package nativebackendexecutor

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"io"
	"log/slog"
	"net/http"
	"os"
	"path/filepath"
	"sync"
	"testing"
	"time"

	"yms-daemon/internal/filestore"
	"yms-daemon/internal/healthcheck"
	"yms-daemon/internal/systemd"
	"yms-daemon/internal/transaction"
)

// TestExecutorInstallsJarStartsExactUnitAndReachesSwitching 验证成功路径：安装 JAR、启动精确单元、
// 槽位软链接指向新版本、事务推进到 switching，且重复运行不会再次启动单元。
func TestExecutorInstallsJarStartsExactUnitAndReachesSwitching(t *testing.T) {
	ctx := context.Background()
	executor, store, releaseStore, units, request, previousTarget := testNativeExecutor(t)
	record := createNativeTransaction(t, store, "success")

	if err := executor.Run(ctx, record.ID, request); err != nil {
		t.Fatalf("run native backend executor: %v", err)
	}
	current, err := store.Transaction(ctx, record.ID)
	if err != nil || current.State != transaction.StateSwitching {
		t.Fatalf("unexpected transaction after native preparation: record=%+v err=%v", current, err)
	}
	installed, found, err := releaseStore.Inspect(request.ReleasePath, request.ArtifactIdentity)
	if err != nil || !found {
		t.Fatalf("inspect installed backend JAR: file=%+v found=%t err=%v", installed, found, err)
	}
	actualTarget, err := os.Readlink(request.SlotJarPath)
	if err != nil || actualTarget != installed.Path || actualTarget == previousTarget {
		t.Fatalf("unexpected slot link: target=%q installed=%q previous=%q err=%v", actualTarget, installed.Path, previousTarget, err)
	}
	units.mu.Lock()
	startCalls := units.startCalls
	stopCalls := units.stopCalls
	unitActiveState := units.unit.ActiveState
	startedName := units.startedName
	units.mu.Unlock()
	if startCalls != 1 || stopCalls != 0 || unitActiveState != activeState || startedName != request.UnitName {
		t.Fatalf("unexpected systemd calls: start=%d stop=%d state=%s name=%s", startCalls, stopCalls, unitActiveState, startedName)
	}
	pending, err := store.PendingSteps(ctx, record.ID)
	if err != nil || len(pending) != 0 {
		t.Fatalf("unexpected pending native steps: steps=%+v err=%v", pending, err)
	}

	if err := executor.Run(ctx, record.ID, request); err != nil {
		t.Fatalf("repeat executor at switching state: %v", err)
	}
	units.mu.Lock()
	repeatedStartCalls := units.startCalls
	units.mu.Unlock()
	if repeatedStartCalls != startCalls {
		t.Fatalf("switching state repeated systemd start: before=%d after=%d", startCalls, repeatedStartCalls)
	}
}

// TestExecutorRollsBackSlotAndStopsUnitWhenHealthFails 验证健康检查失败时：事务回滚、槽位软链接恢复、
// 单元被停止且状态回到非活跃。
func TestExecutorRollsBackSlotAndStopsUnitWhenHealthFails(t *testing.T) {
	ctx := context.Background()
	executor, store, _, units, request, previousTarget := testNativeExecutor(t)
	executor.checker = &fakeActuatorChecker{
		waitErr:    errors.New("Actuator rejected native backend"),
		checkReady: false,
	}
	record := createNativeTransaction(t, store, "health-failure")

	err := executor.Run(ctx, record.ID, request)
	if err == nil {
		t.Fatal("expected native backend health failure")
	}
	current, readErr := store.Transaction(ctx, record.ID)
	if readErr != nil || current.State != transaction.StateRolledBack {
		t.Fatalf("unexpected compensated transaction: record=%+v err=%v", current, readErr)
	}
	actualTarget, linkErr := os.Readlink(request.SlotJarPath)
	if linkErr != nil || actualTarget != previousTarget {
		t.Fatalf("native slot was not restored: target=%q previous=%q err=%v", actualTarget, previousTarget, linkErr)
	}
	units.mu.Lock()
	startCalls := units.startCalls
	stopCalls := units.stopCalls
	unitActiveState := units.unit.ActiveState
	units.mu.Unlock()
	if startCalls != 1 || stopCalls != 1 || unitActiveState != inactiveState {
		t.Fatalf("unexpected compensated systemd state: start=%d stop=%d state=%s", startCalls, stopCalls, unitActiveState)
	}
}

