package execute

import (
	"context"
	"encoding/binary"
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strings"
	"sync"
	"syscall"
	"time"

	"ollie/internal/sandbox"
	"ollie/pkg/paths"
	"ollie/pkg/tools"
	"ollie/pkg/skills"
)

const (
	failureWindow = 1 * time.Minute
	maxFailures   = 5
	blockDuration = 5 * time.Minute
)

// Server runs code in a sandboxed environment.
type Server struct {
	// cwd is the working directory for sandboxed commands. If empty,
	// the process working directory is used.
	wdMu sync.RWMutex
	cwd  string

	// envExtra holds per-session environment variables injected via SetEnv.
	envMu    sync.RWMutex
	envExtra map[string]string

	// Hooks for lifecycle events (harnesses like 9P can inject mount logic here)
	OnPreDispatch func()
	OnClose       func()
	OnEnvSet      func(key, value string)

	// Strict rejects inline {code} steps; only {tool} steps are allowed.
	Strict bool

	// Yolo skips the landrun sandbox for all execution.
	Yolo bool

	// allowTools restricts which named tool scripts can be invoked via call_tool/pipe.
	// Empty means all are allowed.
	allowTools map[string]bool

	toolRegistry *Registry
	skillsRegistry *skills.Registry
	sessionID string

	// OnInjection is called when a skill is loaded and its content
	// should be injected into the agent's context.
	OnInjection func(content string)

	// rate limiting state (per-Server)
	rateLimitMu        sync.Mutex
	validationFailures int
	lastFailure        time.Time
	blockedUntil       time.Time

	// Detached process management
	detachMu sync.Mutex
	detachCh chan struct{} // signal to detach the currently running process
	detached []*DetachedProcess
	OnDetach func(pid int, cmd string)   // hook: called when a process is detached
	OnExit   func(pid int, exitCode int) // hook: called when a detached process exits
}

// Option configures a Server.
type Option func(*Server)

// WithStrict rejects inline {code} steps; only {tool} steps are allowed.
func WithStrict() Option { return func(s *Server) { s.Strict = true } }

// WithYolo skips the landrun sandbox.
func WithYolo() Option { return func(s *Server) { s.Yolo = true } }

// WithOnPreDispatch registers a hook called before each Dispatch.
func WithOnPreDispatch(fn func()) Option { return func(s *Server) { s.OnPreDispatch = fn } }

// WithOnClose registers a hook called during Close.
func WithOnClose(fn func()) Option { return func(s *Server) { s.OnClose = fn } }

// SetOnExit sets the hook called when a detached process exits.
func (e *Server) SetOnExit(fn func(pid, exitCode int)) { e.OnExit = fn }

// WithOnEnvSet registers a hook called each time SetEnv is called.
func WithOnEnvSet(fn func(key, value string)) Option { return func(s *Server) { s.OnEnvSet = fn } }

// WithAllowTools restricts which tool scripts can be invoked.
func WithAllowTools(names []string) Option {
	return func(s *Server) {
		if len(names) > 0 {
			s.allowTools = make(map[string]bool, len(names))
			for _, n := range names {
				s.allowTools[n] = true
			}
		}
	}
}

// AllowTools returns the set of allowed tool names, or nil if unrestricted.
func (e *Server) AllowTools() []string {
	if len(e.allowTools) == 0 {
		return nil
	}
	out := make([]string, 0, len(e.allowTools))
	for k := range e.allowTools {
		out = append(out, k)
	}
	return out
}

// Decl returns a factory for an execute Server with the given working directory.
func Decl(cwd string, opts ...Option) func() tools.Server {
	return func() tools.Server {
		s := New(cwd)
		for _, o := range opts {
			o(s)
		}
		return s
	}
}

// ListTools implements tools.Server, returning shell plus any
// tools promoted in the session's tool registry.
func (e *Server) ListTools() ([]tools.ToolInfo, error) {
	all := []tools.ToolInfo{
		{
			Name: "shell",
			Description: `Execute a single bash command in a sandboxed environment.

