/*
Copyright 2024 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package feature

import (
	"context"
	"fmt"
	"testing"

	"github.com/stretchr/testify/assert"
	clientv3 "go.etcd.io/etcd/client/v3"
	"k8s.io/apiserver/pkg/storage"
)

type mockEndpointVersion struct {
	Endpoint string
	Version  string
	Error    error
}

// MockEtcdClient is a mock implementation of the EtcdClientInterface interface.
type MockEtcdClient struct {
	EndpointVersion []mockEndpointVersion
}

func (m MockEtcdClient) getEndpoints() []string {
	var endpoints []string
	for _, ev := range m.EndpointVersion {
		endpoints = append(endpoints, ev.Endpoint)
	}
	return endpoints
}

func (m MockEtcdClient) getVersion(endpoint string) (string, error) {
	for _, ev := range m.EndpointVersion {
		if ev.Endpoint == endpoint {
			return ev.Version, ev.Error
		}
	}
	// Never should happen, unless tests having a problem.
	return "", fmt.Errorf("No version found")
}

func (m *MockEtcdClient) Endpoints() []string {
	return m.getEndpoints()
}

// Status returns a mock status response.
func (m *MockEtcdClient) Status(ctx context.Context, endpoint string) (*clientv3.StatusResponse, error) {
	version, err := m.getVersion(endpoint)
	if err != nil {
		return nil, err
	}
	// Return a mock status response
	return &clientv3.StatusResponse{
		Version: version,
	}, nil
}

func TestSupports(t *testing.T) {
	tests := []struct {
		testName       string
		featureName    string
		expectedResult bool
	}{
		{
			testName:    "Disabled - with unknown feature",
			featureName: "some unknown feature",
		},
		{
			testName:    "Disabled - with empty feature",
			featureName: "",
		},
		{
			testName:       "Disabled - default",
			featureName:    storage.RequestWatchProgress,
			expectedResult: false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.testName, func(t *testing.T) {
			var testFeatureSupportChecker FeatureSupportChecker = newDefaultFeatureSupportChecker()

			supported := testFeatureSupportChecker.Supports(tt.featureName)

			assert.Equal(t, tt.expectedResult, supported)
		})
	}
}

func TestSupportsRequestWatchProgress(t *testing.T) {
	type testCase struct {
		endpointsVersion []mockEndpointVersion
		expectedResult   bool
		expectedError    error
	}
	tests := []struct {
		testName string
		rounds   []testCase
	}{
		{
			testName: "Disabled - default disabled",
			rounds:   []testCase{{expectedResult: false}},
		},
		{
			testName: "Enabled - supported versions bound",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.4.31", Endpoint: "localhost:2390"}},
					expectedResult: true,
				},
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.5.13", Endpoint: "localhost:2391"}},
					expectedResult: true,
				},
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.6.0", Endpoint: "localhost:2392"}},
					expectedResult: true}},
		},
		{
			testName: "Disabled - supported versions bound, 3.4.30",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.4.30", Endpoint: "localhost:2390"}},
					expectedResult: false}},
		},
		{
			testName: "Disabled - supported versions bound, 3.5.0",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.5.0", Endpoint: "localhost:2390"}},
					expectedResult: false}},
		},
		{
			testName: "Disabled - supported versions bound, 3.5.12",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.5.12", Endpoint: "localhost:2390"}},
					expectedResult: false}},
		},
		{
			testName: "Disabled - disables if called with one client doesn't support it",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.5.13", Endpoint: "localhost:2390"},
					{Version: "3.5.10", Endpoint: "localhost:2391"}},
					expectedResult: false}},
		},
		{
			testName: "Disabled - disables if called with all client doesn't support it",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.5.9", Endpoint: "localhost:2390"},
					{Version: "3.5.10", Endpoint: "localhost:2391"}},
					expectedResult: false}},
		},
		{
			testName: "Enabled - if provided client has at least one endpoint that supports it and no client that doesn't",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.4.31", Endpoint: "localhost:2390"},
					{Version: "3.5.13", Endpoint: "localhost:2391"},
					{Version: "3.5.14", Endpoint: "localhost:2392"},
					{Version: "3.6.0", Endpoint: "localhost:2393"}},
					expectedResult: true}},
		},
		{
			testName: "Disabled - cannot be re-enabled",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.4.0", Endpoint: "localhost:2390"},
					{Version: "3.4.1", Endpoint: "localhost:2391"}},
					expectedResult: false},
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.6.0", Endpoint: "localhost:2392"}},
					expectedResult: false}},
		},
		{
			testName: "Enabled - one client supports it and later disabled it with second client",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.6.0", Endpoint: "localhost:2390"},
					{Version: "3.5.14", Endpoint: "localhost:2391"}},
					expectedResult: true},
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.4.0", Endpoint: "localhost:2392"}},
					expectedResult: false}},
		},
		{
			testName: "Disabled - malformed version would disable the supported cluster and can not be re-enabled again",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.6.0", Endpoint: "localhost:2390"}},
					expectedResult: true,
				},
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.4.--aaa", Endpoint: "localhost:2392"}},
					expectedResult: false},
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.5.13", Endpoint: "localhost:2393"}},
					expectedResult: false}},
		},
		{
			testName: "Enabled - error on first client, enabled success on second client",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.6.0", Endpoint: "localhost:2390", Error: fmt.Errorf("some error")}},
					expectedResult: false,
					expectedError:  fmt.Errorf("failed checking etcd version, endpoint: %q: %w", "localhost:2390", fmt.Errorf("some error")),
				},
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.5.14", Endpoint: "localhost:2391"}},
					expectedResult: true}},
		},
		{
			testName: "Disabled - enabled success on first client, error on second client, disabled success on third client",
			rounds: []testCase{
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.6.0", Endpoint: "localhost:2390"}},
					expectedResult: true,
				},
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.6.0", Endpoint: "localhost:2391", Error: fmt.Errorf("some error")}},
					expectedResult: true,
					expectedError:  fmt.Errorf("failed checking etcd version, endpoint: %q: %w", "localhost:2391", fmt.Errorf("some error")),
				},
				{endpointsVersion: []mockEndpointVersion{
					{Version: "3.5.10", Endpoint: "localhost:2392"}},
					expectedResult: false}},
		},
		{
			testName: "Disabled - client doesn't have any endpoints",
			rounds:   []testCase{{endpointsVersion: []mockEndpointVersion{}, expectedResult: false}},
		},
	}
	for _, tt := range tests {
		t.Run(tt.testName, func(t *testing.T) {
			var testFeatureSupportChecker = newDefaultFeatureSupportChecker()
			for _, round := range tt.rounds {
				// Mock Etcd client
				mockClient := &MockEtcdClient{EndpointVersion: round.endpointsVersion}
				ctx := context.Background()

				for _, ep := range mockClient.Endpoints() {
					err := testFeatureSupportChecker.clientSupportsRequestWatchProgress(ctx, mockClient, ep)
					assert.Equal(t, round.expectedError, err)
				}

				supported := testFeatureSupportChecker.Supports(storage.RequestWatchProgress)
				assert.Equal(t, round.expectedResult, supported)
			}
		})
	}
}