package backendexecutor

import (
	"bytes"
	"context"
	"errors"
	"io"
	"log/slog"
	"net/http"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"sync"
	"testing"

	"yms-daemon/internal/containerengine"
	"yms-daemon/internal/transaction"
)

const (
	// testDigest 测试中使用的固定镜像清单摘要。
	testDigest = "sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
	// testRepository 测试中使用的镜像仓库前缀。
	testRepository = "harbor.ymswell.asia/ymswell/glory-ymswell"
	// healthyResponse 测试中健康检查端点返回的固定 UP 响应体。
	healthyResponse = `{"status":"UP","components":{"db":{"status":"UP"},"diskSpace":{"status":"UP"},"ping":{"status":"UP"},"redis":{"status":"UP"}}}`
)

// TestExecutorPreservesOpaqueImageTagsAndReachesSwitching 验证执行器对不透明镜像标签保持原样传递，
// 并能使事务推进到 StateSwitching；同时验证在 StateSwitching 状态重复执行不会产生额外引擎调用。
func TestExecutorPreservesOpaqueImageTagsAndReachesSwitching(t *testing.T) {
	tags := []string{
		"20260814-093609-d7ed70f0-v1.1.8.1",
		"20260814-093609-d7ed70f0",
	}
	for _, tag := range tags {
		tag := tag
		t.Run(tag, func(t *testing.T) {
			ctx := context.Background()
			store, coordinator := testTransactionKernel(t)
			imageReference := testRepository + ":" + tag
			request := testRequest(t, imageReference)
			engine := newFakeEngine(request)
			executor := testExecutor(t, store, coordinator, engine, healthyResponse)
			record := createTransaction(t, store, "opaque-"+tag)

			if err := executor.Run(ctx, record.ID, request); err != nil {
				t.Fatalf("run backend executor: %v", err)
			}
			current, err := store.Transaction(ctx, record.ID)
			if err != nil {
				t.Fatalf("read completed preparation: %v", err)
			}
			if current.State != transaction.StateSwitching {
				t.Fatalf("unexpected transaction state: %s", current.State)
			}
			pending, err := store.PendingSteps(ctx, record.ID)
			if err != nil || len(pending) != 0 {
				t.Fatalf("unexpected pending steps: steps=%+v err=%v", pending, err)
			}

			engine.mu.Lock()
			if engine.lastCreateSpec.ImageReference != imageReference {
				engine.mu.Unlock()
				t.Fatalf("image reference changed: got %q want %q", engine.lastCreateSpec.ImageReference, imageReference)
			}
			if !slices.Contains(engine.lastCreateSpec.Environment, "SERVER_PORT=8081") || !slices.Contains(engine.lastCreateSpec.Environment, "SPRING_CONFIG_LOCATION=file:/app/config/yms.yaml") {
				engine.mu.Unlock()
				t.Fatalf("missing explicit port environment: %+v", engine.lastCreateSpec.Environment)
			}
			initialCalls := engine.callCounts()
			engine.mu.Unlock()

			if err := executor.Run(ctx, record.ID, request); err != nil {
				t.Fatalf("repeat executor at switching state: %v", err)
			}
			engine.mu.Lock()
			repeatedCalls := engine.callCounts()
			engine.mu.Unlock()
			if repeatedCalls != initialCalls {
				t.Fatalf("switching state repeated engine calls: before=%+v after=%+v", initialCalls, repeatedCalls)
			}
		})
	}
}

// TestExecutorRecoversRecordedCreateIntentWithoutRepeatingCreate 验证在 crash 窗口内已记录创建步骤意图后，
// 恢复执行不会重复创建容器，而是直接复用已完成的创建步骤并最终进入 StateSwitching。
func TestExecutorRecoversRecordedCreateIntentWithoutRepeatingCreate(t *testing.T) {
	ctx := context.Background()
	store, coordinator := testTransactionKernel(t)
	request := testRequest(t, testRepository+":20260814-093609-d7ed70f0-v1.1.8.1")
	engine := newFakeEngine(request)
	engine.imageAvailable = true
	engine.containers[request.ContainerName] = engine.containerFromSpec(containerSpec(request), false)
	executor := testExecutor(t, store, coordinator, engine, healthyResponse)
	record := createTransaction(t, store, "recover-create")
	transitionToPrepared(t, store, record.ID)