Usage: {"cmd": "your command here"}

Sandbox prevents dangerous operations. Use for computation, builds, scripting.
timeout applies to each call (default: 30s). A non-zero exit is an error.`,
			InputSchema: json.RawMessage(`{
				"type": "object",
				"required": ["cmd"],
				"properties": {
					"cmd":     {"type": "string", "description": "Bash command to execute."},
					"timeout": {"type": "integer", "description": "Timeout in seconds (default: 30). Use 0 for no timeout."},
					"sandbox": {"type": "string",  "description": "Sandbox profile name (default: default)."}
				}
			}`),
		},
		{
			Name: "tool_list",
			Description: `List all available tools that can be loaded.

Usage: {"name": "toolname"} — if name is provided, loads that tool.
Otherwise lists all tools with descriptions.`,
			InputSchema: json.RawMessage(`{
				"type": "object",
				"properties": {}
			}`),
		},
		{
			Name: "tool_load",
			Description: `Load a tool by name into the current session.

Usage: {"name": "toolname"}

After loading, the tool becomes a native callable function.`,
			InputSchema: json.RawMessage(`{
				"type": "object",
				"required": ["name"],
				"properties": {
					"name": {"type": "string", "description": "Tool name to load."}
				}
			}`),
		},
		{
			Name: "tool_active",
			Description: `List tools currently loaded (promoted) in this session.

Usage: (no arguments)

Returns tools with descriptions, one per line.`,
			InputSchema: json.RawMessage(`{
				"type": "object",
				"properties": {}
			}`),
		},
	}

	if e.toolRegistry != nil && e.sessionID != "" {
		all = append(all, e.toolRegistry.Loaded(e.sessionID)...)
	}
	// Append skill tools if skills registry is available
	skillTools := ListSkillsTools(e.skillsRegistry, e.sessionID)
	all = append(all, skillTools...)
	return all, nil
}

// CallTool implements tools.Server.
func (e *Server) CallTool(ctx context.Context, tool string, args json.RawMessage) (json.RawMessage, error) {
	if e.toolRegistry != nil && e.sessionID != "" {
		if _, promoted := e.toolRegistry.Lookup(e.sessionID, tool); promoted {
			return e.callPromotedTool(ctx, tool, args)
		}
	}
	result, err := e.Dispatch(ctx, tool, args)
	if err != nil {
		return json.Marshal(map[string]any{
			"isError": true,
			"content": []map[string]string{{"type": "text", "text": err.Error()}},
		})
	}
	// If the tool output is already structured content-block JSON, pass it through.
	var structured map[string]json.RawMessage
	if json.Unmarshal([]byte(result), &structured) == nil {
		if _, ok := structured["content"]; ok {
			return []byte(result), nil
		}
	}
	return json.Marshal(map[string]any{
		"content": []map[string]string{{"type": "text", "text": result}},
	})
}

// New creates a new Server with the given working directory.
func New(cwd string) *Server { return &Server{cwd: paths.ExpandHome(cwd)} }

// SetCWD updates the working directory used for subsequent command executions.
func (e *Server) SetCWD(dir string) {
	e.wdMu.Lock()
	e.cwd = paths.ExpandHome(dir)
	e.wdMu.Unlock()
}

// SetAllowTools restricts which tool scripts can be invoked.
func (e *Server) SetAllowTools(names []string) {
	if len(names) > 0 {
		e.allowTools = make(map[string]bool, len(names))
		for _, n := range names {
			e.allowTools[n] = true
		}
	} else {
		e.allowTools = nil
	}
}

// SetEnv adds a session-scoped environment variable injected into all
// subsequent subprocess invocations for this session.
func (e *Server) SetEnv(key, value string) {
	e.envMu.Lock()
	if e.envExtra == nil {
		e.envExtra = make(map[string]string)
	}
	e.envExtra[key] = value
	e.envMu.Unlock()
	if e.OnEnvSet != nil {
		e.OnEnvSet(key, value)
	}
}

// SetToolRegistry attaches a session-local tool registry.
func (e *Server) SetToolRegistry(r *Registry, sessionID string) {
	e.toolRegistry = r
	e.sessionID = sessionID
}

