package nginx

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"fmt"
	"io/fs"
	"log/slog"
	"net"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
	"time"

	"openflare-agent/internal/protocol"
)

const CertDirPlaceholder = "__OPENFLARE_CERT_DIR__"
const RouteConfigPlaceholder = "__OPENFLARE_ROUTE_CONFIG__"
const AccessLogPlaceholder = "__OPENFLARE_ACCESS_LOG__"
const LuaDirPlaceholder = "__OPENFLARE_LUA_DIR__"
const RuntimeConfigDirPlaceholder = "__OPENFLARE_RUNTIME_CONFIG_DIR__"
const ObservabilityListenPlaceholder = "__OPENFLARE_OBSERVABILITY_LISTEN__"
const ObservabilityPortPlaceholder = "__OPENFLARE_OBSERVABILITY_PORT__"
const ResolverDirectivePlaceholder = "__OPENFLARE_RESOLVER_DIRECTIVE__"
const PowStaticDirPlaceholder = "__OPENFLARE_POW_STATIC_DIR__"

type Executor interface {
	Test(ctx context.Context) error
	Reload(ctx context.Context) error
	EnsureRuntime(ctx context.Context, recreate bool) error
	CheckHealth(ctx context.Context) error
	Restart(ctx context.Context) error
}

type CommandRunner interface {
	Run(ctx context.Context, name string, args ...string) ([]byte, error)
}

type OSCommandRunner struct{}

func (r *OSCommandRunner) Run(ctx context.Context, name string, args ...string) ([]byte, error) {
	slog.Debug("OSCommandRunner starting command", "name", name, "args", args)
	tmpFile, err := os.CreateTemp("", "openflare-cmd-*")
	if err != nil {
		slog.Error("OSCommandRunner failed to create temp file, falling back to CombinedOutput", "error", err)
		cmd := exec.CommandContext(ctx, name, args...)
		output, outErr := cmd.CombinedOutput()
		slog.Debug("OSCommandRunner finished CombinedOutput", "name", name, "error", outErr)
		return output, outErr
	}
	defer os.Remove(tmpFile.Name())

	cmd := exec.CommandContext(ctx, name, args...)
	cmd.Stdout = tmpFile
	cmd.Stderr = tmpFile

	slog.Debug("OSCommandRunner executing cmd.Run()", "name", name)
	runErr := cmd.Run()
	slog.Debug("OSCommandRunner cmd.Run() returned", "name", name, "error", runErr)
	tmpFile.Close()

	output, _ := os.ReadFile(tmpFile.Name())
	slog.Debug("OSCommandRunner command complete", "name", name, "output_len", len(output))
	return output, runErr
}

type PathExecutor struct {
	Path       string
	ConfigPath string
	Runner     CommandRunner
}

func (e *PathExecutor) Test(ctx context.Context) error {
	slog.Debug("running openresty test with binary", "path", e.Path, "config", e.ConfigPath)
	output, err := e.Runner.Run(ctx, e.Path, "-t", "-c", e.ConfigPath)
	if err != nil {
		return fmt.Errorf("openresty -t failed: %w: %s", err, string(output))
	}
	slog.Debug("openresty test succeeded with binary", "path", e.Path)
	return nil
}

func (e *PathExecutor) Reload(ctx context.Context) error {
	slog.Debug("running openresty reload with binary", "path", e.Path, "config", e.ConfigPath)
	output, err := e.Runner.Run(ctx, e.Path, "-s", "reload", "-c", e.ConfigPath)
	if err != nil {
		if isOpenrestyNotRunningError(string(output)) {
			slog.Warn("openresty reload reported runtime is not running, starting binary", "path", e.Path)
			startOutput, startErr := e.Runner.Run(ctx, e.Path, "-c", e.ConfigPath)
			if startErr != nil {
				return fmt.Errorf("openresty reload failed: %w: %s; start failed: %v: %s", err, string(output), startErr, string(startOutput))
			}
			return nil
		}
		return fmt.Errorf("openresty reload failed: %w: %s", err, string(output))
	}
	slog.Debug("openresty reload succeeded with binary", "path", e.Path)
	return nil
}

func (e *PathExecutor) EnsureRuntime(ctx context.Context, recreate bool) error {
	if err := e.Test(ctx); err != nil {
		return err
	}
	return e.Reload(ctx)
}

func (e *PathExecutor) CheckHealth(ctx context.Context) error {
	return e.Test(ctx)
}

func (e *PathExecutor) Restart(ctx context.Context) error {
	slog.Info("restarting openresty with binary", "path", e.Path, "config", e.ConfigPath)
	output, err := e.Runner.Run(ctx, e.Path, "-s", "quit", "-c", e.ConfigPath)
	if err != nil {
		text := string(output)
		if !isIgnorableOpenrestyStopError(text) {
			return fmt.Errorf("openresty stop failed: %w: %s", err, text)
		}
	}
	output, err = e.Runner.Run(ctx, e.Path, "-c", e.ConfigPath)
	if err != nil {
		return fmt.Errorf("openresty start failed: %w: %s", err, string(output))
	}
	slog.Info("openresty restart succeeded with binary", "path", e.Path)
	return nil
}