// TestExecutorResumesPersistedRollback 验证从持久化的 rolling back 状态恢复补偿：恢复槽位并停止单元。
func TestExecutorResumesPersistedRollback(t *testing.T) {
	ctx := context.Background()
	executor, store, _, units, request, previousTarget := testNativeExecutor(t)
	record := createNativeTransaction(t, store, "resume-rollback")
	transitionNativeToPrepared(t, store, record.ID)
	if _, err := executor.prepare(ctx, record.ID, request); err != nil {
		t.Fatalf("prepare native backend before rollback interruption: %v", err)
	}
	if _, err := store.Transition(ctx, record.ID, transaction.StateStarting, "test starting"); err != nil {
		t.Fatalf("transition native transaction to starting: %v", err)
	}
	if err := units.Start(ctx, request.UnitName); err != nil {
		t.Fatalf("start native backend before rollback interruption: %v", err)
	}
	if _, err := store.Transition(ctx, record.ID, transaction.StateRollingBack, "test interrupted rollback"); err != nil {
		t.Fatalf("persist interrupted rollback state: %v", err)
	}

	if err := executor.Run(ctx, record.ID, request); err != nil {
		t.Fatalf("resume native backend rollback: %v", err)
	}
	current, err := store.Transaction(ctx, record.ID)
	if err != nil || current.State != transaction.StateRolledBack {
		t.Fatalf("unexpected resumed rollback state: record=%+v err=%v", current, err)
	}
	actualTarget, err := os.Readlink(request.SlotJarPath)
	if err != nil || actualTarget != previousTarget {
		t.Fatalf("resumed rollback did not restore slot: target=%q previous=%q err=%v", actualTarget, previousTarget, err)
	}
	units.mu.Lock()
	stopCalls := units.stopCalls
	unitActiveState := units.unit.ActiveState
	units.mu.Unlock()
	if stopCalls != 1 || unitActiveState != inactiveState {
		t.Fatalf("resumed rollback did not stop unit: stop=%d state=%s", stopCalls, unitActiveState)
	}
}

// TestExecutorRollbackRemovesFirstDeploymentSlotLink 验证首次部署（无先前目标）失败时，回滚会移除槽位软链接。
func TestExecutorRollbackRemovesFirstDeploymentSlotLink(t *testing.T) {
	ctx := context.Background()
	executor, store, _, _, request, _ := testNativeExecutor(t)
	if err := os.Remove(request.SlotJarPath); err != nil {
		t.Fatalf("remove seeded slot link: %v", err)
	}
	request.PreviousSlotTarget = ""
	executor.checker = &fakeActuatorChecker{
		waitErr:    errors.New("Actuator rejected first native backend deployment"),
		checkReady: false,
	}
	record := createNativeTransaction(t, store, "first-deployment-rollback")

	if err := executor.Run(ctx, record.ID, request); err == nil {
		t.Fatal("expected first native backend deployment health failure")
	}
	current, err := store.Transaction(ctx, record.ID)
	if err != nil || current.State != transaction.StateRolledBack {
		t.Fatalf("unexpected first deployment rollback state: record=%+v err=%v", current, err)
	}
	if _, err := os.Lstat(request.SlotJarPath); !errors.Is(err, os.ErrNotExist) {
		t.Fatalf("first deployment rollback retained slot link: %v", err)
	}
}

