package updater

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"sort"
	"strings"
	"time"

	"scout/pkg/client"
	"scout/pkg/scoutpkg"
)

const ExitRestartNow = 42

type Config struct {
	Client         *client.Client
	Adapter        PlatformAdapter
	PackageName    string
	CurrentVersion string
	CurrentPath    string
	RootDir        string
	Platform       string
	Architecture   string
	Channel        string
	Entrypoint     string
	HealthTimeout  time.Duration
	KeepReleases   int
}

type ReleasePointer struct {
	Version      string    `json:"version"`
	Path         string    `json:"path"`
	Entrypoint   string    `json:"entrypoint"`
	Platform     string    `json:"platform"`
	Architecture string    `json:"architecture"`
	PackageType  string    `json:"package_type"`
	SHA256       string    `json:"sha256"`
	PreparedAt   time.Time `json:"prepared_at"`
	ActivatedAt  time.Time `json:"activated_at,omitempty"`
	HealthyAt    time.Time `json:"healthy_at,omitempty"`
}

type State struct {
	Stage           string          `json:"stage"`
	CurrentVersion  string          `json:"current_version,omitempty"`
	PreviousVersion string          `json:"previous_version,omitempty"`
	Previous        *ReleasePointer `json:"previous,omitempty"`
	PendingVersion  string          `json:"pending_version,omitempty"`
	ActivatedAt     time.Time       `json:"activated_at,omitempty"`
	Healthy         bool            `json:"healthy"`
	LastError       string          `json:"last_error,omitempty"`
	UpdatedAt       time.Time       `json:"updated_at"`
}

type Status struct {
	Current *ReleasePointer `json:"current,omitempty"`
	Pending *ReleasePointer `json:"pending,omitempty"`
	State   State           `json:"state"`
}

type Manager struct {
	config Config
}

func New(config Config) (*Manager, error) {
	if config.Client == nil {
		return nil, errors.New("\u5ba2\u6237\u7aef\u4e0d\u80fd\u4e3a\u7a7a")
	}
	if strings.TrimSpace(config.PackageName) == "" {
		return nil, errors.New("\u5305\u540d\u4e0d\u80fd\u4e3a\u7a7a")
	}
	if strings.TrimSpace(config.RootDir) == "" {
		return nil, errors.New("\u66f4\u65b0\u6839\u76ee\u5f55\u4e0d\u80fd\u4e3a\u7a7a")
	}
	platform, architecture := config.Platform, config.Architecture
	if platform == "" && architecture == "" {
		platform, architecture = scoutpkg.CurrentTarget()
	} else {
		var err error
		platform, err = scoutpkg.NormalizePlatform(platform)
		if err != nil {
			return nil, err
		}
		architecture, err = scoutpkg.NormalizeArchitecture(architecture)
		if err != nil {
			return nil, err
		}
	}
	config.Platform = platform
	config.Architecture = architecture
	if config.Channel == "" {
		config.Channel = "stable"
	}
	if config.HealthTimeout <= 0 {
		config.HealthTimeout = 2 * time.Minute
	}
	if config.KeepReleases <= 0 {
		config.KeepReleases = 2
	}
	root, err := filepath.Abs(config.RootDir)
	if err != nil {
		return nil, fmt.Errorf("\u89e3\u6790\u66f4\u65b0\u6839\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	config.RootDir = root
	if config.Adapter == nil {
		config.Adapter, err = NewPlatformAdapter(config.Platform)
		if err != nil {
			return nil, err
		}
	}
	for _, name := range []string{"releases", "downloads"} {
		if err := os.MkdirAll(filepath.Join(root, name), 0o755); err != nil {
			return nil, fmt.Errorf("\u521b\u5efa\u66f4\u65b0\u76ee\u5f55\u5931\u8d25: %w", err)
		}
	}
	manager := &Manager{config: config}
	if _, err := manager.readPointer("current.json"); os.IsNotExist(err) && config.CurrentVersion != "" && config.CurrentPath != "" && config.Entrypoint != "" {
		if _, err := manager.RegisterCurrent(config.CurrentVersion, config.CurrentPath, config.Entrypoint); err != nil {
			return nil, err
		}
	}
	return manager, nil
}