type Manager struct {
	MainConfigPath               string
	RouteConfigPath              string
	AccessLogPath                string
	CertDir                      string
	NginxCertDir                 string
	LuaDir                       string
	NginxLuaDir                  string
	RuntimeConfigDir             string
	OpenrestyObservabilityListen string
	OpenrestyObservabilityPort   int
	OpenrestyResolverDirective   string
	Executor                     Executor
}

type ApplyStatus string

const (
	ApplyStatusSuccess ApplyStatus = "success"
	ApplyStatusWarning ApplyStatus = "warning"
	ApplyStatusFatal   ApplyStatus = "fatal"
)

const safeDefaultFallbackMainConfig = `# This file is generated by OpenFlare safe default fallback.
worker_processes auto;
pid logs/nginx.pid;

events {
    worker_connections 1024;
}

http {
    default_type text/plain;

    server {
        listen 80 default_server;
        server_name _;
        return 503 "OpenFlare: No Valid Configuration\n";
    }
%s
}
`

const safeDefaultFallbackObservabilityServerBlock = `
    server {
        listen %s;
        server_name openflare-observability;
        access_log off;

        location = /openflare/stub_status {
            stub_status;
        }
    }
`

type ApplyOutcome struct {
	Status  ApplyStatus
	Message string
}

func (m *Manager) Apply(ctx context.Context, mainConfig string, routeConfig string, supportFiles []protocol.SupportFile) ApplyOutcome {
	slog.Info("openresty apply started", "main_config", m.MainConfigPath, "route_config", m.RouteConfigPath, "cert_files", len(supportFiles))
	backup, err := m.backup()
	if err != nil {
		return fatalApplyOutcome(fmt.Errorf("backup openresty config failed: %w", err))
	}
	if err = m.writeTargetFiles(mainConfig, routeConfig, supportFiles); err != nil {
		return m.rollbackAfterFailedApply(ctx, backup, fmt.Errorf("write openresty config failed: %w", err))
	}
	if err = m.activateConfig(ctx); err != nil {
		return m.rollbackAfterFailedApply(ctx, backup, fmt.Errorf("activate openresty runtime failed: %w", err))
	}
	slog.Info("openresty apply completed successfully", "main_config", m.MainConfigPath, "route_config", m.RouteConfigPath)
	return ApplyOutcome{Status: ApplyStatusSuccess}
}

func (m *Manager) writeTargetFiles(mainConfig string, routeConfig string, supportFiles []protocol.SupportFile) error {
	if err := m.EnsureLuaAssets(); err != nil {
		return err
	}
	if err := m.writeCertFiles(supportFiles); err != nil {
		return err
	}
	if err := m.writePowConfig(supportFiles); err != nil {
		return err
	}
	if err := m.writeWAFConfig(supportFiles); err != nil {
		return err
	}
	if err := m.ensureMimeTypes(); err != nil {
		return err
	}
	if strings.TrimSpace(m.OpenrestyResolverDirective) == "" && strings.Contains(routeConfig, "set $openflare_upstream ") {
		slog.Warn("runtime-resolved hostname upstreams detected without available resolvers; hostname origin requests may fail until resolvers are configured")
	}
	renderedMainConfig := m.renderMainConfig(mainConfig)
	if err := os.WriteFile(m.MainConfigPath, []byte(renderedMainConfig), 0o644); err != nil {
		return err
	}
	renderedRouteConfig := m.renderRouteConfig(routeConfig)
	if err := os.WriteFile(m.RouteConfigPath, []byte(renderedRouteConfig), 0o644); err != nil {
		return err
	}
	return nil
}

func (m *Manager) activateConfig(ctx context.Context) error {
	if m.Executor == nil {
		return errors.New("executor 未配置")
	}
	if err := m.Executor.Test(ctx); err != nil {
		return err
	}
	return m.Executor.Reload(ctx)
}

func (m *Manager) rollbackAfterFailedApply(ctx context.Context, backup *backupState, applyErr error) ApplyOutcome {
	slog.Warn("openresty apply failed, restoring previous config", "error", applyErr)
	if err := m.restore(backup); err != nil {
		return fatalApplyOutcome(fmt.Errorf("restore openresty backup failed after apply error %v: %w", applyErr, err))
	}
	if err := m.activateConfig(ctx); err != nil {
		if backup != nil && backup.MainExisted {
			return fatalApplyOutcome(fmt.Errorf("apply failed: %v; rollback recovery failed: %w", applyErr, err))
		}
		if fallbackErr := m.EnsureSafeFallbackRuntime(ctx, fmt.Sprintf("apply failed: %v; rollback recovery failed: %v", applyErr, err)); fallbackErr != nil {
			return fatalApplyOutcome(fmt.Errorf("apply failed: %v; rollback recovery failed: %w; fallback recovery failed: %v", applyErr, err, fallbackErr))
		}
		message := fmt.Sprintf("apply failed, but fallback runtime started: %v; rollback recovery failed: %v", applyErr, err)
		slog.Warn("openresty apply recovered with safe default fallback", "message", message)
		return ApplyOutcome{
			Status:  ApplyStatusWarning,
			Message: message,
		}
	}
	message := fmt.Sprintf("apply failed, rolled back to previous config: %v", applyErr)
	slog.Warn("openresty apply rolled back successfully", "message", message)
	return ApplyOutcome{
		Status:  ApplyStatusWarning,
		Message: message,
	}
}