// TestExecutorRecoversRecordedSlotIntentWithoutChangingRequest 验证崩溃恢复：已记录的槽位意图不依赖请求变更，
// 执行器能直接复用并完成后续步骤。
func TestExecutorRecoversRecordedSlotIntentWithoutChangingRequest(t *testing.T) {
	ctx := context.Background()
	executor, store, releaseStore, units, request, _ := testNativeExecutor(t)
	record := createNativeTransaction(t, store, "recover-slot")
	transitionNativeToPrepared(t, store, record.ID)

	installOperation := &installJarOperation{
		store:       releaseStore,
		sourcePath:  request.ArtifactPath,
		releasePath: request.ReleasePath,
		identity:    request.ArtifactIdentity,
	}
	if _, err := executor.coordinator.ExecuteStep(ctx, record.ID, installIntent(request), installOperation); err != nil {
		t.Fatalf("install backend JAR before simulated crash: %v", err)
	}
	installed, found, err := releaseStore.Inspect(request.ReleasePath, request.ArtifactIdentity)
	if err != nil || !found {
		t.Fatalf("inspect backend JAR before simulated crash: file=%+v found=%t err=%v", installed, found, err)
	}
	if _, _, err := store.RecordStepIntent(ctx, record.ID, bindIntent(request, installed.Path)); err != nil {
		t.Fatalf("record slot intent before simulated crash: %v", err)
	}

	if err := executor.Run(ctx, record.ID, request); err != nil {
		t.Fatalf("recover native backend executor: %v", err)
	}
	actualTarget, err := os.Readlink(request.SlotJarPath)
	if err != nil || actualTarget != installed.Path {
		t.Fatalf("unexpected recovered slot link: target=%q installed=%q err=%v", actualTarget, installed.Path, err)
	}
	units.mu.Lock()
	startCalls := units.startCalls
	units.mu.Unlock()
	if startCalls != 1 {
		t.Fatalf("unexpected recovered systemd start count: %d", startCalls)
	}
}

// TestExecutorRejectsChangedRecoveryIntentAndPreservesStartingState 验证请求变更导致步骤冲突时被拒绝，且事务停留在 starting 状态。
func TestExecutorRejectsChangedRecoveryIntentAndPreservesStartingState(t *testing.T) {
	ctx := context.Background()
	executor, store, _, _, request, _ := testNativeExecutor(t)
	record := createNativeTransaction(t, store, "changed-request")
	transitionNativeToPrepared(t, store, record.ID)
	if _, err := executor.prepare(ctx, record.ID, request); err != nil {
		t.Fatalf("prepare original native backend request: %v", err)
	}
	if _, err := store.Transition(ctx, record.ID, transaction.StateStarting, "test starting"); err != nil {
		t.Fatalf("transition native backend to starting: %v", err)
	}

	changed := request
	changed.ReleasePath = "different-release.jar"
	err := executor.Run(ctx, record.ID, changed)
	if !errors.Is(err, transaction.ErrStepConflict) {
		t.Fatalf("expected persisted native 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)
	}
}

// TestExecutorRejectsActiveUnitBeforeChangingFiles 验证单元已活跃时校验失败：事务进入 failed，且不改动发布存储与槽位软链接。
func TestExecutorRejectsActiveUnitBeforeChangingFiles(t *testing.T) {
	ctx := context.Background()
	executor, store, releaseStore, units, request, previousTarget := testNativeExecutor(t)
	units.mu.Lock()
	units.unit.ActiveState = activeState
	units.unit.SubState = "running"
	units.mu.Unlock()
	record := createNativeTransaction(t, store, "active-unit")

	if err := executor.Run(ctx, record.ID, request); err == nil {
		t.Fatal("expected active unit validation failure")
	}
	current, err := store.Transaction(ctx, record.ID)
	if err != nil || current.State != transaction.StateFailed {
		t.Fatalf("unexpected active-unit transaction state: record=%+v err=%v", current, err)
	}
	if _, found, err := releaseStore.Inspect(request.ReleasePath, request.ArtifactIdentity); err != nil || found {
		t.Fatalf("validation failure changed release store: found=%t err=%v", found, err)
	}
	actualTarget, err := os.Readlink(request.SlotJarPath)
	if err != nil || actualTarget != previousTarget {
		t.Fatalf("validation failure changed slot link: target=%q previous=%q err=%v", actualTarget, previousTarget, err)
	}
}