	loadStep := loadIntent(request)
	if _, _, err := store.RecordStepIntent(ctx, record.ID, loadStep); err != nil {
		t.Fatalf("record completed image intent: %v", err)
	}
	if _, err := store.CompleteStep(ctx, record.ID, loadStep.Key, transaction.StepSucceeded, []byte(`{"loaded":true}`), ""); err != nil {
		t.Fatalf("complete image step: %v", err)
	}
	removeStep := removeIntent(request)
	if _, _, err := store.RecordStepIntent(ctx, record.ID, removeStep); err != nil {
		t.Fatalf("record completed remove intent: %v", err)
	}
	if _, err := store.CompleteStep(ctx, record.ID, removeStep.Key, transaction.StepSucceeded, []byte(`{"absent":true}`), ""); err != nil {
		t.Fatalf("complete remove step: %v", err)
	}
	createStep := createIntent(request, engine.loadedImage.ID)
	if _, _, err := store.RecordStepIntent(ctx, record.ID, createStep); err != nil {
		t.Fatalf("record crash-window create intent: %v", err)
	}

	if err := executor.Run(ctx, record.ID, request); err != nil {
		t.Fatalf("recover backend executor: %v", err)
	}
	engine.mu.Lock()
	calls := engine.callCounts()
	engine.mu.Unlock()
	if calls.load != 0 || calls.remove != 0 || calls.create != 0 || calls.start != 1 {
		t.Fatalf("unexpected recovery calls: %+v", calls)
	}
	current, err := store.Transaction(ctx, record.ID)
	if err != nil || current.State != transaction.StateSwitching {
		t.Fatalf("unexpected recovered state: record=%+v err=%v", current, err)
	}
}

// TestExecutorMarksValidationFailureTerminal 验证请求校验失败时事务被置为 StateFailed 终态。
func TestExecutorMarksValidationFailureTerminal(t *testing.T) {
	ctx := context.Background()
	store, coordinator := testTransactionKernel(t)
	request := testRequest(t, testRepository+":20260814-093609-d7ed70f0")
	request.Port = 9090
	engine := newFakeEngine(request)
	executor := testExecutor(t, store, coordinator, engine, healthyResponse)
	record := createTransaction(t, store, "invalid-port")

	if err := executor.Run(ctx, record.ID, request); err == nil {
		t.Fatal("expected validation failure")
	}
	current, err := store.Transaction(ctx, record.ID)
	if err != nil || current.State != transaction.StateFailed {
		t.Fatalf("unexpected failed transaction: record=%+v err=%v", current, err)
	}
}

// TestExecutorReplacesInactiveContainerWithConflictingImage 验证当存在镜像标识冲突的非活动容器时，
// 执行器会移除该容器并重新创建，最终进入 StateSwitching。
func TestExecutorReplacesInactiveContainerWithConflictingImage(t *testing.T) {
	ctx := context.Background()
	store, coordinator := testTransactionKernel(t)
	request := testRequest(t, testRepository+":20260814-093609-d7ed70f0")
	engine := newFakeEngine(request)
	engine.imageAvailable = true
	conflicting := engine.containerFromSpec(containerSpec(request), false)
	conflicting.ImageID = "sha256:bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
	engine.containers[request.ContainerName] = conflicting
	executor := testExecutor(t, store, coordinator, engine, healthyResponse)
	record := createTransaction(t, store, "container-conflict")

	if err := executor.Run(ctx, record.ID, request); err != nil {
		t.Fatalf("replace inactive container: %v", err)
	}
	current, readErr := store.Transaction(ctx, record.ID)
	if readErr != nil || current.State != transaction.StateSwitching {
		t.Fatalf("replacement did not reach switching: record=%+v err=%v", current, readErr)
	}
	engine.mu.Lock()
	calls := engine.callCounts()
	engine.mu.Unlock()
	if calls.remove != 1 || calls.create != 1 {
		t.Fatalf("inactive replacement calls mismatch: %+v", calls)
	}
}