func fatalApplyOutcome(err error) ApplyOutcome {
	if err == nil {
		return ApplyOutcome{Status: ApplyStatusFatal}
	}
	return ApplyOutcome{
		Status:  ApplyStatusFatal,
		Message: strings.TrimSpace(err.Error()),
	}
}

func (m *Manager) EnsureLuaAssets() error {
	if strings.TrimSpace(m.LuaDir) == "" {
		return nil
	}
	allSupportFiles := append(ManagedObservabilityLuaFiles(), m.managedPowLuaFiles()...)
	allSupportFiles = append(allSupportFiles, m.managedWAFLuaFiles()...)
	powStaticFiles, err := ManagedPowStaticFiles()
	if err != nil {
		return fmt.Errorf("load pow static files: %w", err)
	}
	allSupportFiles = append(allSupportFiles, powStaticFiles...)
	files := make([]managedFile, 0, len(allSupportFiles))
	for _, file := range allSupportFiles {
		targetPath, err := luaFileTargetPath(m.LuaDir, file.Path)
		if err != nil {
			return err
		}
		relativePath, err := filepath.Rel(m.LuaDir, targetPath)
		if err != nil {
			return err
		}
		files = append(files, managedFile{
			Path:    filepath.ToSlash(relativePath),
			Content: []byte(file.Content),
			Mode:    0o644,
		})
	}
	return syncManagedFiles(m.LuaDir, files)
}

func (m *Manager) EnsureRuntime(ctx context.Context, recreate bool) error {
	if m.Executor == nil {
		return errors.New("executor 未配置")
	}
	slog.Info("openresty ensure runtime requested", "recreate", recreate)
	return m.Executor.EnsureRuntime(ctx, recreate)
}

func (m *Manager) EnsureSafeFallbackRuntime(ctx context.Context, reason string) error {
	if m.Executor == nil {
		return errors.New("executor 未配置")
	}
	trimmedReason := strings.TrimSpace(reason)
	if trimmedReason == "" {
		trimmedReason = "no valid local openresty config is available"
	}
	slog.Warn("starting openresty safe default fallback runtime", "reason", trimmedReason)
	if err := m.writeSafeDefaultFallbackFiles(); err != nil {
		return fmt.Errorf("write safe default fallback config failed: %w", err)
	}
	if err := m.activateConfig(ctx); err != nil {
		return fmt.Errorf("activate safe default fallback runtime failed: %w", err)
	}
	slog.Warn("openresty safe default fallback runtime started", "main_config", m.MainConfigPath, "route_config", m.RouteConfigPath)
	return nil
}

func (m *Manager) CheckHealth(ctx context.Context) error {
	if m.Executor == nil {
		return errors.New("executor 未配置")
	}
	if m.MainConfigPath != "" {
		if _, err := os.Stat(m.MainConfigPath); os.IsNotExist(err) {
			return errors.New("openresty config not exists: waiting for initial sync")
		}
	}
	if m.OpenrestyObservabilityPort <= 0 {
		return m.Executor.CheckHealth(ctx)
	}
	return m.checkStubStatus(ctx)
}

func (m *Manager) Restart(ctx context.Context) error {
	if m.Executor == nil {
		return errors.New("executor 未配置")
	}
	slog.Info("openresty restart requested")
	return m.Executor.Restart(ctx)
}

func (m *Manager) CurrentChecksum() (string, error) {
	if m.RouteConfigPath == "" {
		return "", errors.New("route config path 不能为空")
	}
	if m.MainConfigPath == "" {
		return "", errors.New("main config path 不能为空")
	}
	mainData, err := os.ReadFile(m.MainConfigPath)
	if err != nil {
		if os.IsNotExist(err) {
			return "", nil
		}
		return "", err
	}
	data, err := os.ReadFile(m.RouteConfigPath)
	if err != nil {
		if os.IsNotExist(err) {
			return "", nil
		}
		return "", err
	}
	normalizedMain := string(mainData)
	if includePath := m.routeConfigIncludePath(); includePath != "" {
		normalizedMain = strings.ReplaceAll(normalizedMain, includePath, RouteConfigPlaceholder)
	}
	if accessLogPath := m.accessLogRuntimePath(); accessLogPath != "" {
		normalizedMain = strings.ReplaceAll(normalizedMain, accessLogPath, AccessLogPlaceholder)
	}
	if luaDir := m.luaRuntimePath(); luaDir != "" {
		normalizedMain = strings.ReplaceAll(normalizedMain, luaDir, LuaDirPlaceholder)
	}
	if listen := strings.TrimSpace(m.OpenrestyObservabilityListen); listen != "" {
		normalizedMain = strings.ReplaceAll(normalizedMain, listen, ObservabilityListenPlaceholder)
	}
	if m.OpenrestyObservabilityPort > 0 {
		normalizedMain = strings.ReplaceAll(normalizedMain, fmt.Sprintf("%d", m.OpenrestyObservabilityPort), ObservabilityPortPlaceholder)
	}
	if resolverDirective := strings.TrimSpace(m.OpenrestyResolverDirective); resolverDirective != "" {
		normalizedMain = strings.ReplaceAll(normalizedMain, resolverDirective, ResolverDirectivePlaceholder)
	}
	normalizedRoute := string(data)
	if m.NginxCertDir != "" {
		normalizedRoute = strings.ReplaceAll(normalizedRoute, m.NginxCertDir, CertDirPlaceholder)
	}
	if luaDir := m.luaRuntimePath(); luaDir != "" {
		normalizedRoute = strings.ReplaceAll(normalizedRoute, luaDir+"/pow/static", PowStaticDirPlaceholder)
		normalizedRoute = strings.ReplaceAll(normalizedRoute, luaDir, LuaDirPlaceholder)
	}
	files, err := m.readManagedSupportFiles()
	if err != nil {
		return "", err
	}
	result := bundleChecksum(normalizedMain, normalizedRoute, files)
	slog.Debug("openresty current checksum calculated", "main_config", m.MainConfigPath, "route_config", m.RouteConfigPath, "checksum", result, "cert_files", len(files))
	return result, nil
}

