package handlers

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

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

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

// mockInventoryNetBoxClient implements InventoryNetBoxClient for unit tests.
type mockInventoryNetBoxClient struct {
	listDevices func(ctx context.Context, limit int) ([]netbox.Device, error)
	getDevice   func(ctx context.Context, id int) (*netbox.Device, error)
}

func (m *mockInventoryNetBoxClient) ListDevices(ctx context.Context, limit int) ([]netbox.Device, error) {
	return m.listDevices(ctx, limit)
}

func (m *mockInventoryNetBoxClient) GetDevice(ctx context.Context, id int) (*netbox.Device, error) {
	return m.getDevice(ctx, id)
}

// newInventoryRouter wraps the handler in a chi router with the {id} param registered,
// so chi.URLParam works in tests.
func newInventoryRouter(h *InventoryHandler) http.Handler {
	r := chi.NewRouter()
	r.Get("/api/inventory", h.ListInventory)
	r.Get("/api/inventory/{id}", h.GetInventoryItem)
	return r
}

// TestListInventoryEmpty: mock returns [], handler returns 200 with JSON `[]`.
func TestListInventoryEmpty(t *testing.T) {
	mock := &mockInventoryNetBoxClient{
		listDevices: func(_ context.Context, _ int) ([]netbox.Device, error) {
			return []netbox.Device{}, nil
		},
	}
	h := NewInventoryHandler(mock)
	router := newInventoryRouter(h)

	req := httptest.NewRequest(http.MethodGet, "/api/inventory", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}
	var items []InventoryItemResponse
	if err := json.NewDecoder(w.Body).Decode(&items); err != nil {
		t.Fatalf("decode error: %v", err)
	}
	if len(items) != 0 {
		t.Errorf("expected empty array, got %d items", len(items))
	}
}

// TestListInventoryItems: mock returns 2 devices, handler returns 200 with JSON array of 2 items.
func TestListInventoryItems(t *testing.T) {
	mock := &mockInventoryNetBoxClient{
		listDevices: func(_ context.Context, _ int) ([]netbox.Device, error) {
			return []netbox.Device{
				{
					ID:       1,
					Name:     "Raspberry Pi 4",
					AssetTag: "HW-00001",
					CustomFields: netbox.CustomFields{
						HWID:          "HW-00001",
						CatalogStatus: "indexed",
						PhotoURLs:     []string{"http://example.com/photo1.jpg"},
					},
				},
				{
					ID:       2,
					Name:     "Cisco Switch",
					AssetTag: "HW-00002",
					CustomFields: netbox.CustomFields{
						HWID:          "HW-00002",
						CatalogStatus: "needs_research",
						PhotoURLs:     nil,
					},
				},
			}, nil
		},
	}
	h := NewInventoryHandler(mock)
	router := newInventoryRouter(h)

	req := httptest.NewRequest(http.MethodGet, "/api/inventory", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}
	var items []InventoryItemResponse
	if err := json.NewDecoder(w.Body).Decode(&items); err != nil {
		t.Fatalf("decode error: %v", err)
	}
	if len(items) != 2 {
		t.Fatalf("expected 2 items, got %d", len(items))
	}

	// Check first item fields
	if items[0].HWID != "HW-00001" {
		t.Errorf("item[0] hw_id: expected HW-00001, got %s", items[0].HWID)
	}
	if items[0].Name != "Raspberry Pi 4" {
		t.Errorf("item[0] name: expected 'Raspberry Pi 4', got %s", items[0].Name)
	}
	if items[0].CatalogStatus != "indexed" {
		t.Errorf("item[0] catalog_status: expected indexed, got %s", items[0].CatalogStatus)
	}
	if items[0].AssetTag != "HW-00001" {
		t.Errorf("item[0] asset_tag: expected HW-00001, got %s", items[0].AssetTag)
	}
	if len(items[0].PhotoURLs) != 1 {
		t.Errorf("item[0] photo_urls: expected 1, got %d", len(items[0].PhotoURLs))
	}

	// Second item — nil PhotoURLs should become empty slice in JSON
	if items[1].PhotoURLs == nil {
		t.Errorf("item[1] photo_urls: expected non-nil empty slice, got nil")
	}
}