// TestExecutorRejectsChangedRecoveryRequestWithoutChangingState 验证恢复执行时若请求参数被改动，
// 执行器会因持久化意图冲突而拒绝，且不改变事务的 StateStarting 状态。
func TestExecutorRejectsChangedRecoveryRequestWithoutChangingState(t *testing.T) {
	ctx := context.Background()
	store, coordinator := testTransactionKernel(t)
	request := testRequest(t, testRepository+":20260814-093609-d7ed70f0-v1.1.8.1")
	engine := newFakeEngine(request)
	engine.imageAvailable = true
	executor := testExecutor(t, store, coordinator, engine, healthyResponse)
	record := createTransaction(t, store, "changed-recovery-request")
	transitionToPrepared(t, store, record.ID)
	if err := executor.prepare(ctx, record.ID, request); err != nil {
		t.Fatalf("prepare original request: %v", err)
	}
	if _, err := store.Transition(ctx, record.ID, transaction.StateStarting, "test starting"); err != nil {
		t.Fatalf("transition to starting: %v", err)
	}

	changed := request
	changed.ImageReference = testRepository + ":20260814-093609-d7ed70f0"
	err := executor.Run(ctx, record.ID, changed)
	if !errors.Is(err, transaction.ErrStepConflict) {
		t.Fatalf("expected persisted intent conflict, got %v", err)
	}
	current, readErr := store.Transaction(ctx, record.ID)
	if readErr != nil || current.State != transaction.StateStarting {
		t.Fatalf("changed recovery request altered transaction: record=%+v err=%v", current, readErr)
	}
}

// TestImageMatchesRequiresDigestEvidenceAndExactPlatform 验证镜像匹配逻辑要求存在摘要证据且平台完全一致，
// 镜像 ID 单独存在不足以满足清单摘要匹配，平台不一致时不得判定匹配。
func TestImageMatchesRequiresDigestEvidenceAndExactPlatform(t *testing.T) {
	t.Parallel()
	platform := containerengine.Platform{OS: "linux", Architecture: "arm64"}
	image := containerengine.Image{
		ID:          "sha256:cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
		RepoDigests: []string{testRepository + "@" + testDigest},
		Platform:    platform,
	}
	matched, err := imageMatches(image, testDigest, platform)
	if err != nil || !matched {
		t.Fatalf("expected exact image match: matched=%t err=%v", matched, err)
	}
	image.RepoDigests = nil
	matched, err = imageMatches(image, testDigest, platform)
	if err != nil || matched {
		t.Fatalf("image ID alone must not satisfy manifest digest: matched=%t err=%v", matched, err)
	}
	image.DescriptorDigest = testDigest
	matched, err = imageMatches(image, testDigest, containerengine.Platform{OS: "linux", Architecture: "amd64"})
	if err != nil || matched {
		t.Fatalf("platform mismatch accepted: matched=%t err=%v", matched, err)
	}
}

// testRequest 构造一个合法的测试请求，并在临时目录中写入镜像归档与后端配置文件。
func testRequest(t *testing.T, imageReference string) Request {
	t.Helper()
	directory := t.TempDir()
	archivePath := filepath.Join(directory, "backend-image.tar")
	configPath := filepath.Join(directory, "yms.yaml")
	if err := os.WriteFile(archivePath, []byte("image archive"), 0o600); err != nil {
		t.Fatalf("write image archive: %v", err)
	}
	if err := os.WriteFile(configPath, []byte("server: {}\n"), 0o600); err != nil {
		t.Fatalf("write backend configuration: %v", err)
	}
	return Request{
		ImageAcquisition:     ImageAcquisitionLoad,
		ArchivePath:          archivePath,
		ImageReference:       imageReference,
		ExpectedImageDigest:  testDigest,
		Platform:             containerengine.Platform{OS: "linux", Architecture: "amd64"},
		ContainerName:        "explicit-backend-8081",
		Port:                 8081,
		PortEnvironmentKey:   "SERVER_PORT",
		ConfigSource:         configPath,
		ConfigTarget:         "/app/config/yms.yaml",
		TmpSource:            directory,
		TmpTarget:            "/home/yms/tmp",
		ConfigEnvironmentKey: "SPRING_CONFIG_LOCATION",
		ConfigLocation:       "file:/app/config/yms.yaml",
		RestartPolicy:        containerengine.RestartPolicy{Name: "unless-stopped"},
		HealthEndpoint:       "http://127.0.0.1:8081/yms/actuator/health",
	}
}

// testTransactionKernel 创建测试用的事务存储与协调器，并在测试结束时自动关闭存储。
func testTransactionKernel(t *testing.T) (*transaction.Store, *transaction.Coordinator) {
	t.Helper()
	store, err := transaction.OpenStore(context.Background(), filepath.Join(t.TempDir(), "transactions.db"))
	if err != nil {
		t.Fatalf("open transaction store: %v", err)
	}
	t.Cleanup(func() { _ = store.Close() })
	coordinator, err := transaction.NewCoordinator(store, slog.New(slog.NewTextHandler(io.Discard, nil)))
	if err != nil {
		t.Fatalf("create transaction coordinator: %v", err)
	}
	return store, coordinator
}