func (manager *Manager) RegisterCurrent(version, releasePath, entrypoint string) (ReleasePointer, error) {
	if strings.TrimSpace(version) == "" {
		return ReleasePointer{}, errors.New("\u5f53\u524d\u7248\u672c\u4e0d\u80fd\u4e3a\u7a7a")
	}
	releasePath, err := filepath.Abs(releasePath)
	if err != nil {
		return ReleasePointer{}, fmt.Errorf("\u89e3\u6790\u5f53\u524d\u7a0b\u5e8f\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	executable, err := safeEntrypoint(releasePath, entrypoint)
	if err != nil {
		return ReleasePointer{}, err
	}
	if _, err := os.Stat(executable); err != nil {
		return ReleasePointer{}, fmt.Errorf("\u5f53\u524d\u7a0b\u5e8f\u5165\u53e3\u4e0d\u5b58\u5728: %w", err)
	}
	if err := manager.config.Adapter.Validate(ReleasePointer{
		Version:      version,
		Path:         releasePath,
		Entrypoint:   entrypoint,
		Platform:     manager.config.Platform,
		Architecture: manager.config.Architecture,
		PackageType:  "full",
	}); err != nil {
		return ReleasePointer{}, err
	}
	now := time.Now().UTC()
	pointer := ReleasePointer{
		Version:      version,
		Path:         releasePath,
		Entrypoint:   entrypoint,
		Platform:     manager.config.Platform,
		Architecture: manager.config.Architecture,
		PackageType:  "full",
		PreparedAt:   now,
		ActivatedAt:  now,
		HealthyAt:    now,
	}
	if err := manager.writeJSON("current.json", pointer); err != nil {
		return ReleasePointer{}, err
	}
	state := State{Stage: "healthy", CurrentVersion: version, Healthy: true, UpdatedAt: now}
	if err := manager.writeJSON("state.json", state); err != nil {
		return ReleasePointer{}, err
	}
	return pointer, nil
}

func (manager *Manager) Check(ctx context.Context) (client.Package, bool, error) {
	currentVersion := manager.currentVersion()
	return manager.config.Client.CheckUpdateFor(ctx, manager.config.PackageName, currentVersion, manager.queryOptions(currentVersion))
}

func (manager *Manager) Watch(ctx context.Context) (<-chan client.Update, error) {
	currentVersion := manager.currentVersion()
	return manager.config.Client.WatchUpdatesFor(ctx, client.WatchRequest{
		Packages:     []string{manager.config.PackageName},
		Versions:     map[string]string{manager.config.PackageName: currentVersion},
		Platform:     manager.config.Platform,
		Architecture: manager.config.Architecture,
		Channel:      manager.config.Channel,
	})
}

func (manager *Manager) Prepare(ctx context.Context, version string) (ReleasePointer, error) {
	if pending, err := manager.readPointer("pending.json"); err == nil {
		return ReleasePointer{}, fmt.Errorf("\u5df2\u6709\u5f85\u6fc0\u6d3b\u7248\u672c %s", pending.Version)
	}
	currentVersion := manager.currentVersion()
	options := manager.queryOptions(currentVersion)
	item, err := manager.resolvePackage(ctx, version, options)
	if err != nil {
		return ReleasePointer{}, err
	}
	if currentVersion != "" && client.CompareVersions(item.Version, currentVersion) <= 0 {
		return ReleasePointer{}, errors.New("\u76ee\u6807\u7248\u672c\u5fc5\u987b\u9ad8\u4e8e\u5f53\u524d\u7248\u672c")
	}
	releaseDir, err := manager.safeReleaseDir(item.Version)
	if err != nil {
		return ReleasePointer{}, err
	}
	if _, err := os.Stat(releaseDir); err == nil {
		return ReleasePointer{}, errors.New("\u76ee\u6807\u7248\u672c\u76ee\u5f55\u5df2\u7ecf\u5b58\u5728")
	} else if !os.IsNotExist(err) {
		return ReleasePointer{}, fmt.Errorf("\u68c0\u67e5\u7248\u672c\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	stagingDir, err := os.MkdirTemp(filepath.Dir(releaseDir), ".staging-"+item.Version+"-")
	if err != nil {
		return ReleasePointer{}, fmt.Errorf("\u521b\u5efa\u7248\u672c\u4e34\u65f6\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	stagingReady := false
	defer func() {
		if !stagingReady {
			_ = os.RemoveAll(stagingDir)
		}
	}()

