package chat

import (
	"context"
	"strings"
	"testing"

	"trankilou.fr/lassistanoque/backend/internal/domain"
)

type fakeEngine struct{ summary string }

func (f *fakeEngine) ListProviderTypes() []domain.Item { return nil }
func (f *fakeEngine) ListModelsFromProvider(ctx context.Context, p *domain.Provider) ([]string, error) {
	return nil, nil
}
func (f *fakeEngine) Stream(ctx context.Context, p *domain.Provider, m string, params *domain.LLMParams, msgs []*domain.Message) *domain.Message {
	return &domain.Message{}
}
func (f *fakeEngine) Generate(ctx context.Context, p *domain.Provider, m string, msgs []*domain.Message) (string, error) {
	return f.summary, nil
}

func mk(role, content string) *domain.Message {
	return &domain.Message{Role: role, Content: content}
}

func TestEstimateTokens(t *testing.T) {
	if got := estimateTokens(""); got != 0 {
		t.Errorf("empty = %d", got)
	}
	if got := estimateTokens("abcd"); got != 1 {
		t.Errorf("abcd = %d", got)
	}
	if got := estimateTokens("abcde"); got != 2 {
		t.Errorf("abcde = %d", got)
	}
}

func TestShouldCompactThreshold(t *testing.T) {
	s := &ChatSession{
		messages:          []*domain.Message{mk(string(domain.RoleUser), strings.Repeat("a", 320))}, // 80 tokens
		contextMaxTokens:  100,
		maxResponseTokens: 20,
	}
	if !s.shouldCompact("system") { // 80 + 1 >= 100-20
		t.Errorf("should compact at contextMax - maxResponse boundary")
	}
	s.maxResponseTokens = 40
	s.contextMaxTokens = 130 // seuil 130-40=90 > 82 : pas de compaction
	if s.shouldCompact("system") {
		t.Errorf("should not compact below threshold")
	}
}

func TestCompactContext(t *testing.T) {
	s := &ChatSession{
		provider:          &domain.Provider{},
		llmEngine:         &fakeEngine{summary: "resume des echanges"},
		contextMaxTokens:  100,
		maxResponseTokens: 10,
		messages: []*domain.Message{
			mk(string(domain.RoleUser), "ancienne question 1"),
			mk(string(domain.RoleAssistant), "ancienne reponse 1"),
			mk(string(domain.RoleUser), "question courante"),
			mk(string(domain.RoleAssistant), "reponse courante"),
		},
	}

	s.compactContext(context.Background())

	if len(s.messages) != 3 {
		t.Fatalf("expected 3 messages after compaction, got %d", len(s.messages))
	}
	if !strings.Contains(s.messages[0].Content, "resume des echanges") {
		t.Errorf("first message should be the summary, got %q", s.messages[0].Content)
	}
	if s.messages[0].Role != string(domain.RoleUser) {
		t.Errorf("summary role = %s", s.messages[0].Role)
	}
	if s.messages[1].Content != "question courante" || s.messages[2].Content != "reponse courante" {
		t.Errorf("tail not preserved: %v", s.messages)
	}
}

func TestCompactContextNoUserCut(t *testing.T) {
	s := &ChatSession{
		messages: []*domain.Message{
			mk(string(domain.RoleUser), "seule question"),
			mk(string(domain.RoleAssistant), "reponse"),
		},
	}
	s.compactContext(context.Background())
	if len(s.messages) != 2 {
		t.Errorf("nothing to compact, expected 2 messages, got %d", len(s.messages))
	}
}