runtime.go

package goja

import (
	"bytes"
	"errors"
	"fmt"
	"go/ast"
	"math"
	"math/rand"
	"reflect"
	"strconv"

	js_ast "github.com/EncoreJiang/goja/ast"
	"github.com/EncoreJiang/goja/parser"
)

const (
	sqrt1_2 float64 = math.Sqrt2 / 2
)

var (
	typeCallable = reflect.TypeOf(Callable(nil))
	typeValue    = reflect.TypeOf((*Value)(nil)).Elem()
)

type global struct {
	Object   *Object
	Array    *Object
	Function *Object
	String   *Object
	Number   *Object
	Boolean  *Object
	RegExp   *Object
	Date     *Object

	ArrayBuffer *Object

	Error          *Object
	TypeError      *Object
	ReferenceError *Object
	SyntaxError    *Object
	RangeError     *Object
	EvalError      *Object
	URIError       *Object

	GoError *Object

	ObjectPrototype   *Object
	ArrayPrototype    *Object
	NumberPrototype   *Object
	StringPrototype   *Object
	BooleanPrototype  *Object
	FunctionPrototype *Object
	RegExpPrototype   *Object
	DatePrototype     *Object

	ArrayBufferPrototype *Object

	ErrorPrototype          *Object
	TypeErrorPrototype      *Object
	SyntaxErrorPrototype    *Object
	RangeErrorPrototype     *Object
	ReferenceErrorPrototype *Object
	EvalErrorPrototype      *Object
	URIErrorPrototype       *Object

	GoErrorPrototype *Object

	Eval *Object

	thrower         *Object
	throwerProperty Value
}

type Flag int

const (
	FLAG_NOT_SET Flag = iota
	FLAG_FALSE
	FLAG_TRUE
)

func (f Flag) Bool() bool {
	return f == FLAG_TRUE
}

func ToFlag(b bool) Flag {
	if b {
		return FLAG_TRUE
	}
	return FLAG_FALSE
}

type RandSource func() float64

type Runtime struct {
	global          global
	globalObject    *Object
	stringSingleton *stringObject
	rand            RandSource

	typeInfoCache   map[reflect.Type]*reflectTypeInfo
	fieldNameMapper FieldNameMapper

	vm *vm
}

type stackFrame struct {
	prg      *Program
	funcName string
	pc       int
}

func (f *stackFrame) position() Position {
	return f.prg.src.Position(f.prg.sourceOffset(f.pc))
}

func (f *stackFrame) write(b *bytes.Buffer) {
	if f.prg != nil {
		if n := f.prg.funcName; n != "" {
			b.WriteString(n)
			b.WriteString(" (")
		}
		if n := f.prg.src.name; n != "" {
			b.WriteString(n)
		} else {
			b.WriteString("<eval>")
		}
		b.WriteByte(':')
		b.WriteString(f.position().String())
		b.WriteByte('(')
		b.WriteString(strconv.Itoa(f.pc))
		b.WriteByte(')')
		if f.prg.funcName != "" {
			b.WriteByte(')')
		}
	} else {
		if f.funcName != "" {
			b.WriteString(f.funcName)
			b.WriteString(" (")
		}
		b.WriteString("native")
		if f.funcName != "" {
			b.WriteByte(')')
		}
	}
}

type Exception struct {
	SourceMap func()
	val       Value
	stack     []stackFrame
}

type InterruptedError struct {
	Exception
	iface interface{}
}

func (e *InterruptedError) Value() interface{} {
	return e.iface
}

func (e *InterruptedError) String() string {
	if e == nil {
		return "<nil>"
	}
	var b bytes.Buffer
	if e.iface != nil {
		b.WriteString(fmt.Sprint(e.iface))
		b.WriteByte('\n')
	}
	e.writeFullStack(&b)
	return b.String()
}

func (e *InterruptedError) Error() string {
	if e == nil || e.iface == nil {
		return "<nil>"
	}
	var b bytes.Buffer
	b.WriteString(fmt.Sprint(e.iface))
	e.writeShortStack(&b)
	return b.String()
}

func (e *Exception) writeFullStack(b *bytes.Buffer) {
	for _, frame := range e.stack {
		b.WriteString("\tat ")
		frame.write(b)
		b.WriteByte('\n')
	}
}

func (e *Exception) writeShortStack(b *bytes.Buffer) {
	for _, stack := range e.stack {
		if stack.prg != nil || stack.funcName != "" {
			if stack.prg != nil && stack.prg.src != nil && stack.prg.src.name == "<builtin>" {
				continue
			}
			b.WriteString(" at ")
			stack.write(b)
			break
		}
	}
}

func (e *Exception) String() string {
	if e == nil {
		return "<nil>"
	}
	var b bytes.Buffer
	if e.val != nil {
		b.WriteString(e.val.String())
		b.WriteByte('\n')
	}
	e.writeFullStack(&b)
	return b.String()
}

func (e *Exception) Error() string {
	if e == nil || e.val == nil {
		return "<nil>"
	}
	var b bytes.Buffer
	b.WriteString(e.val.String())
	e.writeShortStack(&b)
	return b.String()
}

