package handler

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

	"github.com/shankar0123/certctl/internal/domain"
)

// MockNotificationService is a mock implementation of NotificationService interface.
type MockNotificationService struct {
	ListNotificationsFn         func(page, perPage int) ([]domain.NotificationEvent, int64, error)
	ListNotificationsByStatusFn func(status string, page, perPage int) ([]domain.NotificationEvent, int64, error)
	GetNotificationFn           func(id string) (*domain.NotificationEvent, error)
	MarkAsReadFn                func(id string) error
	RequeueFn                   func(id string) error
}

func (m *MockNotificationService) ListNotifications(_ context.Context, page, perPage int) ([]domain.NotificationEvent, int64, error) {
	if m.ListNotificationsFn != nil {
		return m.ListNotificationsFn(page, perPage)
	}
	return nil, 0, nil
}

func (m *MockNotificationService) ListNotificationsByStatus(_ context.Context, status string, page, perPage int) ([]domain.NotificationEvent, int64, error) {
	if m.ListNotificationsByStatusFn != nil {
		return m.ListNotificationsByStatusFn(status, page, perPage)
	}
	return nil, 0, nil
}

func (m *MockNotificationService) GetNotification(_ context.Context, id string) (*domain.NotificationEvent, error) {
	if m.GetNotificationFn != nil {
		return m.GetNotificationFn(id)
	}
	return nil, nil
}

func (m *MockNotificationService) MarkAsRead(_ context.Context, id string) error {
	if m.MarkAsReadFn != nil {
		return m.MarkAsReadFn(id)
	}
	return nil
}

func (m *MockNotificationService) RequeueNotification(_ context.Context, id string) error {
	if m.RequeueFn != nil {
		return m.RequeueFn(id)
	}
	return nil
}

func TestListNotifications_Success(t *testing.T) {
	now := time.Now()
	certID := "mc-prod-001"
	n1 := domain.NotificationEvent{
		ID:            "notif-001",
		Type:          domain.NotificationTypeExpirationWarning,
		CertificateID: &certID,
		Channel:       domain.NotificationChannelEmail,
		Recipient:     "admin@example.com",
		Message:       "Certificate expiring in 30 days",
		Status:        "sent",
		CreatedAt:     now,
	}
	n2 := domain.NotificationEvent{
		ID:            "notif-002",
		Type:          domain.NotificationTypeRenewalSuccess,
		CertificateID: &certID,
		Channel:       domain.NotificationChannelWebhook,
		Recipient:     "https://hooks.example.com/cert",
		Message:       "Certificate renewed successfully",
		Status:        "sent",
		CreatedAt:     now,
	}

	mock := &MockNotificationService{
		ListNotificationsFn: func(page, perPage int) ([]domain.NotificationEvent, int64, error) {
			return []domain.NotificationEvent{n1, n2}, 2, nil
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.ListNotifications(w, req)

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

	var resp PagedResponse
	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
		t.Fatalf("failed to decode response: %v", err)
	}
	if resp.Total != 2 {
		t.Errorf("expected total 2, got %d", resp.Total)
	}
}

func TestListNotifications_Pagination(t *testing.T) {
	var capturedPage, capturedPerPage int
	mock := &MockNotificationService{
		ListNotificationsFn: func(page, perPage int) ([]domain.NotificationEvent, int64, error) {
			capturedPage = page
			capturedPerPage = perPage
			return []domain.NotificationEvent{}, 0, nil
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications?page=2&per_page=10", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.ListNotifications(w, req)

	if capturedPage != 2 {
		t.Errorf("expected page 2, got %d", capturedPage)
	}
	if capturedPerPage != 10 {
		t.Errorf("expected per_page 10, got %d", capturedPerPage)
	}
}

func TestListNotifications_ServiceError(t *testing.T) {
	mock := &MockNotificationService{
		ListNotificationsFn: func(page, perPage int) ([]domain.NotificationEvent, int64, error) {
			return nil, 0, ErrMockServiceFailed
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.ListNotifications(w, req)

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected status 500, got %d", w.Code)
	}
}

func TestListNotifications_MethodNotAllowed(t *testing.T) {
	handler := NewNotificationHandler(&MockNotificationService{})
	req := httptest.NewRequest(http.MethodPost, "/api/v1/notifications", nil)
	w := httptest.NewRecorder()

	handler.ListNotifications(w, req)

	if w.Code != http.StatusMethodNotAllowed {
		t.Fatalf("expected status 405, got %d", w.Code)
	}
}

func TestGetNotification_Success(t *testing.T) {
	now := time.Now()
	certID := "mc-prod-001"
	mock := &MockNotificationService{
		GetNotificationFn: func(id string) (*domain.NotificationEvent, error) {
			return &domain.NotificationEvent{
				ID:            id,
				Type:          domain.NotificationTypeExpirationWarning,
				CertificateID: &certID,
				Channel:       domain.NotificationChannelEmail,
				Recipient:     "admin@example.com",
				Message:       "Certificate expiring",
				Status:        "sent",
				CreatedAt:     now,
			}, nil
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications/notif-001", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.GetNotification(w, req)

