package app

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"testing"

	"github.com/grafana/grafana-app-sdk/logging"
	"github.com/grafana/grafana-app-sdk/resource"
	advisorv0alpha1 "github.com/grafana/grafana/apps/advisor/pkg/apis/advisor/v0alpha1"
	"github.com/grafana/grafana/apps/advisor/pkg/app/checks"
	"github.com/grafana/grafana/pkg/apimachinery/utils"
	"github.com/grafana/grafana/pkg/services/contexthandler"
	"github.com/grafana/grafana/pkg/services/contexthandler/ctxkey"
	contextmodel "github.com/grafana/grafana/pkg/services/contexthandler/model"
	"github.com/grafana/grafana/pkg/services/user"
	"github.com/grafana/grafana/pkg/web"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestGetCheck(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetLabels(map[string]string{checks.TypeLabel: "testType"})

	checkMap := map[string]checks.Check{
		"testType": &mockCheck{},
	}

	check, err := getCheck(obj, checkMap)
	assert.NoError(t, err)
	assert.NotNil(t, check)
}

func TestGetCheck_MissingLabel(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	checkMap := map[string]checks.Check{}

	_, err := getCheck(obj, checkMap)
	assert.Error(t, err)
	assert.Equal(t, "missing check type as label", err.Error())
}

func TestGetCheck_UnknownType(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetLabels(map[string]string{checks.TypeLabel: "unknownType"})

	checkMap := map[string]checks.Check{
		"testType": &mockCheck{},
	}

	_, err := getCheck(obj, checkMap)
	assert.Error(t, err)
	assert.Contains(t, err.Error(), "unknown check type unknownType")
}

func TestProcessCheck(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{})
	meta, err := utils.MetaAccessor(obj)
	if err != nil {
		t.Fatal(err)
	}
	meta.SetCreatedBy("user:1")
	client := &mockClient{}
	typesClient := &mockTypesClient{}
	ctx := context.TODO()
	check := &mockCheck{
		items: []any{"item"},
	}

	err = processCheck(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.NoError(t, err)
	assert.Equal(t, checks.StatusAnnotationProcessed, obj.GetAnnotations()[checks.StatusAnnotation])
}

func TestProcessMultipleCheckItems(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{})
	meta, err := utils.MetaAccessor(obj)
	if err != nil {
		t.Fatal(err)
	}
	meta.SetCreatedBy("user:1")
	client := &mockClient{}
	typesClient := &mockTypesClient{}
	ctx := context.TODO()
	items := make([]any, 100)
	for i := range items {
		if i%2 == 0 {
			items[i] = fmt.Sprintf("item-%d", i)
		} else {
			items[i] = errors.New("error")
		}
	}
	check := &mockCheck{
		items: items,
	}

	err = processCheck(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.NoError(t, err)
	assert.Equal(t, checks.StatusAnnotationProcessed, obj.GetAnnotations()[checks.StatusAnnotation])
	r := client.values[0].(advisorv0alpha1.CheckStatus)
	assert.Equal(t, r.Report.Count, int64(100))
	assert.Len(t, r.Report.Failures, 50)
}

func TestProcessCheck_AlreadyProcessed(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{checks.StatusAnnotation: checks.StatusAnnotationProcessed})
	client := &mockClient{}
	typesClient := &mockTypesClient{}
	ctx := context.TODO()
	check := &mockCheck{}

	err := processCheck(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.NoError(t, err)
}

func TestProcessCheck_RunError(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{})
	meta, err := utils.MetaAccessor(obj)
	if err != nil {
		t.Fatal(err)
	}
	meta.SetCreatedBy("user:1")
	client := &mockClient{}
	typesClient := &mockTypesClient{}
	ctx := context.TODO()

	check := &mockCheck{
		items: []any{"item"},
		err:   errors.New("run error"),
	}

	err = processCheck(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.Error(t, err)
	assert.Equal(t, checks.StatusAnnotationError, obj.GetAnnotations()[checks.StatusAnnotation])
}

func TestProcessCheck_IgnoreSteps(t *testing.T) {
	checkType := &advisorv0alpha1.CheckType{}
	checkType.SetAnnotations(map[string]string{checks.IgnoreStepsAnnotationList: "mock"})
	typesClient := &mockTypesClient{
		res: checkType,
	}
	ctx := context.TODO()
	check := &mockCheck{
		items: []any{"item"},
		err:   errors.New("run error, should not be triggered"),
	}
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{})
	meta, err := utils.MetaAccessor(obj)
	if err != nil {
		t.Fatal(err)
	}
	meta.SetCreatedBy("user:1")
	client := &mockClient{}

	err = processCheck(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.NoError(t, err)
	assert.Equal(t, checks.StatusAnnotationProcessed, obj.GetAnnotations()[checks.StatusAnnotation])
	assert.Equal(t, "mock", obj.GetAnnotations()[checks.IgnoreStepsAnnotationList])
}

