1:- module(llm, [llm/2]).

   21:- use_module(library(error)).   22:- use_module(library(apply)).   23:- use_module(library(http/http_client)).   24:- use_module(library(http/http_json)).   25:- use_module(library(http/http_ssl_plugin)).

 llm(+Input, -Output) is det

Send Input as a prompt to the configured LLM endpoint and unify Output with the assistant's response text.

   32llm(Input, Output) :-
   33    (   var(Input)
   34    ->  ensure_prompt(Output, Target),
   35        generate_prompt(Target, Prompt),
   36        Input = Prompt,
   37        constrained_prompt(Target, Prompt, PromptWithConstraint),
   38        llm_prompt_text(PromptWithConstraint, Text),
   39        unify_text(Text, Output)
   40    ;   llm_prompt_text(Input, Text),
   41        unify_text(Text, Output)
   42    ).
   43
   44llm_prompt_text(Input, Text) :-
   45    ensure_prompt(Input, Prompt),
   46    llm_request_body(Prompt, Body),
   47    llm_post_json(Body, Response),
   48    llm_extract_text(Response, Text).
   49
   50ensure_prompt(Input, Prompt) :-
   51    (   string(Input)
   52    ->  Prompt = Input
   53    ;   atom(Input)
   54    ->  atom_string(Input, Prompt)
   55    ;   is_list(Input)
   56    ->  string_codes(Prompt, Input)
   57    ;   throw(error(type_error(text, Input), _))
   58    ).
   59
   60llm_request_body(Prompt, _{model:Model, messages:[_{role:'user', content:Prompt}]}) :-
   61    llm_model(Model).
   62
   63llm_model(Model) :-
   64    (   getenv('LLM_MODEL', Raw), Raw \= ''
   65    ->  ensure_string(Raw, Model)
   66    ;   Model = "gpt-4o-mini"
   67    ).
   68
   69llm_post_json(Body, Response) :-
   70    llm_endpoint(URL),
   71    llm_auth_header(Header),
   72    llm_timeout(Timeout),
   73    Options = [
   74        request_header('Authorization'=Header),
   75        accept(json),
   76        timeout(Timeout),
   77        json_object(dict),
   78        status_error(false),
   79        status_code(Status)
   80    ],
   81    catch(
   82        http_post(URL, json(Body), Data, Options),
   83        Error,
   84        throw(error(llm_request_failed(Error), _))
   85    ),
   86    handle_status(Status, Data, Response).
   87
   88handle_status(Status, Data, Response) :-
   89    between(200, 299, Status),
   90    !,
   91    Response = Data.
   92handle_status(Status, Data, _) :-
   93    throw(error(llm_http_error(Status, Data), _)).
   94
   95unify_text(Text, Output) :-
   96    (   var(Output)
   97    ->  Output = Text
   98    ;   ensure_prompt(Output, Expected),
   99        Expected = Text
  100    ).
  101
  102generate_prompt(Target, Prompt) :-
  103    format(string(Request),
  104           "Provide a single user prompt that would make you reply with the exact text \"~w\". Return only the prompt.",
  105           [Target]),
  106    llm_prompt_text(Request, Suggestion),
  107    ensure_prompt(Suggestion, Prompt).
  108
  109constrained_prompt(Target, Prompt, FinalPrompt) :-
  110    format(string(FinalPrompt),
  111           "You must answer ONLY with the exact text \"~w\" (case sensitive, no punctuation or extra words). Now respond to the following prompt:\n\n~w",
  112           [Target, Prompt]).
  113
  114llm_endpoint(URL) :-
  115    (   getenv('LLM_API_URL', URL), URL \= ''
  116    ->  true
  117    ;   throw(error(existence_error(environment_variable, 'LLM_API_URL'), _))
  118    ).
  119
  120llm_auth_header(Header) :-
  121    (   getenv('LLM_API_KEY', Key), Key \= ''
  122    ->  ensure_string(Key, KeyStr),
  123        format(string(Header), 'Bearer ~w', [KeyStr])
  124    ;   throw(error(existence_error(environment_variable, 'LLM_API_KEY'), _))
  125    ).
  126
  127llm_timeout(Timeout) :-
  128    (   getenv('LLM_API_TIMEOUT', Raw), Raw \= '',
  129        catch(number_string(Timeout, Raw), _, fail)
  130    ->  true
  131    ;   Timeout = 60
  132    ).
  133
  134llm_extract_text(Response, Output) :-
  135    (   _{choices:[First|_]} :< Response
  136    ->  extract_choice_text(First, Output0)
  137    ;   (   get_dict(output, Response, Output0)
  138        ;   get_dict(response, Response, Output0)
  139        )
  140    ),
  141    ensure_string(Output0, Output),
  142    !.
  143llm_extract_text(Response, _) :-
  144    throw(error(domain_error(llm_response, Response), _)).
  145
  146extract_choice_text(Choice, Text) :-
  147    (   get_dict(message, Choice, Message),
  148        get_dict(content, Message, Content)
  149    ->  normalize_content(Content, Text)
  150    ;   get_dict(text, Choice, Text)
  151    ).
  152
  153normalize_content(Content, Text) :-
  154    (   string(Content)
  155    ->  Text = Content
  156    ;   is_list(Content)
  157    ->  maplist(segment_text, Content, Segments),
  158        atomics_to_string(Segments, Text)
  159    ;   atom(Content)
  160    ->  atom_string(Content, Text)
  161    ;   throw(error(type_error(llm_content, Content), _))
  162    ).
  163
  164segment_text(Dict, Text) :-
  165    (   is_dict(Dict),
  166        get_dict(type, Dict, 'text'),
  167        get_dict(text, Dict, Text0)
  168    ->  ensure_string(Text0, Text)
  169    ;   ensure_string(Dict, Text)
  170    ).
  171
  172ensure_string(Value, Text) :-
  173    (   string(Value)
  174    ->  Text = Value
  175    ;   atom(Value)
  176    ->  atom_string(Value, Text)
  177    ;   is_list(Value)
  178    ->  string_codes(Text, Value)
  179    ;   throw(error(type_error(text, Value), _))
  180    )