package api

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"testing"
	"time"

	"github.com/kami/hexis/internal/domain"
	"github.com/kami/hexis/internal/execution"
	"github.com/kami/hexis/internal/provider"
	"github.com/kami/hexis/internal/storage"
)

func newTestHandler(t *testing.T) (*Handler, *storage.Store) {
	t.Helper()
	path := filepath.Join(t.TempDir(), "hexis.db")
	store, err := storage.Open(path)
	if err != nil {
		t.Fatalf("open store: %v", err)
	}
	t.Cleanup(func() { store.Close() })
	engine := execution.New(store, provider.NewRegistry())
	return NewHandler(store, engine), store
}

// TestHandleChanges_SinceFiltersEvents verifies the `since` query param
// actually filters to events after that sequence number, rather than being
// silently reset to 0 (the bug: `since = 0` unconditionally, ignoring the
// parsed value).
func TestHandleChanges_SinceFiltersEvents(t *testing.T) {
	h, store := newTestHandler(t)

	for i := 0; i < 3; i++ {
		if err := store.AppendEvent(&domain.Event{
			ID:        domain.NewEventID(),
			Type:      domain.EventCapabilityRegistered,
			Timestamp: time.Now().UTC(),
		}); err != nil {
			t.Fatalf("append event %d: %v", i, err)
		}
	}

	all, err := store.EventsAfter(0, 100)
	if err != nil {
		t.Fatalf("events after 0: %v", err)
	}
	if len(all) != 3 {
		t.Fatalf("expected 3 seed events, got %d", len(all))
	}
	cutoff := all[0].Sequence

	req := httptest.NewRequest(http.MethodGet, "/api/v1/changes?since="+itoa(cutoff), nil)
	w := httptest.NewRecorder()
	h.handleChanges(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var events []*domain.Event
	if err := json.Unmarshal(w.Body.Bytes(), &events); err != nil {
		t.Fatalf("decode response: %v", err)
	}
	if len(events) != 2 {
		t.Fatalf("expected 2 events after sequence %d, got %d", cutoff, len(events))
	}
	for _, e := range events {
		if e.Sequence <= cutoff {
			t.Errorf("event with sequence %d should have been excluded by since=%d", e.Sequence, cutoff)
		}
	}
}

func itoa(n int64) string {
	b, _ := json.Marshal(n)
	return string(b)
}