func (e *Exception) Value() Value {
	return e.val
}

func (r *Runtime) addToGlobal(name string, value Value) {
	r.globalObject.self._putProp(name, value, true, false, true)
}

func (r *Runtime) init() {
	r.rand = rand.Float64
	r.global.ObjectPrototype = r.newBaseObject(nil, classObject).val
	r.globalObject = r.NewObject()

	r.vm = &vm{
		r: r,
	}
	r.vm.init()

	r.global.FunctionPrototype = r.newNativeFunc(nil, nil, "Empty", nil, 0)
	r.initObject()
	r.initFunction()
	r.initArray()
	r.initString()
	r.initNumber()
	r.initRegExp()
	r.initDate()
	r.initBoolean()

	r.initErrors()

	r.global.Eval = r.newNativeFunc(r.builtin_eval, nil, "eval", nil, 1)
	r.addToGlobal("eval", r.global.Eval)

	r.initGlobalObject()

	r.initMath()
	r.initJSON()

	//r.initTypedArrays()

	r.global.thrower = r.newNativeFunc(r.builtin_thrower, nil, "thrower", nil, 0)
	r.global.throwerProperty = &valueProperty{
		getterFunc: r.global.thrower,
		setterFunc: r.global.thrower,
		accessor:   true,
	}
}

func (r *Runtime) typeErrorResult(throw bool, args ...interface{}) {
	if throw {
		panic(r.NewTypeError(args...))
	}
}

func (r *Runtime) newError(typ *Object, format string, args ...interface{}) Value {
	msg := fmt.Sprintf(format, args...)
	return r.builtin_new(typ, []Value{newStringValue(msg)})
}

func (r *Runtime) throwReferenceError(name string) {
	panic(r.newError(r.global.ReferenceError, "%s is not defined", name))
}

func (r *Runtime) newSyntaxError(msg string, offset int) Value {
	return r.builtin_new((r.global.SyntaxError), []Value{newStringValue(msg)})
}

func (r *Runtime) newArray(prototype *Object) (a *arrayObject) {
	v := &Object{runtime: r}

	a = &arrayObject{}
	a.class = classArray
	a.val = v
	a.extensible = true
	v.self = a
	a.prototype = prototype
	a.init()
	return
}

func (r *Runtime) newArrayObject() *arrayObject {
	return r.newArray(r.global.ArrayPrototype)
}

func (r *Runtime) newArrayValues(values []Value) *Object {
	v := &Object{runtime: r}

	a := &arrayObject{}
	a.class = classArray
	a.val = v
	a.extensible = true
	v.self = a
	a.prototype = r.global.ArrayPrototype
	a.init()
	a.values = values
	a.length = int64(len(values))
	a.objCount = a.length
	return v
}

func (r *Runtime) newArrayLength(l int64) *Object {
	a := r.newArrayValues(nil)
	a.self.putStr("length", intToValue(l), true)
	return a
}

func (r *Runtime) newBaseObject(proto *Object, class string) (o *baseObject) {
	v := &Object{runtime: r}

	o = &baseObject{}
	o.class = class
	o.val = v
	o.extensible = true
	v.self = o
	o.prototype = proto
	o.init()
	return
}

func (r *Runtime) NewObject() (v *Object) {
	return r.newBaseObject(r.global.ObjectPrototype, classObject).val
}

// CreateObject creates an object with given prototype. Equivalent of Object.create(proto).
func (r *Runtime) CreateObject(proto *Object) *Object {
	return r.newBaseObject(proto, classObject).val
}

func (r *Runtime) NewTypeError(args ...interface{}) *Object {
	msg := ""
	if len(args) > 0 {
		f, _ := args[0].(string)
		msg = fmt.Sprintf(f, args[1:]...)
	}
	return r.builtin_new(r.global.TypeError, []Value{newStringValue(msg)})
}

func (r *Runtime) NewGoError(err error) *Object {
	e := r.newError(r.global.GoError, err.Error()).(*Object)
	e.Set("value", err)
	return e
}

func (r *Runtime) newFunc(name string, len int, strict bool) (f *funcObject) {
	v := &Object{runtime: r}

	f = &funcObject{}
	f.class = classFunction
	f.val = v
	f.extensible = true
	v.self = f
	f.prototype = r.global.FunctionPrototype
	f.init(name, len)
	if strict {
		f._put("caller", r.global.throwerProperty)
		f._put("arguments", r.global.throwerProperty)
	}
	return
}

func (r *Runtime) newNativeFuncObj(v *Object, call func(FunctionCall) Value, construct func(args []Value) *Object, name string, proto *Object, length int) *nativeFuncObject {
	f := &nativeFuncObject{
		baseFuncObject: baseFuncObject{
			baseObject: baseObject{
				class:      classFunction,
				val:        v,
				extensible: true,
				prototype:  r.global.FunctionPrototype,
			},
		},
		f:         call,
		construct: construct,
	}
	v.self = f
	f.init(name, length)
	if proto != nil {
		f._putProp("prototype", proto, false, false, false)
	}
	return f
}

