Name@3 | Rest@7] ->
            with_tail(<<"requestBodies."/utf8, Name@3/binary>>, Rest@7);

        [<<"components"/utf8>>, Kind, Name@4 | Rest@8] ->
            with_tail(
                <<<<Kind/binary, "."/utf8>>/binary, Name@4/binary>>,
                Rest@8
            );

        _ ->
            default_format(Segments, Original)
    end.

-file("src/oaspec/openapi/diagnostic_format.gleam", 32).
?DOC(
    " Translate a diagnostic pointer into a human-readable location string.\n"
    "\n"
    " Recognised shapes:\n"
    " - `paths.<escaped>.<method>.parameters.<idx>[...]`\n"
    "   → `METHOD /path, parameter #idx[...]`\n"
    " - `paths.<escaped>.<method>.requestBody[...]`\n"
    "   → `METHOD /path, requestBody[...]`\n"
    " - `paths.<escaped>.<method>.responses.<status>[...]`\n"
    "   → `METHOD /path, response <status>[...]`\n"
    " - `paths.<escaped>.<method>[...]`\n"
    "   → `METHOD /path[...]`\n"
    " - `components.<kind>.<name>[...]`\n"
    "   → `<kind>.<name>[...]`\n"
    "\n"
    " Falls back to the escape-decoded pointer if no pattern matches, so\n"
    " callers always get *something* intelligible.\n"
).
-spec pointer_to_human(binary()) -> binary().
pointer_to_human(Pointer) ->
    case Pointer of
        <<""/utf8>> ->
            <<"root"/utf8>>;

        _ ->
            format_segments(split_pointer(Pointer), Pointer)
    end.