type ExecutorOptions struct {
	NginxPath                  string
	MainConfigPath             string
	RouteConfigPath            string
	CertDir                    string
	NginxCertDir               string
	LuaDir                     string
	NginxLuaDir                string
	OpenrestyObservabilityPort int
}

func NewExecutor(options ExecutorOptions) Executor {
	runner := &OSCommandRunner{}
	return &PathExecutor{
		Path:       strings.TrimSpace(options.NginxPath),
		ConfigPath: strings.TrimSpace(options.MainConfigPath),
		Runner:     runner,
	}
}

func DetectVersion(ctx context.Context, options ExecutorOptions) string {
	version, err := detectVersion(ctx, options, &OSCommandRunner{})
	if err != nil {
		slog.Error("detect openresty version failed", "error", err)
		return ""
	}
	slog.Info("detected openresty version", "version", version)
	return version
}

func detectVersion(ctx context.Context, options ExecutorOptions, runner CommandRunner) (string, error) {
	if runner == nil {
		runner = &OSCommandRunner{}
	}
	if options.NginxPath != "" {
		output, err := runner.Run(ctx, options.NginxPath, "-v")
		if err != nil {
			return "", fmt.Errorf("run runtime -v failed: %w: %s", err, string(output))
		}
		version := parseNginxVersion(string(output))
		if version == "" {
			return "", errors.New("cannot parse runtime version from binary output")
		}
		return version, nil
	}
	return "", errors.New("openresty path is empty")
}

func parseNginxVersion(output string) string {
	matches := nginxVersionPattern.FindStringSubmatch(output)
	if len(matches) != 2 {
		return ""
	}
	return matches[1]
}

var nginxVersionPattern = regexp.MustCompile(`(?im)(?:nginx|openresty) version:\s*(?:nginx|openresty)/([^\s]+)`)

func isIgnorableOpenrestyStopError(output string) bool {
	text := strings.ToLower(strings.TrimSpace(output))
	if text == "" {
		return false
	}
	return strings.Contains(text, "invalid pid") || strings.Contains(text, "no such process")
}

func isOpenrestyNotRunningError(output string) bool {
	text := strings.ToLower(strings.TrimSpace(output))
	if text == "" {
		return false
	}
	return strings.Contains(text, "invalid pid") ||
		strings.Contains(text, "no such process") ||
		strings.Contains(text, "open()") && strings.Contains(text, "nginx.pid") && strings.Contains(text, "failed")
}

type backupState struct {
	MainExisted  bool
	MainData     []byte
	RouteExisted bool
	RouteData    []byte
	Files        []protocol.SupportFile
	PowConfig    *protocol.SupportFile
}

type managedFile struct {
	Path    string
	Content []byte
	Mode    fs.FileMode
}

func (m *Manager) backup() (*backupState, error) {
	if m.MainConfigPath == "" {
		return nil, errors.New("main config path 不能为空")
	}
	if m.RouteConfigPath == "" {
		return nil, errors.New("route config path 不能为空")
	}
	if err := os.MkdirAll(filepath.Dir(m.MainConfigPath), 0o755); err != nil {
		return nil, err
	}
	if err := os.MkdirAll(filepath.Dir(m.RouteConfigPath), 0o755); err != nil {
		return nil, err
	}
	if m.AccessLogPath != "" {
		if err := os.MkdirAll(filepath.Dir(m.AccessLogPath), 0o755); err != nil {
			return nil, err
		}
	}
	if m.CertDir != "" {
		if err := os.MkdirAll(m.CertDir, 0o755); err != nil {
			return nil, err
		}
	}
	if m.RuntimeConfigDir != "" {
		if err := os.MkdirAll(m.RuntimeConfigDir, 0o755); err != nil {
			return nil, err
		}
	}
	state := &backupState{}
	mainData, err := os.ReadFile(m.MainConfigPath)
	if err == nil {
		state.MainExisted = true
		state.MainData = mainData
	} else if !os.IsNotExist(err) {
		return nil, err
	}
	data, err := os.ReadFile(m.RouteConfigPath)
	if err == nil {
		state.RouteExisted = true
		state.RouteData = data
	} else if !os.IsNotExist(err) {
		return nil, err
	}
	files, err := m.readCertFiles()
	if err != nil {
		return nil, err
	}
	state.Files = files
	powConfig, err := m.readPowConfigFile()
	if err != nil {
		return nil, err
	}
	state.PowConfig = powConfig
	slog.Debug("backup captured", "main_exists", state.MainExisted, "route_exists", state.RouteExisted, "cert_files", len(state.Files))
	return state, nil
}