// TestUnitStopOperationAcceptsSystemdFailedAsStopped 验证 unitStopOperation 把 systemd 的 failed 状态视为已停止。
func TestUnitStopOperationAcceptsSystemdFailedAsStopped(t *testing.T) {
	units := &fakeUnitManager{unit: systemd.Unit{
		Name:        "yms-backend@8080.service",
		LoadState:   "loaded",
		ActiveState: failedState,
		SubState:    "failed",
	}}
	operation := &unitStopOperation{units: units, name: units.unit.Name}
	inspection, err := operation.Inspect(context.Background())
	if err != nil {
		t.Fatalf("inspect stopped native backend unit: %v", err)
	}
	if inspection.Status != transaction.InspectionApplied {
		t.Fatalf("unexpected stopped native backend unit inspection: %+v", inspection)
	}
}

// testNativeExecutor 构造一套完整且可复用的原生后端测试夹具。
// t 用于失败报告与清理注册。返回执行器、事务存储、发布存储、伪造的单元管理器、请求与先前槽位目标。
func testNativeExecutor(t *testing.T) (*Executor, *transaction.Store, *filestore.Store, *fakeUnitManager, Request, string) {
	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)
	}
	releaseStore, err := filestore.New(t.TempDir())
	if err != nil {
		t.Fatalf("create native release store: %v", err)
	}
	artifactContent := []byte("native backend jar content")
	artifactPath := filepath.Join(t.TempDir(), "glory-soft-yms.jar")
	if err := os.WriteFile(artifactPath, artifactContent, 0o640); err != nil {
		t.Fatalf("write native backend artifact: %v", err)
	}
	previousTarget := filepath.Join(t.TempDir(), "previous-backend.jar")
	if err := os.WriteFile(previousTarget, []byte("previous backend jar"), 0o640); err != nil {
		t.Fatalf("write previous backend JAR: %v", err)
	}
	slotDirectory := t.TempDir()
	slotJarPath := filepath.Join(slotDirectory, "backend-green.jar")
	if err := os.Symlink(previousTarget, slotJarPath); err != nil {
		t.Fatalf("create previous native backend slot link: %v", err)
	}
	request := Request{
		ArtifactPath:       artifactPath,
		ArtifactIdentity:   testIdentity(artifactContent),
		ReleasePath:        "glory-soft-yms-20260815.jar",
		SlotJarPath:        slotJarPath,
		PreviousSlotTarget: previousTarget,
		UnitName:           "yms-green.service",
		Port:               8081,
		HealthEndpoint:     "http://127.0.0.1:8081/yms/actuator/health",
	}
	units := &fakeUnitManager{unit: systemd.Unit{
		Name:        request.UnitName,
		LoadState:   "loaded",
		ActiveState: inactiveState,
		SubState:    "dead",
	}}
	executor, err := New(store, coordinator, releaseStore, units, &http.Client{})
	if err != nil {
		t.Fatalf("create native backend executor: %v", err)
	}
	executor.checker = &fakeActuatorChecker{
		waitReport:  healthcheck.ActuatorReport{Status: "UP", Components: map[string]string{"db": "UP"}},
		checkReport: healthcheck.ActuatorReport{Status: "UP", Components: map[string]string{"db": "UP"}},
		checkReady:  true,
	}
	return executor, store, releaseStore, units, request, previousTarget
}

// createNativeTransaction 在测试事务存储中创建一条原生后端事务记录。
// t 用于失败报告；store 是事务存储；suffix 用于构造唯一的事务 ID。返回创建的事务记录。
func createNativeTransaction(t *testing.T, store *transaction.Store, suffix string) transaction.Transaction {
	t.Helper()
	record, _, err := store.CreateTransaction(context.Background(), transaction.CreateRequest{
		ID:             "native-backend-" + suffix,
		IdempotencyKey: "native-backend-request-" + suffix,
		Source:         "test",
		Service:        "backend",
	})
	if err != nil {
		t.Fatalf("create native backend transaction: %v", err)
	}
	return record
}

// transitionNativeToPrepared 把事务依次推进到 validating 与 prepared 状态，供测试预置前置步骤。
// t 用于失败报告；store 是事务存储；transactionID 定位事务。
func transitionNativeToPrepared(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 native transaction to validating: %v", err)
	}
	if _, err := store.Transition(ctx, transactionID, transaction.StatePrepared, "test prepared"); err != nil {
		t.Fatalf("transition native transaction to prepared: %v", err)
	}
}