func (r *Runtime) newNativeConstructor(call func(ConstructorCall) *Object, name string, length int) *Object {
	v := &Object{runtime: r}

	f := &nativeFuncObject{
		baseFuncObject: baseFuncObject{
			baseObject: baseObject{
				class:      classFunction,
				val:        v,
				extensible: true,
				prototype:  r.global.FunctionPrototype,
			},
		},
	}

	f.f = func(c FunctionCall) Value {
		return f.defaultConstruct(call, c.Arguments)
	}

	f.construct = func(args []Value) *Object {
		return f.defaultConstruct(call, args)
	}

	v.self = f
	f.init(name, length)

	proto := r.NewObject()
	proto.self._putProp("constructor", v, true, false, true)
	f._putProp("prototype", proto, true, false, false)

	return v
}

func (r *Runtime) newNativeFunc(call func(FunctionCall) Value, construct func(args []Value) *Object, name string, proto *Object, length int) *Object {
	v := &Object{runtime: r}

	f := &nativeFuncObject{
		baseFuncObject: baseFuncObject{
			baseObject: baseObject{
				class:      classFunction,
				val:        v,
				extensible: true,
				prototype:  r.global.FunctionPrototype,
			},
		},
		f:         call,
		construct: construct,
	}
	v.self = f
	f.init(name, length)
	if proto != nil {
		f._putProp("prototype", proto, false, false, false)
		proto.self._putProp("constructor", v, true, false, true)
	}
	return v
}

func (r *Runtime) newNativeFuncConstructObj(v *Object, construct func(args []Value, proto *Object) *Object, name string, proto *Object, length int) *nativeFuncObject {
	f := &nativeFuncObject{
		baseFuncObject: baseFuncObject{
			baseObject: baseObject{
				class:      classFunction,
				val:        v,
				extensible: true,
				prototype:  r.global.FunctionPrototype,
			},
		},
		f: r.constructWrap(construct, proto),
		construct: func(args []Value) *Object {
			return construct(args, proto)
		},
	}

	f.init(name, length)
	if proto != nil {
		f._putProp("prototype", proto, false, false, false)
	}
	return f
}

func (r *Runtime) newNativeFuncConstruct(construct func(args []Value, proto *Object) *Object, name string, prototype *Object, length int) *Object {
	return r.newNativeFuncConstructProto(construct, name, prototype, r.global.FunctionPrototype, length)
}

func (r *Runtime) newNativeFuncConstructProto(construct func(args []Value, proto *Object) *Object, name string, prototype, proto *Object, length int) *Object {
	v := &Object{runtime: r}

	f := &nativeFuncObject{}
	f.class = classFunction
	f.val = v
	f.extensible = true
	v.self = f
	f.prototype = proto
	f.f = r.constructWrap(construct, prototype)
	f.construct = func(args []Value) *Object {
		return construct(args, prototype)
	}
	f.init(name, length)
	if prototype != nil {
		f._putProp("prototype", prototype, false, false, false)
		prototype.self._putProp("constructor", v, true, false, true)
	}
	return v
}

func (r *Runtime) newPrimitiveObject(value Value, proto *Object, class string) *Object {
	v := &Object{runtime: r}

	o := &primitiveValueObject{}
	o.class = class
	o.val = v
	o.extensible = true
	v.self = o
	o.prototype = proto
	o.pValue = value
	o.init()
	return v
}

func (r *Runtime) builtin_Number(call FunctionCall) Value {
	if len(call.Arguments) > 0 {
		return call.Arguments[0].ToNumber()
	} else {
		return intToValue(0)
	}
}

func (r *Runtime) builtin_newNumber(args []Value) *Object {
	var v Value
	if len(args) > 0 {
		v = args[0].ToNumber()
	} else {
		v = intToValue(0)
	}
	return r.newPrimitiveObject(v, r.global.NumberPrototype, classNumber)
}

func (r *Runtime) builtin_Boolean(call FunctionCall) Value {
	if len(call.Arguments) > 0 {
		if call.Arguments[0].ToBoolean() {
			return valueTrue
		} else {
			return valueFalse
		}
	} else {
		return valueFalse
	}
}

func (r *Runtime) builtin_newBoolean(args []Value) *Object {
	var v Value
	if len(args) > 0 {
		if args[0].ToBoolean() {
			v = valueTrue
		} else {
			v = valueFalse
		}
	} else {
		v = valueFalse
	}
	return r.newPrimitiveObject(v, r.global.BooleanPrototype, classBoolean)
}

func (r *Runtime) error_toString(call FunctionCall) Value {
	obj := call.This.ToObject(r).self
	msg := obj.getStr("message")
	name := obj.getStr("name")
	var nameStr, msgStr string
	if name != nil && name != _undefined {
		nameStr = name.String()
	}
	if msg != nil && msg != _undefined {
		msgStr = msg.String()
	}
	if nameStr != "" && msgStr != "" {
		return newStringValue(fmt.Sprintf("%s: %s", name.String(), msgStr))
	} else {
		if nameStr != "" {
			return name.ToString()
		} else {
			return msg.ToString()
		}
	}
}