	fileName := item.FileName
	if fileName == "" && len(item.Targets) > 0 {
		fileName = item.Targets[0].FileName
	}
	if fileName == "" {
		fileName = fmt.Sprintf("%s-%s.pkg", item.Name, item.Version)
	}
	downloadPath := filepath.Join(manager.config.RootDir, "downloads", item.Version+"-"+filepath.Base(fileName))
	downloaded, err := manager.config.Client.DownloadFor(ctx, item.Name, item.Version, downloadPath, options)
	if err != nil {
		return ReleasePointer{}, err
	}

	entrypoint := manager.config.Entrypoint
	if strings.EqualFold(filepath.Ext(fileName), ".scout") {
		entrypoint, err = manager.extractScout(downloadPath, stagingDir, entrypoint)
		if err != nil {
			return ReleasePointer{}, err
		}
	} else {
		destination := filepath.Join(stagingDir, filepath.Base(fileName))
		if err := moveDownloadedFile(downloadPath, destination); err != nil {
			return ReleasePointer{}, err
		}
		if entrypoint == "" {
			entrypoint = filepath.Base(fileName)
		}
	}
	if entrypoint == "" {
		return ReleasePointer{}, errors.New("\u66f4\u65b0\u5305\u672a\u6307\u5b9a\u7a0b\u5e8f\u5165\u53e3")
	}
	executable, err := safeEntrypoint(stagingDir, entrypoint)
	if err != nil {
		return ReleasePointer{}, err
	}
	if _, err := os.Stat(executable); err != nil {
		return ReleasePointer{}, fmt.Errorf("\u65b0\u7248\u672c\u7a0b\u5e8f\u5165\u53e3\u4e0d\u5b58\u5728: %w", err)
	}
	if err := manager.config.Adapter.Validate(ReleasePointer{
		Version:      item.Version,
		Path:         stagingDir,
		Entrypoint:   entrypoint,
		Platform:     manager.config.Platform,
		Architecture: manager.config.Architecture,
		PackageType:  item.PackageType,
		SHA256:       item.SHA256,
	}); err != nil {
		return ReleasePointer{}, err
	}
	if runtime.GOOS != "windows" && manager.config.Platform != "android" {
		if info, err := os.Stat(executable); err == nil && info.Mode().Perm()&0o111 == 0 {
			_ = os.Chmod(executable, info.Mode().Perm()|0o755)
		}
	}

	now := time.Now().UTC()
	pointer := ReleasePointer{
		Version:      item.Version,
		Path:         releaseDir,
		Entrypoint:   entrypoint,
		Platform:     item.Platform,
		Architecture: item.Architecture,
		PackageType:  item.PackageType,
		SHA256:       downloaded.SHA256,
		PreparedAt:   now,
	}
	if err := manager.writeReleaseMetadataAt(stagingDir, pointer); err != nil {
		return ReleasePointer{}, err
	}
	if err := os.Rename(stagingDir, releaseDir); err != nil {
		return ReleasePointer{}, fmt.Errorf("\u6fc0\u6d3b\u7248\u672c\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	stagingReady = true
	if err := manager.writeJSON("pending.json", pointer); err != nil {
		return ReleasePointer{}, err
	}
	state := State{
		Stage:          "prepared",
		CurrentVersion: currentVersion,
		PendingVersion: pointer.Version,
		Healthy:        false,
		UpdatedAt:      now,
	}
	if err := manager.writeJSON("state.json", state); err != nil {
		return ReleasePointer{}, err
	}
	return pointer, nil
}