// TestListInventoryNetBoxError: mock returns error, handler returns 502.
func TestListInventoryNetBoxError(t *testing.T) {
	mock := &mockInventoryNetBoxClient{
		listDevices: func(_ context.Context, _ int) ([]netbox.Device, error) {
			return nil, errors.New("connection refused")
		},
	}
	h := NewInventoryHandler(mock)
	router := newInventoryRouter(h)

	req := httptest.NewRequest(http.MethodGet, "/api/inventory", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusBadGateway {
		t.Fatalf("expected 502, got %d", w.Code)
	}
	var body map[string]string
	if err := json.NewDecoder(w.Body).Decode(&body); err != nil {
		t.Fatalf("decode error: %v", err)
	}
	if body["error"] == "" {
		t.Error("expected non-empty error field")
	}
}

// TestGetInventoryItemFound: mock returns device with id=42, GET /api/inventory/42 returns 200.
func TestGetInventoryItemFound(t *testing.T) {
	mock := &mockInventoryNetBoxClient{
		getDevice: func(_ context.Context, id int) (*netbox.Device, error) {
			if id != 42 {
				t.Errorf("expected id=42, got %d", id)
			}
			return &netbox.Device{
				ID:       42,
				Name:     "Test Device",
				AssetTag: "HW-00042",
				CustomFields: netbox.CustomFields{
					HWID:          "HW-00042",
					CatalogStatus: "indexed",
					AINotes:       "some notes",
					PhotoURLs:     []string{},
				},
			}, nil
		},
	}
	h := NewInventoryHandler(mock)
	router := newInventoryRouter(h)

	req := httptest.NewRequest(http.MethodGet, "/api/inventory/42", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}
	var item InventoryItemResponse
	if err := json.NewDecoder(w.Body).Decode(&item); err != nil {
		t.Fatalf("decode error: %v", err)
	}
	if item.ID != 42 {
		t.Errorf("expected id=42, got %d", item.ID)
	}
	if item.HWID != "HW-00042" {
		t.Errorf("expected hw_id=HW-00042, got %s", item.HWID)
	}
}

// TestGetInventoryItemNotFound: mock returns error containing "404", handler returns 404.
func TestGetInventoryItemNotFound(t *testing.T) {
	mock := &mockInventoryNetBoxClient{
		getDevice: func(_ context.Context, _ int) (*netbox.Device, error) {
			return nil, errors.New("get device 99: 404 not found")
		},
	}
	h := NewInventoryHandler(mock)
	router := newInventoryRouter(h)

	req := httptest.NewRequest(http.MethodGet, "/api/inventory/99", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d", w.Code)
	}
	var body map[string]string
	if err := json.NewDecoder(w.Body).Decode(&body); err != nil {
		t.Fatalf("decode error: %v", err)
	}
	if body["error"] == "" {
		t.Error("expected non-empty error field")
	}
}

// TestGetInventoryItemInvalidID: GET /api/inventory/abc returns 400.
func TestGetInventoryItemInvalidID(t *testing.T) {
	mock := &mockInventoryNetBoxClient{
		getDevice: func(_ context.Context, _ int) (*netbox.Device, error) {
			t.Error("GetDevice should not be called for invalid ID")
			return nil, nil
		},
	}
	h := NewInventoryHandler(mock)
	router := newInventoryRouter(h)

	req := httptest.NewRequest(http.MethodGet, "/api/inventory/abc", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected 400, got %d", w.Code)
	}
	var body map[string]string
	if err := json.NewDecoder(w.Body).Decode(&body); err != nil {
		t.Fatalf("decode error: %v", err)
	}
	if body["error"] == "" {
		t.Error("expected non-empty error field")
	}
}

// TestGetInventoryItemNetBoxError: mock returns server error, handler returns 502.
func TestGetInventoryItemNetBoxError(t *testing.T) {
	mock := &mockInventoryNetBoxClient{
		getDevice: func(_ context.Context, _ int) (*netbox.Device, error) {
			return nil, errors.New("internal server error")
		},
	}
	h := NewInventoryHandler(mock)
	router := newInventoryRouter(h)

	req := httptest.NewRequest(http.MethodGet, "/api/inventory/5", nil)
	w := httptest.NewRecorder()
	router.ServeHTTP(w, req)

	if w.Code != http.StatusBadGateway {
		t.Fatalf("expected 502, got %d", w.Code)
	}
	var body map[string]string
	if err := json.NewDecoder(w.Body).Decode(&body); err != nil {
		t.Fatalf("decode error: %v", err)
	}
	if body["error"] == "" {
		t.Error("expected non-empty error field")
	}
}