func (r *Runtime) builtin_Error(args []Value, proto *Object) *Object {
	obj := r.newBaseObject(proto, classError)
	if len(args) > 0 && args[0] != _undefined {
		obj._putProp("message", args[0], true, false, true)
	}
	return obj.val
}

func (r *Runtime) builtin_new(construct *Object, args []Value) *Object {
repeat:
	switch f := construct.self.(type) {
	case *nativeFuncObject:
		if f.construct != nil {
			return f.construct(args)
		} else {
			panic("Not a constructor")
		}
	case *boundFuncObject:
		if f.construct != nil {
			return f.construct(args)
		} else {
			panic("Not a constructor")
		}
	case *funcObject:
		// TODO: implement
		panic("Not implemented")
	case *lazyObject:
		construct.self = f.create(construct)
		goto repeat
	default:
		panic("Not a constructor")
	}
}

func (r *Runtime) throw(e Value) {
	panic(e)
}

func (r *Runtime) builtin_thrower(call FunctionCall) Value {
	r.typeErrorResult(true, "'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them")
	return nil
}

func (r *Runtime) eval(src string, direct, strict bool, this Value) Value {

	p, err := r.compile("<eval>", src, strict, true)
	if err != nil {
		panic(err)
	}

	vm := r.vm

	vm.pushCtx()
	vm.prg = p
	vm.pc = 0
	if !direct {
		vm.stash = nil
	}
	vm.sb = vm.sp
	vm.push(this)
	if strict {
		vm.push(valueTrue)
	} else {
		vm.push(valueFalse)
	}
	vm.run()
	vm.popCtx()
	vm.halt = false
	retval := vm.stack[vm.sp-1]
	vm.sp -= 2
	return retval
}

func (r *Runtime) builtin_eval(call FunctionCall) Value {
	if len(call.Arguments) == 0 {
		return _undefined
	}
	if str, ok := call.Arguments[0].assertString(); ok {
		return r.eval(str.String(), false, false, r.globalObject)
	}
	return call.Arguments[0]
}

func (r *Runtime) constructWrap(construct func(args []Value, proto *Object) *Object, proto *Object) func(call FunctionCall) Value {
	return func(call FunctionCall) Value {
		return construct(call.Arguments, proto)
	}
}

func (r *Runtime) toCallable(v Value) func(FunctionCall) Value {
	if call, ok := r.toObject(v).self.assertCallable(); ok {
		return call
	}
	r.typeErrorResult(true, "Value is not callable: %s", v.ToString())
	return nil
}

func (r *Runtime) checkObjectCoercible(v Value) {
	switch v.(type) {
	case valueUndefined, valueNull:
		r.typeErrorResult(true, "Value is not object coercible")
	}
}

func toUInt32(v Value) uint32 {
	v = v.ToNumber()
	if i, ok := v.assertInt(); ok {
		return uint32(i)
	}

	if f, ok := v.assertFloat(); ok {
		if !math.IsNaN(f) && !math.IsInf(f, 0) {
			return uint32(int64(f))
		}
	}
	return 0
}

func toUInt16(v Value) uint16 {
	v = v.ToNumber()
	if i, ok := v.assertInt(); ok {
		return uint16(i)
	}

	if f, ok := v.assertFloat(); ok {
		if !math.IsNaN(f) && !math.IsInf(f, 0) {
			return uint16(int64(f))
		}
	}
	return 0
}

func toLength(v Value) int64 {
	if v == nil {
		return 0
	}
	i := v.ToInteger()
	if i < 0 {
		return 0
	}
	if i >= maxInt {
		return maxInt - 1
	}
	return i
}

func toInt32(v Value) int32 {
	v = v.ToNumber()
	if i, ok := v.assertInt(); ok {
		return int32(i)
	}

	if f, ok := v.assertFloat(); ok {
		if !math.IsNaN(f) && !math.IsInf(f, 0) {
			return int32(int64(f))
		}
	}
	return 0
}

func (r *Runtime) toBoolean(b bool) Value {
	if b {
		return valueTrue
	} else {
		return valueFalse
	}
}

// New creates an instance of a Javascript runtime that can be used to run code. Multiple instances may be created and
// used simultaneously, however it is not possible to pass JS values across runtimes.
func New() *Runtime {
	r := &Runtime{}
	r.init()
	return r
}

// Compile creates an internal representation of the JavaScript code that can be later run using the Runtime.RunProgram()
// method. This representation is not linked to a runtime in any way and can be run in multiple runtimes (possibly
// at the same time).
func Compile(name, src string, strict bool) (*Program, error) {
	return compile(name, src, strict, false)
}

// CompileAST creates an internal representation of the JavaScript code that can be later run using the Runtime.RunProgram()
// method. This representation is not linked to a runtime in any way and can be run in multiple runtimes (possibly
// at the same time).
func CompileAST(prg *js_ast.Program, strict bool) (*Program, error) {
	return compileAST(prg, strict, false)
}

