package router

import (
	"context"
	"fmt"
	"strings"
	"testing"
	"time"

	"github.com/kami/maven/internal/llm"
)

type mockLLM struct {
	out string
	err error
	got *llm.Req // last request, when the test wants to inspect it
}

func (m mockLLM) Complete(_ context.Context, r llm.Req) (string, error) {
	if m.got != nil {
		*m.got = r
	}
	return m.out, m.err
}

// Without a repeat penalty the model loops inside the text field until MaxTokens
// and the truncated JSON fails to parse.
func TestLLMRouterSetsRepeatPenalty(t *testing.T) {
	var got llm.Req
	lr := NewLLMRouter(mockLLM{out: `{"intent":"chat","text":"привет"}`, got: &got})
	if _, _, err := lr.Route(context.Background(), "привет", time.Now()); err != nil {
		t.Fatalf("route: %v", err)
	}
	if got.RepeatPenalty <= 1 {
		t.Fatalf("want repeat penalty above 1, got %v", got.RepeatPenalty)
	}
}

// An unbounded string rule lets one field eat the whole token budget.
func TestRouteGrammarBoundsStrings(t *testing.T) {
	if !strings.Contains(routeGrammar, `string ::= "\"" ([^"\\] | "\\" .){0,120} "\""`) {
		t.Fatal("grammar string rule lost its length bound")
	}
}

// A question naming a fact key used to be stored as a fact because the fact rule
// was tested first. Keep the query rule above it.
func TestRoutePromptTestsQueryBeforeFact(t *testing.T) {
	query := strings.Index(routeSystem, "→ query")
	fact := strings.Index(routeSystem, "состояние/событие → fact")
	if query < 0 || fact < 0 {
		t.Fatalf("prompt lost a rule: query=%d fact=%d", query, fact)
	}
	if query > fact {
		t.Fatal("query rule must come before the fact rule")
	}
	if !strings.Contains(routeSystem, "Задаёт вопрос") {
		t.Fatal("prompt lost the explicit question test")
	}
}

func TestLLMRouterFactMapping(t *testing.T) {
	lr := NewLLMRouter(mockLLM{out: `{"intent":"fact","key":"water","value":"выпил"}`})
	d, ok, err := lr.Route(context.Background(), "я выпил воду", time.Now())
	if err != nil || !ok {
		t.Fatalf("ok=%v err=%v", ok, err)
	}
	if d.Intent != IntentFact || d.Slots.Key != "water" || !d.Slots.HasKey {
		t.Fatalf("bad decision %+v", d)
	}
}

func TestLLMRouterNoteMapping(t *testing.T) {
	lr := NewLLMRouter(mockLLM{out: `{"intent":"note","text":"кофе закончился"}`})
	d, ok, err := lr.Route(context.Background(), "запомни что кофе закончился", time.Now())
	if err != nil || !ok {
		t.Fatalf("ok=%v err=%v", ok, err)
	}
	if d.Intent != IntentNote || d.Slots.Text != "кофе закончился" {
		t.Fatalf("bad decision %+v", d)
	}
}

func TestLLMRouterBadJSONFallsBack(t *testing.T) {
	lr := NewLLMRouter(mockLLM{out: `garbage`})
	_, ok, err := lr.Route(context.Background(), "x", time.Now())
	if ok || err == nil {
		t.Fatal("want ok=false, err!=nil on bad json")
	}
}

func TestLLMRouterReminderMapping(t *testing.T) {
	lr := NewLLMRouter(mockLLM{out: `{"intent":"reminder","text":"позвонить маме"}`})
	d, ok, err := lr.Route(context.Background(), "напомни позвонить маме", time.Now())
	if err != nil || !ok {
		t.Fatalf("ok=%v err=%v", ok, err)
	}
	if d.Intent != IntentReminder || d.Slots.Text != "позвонить маме" {
		t.Fatalf("bad decision %+v", d)
	}
}

func TestLLMRouterChatFallback(t *testing.T) {
	lr := NewLLMRouter(mockLLM{out: `{"intent":"unknown"}`})
	d, ok, err := lr.Route(context.Background(), "как дела?", time.Now())
	if err != nil || !ok {
		t.Fatalf("ok=%v err=%v", ok, err)
	}
	if d.Intent != IntentChat {
		t.Fatalf("unknown intent should default to chat, got %s", d.Intent)
	}
}

func TestLLMRouterLLMError(t *testing.T) {
	lr := NewLLMRouter(mockLLM{out: "", err: fmt.Errorf("llm down")})
	_, ok, err := lr.Route(context.Background(), "x", time.Now())
	if ok || err == nil {
		t.Fatal("want ok=false, err!=nil on llm error")
	}
}