// callPromotedTool executes a tool promoted via the registry by running the
// script file directly as an executable.
func (e *Server) callPromotedTool(ctx context.Context, tool string, args json.RawMessage) (json.RawMessage, error) {
	// Resolve script path.
	if strings.Contains(tool, "/") || strings.Contains(tool, "..") {
		return nil, fmt.Errorf("invalid tool name")
	}
	path := filepath.Join(ToolsPath(), tool)

	// Parse positional args.
	var positional []string
	var argMap map[string]interface{}
	if err := json.Unmarshal(args, &argMap); err == nil {
		if argsArr, ok := argMap["args"]; ok {
			if arr, ok := argsArr.([]interface{}); ok {
				for _, v := range arr {
					positional = append(positional, fmt.Sprintf("%v", v))
				}
			}
		}
	}

	var cancel context.CancelFunc
	ctx, cancel = context.WithTimeout(ctx, 30*time.Second)
	defer cancel()

	// Execute the script directly — shebang handles the interpreter.
	e.wdMu.RLock()
	workDir := e.cwd
	e.wdMu.RUnlock()
	if workDir == "" {
		workDir, _ = os.Getwd()
	}
	cmd := exec.CommandContext(ctx, path, positional...)
	cmd.Dir = workDir

	output, err := cmd.CombinedOutput()
	if err != nil {
		return json.Marshal(map[string]interface{}{
			"isError": true,
			"content": []map[string]string{{"type": "text", "text": string(output) + ": " + err.Error()}},
		})
	}
	return json.Marshal(map[string]interface{}{
		"content": []map[string]string{{"type": "text", "text": string(output)}},
	})
}



// Close is called when the session ends. Calls OnClose hook if registered.
func (e *Server) Close() {
	e.cleanupDetached()
	if e.OnClose != nil {
		e.OnClose()
	}
}

// executeElevated runs cmd outside the sandbox via the integrated elevation broker.
// Connects to the broker socket, sends the request with the current env,
// and streams the framed response back.
func (e *Server) executeElevated(ctx context.Context, cmd, dir string, timeout int, detach ...bool) (string, error) {
	sockPath := os.Getenv("OLLIE_ELEVATE_SOCKET")
	if sockPath == "" {
		xdg := os.Getenv("XDG_RUNTIME_DIR")
		if xdg == "" {
			return "", fmt.Errorf("elevation not available: no XDG_RUNTIME_DIR")
		}
		sockPath = filepath.Join(xdg, "ollie", "elevate.sock")
	}

	wantDetach := len(detach) > 0 && detach[0]

	var cancel context.CancelFunc
	if wantDetach || timeout <= 0 {
		ctx, cancel = context.WithCancel(ctx)
	} else {
		ctx, cancel = context.WithTimeout(ctx, time.Duration(timeout)*time.Second)
	}

	// Connect to broker
	conn, err := net.DialTimeout("unix", sockPath, 5*time.Second)
	if err != nil {
		cancel()
		return "", fmt.Errorf("elevation not available: %w", err)
	}

	// Send request
	envMap := make(map[string]string, len(os.Environ()))
	for _, kv := range os.Environ() {
		if k, v, ok := strings.Cut(kv, "="); ok {
			envMap[k] = v
		}
	}
	reqJSON, _ := json.Marshal(struct {
		Cmd string            `json:"cmd"`
		Cwd string            `json:"cwd"`
		Env map[string]string `json:"env"`
	}{Cmd: cmd, Cwd: dir, Env: envMap})
	reqJSON = append(reqJSON, '\n')
	if _, err := conn.Write(reqJSON); err != nil {
		conn.Close()
		cancel()
		return "", fmt.Errorf("elevated execution failed: write: %w", err)
	}

	// Set up detach channel
	detachCh := make(chan struct{}, 1)
	e.detachMu.Lock()
	e.detachCh = detachCh
	e.detachMu.Unlock()
	defer func() {
		e.detachMu.Lock()
		e.detachCh = nil
		e.detachMu.Unlock()
	}()

	if wantDetach {
		close(detachCh)
	}

	// readFrames reads from the connection, writing to w and streaming.
	// Returns exit code when 'x' frame arrives or -1 on error.
	readFrames := func(w io.Writer, stream func(string)) int {
		header := make([]byte, 5)
		for {
			conn.SetReadDeadline(time.Now().Add(1 * time.Second)) //nolint:errcheck
			_, err := io.ReadFull(conn, header)
			if err != nil {
				if ne, ok := err.(net.Error); ok && ne.Timeout() {
					// Check for context cancellation
					select {
					case <-ctx.Done():
						return -1
					default:
						continue
					}
				}
				return -1
			}