// MustCompile is like Compile but panics if the code cannot be compiled.
// It simplifies safe initialization of global variables holding compiled JavaScript code.
func MustCompile(name, src string, strict bool) *Program {
	prg, err := Compile(name, src, strict)
	if err != nil {
		panic(err)
	}

	return prg
}

func compile(name, src string, strict, eval bool) (p *Program, err error) {
	prg, err1 := parser.ParseFile(nil, name, src, 0)
	if err1 != nil {
		switch err1 := err1.(type) {
		case parser.ErrorList:
			if len(err1) > 0 && err1[0].Message == "Invalid left-hand side in assignment" {
				err = &CompilerReferenceError{
					CompilerError: CompilerError{
						Message: err1.Error(),
					},
				}
				return
			}
		}
		// FIXME offset
		err = &CompilerSyntaxError{
			CompilerError: CompilerError{
				Message: err1.Error(),
			},
		}
		return
	}

	p, err = compileAST(prg, strict, eval)

	return
}

func compileAST(prg *js_ast.Program, strict, eval bool) (p *Program, err error) {
	c := newCompiler()
	c.scope.strict = strict
	c.scope.eval = eval

	defer func() {
		if x := recover(); x != nil {
			p = nil
			switch x1 := x.(type) {
			case *CompilerSyntaxError:
				err = x1
			default:
				panic(x)
			}
		}
	}()

	c.compile(prg)
	p = c.p
	return
}

func (r *Runtime) compile(name, src string, strict, eval bool) (p *Program, err error) {
	p, err = compile(name, src, strict, eval)
	if err != nil {
		switch x1 := err.(type) {
		case *CompilerSyntaxError:
			err = &Exception{
				val: r.builtin_new(r.global.SyntaxError, []Value{newStringValue(x1.Error())}),
			}
		case *CompilerReferenceError:
			err = &Exception{
				val: r.newError(r.global.ReferenceError, x1.Message),
			} // TODO proper message
		}
	}
	return
}

// RunString executes the given string in the global context.
func (r *Runtime) RunString(str string) (Value, error) {
	return r.RunScript("", str)
}

// RunScript executes the given string in the global context.
func (r *Runtime) RunScript(name, src string) (Value, error) {
	p, err := Compile(name, src, false)

	if err != nil {
		return nil, err
	}

	return r.RunProgram(p)
}

// RunProgram executes a pre-compiled (see Compile()) code in the global context.
func (r *Runtime) RunProgram(p *Program) (result Value, err error) {
	defer func() {
		if x := recover(); x != nil {
			if intr, ok := x.(*InterruptedError); ok {
				err = intr
			} else {
				panic(x)
			}
		}
	}()
	recursive := false
	if len(r.vm.callStack) > 0 {
		recursive = true
		r.vm.pushCtx()
	}
	r.vm.prg = p
	r.vm.pc = 0
	ex := r.vm.runTry()
	if ex == nil {
		result = r.vm.pop()
	} else {
		err = ex
	}
	if recursive {
		r.vm.popCtx()
		r.vm.halt = false
		r.vm.clearStack()
	} else {
		r.vm.stack = nil
	}
	return
}

// Interrupt a running JavaScript. The corresponding Go call will return an *InterruptedError containing v.
// Note, it only works while in JavaScript code, it does not interrupt native Go functions (which includes all built-ins).
func (r *Runtime) Interrupt(v interface{}) {
	r.vm.Interrupt(v)
}


// Caller reports file and line number information about function invocations on the calling script's stack. The argument skip is the number of stack frames to ascend, with 0 identifying the caller of Caller. (For historical reasons the meaning of skip differs between Caller and Callers.) The return values report the program counter, file name, and line number within the file of the corresponding call. The boolean ok is false if it was not possible to recover the information.
func (r *Runtime) Caller(skip int) (pc int, file string, line int, funcName string, ok bool) {
	return r.vm.Caller(skip)
}

/*
ToValue converts a Go value into JavaScript value.

Primitive types (ints and uints, floats, string, bool) are converted to the corresponding JavaScript primitives.

func(FunctionCall) Value is treated as a native JavaScript function.

map[string]interface{} is converted into a host object that largely behaves like a JavaScript Object.

[]interface{} is converted into a host object that behaves largely like a JavaScript Array, however it's not extensible
because extending it can change the pointer so it becomes detached from the original.

*[]interface{} same as above, but the array becomes extensible.

A function is wrapped within a native JavaScript function. When called the arguments are automatically converted to
the appropriate Go types. If conversion is not possible, a TypeError is thrown.

A slice type is converted into a generic reflect based host object that behaves similar to an unexpandable Array.

Any other type is converted to a generic reflect based host object. Depending on the underlying type it behaves similar
to a Number, String, Boolean or Object.