// testIdentity 根据内容计算文件身份（大小与 SHA-256），用于测试夹具与校验。
// content 文件内容。返回对应的 filestore.Identity。
func testIdentity(content []byte) filestore.Identity {
	digest := sha256.Sum256(content)
	return filestore.Identity{Size: int64(len(content)), SHA256: hex.EncodeToString(digest[:])}
}

// fakeUnitManager systemd.Manager 的测试替身，记录单元状态与启动/停止调用次数。
type fakeUnitManager struct {
	mu          sync.Mutex
	unit        systemd.Unit
	startErr    error
	stopErr     error
	startCalls  int
	stopCalls   int
	startedName string
}

// Inspect 返回单元状态：名称不匹配时返回 ErrUnitNotFound。
// 参数 ctx 与 name 用于取消与定位，name 决定返回哪个单元。返回单元状态与错误。
func (m *fakeUnitManager) Inspect(_ context.Context, name string) (systemd.Unit, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	if name != m.unit.Name {
		return systemd.Unit{}, systemd.ErrUnitNotFound
	}
	return m.unit, nil
}

// Start 模拟启动单元：记录调用与名称，成功置为活跃，失败置为 failed 并返回 startErr。
// 参数 ctx 与 name 用于取消与定位，name 决定记录的名称。返回值是启动错误（若配置了 startErr）。
func (m *fakeUnitManager) Start(_ context.Context, name string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.startCalls++
	m.startedName = name
	if m.startErr != nil {
		m.unit.ActiveState = failedState
		m.unit.SubState = "failed"
		return m.startErr
	}
	m.unit.ActiveState = activeState
	m.unit.SubState = "running"
	return nil
}

// Stop 模拟停止单元：记录调用，成功置为非活跃，失败返回 stopErr。
// 参数 ctx 与 name 用于取消与定位。返回值是停止错误（若配置了 stopErr）。
func (m *fakeUnitManager) Stop(context.Context, string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.stopCalls++
	if m.stopErr != nil {
		return m.stopErr
	}
	m.unit.ActiveState = inactiveState
	m.unit.SubState = "dead"
	return nil
}

// fakeActuatorChecker actuatorChecker 的测试替身，返回可配置的健康报告与错误。
type fakeActuatorChecker struct {
	waitReport  healthcheck.ActuatorReport
	waitErr     error
	checkReport healthcheck.ActuatorReport
	checkReady  bool
	checkErr    error
}

// Wait 模拟等待健康检查：先执行运行探针，未运行返回 ErrWorkloadStopped，否则返回 waitReport 与 waitErr。
// ctx 用于取消；running 是运行探针。返回值是健康报告与错误。
func (c *fakeActuatorChecker) Wait(ctx context.Context, _ string, _ time.Duration, running healthcheck.RunningProbe) (healthcheck.ActuatorReport, error) {
	isRunning, err := running(ctx)
	if err != nil {
		return healthcheck.ActuatorReport{}, err
	}
	if !isRunning {
		return healthcheck.ActuatorReport{}, healthcheck.ErrWorkloadStopped
	}
	return c.waitReport, c.waitErr
}

// Check 模拟单次健康检查：先执行运行探针，未运行返回 ErrWorkloadStopped，否则返回 checkReport、checkReady 与 checkErr。
// ctx 用于取消；running 是运行探针。返回值是健康报告、就绪标志与错误。
func (c *fakeActuatorChecker) Check(ctx context.Context, _ string, running healthcheck.RunningProbe) (healthcheck.ActuatorReport, bool, error) {
	isRunning, err := running(ctx)
	if err != nil {
		return healthcheck.ActuatorReport{}, false, err
	}
	if !isRunning {
		return healthcheck.ActuatorReport{}, false, healthcheck.ErrWorkloadStopped
	}
	return c.checkReport, c.checkReady, c.checkErr
}

// 以下编译期断言确保测试替身实现了相应接口。
var _ systemd.Manager = (*fakeUnitManager)(nil)
var _ actuatorChecker = (*fakeActuatorChecker)(nil)