			frameType := header[0]
			length := binary.BigEndian.Uint32(header[1:5])

			payload := make([]byte, length)
			if length > 0 {
				conn.SetReadDeadline(time.Now().Add(30 * time.Second)) //nolint:errcheck
				if _, err := io.ReadFull(conn, payload); err != nil {
					return -1
				}
			}

			switch frameType {
			case 'd':
				w.Write(payload) //nolint:errcheck
				if stream != nil {
					stream(string(payload))
				}
			case 'x':
				var code int
				fmt.Sscanf(string(payload), "%d", &code)
				return code
			}
		}
	}

	// Check if detach was requested
	select {
	case <-detachCh:
		// Detach: background the socket read into a goroutine
		cmdStr := "elevated: " + cmd
		if len(cmdStr) > 80 {
			cmdStr = cmdStr[:77] + "..."
		}
		ring := newRingBuffer(ringBufSize)
		pid := int(time.Now().UnixNano() & 0x7FFFFFFF) // synthetic PID

		proc := &DetachedProcess{
			PID:     pid,
			Command: cmdStr,
			Started: time.Now(),
			ring:    ring,
			done:    make(chan struct{}),
		}
		e.detachMu.Lock()
		e.detached = append(e.detached, proc)
		e.detachMu.Unlock()

		go func() {
			defer conn.Close()
			defer cancel()
			exitCode := readFrames(ring, nil)
			proc.mu.Lock()
			proc.Exited = true
			proc.ExitCode = exitCode
			proc.mu.Unlock()
			close(proc.done)
			if e.OnExit != nil {
				e.OnExit(proc.PID, proc.ExitCode)
			}
		}()

		if e.OnDetach != nil {
			e.OnDetach(proc.PID, cmdStr)
		}
		return fmt.Sprintf("[detached: pid %d]", pid), nil

	default:
		// Normal (foreground) execution
		defer conn.Close()
		defer cancel()

		var outputBuf bytes.Buffer
		streamFn := tools.StreamFunc(ctx)
		exitCode := readFrames(&outputBuf, streamFn)

		combined := outputBuf.String()
		if exitCode != 0 {
			if combined == "" {
				return "", fmt.Errorf("elevated execution failed (exit %d)", exitCode)
			}
			// Cap output in error message to avoid flooding the agent context.
			errOutput := combined
			const maxErrOutput = 8192
			if len(errOutput) > maxErrOutput {
				errOutput = errOutput[:maxErrOutput] + fmt.Sprintf("\n[...truncated %d bytes in error]", len(combined)-maxErrOutput)
			}
			return combined, fmt.Errorf("elevated execution failed (exit %d)\nOutput: %s", exitCode, errOutput)
		}
		return combined, nil
	}
}

var whitespacePattern = regexp.MustCompile(`\s+`)

func (e *Server) checkRateLimit() error {
	e.rateLimitMu.Lock()
	defer e.rateLimitMu.Unlock()

	now := time.Now()
	if now.Before(e.blockedUntil) {
		remaining := e.blockedUntil.Sub(now).Round(time.Second)
		return fmt.Errorf("rate limited: too many validation failures, blocked for %v", remaining)
	}
	return nil
}

func (e *Server) recordValidationFailure() {
	e.rateLimitMu.Lock()
	defer e.rateLimitMu.Unlock()

	now := time.Now()
	if now.Sub(e.lastFailure) > failureWindow {
		e.validationFailures = 0
	}

	e.validationFailures++
	e.lastFailure = now

	if e.validationFailures >= maxFailures {
		e.blockedUntil = now.Add(blockDuration)
		e.validationFailures = 0
	}
}

// Execute runs code in a sandbox and returns combined stdout+stderr.
func (e *Server) Execute(ctx context.Context, code, language string, timeout int, sandboxName string, trusted bool) (string, error) {
	return e.executeWithStdin(ctx, code, language, timeout, sandboxName, trusted, "")
}