Note that the underlying type is not lost, calling Export() returns the original Go value. This applies to all
reflect based types.
*/
func (r *Runtime) ToValue(i interface{}) Value {
	switch i := i.(type) {
	case nil:
		return _null
	case Value:
		// TODO: prevent importing Objects from a different runtime
		return i
	case string:
		return newStringValue(i)
	case bool:
		if i {
			return valueTrue
		} else {
			return valueFalse
		}
	case func(FunctionCall) Value:
		return r.newNativeFunc(i, nil, "", nil, 0)
	case func(ConstructorCall) *Object:
		return r.newNativeConstructor(i, "", 0)
	case int:
		return intToValue(int64(i))
	case int8:
		return intToValue(int64(i))
	case int16:
		return intToValue(int64(i))
	case int32:
		return intToValue(int64(i))
	case int64:
		return intToValue(i)
	case uint:
		if int64(i) <= math.MaxInt64 {
			return intToValue(int64(i))
		} else {
			return floatToValue(float64(i))
		}
	case uint8:
		return intToValue(int64(i))
	case uint16:
		return intToValue(int64(i))
	case uint32:
		return intToValue(int64(i))
	case uint64:
		if i <= math.MaxInt64 {
			return intToValue(int64(i))
		}
		return floatToValue(float64(i))
	case float32:
		return floatToValue(float64(i))
	case float64:
		return floatToValue(i)
	case map[string]interface{}:
		obj := &Object{runtime: r}
		m := &objectGoMapSimple{
			baseObject: baseObject{
				val:        obj,
				extensible: true,
			},
			data: i,
		}
		obj.self = m
		m.init()
		return obj
	case []interface{}:
		obj := &Object{runtime: r}
		a := &objectGoSlice{
			baseObject: baseObject{
				val: obj,
			},
			data: &i,
		}
		obj.self = a
		a.init()
		return obj
	case *[]interface{}:
		obj := &Object{runtime: r}
		a := &objectGoSlice{
			baseObject: baseObject{
				val: obj,
			},
			data:            i,
			sliceExtensible: true,
		}
		obj.self = a
		a.init()
		return obj
	}

	origValue := reflect.ValueOf(i)
	value := origValue
	for value.Kind() == reflect.Ptr {
		value = reflect.Indirect(value)
	}

	if !value.IsValid() {
		return _null
	}

	switch value.Kind() {
	case reflect.Map:
		if value.Type().NumMethod() == 0 {
			switch value.Type().Key().Kind() {
			case reflect.String, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
				reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
				reflect.Float64, reflect.Float32:

				obj := &Object{runtime: r}
				m := &objectGoMapReflect{
					objectGoReflect: objectGoReflect{
						baseObject: baseObject{
							val:        obj,
							extensible: true,
						},
						origValue: origValue,
						value:     value,
					},
				}
				m.init()
				obj.self = m
				return obj
			}
		}
	case reflect.Slice:
		obj := &Object{runtime: r}
		a := &objectGoSliceReflect{
			objectGoReflect: objectGoReflect{
				baseObject: baseObject{
					val: obj,
				},
				origValue: origValue,
				value:     value,
			},
		}
		a.init()
		obj.self = a
		return obj
	case reflect.Func:
		return r.newNativeFunc(r.wrapReflectFunc(value), nil, "", nil, value.Type().NumIn())
	}

	obj := &Object{runtime: r}
	o := &objectGoReflect{
		baseObject: baseObject{
			val: obj,
		},
		origValue: origValue,
		value:     value,
	}
	obj.self = o
	o.init()
	return obj
}

func (r *Runtime) wrapReflectFunc(value reflect.Value) func(FunctionCall) Value {
	return func(call FunctionCall) Value {
		typ := value.Type()
		nargs := typ.NumIn()
		var in []reflect.Value

		if l := len(call.Arguments); l < nargs {
			// fill missing arguments with zero values
			n := nargs
			if typ.IsVariadic() {
				n--
			}
			in = make([]reflect.Value, n)
			for i := l; i < n; i++ {
				in[i] = reflect.Zero(typ.In(i))
			}
		} else {
			if l > nargs && !typ.IsVariadic() {
				l = nargs
			}
			in = make([]reflect.Value, l)
		}

		callSlice := false
		for i, a := range call.Arguments {
			var t reflect.Type

			n := i
			if n >= nargs-1 && typ.IsVariadic() {
				if n > nargs-1 {
					n = nargs - 1
				}

				t = typ.In(n).Elem()
			} else if n > nargs-1 { // ignore extra arguments
				break
			} else {
				t = typ.In(n)
			}