func TestProcessCheck_RunRecoversFromPanic(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{})
	meta, err := utils.MetaAccessor(obj)
	if err != nil {
		t.Fatal(err)
	}
	meta.SetCreatedBy("user:1")
	client := &mockClient{}
	typesClient := &mockTypesClient{}
	ctx := context.TODO()

	check := &mockCheck{
		items:     []any{"item"},
		runPanics: true,
	}

	err = processCheck(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.NoError(t, err)
	assert.Equal(t, checks.StatusAnnotationProcessed, obj.GetAnnotations()[checks.StatusAnnotation])
}

func TestProcessCheckRetry_NoRetry(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{})
	meta, err := utils.MetaAccessor(obj)
	if err != nil {
		t.Fatal(err)
	}
	meta.SetCreatedBy("user:1")
	client := &mockClient{}
	typesClient := &mockTypesClient{}
	ctx := context.TODO()

	check := &mockCheck{}

	err = processCheckRetry(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.NoError(t, err)
}

func TestProcessCheckRetry_RetryError(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{
		checks.RetryAnnotation:  "item",
		checks.StatusAnnotation: checks.StatusAnnotationProcessed,
	})
	meta, err := utils.MetaAccessor(obj)
	if err != nil {
		t.Fatal(err)
	}
	meta.SetCreatedBy("user:1")
	client := &mockClient{}
	typesClient := &mockTypesClient{}
	ctx := context.TODO()

	check := &mockCheck{
		items: []any{"item"},
		err:   errors.New("retry error"),
	}

	err = processCheckRetry(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.Error(t, err)
	assert.Equal(t, checks.StatusAnnotationError, obj.GetAnnotations()[checks.StatusAnnotation])
}

func TestProcessCheckRetry_SkipMissingItem(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{
		checks.RetryAnnotation:  "item",
		checks.StatusAnnotation: checks.StatusAnnotationProcessed,
	})
	obj.Status.Report.Failures = []advisorv0alpha1.CheckReportFailure{
		{
			ItemID: "item",
			StepID: "step",
		},
	}
	meta, err := utils.MetaAccessor(obj)
	if err != nil {
		t.Fatal(err)
	}
	meta.SetCreatedBy("user:1")
	client := &mockClient{}
	typesClient := &mockTypesClient{}
	ctx := context.TODO()

	check := &mockCheck{
		items: []any{nil},
	}

	err = processCheckRetry(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.NoError(t, err)
	assert.Equal(t, checks.StatusAnnotationProcessed, obj.GetAnnotations()[checks.StatusAnnotation])
	assert.Empty(t, obj.GetAnnotations()[checks.RetryAnnotation])
	assert.Empty(t, obj.Status.Report.Failures)
}

func TestProcessCheckRetry_Success(t *testing.T) {
	obj := &advisorv0alpha1.Check{}
	obj.SetAnnotations(map[string]string{
		checks.RetryAnnotation:  "item",
		checks.StatusAnnotation: checks.StatusAnnotationProcessed,
	})
	obj.Status.Report.Failures = []advisorv0alpha1.CheckReportFailure{
		{
			ItemID: "item",
			StepID: "step",
		},
	}
	meta, err := utils.MetaAccessor(obj)
	if err != nil {
		t.Fatal(err)
	}
	meta.SetCreatedBy("user:1")
	client := &mockClient{}
	typesClient := &mockTypesClient{}
	ctx := context.TODO()

	check := &mockCheck{
		items: []any{"item"},
	}

	err = processCheckRetry(ctx, logging.DefaultLogger, client, typesClient, obj, check)
	assert.NoError(t, err)
	assert.Equal(t, checks.StatusAnnotationProcessed, obj.GetAnnotations()[checks.StatusAnnotation])
	assert.Empty(t, obj.GetAnnotations()[checks.RetryAnnotation])
	assert.Empty(t, obj.Status.Report.Failures)
}

func TestRunStepsInParallel_ConcurrentHeaderAccess(t *testing.T) {
	// Create an HTTP request with headers to simulate the real scenario
	req, err := http.NewRequest("GET", "/test", nil)
	require.NoError(t, err)
	req.Header.Set("X-Test-Header", "test-value")
	req.Header.Set("X-Panel-Id", "123")
	req.Header.Set("Cookie", "session=abc123; user_pref=dark")

	// Create a context with ReqContext that includes the HTTP request
	webCtx := &web.Context{
		Req: req,
	}
	reqCtx := &contextmodel.ReqContext{
		Context:      webCtx,
		SignedInUser: &user.SignedInUser{},
	}

	ctx := ctxkey.Set(context.Background(), reqCtx)