// executeWithStdin is like Execute but feeds stdinData to the command's stdin.
// For languages where code is itself passed via stdin (ed, expect, bc), stdinData is ignored.
func (e *Server) executeWithStdin(ctx context.Context, code, language string, timeout int, sandboxName string, trusted bool, stdinData string, detach ...bool) (string, error) {
	if timeout < 0 {
		timeout = 30
	}

	if !trusted {
		if err := e.ValidateCode(code, language); err != nil {
			return "", err
		}
	}

	var cfg *sandbox.Config
	var err error
	if !e.Yolo {
		cfg, err = loadSandboxConfig(sandboxName)
		if err != nil {
			return "", err
		}
	}

	e.wdMu.RLock()
	workDir := e.cwd
	e.wdMu.RUnlock()
	if workDir == "" {
		workDir, _ = os.Getwd()
	}

	var cancel context.CancelFunc
	if timeout > 0 {
		ctx, cancel = context.WithTimeout(ctx, time.Duration(timeout)*time.Second)
	} else {
		// timeout=0 means no timeout (run indefinitely, e.g. for daemons)
		ctx, cancel = context.WithCancel(ctx)
	}
	// NOTE: do NOT defer cancel() here — the detach path must avoid cancelling
	// the context (which would kill the detached process via cmd.Cancel).
	// Each exit path calls cancel() explicitly except detach.

	var cmd *exec.Cmd
	var interpreter []string
	// codeStdin: non-empty means the code itself is fed via stdin (ed, expect, bc).
	// In these cases stdinData cannot be used simultaneously.
	var codeStdin string
	switch language {
	case "bash", "":
		interpreter = []string{"bash", "-c", code}
	default:
		cancel()
		return "", fmt.Errorf("unsupported language: %s (only bash is supported)", language)
	}
	e.envMu.RLock()
	envMap := make(map[string]string, len(e.envExtra))
	for k, v := range e.envExtra {
		envMap[k] = v
	}
	e.envMu.RUnlock()
	for _, ev := range os.Environ() {
		k, v, _ := strings.Cut(ev, "=")
		if _, ok := envMap[k]; !ok {
			envMap[k] = v
		}
	}
	if _, ok := envMap["NAMESPACE"]; !ok {
		if ns := plan9Namespace(envMap); ns != "" {
			envMap["NAMESPACE"] = ns
		}
	}
	getenv := func(key string) string { return envMap[key] }

	if e.Yolo {
		cmd = exec.CommandContext(ctx, interpreter[0], interpreter[1:]...)
	} else {
		wrapped, wrapErr := sandbox.WrapCommand(cfg, interpreter, workDir, getenv)
		if wrapErr != nil {
			cancel()
			return "", wrapErr
		}
		cmd = exec.CommandContext(ctx, wrapped[0], wrapped[1:]...)
	}
	cmd.Dir = workDir
	switch {
	case codeStdin != "":
		cmd.Stdin = strings.NewReader(codeStdin)
	case stdinData != "":
		cmd.Stdin = strings.NewReader(stdinData)
	}

	e.envMu.RLock()
	baseEnv := os.Environ()
	// Remove keys that envExtra overrides so duplicates don't leak through.
	filtered := baseEnv[:0]
	for _, ev := range baseEnv {
		k, _, _ := strings.Cut(ev, "=")
		if _, overridden := e.envExtra[k]; !overridden {
			filtered = append(filtered, ev)
		}
	}
	cmd.Env = prependOlliePath(filtered, paths.CfgDir())
	cmd.Env = append(cmd.Env, "OLLIE_TOOLS_PATH="+ToolsPath())
	for k, v := range e.envExtra {
		cmd.Env = append(cmd.Env, k+"="+v)
	}
	e.envMu.RUnlock()

	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
	cmd.Cancel = func() error {
		if cmd.Process != nil {
			syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
		}
		return nil
	}
	cmd.WaitDelay = time.Second

	var outputBuf bytes.Buffer
	lw := &limitedWriter{
		w:      &outputBuf,
		limit:  10 * 1024 * 1024,
		stream: tools.StreamFunc(ctx),
	}
	cmd.Stdout = lw
	cmd.Stderr = lw