			// if this is a variadic Go function, and the caller has supplied
			// exactly the number of JavaScript arguments required, and this
			// is the last JavaScript argument, try treating the it as the
			// actual set of variadic Go arguments. if that succeeds, break
			// out of the loop.
			if typ.IsVariadic() && len(call.Arguments) == nargs && i == nargs-1 {
				if v, err := r.toReflectValue(a, typ.In(n)); err == nil {
					in[i] = v
					callSlice = true
					break
				}
			}
			var err error
			in[i], err = r.toReflectValue(a, t)
			if err != nil {
				panic(r.newError(r.global.TypeError, "Could not convert function call parameter %v to %v", a, t))
			}
		}

		var out []reflect.Value

		if callSlice {
			out = value.CallSlice(in)
		} else {
			out = value.Call(in)
		}

		if len(out) == 0 {
			return _undefined
		}

		if last := out[len(out)-1]; last.Type().Name() == "error" {
			if !last.IsNil() {
				err := last.Interface()
				if _, ok := err.(*Exception); ok {
					panic(err)
				}
				panic(err.(error))
			}
			out = out[:len(out)-1]
		}

		switch len(out) {
		case 0:
			return _undefined
		case 1:
			return r.ToValue(out[0].Interface())
		default:
			s := make([]interface{}, len(out))
			for i, v := range out {
				s[i] = v.Interface()
			}

			return r.ToValue(s)
		}
	}
}

func (r *Runtime) toReflectValue(v Value, typ reflect.Type) (reflect.Value, error) {
	switch typ.Kind() {
	case reflect.String:
		return reflect.ValueOf(v.String()).Convert(typ), nil
	case reflect.Bool:
		return reflect.ValueOf(v.ToBoolean()).Convert(typ), nil
	case reflect.Int:
		i, _ := toInt(v)
		return reflect.ValueOf(int(i)).Convert(typ), nil
	case reflect.Int64:
		i, _ := toInt(v)
		return reflect.ValueOf(i).Convert(typ), nil
	case reflect.Int32:
		i, _ := toInt(v)
		return reflect.ValueOf(int32(i)).Convert(typ), nil
	case reflect.Int16:
		i, _ := toInt(v)
		return reflect.ValueOf(int16(i)).Convert(typ), nil
	case reflect.Int8:
		i, _ := toInt(v)
		return reflect.ValueOf(int8(i)).Convert(typ), nil
	case reflect.Uint:
		i, _ := toInt(v)
		return reflect.ValueOf(uint(i)).Convert(typ), nil
	case reflect.Uint64:
		i, _ := toInt(v)
		return reflect.ValueOf(uint64(i)).Convert(typ), nil
	case reflect.Uint32:
		i, _ := toInt(v)
		return reflect.ValueOf(uint32(i)).Convert(typ), nil
	case reflect.Uint16:
		i, _ := toInt(v)
		return reflect.ValueOf(uint16(i)).Convert(typ), nil
	case reflect.Uint8:
		i, _ := toInt(v)
		return reflect.ValueOf(uint8(i)).Convert(typ), nil
	}

	if typ == typeCallable {
		if fn, ok := AssertFunction(v); ok {
			return reflect.ValueOf(fn), nil
		}
	}

	if typ.Implements(typeValue) {
		return reflect.ValueOf(v), nil
	}

	et := v.ExportType()
	if et == nil {
		return reflect.Zero(typ), nil
	}
	if et.AssignableTo(typ) {
		return reflect.ValueOf(v.Export()), nil
	} else if et.ConvertibleTo(typ) {
		return reflect.ValueOf(v.Export()).Convert(typ), nil
	}

	switch typ.Kind() {
	case reflect.Slice:
		if o, ok := v.(*Object); ok {
			if o.self.className() == classArray {
				l := int(toLength(o.self.getStr("length")))
				s := reflect.MakeSlice(typ, l, l)
				elemTyp := typ.Elem()
				for i := 0; i < l; i++ {
					item := o.self.get(intToValue(int64(i)))
					itemval, err := r.toReflectValue(item, elemTyp)
					if err != nil {
						return reflect.Value{}, fmt.Errorf("Could not convert array element %v to %v at %d", v, typ, i)
					}
					s.Index(i).Set(itemval)
				}
				return s, nil
			}
		}
	case reflect.Map:
		if o, ok := v.(*Object); ok {
			m := reflect.MakeMap(typ)
			keyTyp := typ.Key()
			elemTyp := typ.Elem()
			needConvertKeys := !reflect.ValueOf("").Type().AssignableTo(keyTyp)
			for item, f := o.self.enumerate(false, false)(); f != nil; item, f = f() {
				var kv reflect.Value
				var err error
				if needConvertKeys {
					kv, err = r.toReflectValue(newStringValue(item.name), keyTyp)
					if err != nil {
						return reflect.Value{}, fmt.Errorf("Could not convert map key %s to %v", item.name, typ)
					}
				} else {
					kv = reflect.ValueOf(item.name)
				}

				ival := item.value
				if ival == nil {
					ival = o.self.getStr(item.name)
				}
				if ival != nil {
					vv, err := r.toReflectValue(ival, elemTyp)
					if err != nil {
						return reflect.Value{}, fmt.Errorf("Could not convert map value %v to %v at key %s", ival, typ, item.name)
					}
					m.SetMapIndex(kv, vv)
				} else {
					m.SetMapIndex(kv, reflect.Zero(elemTyp))
				}
			}
			return m, nil
		}
	case reflect.Struct:
		if o, ok := v.(*Object); ok {
			s := reflect.New(typ).Elem()
			for i := 0; i < typ.NumField(); i++ {
				field := typ.Field(i)
				if ast.IsExported(field.Name) {
					name := field.Name
					if r.fieldNameMapper != nil {
						name = r.fieldNameMapper.FieldName(typ, field)
					}
					v := o.self.getStr(name)
					if v != nil {
						vv, err := r.toReflectValue(v, field.Type)
						if err != nil {
							return reflect.Value{}, fmt.Errorf("Could not convert struct value %v to %v for field %s", v, field.Type, field.Name)

