-module(pig@tool@execution).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/pig/tool/execution.gleam").
-export([execute_tool/2]).

-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(
    " Pure tool execution.\n"
    "\n"
    " Looks up a tool in the registry, parses the tool call's JSON arguments\n"
    " into `dynamic.Dynamic`, and calls the handler. Returns structured errors\n"
    " for unknown tools, malformed JSON, or handler failures. Never crashes.\n"
).

-file("src/pig/tool/execution.gleam", 18).
?DOC(
    " Execute a tool call against the registry.\n"
    "\n"
    " Parses `arguments_json` into `dynamic.Dynamic` before passing to the handler.\n"
    " Returns:\n"
    " - `Ok(json.Json)` on successful execution\n"
    " - `Error(ToolError)` for unknown tools, malformed args, or handler errors\n"
).
-spec execute_tool(pig@tool:tool_registry(), pig_protocol@message:tool_call()) -> {ok,
        gleam@json:json()} |
    {error, pig@tool:tool_error()}.
execute_tool(Registry, Call) ->
    case pig@tool:lookup(Registry, erlang:element(3, Call)) of
        {ok, T} ->
            case gleam@json:parse(
                erlang:element(4, Call),
                {decoder, fun gleam@dynamic@decode:decode_dynamic/1}
            ) of
                {ok, Args} ->
                    (erlang:element(3, T))(Args);

                {error, _} ->
                    {error,
                        {tool_error,
                            <<<<"invalid JSON arguments for tool \""/utf8,
                                    (erlang:element(3, Call))/binary>>/binary,
                                "\""/utf8>>}}
            end;

        {error, nil} ->
            {error,
                {tool_error,
                    <<<<"unknown tool \""/utf8,
                            (erlang:element(3, Call))/binary>>/binary,
                        "\""/utf8>>}}
    end.