func (manager *Manager) Activate() (ReleasePointer, error) {
	pending, err := manager.readPointer("pending.json")
	if err != nil {
		return ReleasePointer{}, errors.New("\u6ca1\u6709\u5f85\u6fc0\u6d3b\u7248\u672c")
	}
	var previous *ReleasePointer
	if current, err := manager.readPointer("current.json"); err == nil {
		previous = &current
	}
	now := time.Now().UTC()
	pending.ActivatedAt = now
	pending.HealthyAt = time.Time{}
	if err := manager.writeJSON("current.json", pending); err != nil {
		return ReleasePointer{}, err
	}
	state := State{
		Stage:          "activated",
		CurrentVersion: pending.Version,
		PendingVersion: pending.Version,
		ActivatedAt:    now,
		Healthy:        false,
		UpdatedAt:      now,
	}
	if previous != nil {
		state.Previous = previous
		state.PreviousVersion = previous.Version
	}
	if err := manager.writeJSON("state.json", state); err != nil {
		return ReleasePointer{}, err
	}
	return pending, nil
}

// Install 将待激活版本交给平台适配器处理。
// 桌面平台通常只需要准备文件，Android 等平台由宿主应用注入系统安装实现。
func (manager *Manager) Install(ctx context.Context) error {
	pending, err := manager.readPointer("pending.json")
	if err != nil {
		if os.IsNotExist(err) {
			return errors.New("没有待安装版本，请先准备更新")
		}
		return err
	}
	return manager.config.Adapter.Install(ctx, pending)
}

func (manager *Manager) ConfirmHealthy(version string) error {
	current, err := manager.readPointer("current.json")
	if err != nil {
		return errors.New("\u5f53\u524d\u7248\u672c\u6307\u9488\u4e0d\u5b58\u5728")
	}
	if version != "" && current.Version != version {
		return errors.New("\u5065\u5eb7\u786e\u8ba4\u7248\u672c\u4e0e\u5f53\u524d\u7248\u672c\u4e0d\u4e00\u81f4")
	}
	state, err := manager.readState()
	if err != nil {
		return err
	}
	if state.Stage != "activated" || state.CurrentVersion != current.Version {
		return errors.New("\u5f53\u524d\u72b6\u6001\u4e0d\u5141\u8bb8\u5065\u5eb7\u786e\u8ba4")
	}
	now := time.Now().UTC()
	current.HealthyAt = now
	if err := manager.writeJSON("current.json", current); err != nil {
		return err
	}
	state.Stage = "healthy"
	state.PendingVersion = ""
	state.Healthy = true
	state.UpdatedAt = now
	if err := manager.writeJSON("state.json", state); err != nil {
		return err
	}
	_ = os.Remove(manager.filePath("pending.json"))
	return manager.Cleanup()
}

func (manager *Manager) Rollback(reason error) (ReleasePointer, error) {
	state, err := manager.readState()
	if err != nil {
		return ReleasePointer{}, err
	}
	if state.Previous == nil {
		return ReleasePointer{}, errors.New("\u6ca1\u6709\u53ef\u56de\u6eda\u7684\u65e7\u7248\u672c\u6307\u9488")
	}
	previous := *state.Previous
	if _, err := safeEntrypoint(previous.Path, previous.Entrypoint); err != nil {
		return ReleasePointer{}, err
	}
	if err := manager.writeJSON("current.json", previous); err != nil {
		return ReleasePointer{}, err
	}
	state.Stage = "rolled_back"
	state.CurrentVersion = previous.Version
	state.PendingVersion = ""
	state.Healthy = true
	if reason != nil {
		state.LastError = reason.Error()
	}
	state.UpdatedAt = time.Now().UTC()
	if err := manager.writeJSON("state.json", state); err != nil {
		return ReleasePointer{}, err
	}
	_ = os.Remove(manager.filePath("pending.json"))
	return previous, nil
}