func (m *Manager) restore(state *backupState) error {
	if state == nil {
		return nil
	}
	slog.Warn("restoring nginx backup", "main_existed", state.MainExisted, "route_existed", state.RouteExisted, "cert_files", len(state.Files))
	if state.MainExisted {
		if err := os.WriteFile(m.MainConfigPath, state.MainData, 0o644); err != nil {
			return err
		}
	} else if err := os.Remove(m.MainConfigPath); err != nil && !os.IsNotExist(err) {
		return err
	}
	if state.RouteExisted {
		if err := os.WriteFile(m.RouteConfigPath, state.RouteData, 0o644); err != nil {
			return err
		}
	} else if err := os.Remove(m.RouteConfigPath); err != nil && !os.IsNotExist(err) {
		return err
	}
	if m.CertDir != "" {
		if err := m.writeManagedCertFiles(state.Files); err != nil {
			return err
		}
	}
	return m.restorePowConfig(state)
}

func (m *Manager) writeCertFiles(certFiles []protocol.SupportFile) error {
	if m.CertDir == "" {
		return nil
	}
	return m.writeManagedCertFiles(certFiles)
}

func (m *Manager) writePowConfig(supportFiles []protocol.SupportFile) error {
	if m.RuntimeConfigDir == "" {
		return nil
	}
	configPath := filepath.Join(m.RuntimeConfigDir, "pow_config.json")
	for _, file := range supportFiles {
		if file.Path == "pow_config.json" {
			if err := os.WriteFile(configPath, []byte(file.Content), 0o644); err != nil {
				return fmt.Errorf("write pow_config.json: %w", err)
			}
			slog.Info("wrote pow config", "path", configPath, "size", len(file.Content))
			return nil
		}
	}
	if err := os.Remove(configPath); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("remove pow_config.json: %w", err)
	}
	if err := removeLegacyPowConfig(filepath.Join(m.LuaDir, "pow_config.json")); err != nil {
		return err
	}
	if err := removeLegacyPowConfig(filepath.Join(m.CertDir, "pow_config.json")); err != nil {
		return err
	}
	return nil
}

func (m *Manager) writeWAFConfig(supportFiles []protocol.SupportFile) error {
	if m.RuntimeConfigDir == "" {
		return nil
	}
	configPath := filepath.Join(m.RuntimeConfigDir, "waf_config.json")
	for _, file := range supportFiles {
		if file.Path == "waf_config.json" {
			if err := os.WriteFile(configPath, []byte(file.Content), 0o644); err != nil {
				return fmt.Errorf("write waf_config.json: %w", err)
			}
			slog.Info("wrote waf config", "path", configPath, "size", len(file.Content))
			return nil
		}
	}
	if err := os.Remove(configPath); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("remove waf_config.json: %w", err)
	}
	return nil
}

func (m *Manager) writeManagedCertFiles(certFiles []protocol.SupportFile) error {
	files := make([]managedFile, 0, len(certFiles))
	for _, file := range certFiles {
		if file.Path == "pow_config.json" || file.Path == "waf_config.json" {
			continue
		}
		targetPath, err := m.certFileTargetPath(file.Path)
		if err != nil {
			return err
		}
		relativePath, err := filepath.Rel(m.CertDir, targetPath)
		if err != nil {
			return err
		}
		files = append(files, managedFile{
			Path:    filepath.ToSlash(relativePath),
			Content: []byte(file.Content),
			Mode:    certFileMode(file.Path),
		})
	}
	return syncManagedFiles(m.CertDir, files)
}

func (m *Manager) readCertFiles() ([]protocol.SupportFile, error) {
	if m.CertDir == "" {
		return nil, nil
	}
	if _, err := os.Stat(m.CertDir); err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, err
	}
	files := make([]protocol.SupportFile, 0)
	err := filepath.Walk(m.CertDir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			return nil
		}
		relativePath, err := filepath.Rel(m.CertDir, path)
		if err != nil {
			return err
		}
		if filepath.ToSlash(relativePath) == "pow_config.json" {
			return nil
		}
		data, err := os.ReadFile(path)
		if err != nil {
			return err
		}
		files = append(files, protocol.SupportFile{
			Path:    filepath.ToSlash(relativePath),
			Content: string(data),
		})
		return nil
	})
	if err != nil {
		return nil, err
	}
	sort.Slice(files, func(i int, j int) bool {
		return files[i].Path < files[j].Path
	})
	return files, nil
}