	// Create steps that modify headers concurrently (simulating CookiesMiddleware behavior)
	steps := []checks.Step{
		&headerModifyingStep{headerName: "X-Test-Header", headerValue: "modified-1"},
		&headerModifyingStep{headerName: "Cookie", headerValue: "session=xyz456"},
		&headerModifyingStep{headerName: "X-Panel-Id", headerValue: "456"},
	}

	// Create multiple items to process
	const numItems = 20
	items := make([]any, numItems)
	for i := 0; i < numItems; i++ {
		items[i] = fmt.Sprintf("item-%d", i)
	}

	// Track panics that might occur during execution
	var panicCount int32
	originalPanicHandler := func() {
		if r := recover(); r != nil {
			panicCount++
			t.Errorf("Unexpected panic during concurrent header access: %v", r)
		}
	}

	// This test should not panic with our fix
	t.Run("should not panic with concurrent header modifications", func(t *testing.T) {
		defer func() {
			if r := recover(); r != nil {
				originalPanicHandler()
			}
		}()

		failures, err := runStepsInParallel(ctx, logging.DefaultLogger, nil, steps, items)

		// Verify no error occurred
		assert.NoError(t, err)
		// Should have no failures since our mock step doesn't report failures
		assert.Empty(t, failures)
		// Verify no panics occurred
		assert.Equal(t, int32(0), panicCount)
	})
}

type mockClient struct {
	resource.Client
	values []any
}

func (m *mockClient) PatchInto(ctx context.Context, id resource.Identifier, req resource.PatchRequest, opts resource.PatchOptions, obj resource.Object) error {
	value := req.Operations[0].Value
	m.values = append(m.values, value)
	return nil
}

type mockTypesClient struct {
	resource.Client
	res resource.Object
}

func (m *mockTypesClient) Get(ctx context.Context, id resource.Identifier) (resource.Object, error) {
	if m.res == nil {
		return advisorv0alpha1.CheckTypeKind().ZeroValue(), nil
	}
	return m.res, nil
}

type mockCheck struct {
	err       error
	items     []any
	runPanics bool
}

func (m *mockCheck) ID() string {
	return "mock"
}

func (m *mockCheck) Name() string {
	return "Mock"
}

func (m *mockCheck) Items(ctx context.Context) ([]any, error) {
	return m.items, nil
}

func (m *mockCheck) Item(ctx context.Context, id string) (any, error) {
	return m.items[0], nil
}

func (m *mockCheck) Init(ctx context.Context) error {
	return nil
}

func (m *mockCheck) Steps() []checks.Step {
	return []checks.Step{
		&mockStep{err: m.err, panics: m.runPanics},
	}
}

type mockStep struct {
	err    error
	panics bool
}

func (m *mockStep) Run(ctx context.Context, log logging.Logger, obj *advisorv0alpha1.CheckSpec, items any) ([]advisorv0alpha1.CheckReportFailure, error) {
	if m.panics {
		panic("panic")
	}
	if m.err != nil {
		return nil, m.err
	}
	if _, ok := items.(error); ok {
		return []advisorv0alpha1.CheckReportFailure{{}}, nil
	}
	return nil, nil
}

func (m *mockStep) Title() string {
	return "mock"
}

func (m *mockStep) Description() string {
	return "mock"
}

func (m *mockStep) Resolution() string {
	return "mock"
}

func (m *mockStep) ID() string {
	return "mock"
}

// headerModifyingStep is a mock step that modifies HTTP headers to simulate
// the behavior of CookiesMiddleware and other middleware that caused the original panic
type headerModifyingStep struct {
	headerName  string
	headerValue string
}

func (h *headerModifyingStep) Run(ctx context.Context, log logging.Logger, obj *advisorv0alpha1.CheckSpec, item any) ([]advisorv0alpha1.CheckReportFailure, error) {
	// Get the request context and modify headers (this used to cause panics)
	reqCtx := contexthandler.FromContext(ctx)
	if reqCtx != nil && reqCtx.Req != nil {
		// This is the type of header modification that was causing the concurrent map access panic
		reqCtx.Req.Header.Set(h.headerName, h.headerValue)
		reqCtx.Req.Header.Add("X-Processed-By", h.ID())

		// Also test header deletion like ClearCookieHeader does
		if h.headerName == "Cookie" {
			reqCtx.Req.Header.Del("Cookie")
			reqCtx.Req.Header.Set("Cookie", h.headerValue)
		}

		// Test reading headers as well
		_ = reqCtx.Req.Header.Get("X-Test-Header")
		_ = reqCtx.Req.Header.Get("X-Panel-Id")
	}

	// No failures to report
	return nil, nil
}

func (h *headerModifyingStep) Title() string {
	return "Header Modifying Step"
}

func (h *headerModifyingStep) Description() string {
	return "A mock step that modifies HTTP headers to test concurrent access"
}

func (h *headerModifyingStep) Resolution() string {
	return "This is a test step"
}

func (h *headerModifyingStep) ID() string {
	return fmt.Sprintf("header-modifier-%s", h.headerName)
}