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

func TestGetNotification_NotFound(t *testing.T) {
	mock := &MockNotificationService{
		GetNotificationFn: func(id string) (*domain.NotificationEvent, error) {
			return nil, ErrMockNotFound
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications/nonexistent", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.GetNotification(w, req)

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

func TestGetNotification_EmptyID(t *testing.T) {
	handler := NewNotificationHandler(&MockNotificationService{})
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications/", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.GetNotification(w, req)

	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected status 400, got %d", w.Code)
	}
}

func TestMarkAsRead_Success(t *testing.T) {
	var markedID string
	mock := &MockNotificationService{
		MarkAsReadFn: func(id string) error {
			markedID = id
			return nil
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodPost, "/api/v1/notifications/notif-001/read", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.MarkAsRead(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected status 200, got %d", w.Code)
	}
	if markedID != "notif-001" {
		t.Errorf("expected marked ID 'notif-001', got '%s'", markedID)
	}

	var resp map[string]string
	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
		t.Fatalf("failed to decode response: %v", err)
	}
	if resp["status"] != "marked_as_read" {
		t.Errorf("expected status 'marked_as_read', got '%s'", resp["status"])
	}
}

func TestMarkAsRead_ServiceError(t *testing.T) {
	mock := &MockNotificationService{
		MarkAsReadFn: func(id string) error {
			return ErrMockServiceFailed
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodPost, "/api/v1/notifications/notif-001/read", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.MarkAsRead(w, req)

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected status 500, got %d", w.Code)
	}
}

func TestMarkAsRead_MethodNotAllowed(t *testing.T) {
	handler := NewNotificationHandler(&MockNotificationService{})
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications/notif-001/read", nil)
	w := httptest.NewRecorder()

	handler.MarkAsRead(w, req)

	if w.Code != http.StatusMethodNotAllowed {
		t.Fatalf("expected status 405, got %d", w.Code)
	}
}

func TestMarkAsRead_EmptyID(t *testing.T) {
	handler := NewNotificationHandler(&MockNotificationService{})
	req := httptest.NewRequest(http.MethodPost, "/api/v1/notifications//read", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.MarkAsRead(w, req)

	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected status 400, got %d", w.Code)
	}
}

// ---------------------------------------------------------------------------
// I-005: Notification Retry + Dead-Letter Queue handler contract (Phase 1 Red)
//
// These tests pin the HTTP surface Phase 2 Green must implement:
//
//   1. POST /api/v1/notifications/{id}/requeue — flips a dead notification
//      back to 'pending' so the retry loop can pick it up again. The handler
//      method does not exist yet (NotificationHandler has no RequeueNotification
//      method) and the NotificationService interface does not declare
//      RequeueNotification — both are compile-time Red halts.
//
//   2. GET /api/v1/notifications?status=dead — routes dead-letter list requests
//      through ListNotificationsByStatus instead of ListNotifications. The
//      status-filter routing does not exist yet, so ListNotificationsByStatusFn
//      never fires — a runtime Red halt.
// ---------------------------------------------------------------------------

func TestRequeueNotification_Success(t *testing.T) {
	var requeuedID string
	mock := &MockNotificationService{
		RequeueFn: func(id string) error {
			requeuedID = id
			return nil
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodPost, "/api/v1/notifications/notif-dead-001/requeue", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.RequeueNotification(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected status 200, got %d", w.Code)
	}
	if requeuedID != "notif-dead-001" {
		t.Errorf("expected requeued ID 'notif-dead-001', got '%s'", requeuedID)
	}

	var resp map[string]string
	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
		t.Fatalf("failed to decode response: %v", err)
	}
	if resp["status"] != "requeued" {
		t.Errorf("expected status 'requeued', got '%s'", resp["status"])
	}
}

func TestRequeueNotification_NotFound(t *testing.T) {
	mock := &MockNotificationService{
		RequeueFn: func(id string) error {
			return ErrMockNotFound
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodPost, "/api/v1/notifications/nonexistent/requeue", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.RequeueNotification(w, req)