func (manager *Manager) RecoverStaleActivation(now time.Time) (bool, error) {
	state, err := manager.readState()
	if err != nil {
		if os.IsNotExist(err) {
			return false, nil
		}
		return false, err
	}
	if state.Stage != "activated" || state.Healthy {
		return false, nil
	}
	if now.Before(state.ActivatedAt.Add(manager.config.HealthTimeout)) {
		return false, nil
	}
	if state.Previous == nil {
		return false, errors.New("\u5065\u5eb7\u786e\u8ba4\u8d85\u65f6\uff0c\u4f46\u6ca1\u6709\u53ef\u56de\u6eda\u7684\u65e7\u7248\u672c")
	}
	_, rollbackErr := manager.Rollback(errors.New("\u65b0\u7248\u672c\u5065\u5eb7\u786e\u8ba4\u8d85\u65f6\uff0c\u5df2\u81ea\u52a8\u56de\u6eda"))
	return rollbackErr == nil, rollbackErr
}

func (manager *Manager) Status() (Status, error) {
	result := Status{}
	if current, err := manager.readPointer("current.json"); err == nil {
		result.Current = &current
	} else if !os.IsNotExist(err) {
		return Status{}, err
	}
	if pending, err := manager.readPointer("pending.json"); err == nil {
		result.Pending = &pending
	} else if !os.IsNotExist(err) {
		return Status{}, err
	}
	state, err := manager.readState()
	if err != nil && !os.IsNotExist(err) {
		return Status{}, err
	}
	result.State = state
	return result, nil
}

func (manager *Manager) ResolveCurrent() (string, ReleasePointer, error) {
	current, err := manager.readPointer("current.json")
	if err != nil {
		return "", ReleasePointer{}, errors.New("\u5f53\u524d\u7248\u672c\u6307\u9488\u4e0d\u5b58\u5728")
	}
	executable, err := safeEntrypoint(current.Path, current.Entrypoint)
	if err != nil {
		return "", ReleasePointer{}, err
	}
	if _, err := os.Stat(executable); err != nil {
		return "", ReleasePointer{}, fmt.Errorf("\u5f53\u524d\u7a0b\u5e8f\u5165\u53e3\u4e0d\u5b58\u5728: %w", err)
	}
	return executable, current, nil
}

func (manager *Manager) Launch(ctx context.Context, args ...string) (*exec.Cmd, error) {
	_, current, err := manager.ResolveCurrent()
	if err != nil {
		return nil, err
	}
	return manager.config.Adapter.Launch(ctx, LaunchRequest{
		Release: current,
		Args:    args,
		Env: append(os.Environ(),
			"SCOUT_PACKAGE="+manager.config.PackageName,
			"SCOUT_VERSION="+current.Version,
			"SCOUT_UPDATE_ROOT="+manager.config.RootDir,
			"SCOUT_PLATFORM="+manager.config.Platform,
			"SCOUT_ARCHITECTURE="+manager.config.Architecture,
		),
	})
}

func (manager *Manager) Cleanup() error {
	releasesDir := filepath.Join(manager.config.RootDir, "releases")
	entries, err := os.ReadDir(releasesDir)
	if err != nil {
		return fmt.Errorf("\u8bfb\u53d6\u7248\u672c\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	status, err := manager.Status()
	if err != nil {
		return err
	}
	protected := make(map[string]bool)
	if status.Current != nil && isManagedRelease(releasesDir, status.Current.Path) {
		protected[status.Current.Version] = true
	}
	if status.Pending != nil && isManagedRelease(releasesDir, status.Pending.Path) {
		protected[status.Pending.Version] = true
	}
	candidates := make([]os.DirEntry, 0, len(entries))
	for _, entry := range entries {
		if entry.IsDir() && !protected[entry.Name()] {
			candidates = append(candidates, entry)
		}
	}
	sort.Slice(candidates, func(left, right int) bool {
		leftInfo, _ := candidates[left].Info()
		rightInfo, _ := candidates[right].Info()
		return leftInfo.ModTime().After(rightInfo.ModTime())
	})
	keepCandidates := manager.config.KeepReleases - len(protected)
	if keepCandidates < 0 {
		keepCandidates = 0
	}
	for index, entry := range candidates {
		if index < keepCandidates {
			continue
		}
		target, err := manager.safeReleaseDir(entry.Name())
		if err != nil {
			return err
		}
		if err := os.RemoveAll(target); err != nil {
			return fmt.Errorf("\u6e05\u7406\u65e7\u7248\u672c\u5931\u8d25: %w", err)
		}
	}
	return nil
}