// testExecutor 使用固定响应体构造健康检查 HTTP 客户端并创建后端执行器。
func testExecutor(t *testing.T, store *transaction.Store, coordinator *transaction.Coordinator, engine containerengine.Engine, body string) *Executor {
	t.Helper()
	client := &http.Client{Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
		return &http.Response{StatusCode: http.StatusOK, Header: make(http.Header), Body: io.NopCloser(bytes.NewBufferString(body))}, nil
	})}
	executor, err := New(store, coordinator, engine, client)
	if err != nil {
		t.Fatalf("create backend executor: %v", err)
	}
	return executor
}

// createTransaction 以给定后缀创建一个新的后端测试事务并返回其记录。
func createTransaction(t *testing.T, store *transaction.Store, suffix string) transaction.Transaction {
	t.Helper()
	record, _, err := store.CreateTransaction(context.Background(), transaction.CreateRequest{
		ID:             "backend-" + suffix,
		IdempotencyKey: "backend-request-" + suffix,
		Source:         "test",
		Service:        "backend",
	})
	if err != nil {
		t.Fatalf("create backend transaction: %v", err)
	}
	return record
}

// transitionToPrepared 将指定事务依次推进到 StateValidating 与 StatePrepared 状态。
func transitionToPrepared(t *testing.T, store *transaction.Store, transactionID string) {
	t.Helper()
	ctx := context.Background()
	if _, err := store.Transition(ctx, transactionID, transaction.StateValidating, "test validating"); err != nil {
		t.Fatalf("transition to validating: %v", err)
	}
	if _, err := store.Transition(ctx, transactionID, transaction.StatePrepared, "test prepared"); err != nil {
		t.Fatalf("transition to prepared: %v", err)
	}
}

// roundTripFunc http.RoundTripper 的函数式适配器，用于在测试中固定 HTTP 响应。
type roundTripFunc func(*http.Request) (*http.Response, error)

// RoundTrip 实现 http.RoundTripper 接口，直接调用底层函数。
func (f roundTripFunc) RoundTrip(request *http.Request) (*http.Response, error) {
	return f(request)
}

// engineCalls 记录 fakeEngine 各方法被调用的次数，用于断言执行路径。
type engineCalls struct {
	ping    int
	load    int
	inspect int
	create  int
	start   int
	remove  int
}

// fakeEngine containerengine.Engine 的内存实现，用于测试中模拟容器引擎行为。
type fakeEngine struct {
	// mu 保护下方字段的并发访问。
	mu sync.Mutex
	// request 构造该引擎时使用的请求参数。
	request Request
	// loadedImage 引擎加载后提供的镜像。
	loadedImage containerengine.Image
	// imageAvailable 表示镜像当前是否可用。
	imageAvailable bool
	// containers 引擎维护的容器表，键为容器名称。
	containers map[string]containerengine.Container
	// lastCreateSpec 记录最近一次创建容器所用的规格。
	lastCreateSpec containerengine.ContainerSpec
	pingCalls      int
	loadCalls      int
	inspectCalls   int
	createCalls    int
	startCalls     int
	removeCalls    int
}

// newFakeEngine 构造一个已按请求平台预置镜像的 fakeEngine。
func newFakeEngine(request Request) *fakeEngine {
	return &fakeEngine{
		request: request,
		loadedImage: containerengine.Image{
			ID:          "sha256:cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
			RepoDigests: []string{testRepository + "@" + testDigest},
			Platform:    request.Platform,
		},
		containers: make(map[string]containerengine.Container),
	}
}

// Ping 实现容器引擎的 Ping，记录调用次数并始终返回成功。
func (e *fakeEngine) Ping(context.Context) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.pingCalls++
	return nil
}

// LoadImage 实现容器引擎的 LoadImage，读取输入流后标记镜像可用并记录调用次数。
func (e *fakeEngine) LoadImage(_ context.Context, input io.Reader) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.loadCalls++
	if _, err := io.ReadAll(input); err != nil {
		return err
	}
	e.imageAvailable = true
	return nil
}

// PullImage 实现容器引擎的 PullImage，标记镜像可用并记录调用次数。
func (e *fakeEngine) PullImage(context.Context, string) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.loadCalls++
	e.imageAvailable = true
	return nil
}