func (m *Manager) readPowConfigFile() (*protocol.SupportFile, error) {
	if m.RuntimeConfigDir == "" {
		return nil, nil
	}
	configPath := filepath.Join(m.RuntimeConfigDir, "pow_config.json")
	data, err := os.ReadFile(configPath)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, err
	}
	return &protocol.SupportFile{
		Path:    "pow_config.json",
		Content: string(data),
	}, nil
}

func (m *Manager) readManagedSupportFiles() ([]protocol.SupportFile, error) {
	files, err := m.readCertFiles()
	if err != nil {
		return nil, err
	}
	powConfig, err := m.readPowConfigFile()
	if err != nil {
		return nil, err
	}
	if powConfig != nil {
		files = append(files, *powConfig)
	}
	return files, nil
}

func (m *Manager) restorePowConfig(state *backupState) error {
	if state == nil || m.RuntimeConfigDir == "" {
		return nil
	}
	configPath := filepath.Join(m.RuntimeConfigDir, "pow_config.json")
	if state.PowConfig == nil {
		if err := os.Remove(configPath); err != nil && !os.IsNotExist(err) {
			return err
		}
		return nil
	}
	return os.WriteFile(configPath, []byte(state.PowConfig.Content), 0o644)
}

func (m *Manager) writeSafeDefaultFallbackFiles() error {
	if strings.TrimSpace(m.MainConfigPath) == "" {
		return errors.New("main config path 不能为空")
	}
	if strings.TrimSpace(m.RouteConfigPath) == "" {
		return errors.New("route config path 不能为空")
	}
	if err := os.MkdirAll(filepath.Dir(m.MainConfigPath), 0o755); err != nil {
		return err
	}
	if err := os.MkdirAll(filepath.Dir(m.RouteConfigPath), 0o755); err != nil {
		return err
	}
	if err := os.WriteFile(m.RouteConfigPath, nil, 0o644); err != nil {
		return err
	}
	if err := os.WriteFile(m.MainConfigPath, []byte(m.safeDefaultFallbackMainConfig()), 0o644); err != nil {
		return err
	}
	return nil
}

func (m *Manager) safeDefaultFallbackMainConfig() string {
	observabilityBlock := ""
	if listen := strings.TrimSpace(m.OpenrestyObservabilityListen); listen != "" {
		observabilityBlock = fmt.Sprintf(safeDefaultFallbackObservabilityServerBlock, listen)
	}
	return fmt.Sprintf(safeDefaultFallbackMainConfig, observabilityBlock)
}

func (m *Manager) checkStubStatus(ctx context.Context) error {
	ctx, cancel := context.WithTimeout(ctx, 1500*time.Millisecond)
	defer cancel()
	openrestyStubUrl := fmt.Sprintf("http://127.0.0.1:%d/openflare/stub_status", m.OpenrestyObservabilityPort)
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, openrestyStubUrl, nil)
	if err != nil {
		return err
	}
	resp, err := (&http.Client{}).Do(req)
	if err != nil {
		return fmt.Errorf("openresty health endpoint unreachable: %w", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("openresty health endpoint returned %s", resp.Status)
	}
	slog.Debug("openresty health endpoint is healthy", "url", openrestyStubUrl)
	return nil
}

func removeLegacyPowConfig(path string) error {
	if strings.TrimSpace(path) == "" {
		return nil
	}
	if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("remove legacy pow_config.json %q: %w", path, err)
	}
	return nil
}

func (m *Manager) certFileTargetPath(relativePath string) (string, error) {
	if strings.TrimSpace(m.CertDir) == "" {
		return "", errors.New("cert dir 不能为空")
	}
	candidate := strings.TrimSpace(relativePath)
	if strings.Contains(candidate, `\`) {
		candidate = strings.ReplaceAll(candidate, `\`, "/")
	}
	normalizedPath := filepath.Clean(filepath.FromSlash(candidate))
	if normalizedPath == "." || normalizedPath == "" {
		return "", errors.New("cert file path 不能为空")
	}
	if filepath.IsAbs(normalizedPath) || filepath.VolumeName(normalizedPath) != "" {
		return "", fmt.Errorf("cert file path %q must be relative", relativePath)
	}
	targetPath := filepath.Join(m.CertDir, normalizedPath)
	relativeToBase, err := filepath.Rel(m.CertDir, targetPath)
	if err != nil {
		return "", err
	}
	if relativeToBase == ".." || strings.HasPrefix(relativeToBase, ".."+string(os.PathSeparator)) {
		return "", fmt.Errorf("cert file path %q escapes cert dir", relativePath)
	}
	return targetPath, nil
}

func certFileMode(relativePath string) fs.FileMode {
	switch strings.ToLower(filepath.Ext(strings.TrimSpace(relativePath))) {
	case ".crt", ".pem":
		return 0o644
	case ".key":
		return 0o600
	default:
		return 0o644
	}
}

