package llm

import (
	"context"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"git.d-ma.be/mathias/tapir/internal/errkind"
)

// A non-200 from the gateway is an HTTP status error: its kind can be logged and stored
// without its body, which can echo the prompt (adversarial review F3).

func failingGateway(t *testing.T, status int, body string) *httptest.Server {
	t.Helper()
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(status)
		_, _ = w.Write([]byte(body))
	}))
	t.Cleanup(srv.Close)
	return srv
}

func TestClient_ANon200IsAnHTTPStatusErrorWhoseKindCarriesNoBody(t *testing.T) {
	srv := failingGateway(t, http.StatusBadRequest, `{"error":"prompt was: Anders ansvarar för virket"}`)

	_, err := New(srv.URL, "", "m", 5*time.Second).Complete(context.Background(), "s", "u")

	if err == nil {
		t.Fatal("expected an error")
	}
	if got := errkind.Of(err); got != "http_400" {
		t.Errorf("errkind.Of = %q, want http_400", got)
	}
	var he *HTTPError
	if !errors.As(err, &he) || he.Code != http.StatusBadRequest {
		t.Errorf("error is not an *HTTPError with the status code: %v", err)
	}
}

func TestClient_TheErrorTextIsUnchangedForCallersThatLogIt(t *testing.T) {
	srv := failingGateway(t, http.StatusBadGateway, "upstream down")

	_, err := New(srv.URL, "", "m", 5*time.Second).Complete(context.Background(), "s", "u")

	if err == nil || err.Error() != "LLM returned 502: upstream down" {
		t.Errorf("error text = %v: callers that log it already rely on this form", err)
	}
}

func TestClient_AnEnormousErrorBodyIsBoundedInTheErrorText(t *testing.T) {
	srv := failingGateway(t, http.StatusInternalServerError, strings.Repeat("x", 100_000))

	_, err := New(srv.URL, "", "m", 5*time.Second).Complete(context.Background(), "s", "u")

	if err == nil || len(err.Error()) > 1024 {
		t.Errorf("error text is %d bytes: a gateway's whole body must not become an error message", len(err.Error()))
	}
}