package handlers

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

	"github.com/go-chi/chi/v5"

	"git.georgsen.dk/hwlab/internal/netbox"
	"git.georgsen.dk/hwlab/internal/usb"
)

// --- mock NetBox client for label tests ---

type mockLabelNetBox struct {
	device *netbox.Device
	err    error
}

func (m *mockLabelNetBox) GetDevice(_ context.Context, id int) (*netbox.Device, error) {
	if m.err != nil {
		return nil, m.err
	}
	return m.device, nil
}

// --- mock printer ---

type mockPrinter struct {
	called  int
	returnErr error
}

func (m *mockPrinter) Print(bitmap []byte, width, height int) error {
	m.called++
	return m.returnErr
}

// --- helper: build chi request with deviceID param ---

func labelRequest(deviceID string) *http.Request {
	r := httptest.NewRequest(http.MethodPost, "/api/labels/"+deviceID+"/print", nil)
	rctx := chi.NewRouteContext()
	rctx.URLParams.Add("deviceID", deviceID)
	return r.WithContext(context.WithValue(r.Context(), chi.RouteCtxKey, rctx))
}

// Test 1: valid device — Print() called once, 200 {"status":"printed"}
func TestLabelPrintSuccess(t *testing.T) {
	dev := &netbox.Device{
		ID:   42,
		Name: "Test Switch",
		CustomFields: netbox.CustomFields{
			HWID: "HW-00042",
		},
	}
	nb := &mockLabelNetBox{device: dev}
	p := &mockPrinter{}
	h := NewLabelHandler(nb, p)

	w := httptest.NewRecorder()
	h.PrintLabel(w, labelRequest("42"))

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}
	var resp map[string]string
	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if resp["status"] != "printed" {
		t.Errorf("expected status=printed, got %q", resp["status"])
	}
	if p.called != 1 {
		t.Errorf("expected Print called once, got %d", p.called)
	}
}

// Test 2: device not found → 404
func TestLabelPrintDeviceNotFound(t *testing.T) {
	nb := &mockLabelNetBox{err: errors.New("404 not found")}
	p := &mockPrinter{}
	h := NewLabelHandler(nb, p)

	w := httptest.NewRecorder()
	h.PrintLabel(w, labelRequest("99"))

	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d", w.Code)
	}
}

// Test 3: printer returns error → 500 with {"error":"..."}
func TestLabelPrintPrinterError(t *testing.T) {
	dev := &netbox.Device{
		ID:   42,
		Name: "Test Switch",
		CustomFields: netbox.CustomFields{
			HWID: "HW-00042",
		},
	}
	nb := &mockLabelNetBox{device: dev}
	p := &mockPrinter{returnErr: errors.New("ink jam")}
	h := NewLabelHandler(nb, p)

	w := httptest.NewRecorder()
	h.PrintLabel(w, labelRequest("42"))

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected 500, got %d: %s", w.Code, w.Body.String())
	}
	body := w.Body.String()
	if !strings.Contains(body, "error") {
		t.Errorf("expected error field in response, got %q", body)
	}
}

// --- USB events tests ---

// mockUSBEventSource is a buffered channel that implements USBEventSource.
type mockUSBEventSource struct {
	ch chan usb.DeviceEvent
}

func newMockUSBEventSource(bufSize int) *mockUSBEventSource {
	return &mockUSBEventSource{ch: make(chan usb.DeviceEvent, bufSize)}
}

func (m *mockUSBEventSource) Events() <-chan usb.DeviceEvent {
	return m.ch
}

// Test 4: GET /api/usb/events sets Content-Type: text/event-stream and
// writes "data: {...}\n\n" on DeviceEvent receive.
func TestUSBEventsSSEContentType(t *testing.T) {
	src := newMockUSBEventSource(1)
	h := NewUSBEventsHandler(src)

	// Send one event, then cancel context.
	evt := usb.DeviceEvent{
		VIDPID: "0525:a4a7",
		Spec:   usb.DeviceSpec{VID: "0525", PID: "a4a7", Name: "PRT Qutie", Role: usb.RolePrinter},
		State:  usb.StateConnected,
	}
	src.ch <- evt

	// Use a context with timeout so the handler exits.
	ctx, cancel := context.WithTimeout(context.Background(), 200*time.Millisecond)
	defer cancel()

	req := httptest.NewRequest(http.MethodGet, "/api/usb/events", nil).WithContext(ctx)
	w := httptest.NewRecorder()
	h.ServeEvents(w, req)

	if ct := w.Header().Get("Content-Type"); !strings.HasPrefix(ct, "text/event-stream") {
		t.Errorf("expected Content-Type text/event-stream, got %q", ct)
	}

	body := w.Body.String()
	if !strings.Contains(body, "data:") {
		t.Errorf("expected SSE data line in body, got: %q", body)
	}
	// Verify JSON contains the VIDPID field.
	if !strings.Contains(body, "0525:a4a7") {
		t.Errorf("expected VIDPID in SSE data, got: %q", body)
	}
}

// Test 5: GET /api/usb/events closes cleanly when client disconnects
// (r.Context() cancels). No goroutine leak.
func TestUSBEventsNoGoroutineLeak(t *testing.T) {
	src := newMockUSBEventSource(0) // unbuffered — no events
	h := NewUSBEventsHandler(src)

	ctx, cancel := context.WithCancel(context.Background())
	req := httptest.NewRequest(http.MethodGet, "/api/usb/events", nil).WithContext(ctx)
	w := httptest.NewRecorder()

	done := make(chan struct{})
	go func() {
		h.ServeEvents(w, req)
		close(done)
	}()

	// Cancel after brief delay to simulate client disconnect.
	time.Sleep(10 * time.Millisecond)
	cancel()

	select {
	case <-done:
		// Handler returned — no goroutine leak.
	case <-time.After(2 * time.Second):
		t.Fatal("handler did not return after context cancellation (goroutine leak)")
	}

	// Verify SSE headers were set before the disconnect.
	if ct := w.Header().Get("Content-Type"); !strings.HasPrefix(ct, "text/event-stream") {
		t.Errorf("expected Content-Type text/event-stream, got %q", ct)
	}

	_ = fmt.Sprintf("body: %s", w.Body.String()) // consume body, no assertion needed
}