						}
						s.Field(i).Set(vv)
					}
				}
			}
			return s, nil
		}
	case reflect.Ptr:
		ptr := reflect.New(typ.Elem())
		elem, err := r.toReflectValue(v, typ.Elem())
		if err != nil {
			return reflect.Value{}, err
		}
		ptr.Elem().Set(elem)
		return ptr, nil
	case reflect.Func:
		if fn, ok := AssertFunction(v); ok {
			return reflect.MakeFunc(typ, r.wrapJSFunc(fn, typ)), nil
		}
	}

	return reflect.Value{}, fmt.Errorf("Could not convert %v to %v", v, typ)
}

func (r *Runtime) wrapJSFunc(fn Callable, typ reflect.Type) func(args []reflect.Value) (results []reflect.Value) {
	return func(args []reflect.Value) (results []reflect.Value) {
		jsArgs := make([]Value, len(args))
		for i, arg := range args {
			jsArgs[i] = r.ToValue(arg.Interface())
		}

		results = make([]reflect.Value, typ.NumOut())
		res, err := fn(_undefined, jsArgs...)
		if err == nil {
			if typ.NumOut() > 0 {
				results[0], err = r.toReflectValue(res, typ.Out(0))
			}
		}

		if err != nil {
			if typ.NumOut() == 2 && typ.Out(1).Name() == "error" {
				results[1] = reflect.ValueOf(err).Convert(typ.Out(1))
			} else {
				panic(err)
			}
		}

		for i, v := range results {
			if !v.IsValid() {
				results[i] = reflect.Zero(typ.Out(i))
			}
		}

		return
	}
}

// ExportTo converts a JavaScript value into the specified Go value. The second parameter must be a non-nil pointer.
// Returns error if conversion is not possible.
func (r *Runtime) ExportTo(v Value, target interface{}) error {
	tval := reflect.ValueOf(target)
	if tval.Kind() != reflect.Ptr || tval.IsNil() {
		return errors.New("target must be a non-nil pointer")
	}
	vv, err := r.toReflectValue(v, tval.Elem().Type())
	if err != nil {
		return err
	}
	tval.Elem().Set(vv)
	return nil
}

// GlobalObject returns the global object.
func (r *Runtime) GlobalObject() *Object {
	return r.globalObject
}

// Set the specified value as a property of the global object.
// The value is first converted using ToValue()
func (r *Runtime) Set(name string, value interface{}) {
	r.globalObject.self.putStr(name, r.ToValue(value), false)
}

// Get the specified property of the global object.
func (r *Runtime) Get(name string) Value {
	return r.globalObject.self.getStr(name)
}

// SetRandSource sets random source for this Runtime. If not called, the default math/rand is used.
func (r *Runtime) SetRandSource(source RandSource) {
	r.rand = source
}

// Callable represents a JavaScript function that can be called from Go.
type Callable func(this Value, args ...Value) (Value, error)

// AssertFunction checks if the Value is a function and returns a Callable.
func AssertFunction(v Value) (Callable, bool) {
	if obj, ok := v.(*Object); ok {
		if f, ok := obj.self.assertCallable(); ok {
			return func(this Value, args ...Value) (ret Value, err error) {
				defer func() {
					if x := recover(); x != nil {
						if ex, ok := x.(*InterruptedError); ok {
							err = ex
						} else {
							panic(x)
						}
					}
				}()
				ex := obj.runtime.vm.try(func() {
					ret = f(FunctionCall{
						This:      this,
						Arguments: args,
					})
				})
				if ex != nil {
					err = ex
				}
				obj.runtime.vm.clearStack()
				return
			}, true
		}
	}
	return nil, false
}

// IsUndefined returns true if the supplied Value is undefined. Note, it checks against the real undefined, not
// against the global object's 'undefined' property.
func IsUndefined(v Value) bool {
	return v == _undefined
}

// IsNull returns true if the supplied Value is null.
func IsNull(v Value) bool {
	return v == _null
}

// Undefined returns JS undefined value. Note if global 'undefined' property is changed this still returns the original value.
func Undefined() Value {
	return _undefined
}

// Null returns JS null value.
func Null() Value {
	return _null
}

func tryFunc(f func()) (err error) {
	defer func() {
		if x := recover(); x != nil {
			switch x := x.(type) {
			case *Exception:
				err = x
			case *InterruptedError:
				err = x
			case Value:
				err = &Exception{
					val: x,
				}
			default:
				panic(x)
			}
		}
	}()

	f()

	return nil
}