func luaFileTargetPath(baseDir string, relativePath string) (string, error) {
	if strings.TrimSpace(baseDir) == "" {
		return "", errors.New("lua dir 不能为空")
	}
	candidate := strings.TrimSpace(relativePath)
	if strings.Contains(candidate, `\`) {
		candidate = strings.ReplaceAll(candidate, `\`, "/")
	}
	normalizedPath := filepath.Clean(filepath.FromSlash(candidate))
	if normalizedPath == "." || normalizedPath == "" {
		return "", errors.New("lua file path 不能为空")
	}
	if filepath.IsAbs(normalizedPath) || filepath.VolumeName(normalizedPath) != "" {
		return "", fmt.Errorf("lua file path %q must be relative", relativePath)
	}
	targetPath := filepath.Join(baseDir, normalizedPath)
	relativeToBase, err := filepath.Rel(baseDir, targetPath)
	if err != nil {
		return "", err
	}
	if relativeToBase == ".." || strings.HasPrefix(relativeToBase, ".."+string(os.PathSeparator)) {
		return "", fmt.Errorf("lua file path %q escapes lua dir", relativePath)
	}
	return targetPath, nil
}

func syncManagedFiles(baseDir string, files []managedFile) error {
	if strings.TrimSpace(baseDir) == "" {
		return errors.New("managed dir cannot be empty")
	}
	if info, err := os.Stat(baseDir); err == nil && !info.IsDir() {
		return fmt.Errorf("managed dir %q is not a directory", baseDir)
	} else if err != nil && !os.IsNotExist(err) {
		return err
	}
	if err := os.MkdirAll(baseDir, 0o755); err != nil {
		return err
	}

	desired := make(map[string]managedFile, len(files))
	for _, file := range files {
		cleanPath := filepath.Clean(filepath.FromSlash(strings.TrimSpace(file.Path)))
		if cleanPath == "." || cleanPath == "" {
			return errors.New("managed file path cannot be empty")
		}
		desired[cleanPath] = managedFile{
			Path:    cleanPath,
			Content: file.Content,
			Mode:    file.Mode,
		}
	}

	if err := filepath.Walk(baseDir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			return nil
		}
		relativePath, err := filepath.Rel(baseDir, path)
		if err != nil {
			return err
		}
		if _, ok := desired[filepath.Clean(relativePath)]; ok {
			return nil
		}
		return os.Remove(path)
	}); err != nil {
		return err
	}

	for _, file := range desired {
		targetPath := filepath.Join(baseDir, file.Path)
		if err := os.MkdirAll(filepath.Dir(targetPath), 0o755); err != nil {
			return err
		}
		if err := os.WriteFile(targetPath, file.Content, file.Mode); err != nil {
			return err
		}
	}

	return removeEmptyManagedDirs(baseDir)
}

func removeEmptyManagedDirs(baseDir string) error {
	dirs := make([]string, 0)
	if err := filepath.Walk(baseDir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() && path != baseDir {
			dirs = append(dirs, path)
		}
		return nil
	}); err != nil {
		return err
	}
	sort.Slice(dirs, func(i int, j int) bool {
		return len(dirs[i]) > len(dirs[j])
	})
	for _, dir := range dirs {
		entries, err := os.ReadDir(dir)
		if err != nil {
			return err
		}
		if len(entries) == 0 {
			if err := os.Remove(dir); err != nil && !os.IsNotExist(err) {
				return err
			}
		}
	}
	return nil
}

func (m *Manager) ensureMimeTypes() error {
	if m.MainConfigPath == "" {
		return nil
	}
	configDir := filepath.Dir(m.MainConfigPath)
	mimeTypesPath := filepath.Join(configDir, "mime.types")
	if _, err := os.Stat(mimeTypesPath); err == nil {
		return nil
	} else if !os.IsNotExist(err) {
		return err
	}
	if err := os.MkdirAll(configDir, 0o755); err != nil {
		return err
	}
	return os.WriteFile(mimeTypesPath, []byte(DefaultMimeTypes), 0o644)
}

func (m *Manager) renderRouteConfig(content string) string {
	rendered := content
	if m.NginxCertDir != "" {
		rendered = strings.ReplaceAll(rendered, CertDirPlaceholder, m.NginxCertDir)
	}
	if luaDir := m.luaRuntimePath(); luaDir != "" {
		rendered = strings.ReplaceAll(rendered, LuaDirPlaceholder, luaDir)
		rendered = strings.ReplaceAll(rendered, PowStaticDirPlaceholder, luaDir+"/pow/static")
	}
	return rendered
}

func (m *Manager) renderMainConfig(content string) string {
	rendered := content
	if includePath := m.routeConfigIncludePath(); includePath != "" {
		rendered = strings.ReplaceAll(rendered, RouteConfigPlaceholder, includePath)
	}
	if accessLogPath := m.accessLogRuntimePath(); accessLogPath != "" {
		rendered = strings.ReplaceAll(rendered, AccessLogPlaceholder, accessLogPath)
	}
	if luaDir := m.luaRuntimePath(); luaDir != "" {
		rendered = strings.ReplaceAll(rendered, LuaDirPlaceholder, luaDir)
	}
	if listen := strings.TrimSpace(m.OpenrestyObservabilityListen); listen != "" {
		rendered = strings.ReplaceAll(rendered, ObservabilityListenPlaceholder, listen)
	}
	if m.OpenrestyObservabilityPort > 0 {
		rendered = strings.ReplaceAll(rendered, ObservabilityPortPlaceholder, fmt.Sprintf("%d", m.OpenrestyObservabilityPort))
	}
	if resolverDirective := strings.TrimSpace(m.OpenrestyResolverDirective); resolverDirective != "" {
		rendered = strings.ReplaceAll(rendered, ResolverDirectivePlaceholder, resolverDirective)
	}
	return rendered
}

