jsmod/jsmod.go

package jsmod

import (
	"context"
	"fmt"
	"path/filepath"
	"runtime"
	"strings"
	"sync"
)

type contextKey string

const internalContextKey contextKey = "__GoJSContext__"

// Get retrieves an injected value from the context using the unified context map.
func Get(ctx context.Context, key string) any {
	if ctx == nil {
		return nil
	}
	if m, ok := ctx.Value(internalContextKey).(map[string]any); ok {
		return m[key]
	}
	return nil
}

// NewContext returns a new context with the provided injection map.
func NewContext(parent context.Context, injects map[string]any) context.Context {
	if parent == nil {
		parent = context.Background()
	}
	return context.WithValue(parent, internalContextKey, injects)
}

// IsSafeMode checks if the provided context indicates that the execution is in safe mode.
func IsSafeMode(ctx context.Context) bool {
	if sm, ok := Get(ctx, "SafeMode").(bool); ok {
		return sm
	}
	return false // Default to false if not specified (internal trusted caller)
}

type Module struct {
	Exports    map[string]any
	UnsafeList map[string]bool
}

var (
	modules = make(map[string]*Module)
	mu      sync.RWMutex
)

// Register registers a Go module with its exported functions and properties.
// These modules will be accessible within the JS environment.
// unsafeList identifies methods that require elevated permissions (e.g., file writing, shell execution).
func Register(name string, exports map[string]any, unsafeList ...string) {
	mu.Lock()
	defer mu.Unlock()

	if modules[name] == nil {
		modules[name] = &Module{
			Exports:    make(map[string]any, len(exports)),
			UnsafeList: make(map[string]bool),
		}
	}

	for k, v := range exports {
		modules[name].Exports[k] = v
	}

	for _, method := range unsafeList {
		modules[name].UnsafeList[method] = true
	}
}

// GetModules returns all registered modules and their unsafe status.
func GetModules() map[string]*Module {
	mu.RLock()
	defer mu.RUnlock()

	res := make(map[string]*Module, len(modules))
	for name, mod := range modules {
		res[name] = mod
	}
	return res
}

// Error wraps a Go error with dynamic caller stack frames.
type Error struct {
	Message    string
	CallStacks []string
}

func (e *Error) Error() string {
	return e.Message
}

func (e *Error) Stack() string {
	return strings.Join(e.CallStacks, "\n")
}

// MakeError wraps an existing error into a *jsmod.Error with the captured Go caller stack.
func MakeError(err error) error {
	if err == nil {
		return nil
	}
	if je, ok := err.(*Error); ok {
		return je
	}

	var callStacks []string
	pcs := make([]uintptr, 32)
	n := runtime.Callers(1, pcs) // skip runtime.Callers, start recording from the caller of MakeError
	frames := runtime.CallersFrames(pcs[:n])
	for {
		frame, more := frames.Next()
		if frame.Function == "" {
			break
		}
		// Skip runtime and bridge internals if they creep in
		if isNoiseFrame(frame.File, frame.Function) {
			if !more {
				break
			}
			continue
		}
		file := trimGoPath(frame.File)
		callStacks = append(callStacks, fmt.Sprintf("%s at %s:%d", frame.Function, file, frame.Line))
		if !more {
			break
		}
	}

	return &Error{
		Message:    err.Error(),
		CallStacks: callStacks,
	}
}

func trimGoPath(fullPath string) string {
	dir, file := filepath.Split(fullPath)
	if dir == "" {
		return file
	}
	parent := filepath.Base(filepath.Clean(dir))
	if parent == "." || parent == "/" {
		return file
	}
	return filepath.Join(parent, file)
}

func isNoiseFrame(file, function string) bool {
	// Noise paths to skip
	noisePaths := []string{
		"/jsmod/jsmod.go",
		"/js/bridge.go",
		"/js/pool.go",
		"/goja@",
		"/goja/",
		"/src/runtime/",
		"/src/reflect/",
		"/testing/testing.go",
	}
	for _, p := range noisePaths {
		if strings.Contains(file, p) {
			return true
		}
	}
	// Noise functions to skip
	noiseFuncs := []string{
		"github.com/dop251/goja",
		"apigo.cc/go/js.wrapGoFunc",
		"apigo.cc/go/js.(*Pool)",
		"reflect.Value",
		"reflect.Type",
	}
	for _, f := range noiseFuncs {
		if strings.Contains(function, f) {
			return true
		}
	}
	return false
}