func (manager *Manager) resolvePackage(ctx context.Context, version string, options client.QueryOptions) (client.Package, error) {
	if strings.TrimSpace(version) == "" {
		return manager.config.Client.GetLatestFor(ctx, manager.config.PackageName, options)
	}
	versions, err := manager.config.Client.ListVersionsFor(ctx, manager.config.PackageName, options)
	if err != nil {
		return client.Package{}, err
	}
	for _, item := range versions {
		if item.Version == version {
			return item, nil
		}
	}
	return client.Package{}, errors.New("\u6ca1\u6709\u627e\u5230\u6307\u5b9a\u7684\u517c\u5bb9\u7248\u672c")
}

func (manager *Manager) extractScout(downloadPath, releaseDir, fallbackEntrypoint string) (string, error) {
	archive, err := scoutpkg.Open(downloadPath)
	if err != nil {
		return "", err
	}
	target, extractErr := archive.Extract(manager.config.Platform, manager.config.Architecture, releaseDir)
	closeErr := archive.Close()
	if extractErr != nil {
		return "", extractErr
	}
	if closeErr != nil {
		return "", closeErr
	}
	if target.Entrypoint == "" {
		return fallbackEntrypoint, nil
	}
	relative := strings.TrimPrefix(target.Entrypoint, strings.TrimSuffix(target.Path, "/"))
	relative = strings.TrimPrefix(relative, "/")
	if relative == "" {
		relative = filepath.Base(filepath.FromSlash(target.Path))
	}
	return filepath.FromSlash(relative), nil
}

func (manager *Manager) queryOptions(currentVersion string) client.QueryOptions {
	return client.QueryOptions{
		Platform:       manager.config.Platform,
		Architecture:   manager.config.Architecture,
		Channel:        manager.config.Channel,
		CurrentVersion: currentVersion,
	}
}

func (manager *Manager) currentVersion() string {
	if current, err := manager.readPointer("current.json"); err == nil && current.Version != "" {
		return current.Version
	}
	return manager.config.CurrentVersion
}

func (manager *Manager) writeReleaseMetadata(pointer ReleasePointer) error {
	return manager.writeReleaseMetadataAt(pointer.Path, pointer)
}

func (manager *Manager) writeReleaseMetadataAt(directory string, pointer ReleasePointer) error {
	data, err := json.MarshalIndent(pointer, "", "  ")
	if err != nil {
		return fmt.Errorf("\u7f16\u7801\u7248\u672c\u5143\u6570\u636e\u5931\u8d25: %w", err)
	}
	if err := os.WriteFile(filepath.Join(directory, "scout-release.json"), data, 0o644); err != nil {
		return fmt.Errorf("\u4fdd\u5b58\u7248\u672c\u5143\u6570\u636e\u5931\u8d25: %w", err)
	}
	return nil
}

func (manager *Manager) writeJSON(name string, value any) error {
	data, err := json.MarshalIndent(value, "", "  ")
	if err != nil {
		return fmt.Errorf("\u7f16\u7801\u66f4\u65b0\u72b6\u6001\u5931\u8d25: %w", err)
	}
	temp, err := os.CreateTemp(manager.config.RootDir, ".state-*")
	if err != nil {
		return fmt.Errorf("\u521b\u5efa\u72b6\u6001\u4e34\u65f6\u6587\u4ef6\u5931\u8d25: %w", err)
	}
	tempPath := temp.Name()
	defer os.Remove(tempPath)
	if _, err := temp.Write(data); err != nil {
		temp.Close()
		return fmt.Errorf("\u5199\u5165\u66f4\u65b0\u72b6\u6001\u5931\u8d25: %w", err)
	}
	if err := temp.Close(); err != nil {
		return fmt.Errorf("\u5173\u95ed\u72b6\u6001\u4e34\u65f6\u6587\u4ef6\u5931\u8d25: %w", err)
	}
	if err := os.Rename(tempPath, manager.filePath(name)); err != nil {
		return fmt.Errorf("\u4fdd\u5b58\u66f4\u65b0\u72b6\u6001\u5931\u8d25: %w", err)
	}
	return nil
}