func (m *Manager) managedPowLuaFiles() []protocol.SupportFile {
	files := ManagedPowLuaFiles()
	runtimeConfigDir := filepath.ToSlash(strings.TrimSpace(m.RuntimeConfigDir))
	for index := range files {
		files[index].Content = strings.ReplaceAll(files[index].Content, RuntimeConfigDirPlaceholder, runtimeConfigDir)
	}
	return files
}

func (m *Manager) managedWAFLuaFiles() []protocol.SupportFile {
	files := ManagedWAFLuaFiles()
	runtimeConfigDir := filepath.ToSlash(strings.TrimSpace(m.RuntimeConfigDir))
	for index := range files {
		files[index].Content = strings.ReplaceAll(files[index].Content, RuntimeConfigDirPlaceholder, runtimeConfigDir)
	}
	return files
}

func ObservabilityListenAddress(openrestyPath string, port int) string {
	if port <= 0 {
		return ""
	}
	return fmt.Sprintf("127.0.0.1:%d", port)
}

func ResolverDirective(openrestyPath string, explicitResolvers []string) string {
	resolvers := resolverAddresses(openrestyPath, explicitResolvers)
	if len(resolvers) == 0 {
		return ""
	}
	return fmt.Sprintf("    resolver %s valid=30s ipv6=off;\n    resolver_timeout 5s;\n", strings.Join(resolvers, " "))
}

func resolverAddresses(openrestyPath string, explicitResolvers []string) []string {
	if resolvers := normalizeResolverAddresses(explicitResolvers); len(resolvers) > 0 {
		return resolvers
	}
	data, err := os.ReadFile("/etc/resolv.conf")
	if err != nil {
		return nil
	}
	return parseResolverAddresses(string(data), false)
}

func parseResolverAddresses(content string, dockerMode bool) []string {
	lines := strings.Split(content, "\n")
	resolvers := make([]string, 0, 2)
	seen := make(map[string]struct{})
	for _, line := range lines {
		fields := strings.Fields(strings.TrimSpace(line))
		if len(fields) < 2 || fields[0] != "nameserver" {
			continue
		}
		addr := strings.TrimSpace(fields[1])
		if addr == "" {
			continue
		}
		if dockerMode && !isUsableDockerResolver(addr) {
			continue
		}
		if _, ok := seen[addr]; ok {
			continue
		}
		seen[addr] = struct{}{}
		resolvers = append(resolvers, addr)
	}
	return resolvers
}

func isUsableDockerResolver(addr string) bool {
	ip := net.ParseIP(addr)
	if ip == nil {
		return false
	}
	return !ip.IsLoopback() && !ip.IsUnspecified()
}

func normalizeResolverAddresses(values []string) []string {
	if len(values) == 0 {
		return nil
	}
	resolvers := make([]string, 0, len(values))
	seen := make(map[string]struct{}, len(values))
	for _, value := range values {
		addr := strings.TrimSpace(value)
		if addr == "" {
			continue
		}
		if _, ok := seen[addr]; ok {
			continue
		}
		seen[addr] = struct{}{}
		resolvers = append(resolvers, addr)
	}
	if len(resolvers) == 0 {
		return nil
	}
	return resolvers
}

func RequiresRuntimeResolver(originURL string) bool {
	parsed, err := url.Parse(strings.TrimSpace(originURL))
	if err != nil || parsed.Hostname() == "" {
		return false
	}
	return net.ParseIP(parsed.Hostname()) == nil
}

func (m *Manager) routeConfigIncludePath() string {
	return strings.TrimSpace(m.RouteConfigPath)
}

func (m *Manager) accessLogRuntimePath() string {
	return filepath.ToSlash(strings.TrimSpace(m.AccessLogPath))
}

func (m *Manager) luaRuntimePath() string {
	if strings.TrimSpace(m.NginxLuaDir) == "" {
		return ""
	}
	return filepath.ToSlash(m.NginxLuaDir)
}

func checksum(content string) string {
	sum := sha256.Sum256([]byte(content))
	return hex.EncodeToString(sum[:])
}

func bundleChecksum(mainConfig string, routeConfig string, supportFiles []protocol.SupportFile) string {
	files := append([]protocol.SupportFile(nil), supportFiles...)
	sort.Slice(files, func(i int, j int) bool {
		return files[i].Path < files[j].Path
	})
	var builder strings.Builder
	builder.WriteString(mainConfig)
	builder.WriteString("\n--route-config--\n")
	builder.WriteString(routeConfig)
	builder.WriteString("\n--support-files--\n")
	for _, file := range files {
		builder.WriteString(file.Path)
		builder.WriteString("\n")
		builder.WriteString(file.Content)
		builder.WriteString("\n")
	}
	return checksum(builder.String())
}