	// Set up detach channel for this execution
	detachCh := make(chan struct{}, 1)
	e.detachMu.Lock()
	e.detachCh = detachCh
	e.detachMu.Unlock()
	defer func() {
		e.detachMu.Lock()
		e.detachCh = nil
		e.detachMu.Unlock()
	}()

	if err = cmd.Start(); err != nil {
		cancel()
		return "", fmt.Errorf("execution failed: %v", err)
	}

	// If detach requested, immediately signal the detach channel
	if len(detach) > 0 && detach[0] {
		close(detachCh)
	}

	// Wait for completion, context cancellation, or detach signal
	waitCh := make(chan error, 1)
	go func() { waitCh <- cmd.Wait() }()

	select {
	case err = <-waitCh:
		// Normal completion
		cancel()
		output := outputBuf.Bytes()
		if lw.truncated {
			output = append(output, []byte("\n[output truncated at 10MB]")...)
		}
		if ctx.Err() == context.DeadlineExceeded {
			return "", fmt.Errorf("execution timeout after %d seconds", timeout)
		}
		if err != nil {
			// Cap output in error message to avoid flooding the agent context.
			// The full output is still returned as the first return value.
			errOutput := string(output)
			const maxErrOutput = 8192
			if len(errOutput) > maxErrOutput {
				errOutput = errOutput[:maxErrOutput] + fmt.Sprintf("\n[...truncated %d bytes in error]", len(output)-maxErrOutput)
			}
			return string(output), fmt.Errorf("execution failed: %v\nOutput: %s", err, errOutput)
		}
		return string(output), nil

	case <-ctx.Done():
		// Context cancelled (interrupt or timeout)
		cancel()
		syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
		<-waitCh // reap
		output := outputBuf.Bytes()
		if ctx.Err() == context.DeadlineExceeded {
			return string(output), fmt.Errorf("execution timeout after %d seconds", timeout)
		}
		return string(output), fmt.Errorf("execution interrupted")

	case <-detachCh:
		// Detach: move process to registry, continue running
		// Neutralize cmd.Cancel and WaitDelay so context cancellation
		// won't kill the process after the timeout fires.
		cmd.Cancel = nil
		cmd.WaitDelay = 0
		cancel()

		cmdStr := strings.Join(interpreter, " ")
		if len(cmdStr) > 80 {
			cmdStr = cmdStr[:77] + "..."
		}
		ring := newRingBuffer(ringBufSize)
		// Splice: future output goes to ring buffer instead of outputBuf.
		lw.mu.Lock()
		lw.w = ring
		lw.mu.Unlock()

		proc := &DetachedProcess{
			PID:     cmd.Process.Pid,
			Command: cmdStr,
			Started: time.Now(),
			ring:    ring,
			cmd:     cmd.Process,
			done:    make(chan struct{}),
		}
		e.detachMu.Lock()
		e.detached = append(e.detached, proc)
		e.detachMu.Unlock()

		// Monitor for exit in background
		go func() {
			waitErr := <-waitCh
			proc.mu.Lock()
			proc.Exited = true
			if waitErr != nil {
				if exitErr, ok := waitErr.(*exec.ExitError); ok {
					proc.ExitCode = exitErr.ExitCode()
				} else {
					proc.ExitCode = -1
				}
			}
			proc.mu.Unlock()
			close(proc.done)
			if e.OnExit != nil {
				e.OnExit(proc.PID, proc.ExitCode)
			}
		}()

		if e.OnDetach != nil {
			e.OnDetach(proc.PID, cmdStr)
		}

		partial := outputBuf.String()
		return partial + fmt.Sprintf("\n[detached: pid %d]", proc.PID), nil
	}
}

// prependOlliePath returns env with $OLLIE_CFG_PATH/scripts/x/ prepended to PATH so wrapper
// scripts placed there shadow system binaries.
func prependOlliePath(env []string, cfgDir string) []string {
	if cfgDir == "" {
		return env
	}
	xdir := filepath.Join(cfgDir, "scripts", "x")
	result := make([]string, 0, len(env))
	for _, e := range env {
		if strings.HasPrefix(e, "PATH=") {
			e = "PATH=" + xdir + string(filepath.ListSeparator) + e[5:]
		}
		result = append(result, e)
	}
	return result
}