func (manager *Manager) readPointer(name string) (ReleasePointer, error) {
	data, err := os.ReadFile(manager.filePath(name))
	if err != nil {
		return ReleasePointer{}, err
	}
	var pointer ReleasePointer
	if err := json.Unmarshal(data, &pointer); err != nil {
		return ReleasePointer{}, fmt.Errorf("\u8bfb\u53d6\u7248\u672c\u6307\u9488\u5931\u8d25: %w", err)
	}
	return pointer, nil
}

func (manager *Manager) readState() (State, error) {
	data, err := os.ReadFile(manager.filePath("state.json"))
	if err != nil {
		return State{}, err
	}
	var state State
	if err := json.Unmarshal(data, &state); err != nil {
		return State{}, fmt.Errorf("\u8bfb\u53d6\u66f4\u65b0\u72b6\u6001\u5931\u8d25: %w", err)
	}
	return state, nil
}

func (manager *Manager) safeReleaseDir(version string) (string, error) {
	version = strings.TrimSpace(version)
	if version == "" || version == "." || version == ".." || filepath.Base(version) != version || strings.ContainsAny(version, `/\\`) {
		return "", errors.New("\u7248\u672c\u76ee\u5f55\u540d\u65e0\u6548")
	}
	releasesDir := filepath.Join(manager.config.RootDir, "releases")
	target := filepath.Join(releasesDir, version)
	if !isManagedRelease(releasesDir, target) {
		return "", errors.New("\u7248\u672c\u76ee\u5f55\u8d85\u51fa\u66f4\u65b0\u6839\u76ee\u5f55")
	}
	return target, nil
}

func (manager *Manager) filePath(name string) string {
	return filepath.Join(manager.config.RootDir, name)
}

func safeEntrypoint(releaseDir, entrypoint string) (string, error) {
	if strings.TrimSpace(entrypoint) == "" {
		return "", errors.New("\u7a0b\u5e8f\u5165\u53e3\u4e0d\u80fd\u4e3a\u7a7a")
	}
	releaseDir, err := filepath.Abs(releaseDir)
	if err != nil {
		return "", fmt.Errorf("\u89e3\u6790\u7248\u672c\u76ee\u5f55\u5931\u8d25: %w", err)
	}
	executable := filepath.Join(releaseDir, filepath.FromSlash(entrypoint))
	relation, err := filepath.Rel(releaseDir, executable)
	if err != nil || relation == ".." || strings.HasPrefix(relation, ".."+string(filepath.Separator)) || filepath.IsAbs(entrypoint) {
		return "", errors.New("\u7a0b\u5e8f\u5165\u53e3\u8d85\u51fa\u7248\u672c\u76ee\u5f55")
	}
	return executable, nil
}

func moveDownloadedFile(source, destination string) error {
	if err := os.Rename(source, destination); err == nil {
		return nil
	}
	input, err := os.Open(source)
	if err != nil {
		return fmt.Errorf("\u8bfb\u53d6\u5df2\u4e0b\u8f7d\u6587\u4ef6\u5931\u8d25: %w", err)
	}
	defer input.Close()
	output, err := os.Create(destination)
	if err != nil {
		return fmt.Errorf("\u521b\u5efa\u7248\u672c\u6587\u4ef6\u5931\u8d25: %w", err)
	}
	_, copyErr := io.Copy(output, input)
	closeErr := output.Close()
	if copyErr != nil {
		return fmt.Errorf("\u590d\u5236\u7248\u672c\u6587\u4ef6\u5931\u8d25: %w", copyErr)
	}
	if closeErr != nil {
		return fmt.Errorf("\u5173\u95ed\u7248\u672c\u6587\u4ef6\u5931\u8d25: %w", closeErr)
	}
	return nil
}

func isManagedRelease(releasesDir, candidate string) bool {
	releasesDir, err := filepath.Abs(releasesDir)
	if err != nil {
		return false
	}
	candidate, err = filepath.Abs(candidate)
	if err != nil {
		return false
	}
	relation, err := filepath.Rel(releasesDir, candidate)
	return err == nil && relation != "." && relation != ".." && !strings.HasPrefix(relation, ".."+string(filepath.Separator))
}