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

func TestRequeueNotification_ServiceError(t *testing.T) {
	mock := &MockNotificationService{
		RequeueFn: func(id string) error {
			return ErrMockServiceFailed
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodPost, "/api/v1/notifications/notif-dead-001/requeue", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.RequeueNotification(w, req)

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected status 500, got %d", w.Code)
	}
}

func TestRequeueNotification_MethodNotAllowed(t *testing.T) {
	handler := NewNotificationHandler(&MockNotificationService{})
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications/notif-dead-001/requeue", nil)
	w := httptest.NewRecorder()

	handler.RequeueNotification(w, req)

	if w.Code != http.StatusMethodNotAllowed {
		t.Fatalf("expected status 405, got %d", w.Code)
	}
}

func TestRequeueNotification_EmptyID(t *testing.T) {
	handler := NewNotificationHandler(&MockNotificationService{})
	req := httptest.NewRequest(http.MethodPost, "/api/v1/notifications//requeue", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.RequeueNotification(w, req)

	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected status 400, got %d", w.Code)
	}
}

func TestListNotifications_StatusFilter_Dead(t *testing.T) {
	now := time.Now()
	certID := "mc-prod-001"
	lastErr := "SMTP connection refused"
	nextRetry := now.Add(1 * time.Minute)
	dead := domain.NotificationEvent{
		ID:            "notif-dead-001",
		Type:          domain.NotificationTypeExpirationWarning,
		CertificateID: &certID,
		Channel:       domain.NotificationChannelEmail,
		Recipient:     "admin@example.com",
		Message:       "Certificate expiring in 7 days",
		Status:        "dead",
		CreatedAt:     now,
		RetryCount:    5,
		NextRetryAt:   &nextRetry,
		LastError:     &lastErr,
	}

	var capturedStatus string
	var capturedPage, capturedPerPage int
	byStatusCalled := false
	listCalled := false

	mock := &MockNotificationService{
		ListNotificationsFn: func(page, perPage int) ([]domain.NotificationEvent, int64, error) {
			listCalled = true
			return nil, 0, nil
		},
		ListNotificationsByStatusFn: func(status string, page, perPage int) ([]domain.NotificationEvent, int64, error) {
			byStatusCalled = true
			capturedStatus = status
			capturedPage = page
			capturedPerPage = perPage
			return []domain.NotificationEvent{dead}, 1, nil
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications?status=dead&page=1&per_page=50", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.ListNotifications(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected status 200, got %d", w.Code)
	}
	if !byStatusCalled {
		t.Fatalf("expected ListNotificationsByStatus to be called for ?status=dead, but it was not")
	}
	if listCalled {
		t.Errorf("ListNotifications should not be called when status filter is present")
	}
	if capturedStatus != "dead" {
		t.Errorf("expected status='dead', got '%s'", capturedStatus)
	}
	if capturedPage != 1 {
		t.Errorf("expected page=1, got %d", capturedPage)
	}
	if capturedPerPage != 50 {
		t.Errorf("expected per_page=50, got %d", capturedPerPage)
	}

	var resp PagedResponse
	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
		t.Fatalf("failed to decode response: %v", err)
	}
	if resp.Total != 1 {
		t.Errorf("expected total=1 dead notification, got %d", resp.Total)
	}
}

func TestListNotifications_NoStatusFilter_CallsDefault(t *testing.T) {
	// Pin the inverse: when no ?status= is provided, the handler must call the
	// existing ListNotifications path (not ListNotificationsByStatus). Phase 2
	// Green must not break the default listing behavior for the plain tab.
	listCalled := false
	byStatusCalled := false

	mock := &MockNotificationService{
		ListNotificationsFn: func(page, perPage int) ([]domain.NotificationEvent, int64, error) {
			listCalled = true
			return []domain.NotificationEvent{}, 0, nil
		},
		ListNotificationsByStatusFn: func(status string, page, perPage int) ([]domain.NotificationEvent, int64, error) {
			byStatusCalled = true
			return nil, 0, nil
		},
	}

	handler := NewNotificationHandler(mock)
	req := httptest.NewRequest(http.MethodGet, "/api/v1/notifications", nil)
	req = req.WithContext(contextWithRequestID())
	w := httptest.NewRecorder()

	handler.ListNotifications(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected status 200, got %d", w.Code)
	}
	if !listCalled {
		t.Errorf("expected ListNotifications to be called when no status filter is present")
	}
	if byStatusCalled {
		t.Errorf("ListNotificationsByStatus should not be called when no status filter is present")
	}
}