// InspectImage 实现容器引擎的 InspectImage，镜像不可用时返回 ErrNotFound，否则返回已加载镜像。
func (e *fakeEngine) InspectImage(context.Context, string) (containerengine.Image, error) {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.inspectCalls++
	if !e.imageAvailable {
		return containerengine.Image{}, containerengine.ErrNotFound
	}
	return e.loadedImage, nil
}

// CreateContainer 实现容器引擎的 CreateContainer，记录规格并创建容器，同名时返回错误。
func (e *fakeEngine) CreateContainer(_ context.Context, spec containerengine.ContainerSpec) (containerengine.Container, error) {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.createCalls++
	e.lastCreateSpec = spec
	if _, exists := e.containers[spec.Name]; exists {
		return containerengine.Container{}, errors.New("container name already exists")
	}
	record := e.containerFromSpec(spec, false)
	e.containers[spec.Name] = record
	return record, nil
}

// StartContainer 实现容器引擎的 StartContainer，将指定容器标记为运行状态，不存在时返回 ErrNotFound。
func (e *fakeEngine) StartContainer(_ context.Context, name string) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.startCalls++
	record, exists := e.containers[name]
	if !exists {
		return containerengine.ErrNotFound
	}
	record.Running = true
	record.Status = "running"
	e.containers[name] = record
	return nil
}

// ContainerLogs 实现容器引擎的 ContainerLogs，返回空的日志读取器。
func (e *fakeEngine) ContainerLogs(context.Context, string) (io.ReadCloser, error) {
	return io.NopCloser(strings.NewReader("")), nil
}

// StopContainer 实现容器引擎的 StopContainer，将指定容器标记为已退出状态，不存在时返回 ErrNotFound。
func (e *fakeEngine) StopContainer(_ context.Context, name string) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	record, exists := e.containers[name]
	if !exists {
		return containerengine.ErrNotFound
	}
	record.Running = false
	record.Status = "exited"
	e.containers[name] = record
	return nil
}

// InspectContainer 实现容器引擎的 InspectContainer，返回容器记录，不存在时返回 ErrNotFound。
func (e *fakeEngine) InspectContainer(_ context.Context, name string) (containerengine.Container, error) {
	e.mu.Lock()
	defer e.mu.Unlock()
	record, exists := e.containers[name]
	if !exists {
		return containerengine.Container{}, containerengine.ErrNotFound
	}
	return record, nil
}

// RemoveContainer 实现容器引擎的 RemoveContainer，删除指定容器并记录调用次数，不存在时返回 ErrNotFound。
func (e *fakeEngine) RemoveContainer(_ context.Context, name string, _ bool) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.removeCalls++
	if _, exists := e.containers[name]; !exists {
		return containerengine.ErrNotFound
	}
	delete(e.containers, name)
	return nil
}

// Close 实现容器引擎的 Close，不做任何清理并返回 nil。
func (e *fakeEngine) Close() error { return nil }

// containerFromSpec 根据容器规格构造一条容器记录，running 指定其初始运行状态。
func (e *fakeEngine) containerFromSpec(spec containerengine.ContainerSpec, running bool) containerengine.Container {
	return containerengine.Container{
		ID:                 "container-id-" + spec.Name,
		Name:               spec.Name,
		ImageID:            e.loadedImage.ID,
		ImageReference:     spec.ImageReference,
		Platform:           spec.Platform.OS + "/" + spec.Platform.Architecture,
		Running:            running,
		Status:             "created",
		Environment:        append([]string(nil), spec.Environment...),
		NetworkMode:        spec.NetworkMode,
		RestartPolicy:      spec.RestartPolicy,
		Mounts:             append([]containerengine.Mount(nil), spec.Mounts...),
		User:               spec.User,
		StopTimeoutSeconds: spec.StopTimeoutSeconds,
	}
}

// callCounts 返回 fakeEngine 各方法当前的调用次数快照。
func (e *fakeEngine) callCounts() engineCalls {
	return engineCalls{
		ping:    e.pingCalls,
		load:    e.loadCalls,
		inspect: e.inspectCalls,
		create:  e.createCalls,
		start:   e.startCalls,
		remove:  e.removeCalls,
	}
}

// 编译期断言确保 fakeEngine 实现 containerengine.Engine 接口。
var _ containerengine.Engine = (*fakeEngine)(nil)