// plan9Namespace computes the plan9port namespace directory from the environment.
// Convention: $NAMESPACE if set, else /tmp/ns.<user>.<display> where display is
// $DISPLAY with trailing .0 stripped and / replaced by _.
func plan9Namespace(env map[string]string) string {
	if ns := env["NAMESPACE"]; ns != "" {
		return ns
	}
	user := env["USER"]
	if user == "" {
		return ""
	}
	disp := env["DISPLAY"]
	if disp == "" {
		return ""
	}
	// Canonicalize: strip trailing .0
	if strings.HasSuffix(disp, ".0") {
		disp = disp[:len(disp)-2]
	}
	// Replace / with _
	disp = strings.ReplaceAll(disp, "/", "_")
	return "/tmp/ns." + user + "." + disp
}

// Detach signals the currently running process to be detached from the agent.
// The process continues running; its output is captured in a ring buffer.
// Returns false if no process is currently running.
func (e *Server) Detach() bool {
	e.detachMu.Lock()
	ch := e.detachCh
	e.detachMu.Unlock()
	if ch == nil {
		return false
	}
	select {
	case ch <- struct{}{}:
		return true
	default:
		return false
	}
}

// ListDetached returns all detached processes (running and exited).
func (e *Server) ListDetached() []*DetachedProcess {
	e.detachMu.Lock()
	defer e.detachMu.Unlock()
	out := make([]*DetachedProcess, len(e.detached))
	copy(out, e.detached)
	return out
}

// ListDetachedInfo returns plain-data snapshots of all detached processes.
func (e *Server) ListDetachedInfo() []DetachedInfoData {
	e.detachMu.Lock()
	defer e.detachMu.Unlock()
	out := make([]DetachedInfoData, len(e.detached))
	for i, p := range e.detached {
		out[i] = p.Info()
	}
	return out
}

// ListDetachedRaw returns detached process info as []any (each element is map[string]any)
// for consumption by packages that can't import this package directly.
func (e *Server) ListDetachedRaw() []any {
	e.detachMu.Lock()
	defer e.detachMu.Unlock()
	out := make([]any, len(e.detached))
	for i, p := range e.detached {
		info := p.Info()
		out[i] = map[string]any{
			"pid":       info.PID,
			"command":   info.Command,
			"started":   info.Started,
			"exited":    info.Exited,
			"exit_code": info.ExitCode,
		}
	}
	return out
}

// SignalDetached sends a signal to a detached process by PID.
func (e *Server) SignalDetached(pid int, sig syscall.Signal) error {
	e.detachMu.Lock()
	defer e.detachMu.Unlock()
	for _, p := range e.detached {
		if p.PID == pid {
			return p.Signal(sig)
		}
	}
	return fmt.Errorf("no detached process with pid %d", pid)
}

// GetDetachedOutput returns the ring buffer contents for a detached process.
func (e *Server) GetDetachedOutput(pid int) (string, error) {
	e.detachMu.Lock()
	defer e.detachMu.Unlock()
	for _, p := range e.detached {
		if p.PID == pid {
			return p.Output(), nil
		}
	}
	return "", fmt.Errorf("no detached process with pid %d", pid)
}

// DismissDetached removes an exited process from the list.
func (e *Server) DismissDetached(pid int) bool {
	e.detachMu.Lock()
	defer e.detachMu.Unlock()
	for i, p := range e.detached {
		if p.PID == pid && p.Exited {
			e.detached = append(e.detached[:i], e.detached[i+1:]...)
			return true
		}
	}
	return false
}

// cleanupDetached sends SIGTERM to all running detached processes.
func (e *Server) cleanupDetached() {
	e.detachMu.Lock()
	defer e.detachMu.Unlock()
	for _, p := range e.detached {
		p.mu.Lock()
		if !p.Exited && p.cmd != nil {
			syscall.Kill(-p.PID, syscall.SIGTERM)
		}
		p.mu.Unlock()
	}
}

var _ tools.Server = (*Server)(nil) // compile-time interface check