package otto

type _environment interface {
	HasBinding(string) bool
	CreateMutableBinding(string, bool)
	SetMutableBinding(string, Value, bool)
	GetBindingValue(string, bool) Value
	DeleteBinding(string) bool
	ImplicitThisValue() *_object

	Outer() _environment

	newReference(string, bool) _reference

	// SetMutableBinding with Lazy CreateMutableBinding(..., true)
	SetValue(string, Value, bool)
	// Alias for GetBindingValue
	GetValue(string, bool) Value

	newObjectEnvironment(object *_object) *_objectEnvironment
	newDeclarativeEnvironment() _environment
}

func (runtime *_runtime) newDeclarativeEnvironment(outer _environment) *_objectEnvironment {
	// Just an _objectEnvironment (for now)
	return &_objectEnvironment{
		runtime: runtime,
		outer: outer,
		Object: runtime.newBaseObject(),
	}
}

type _functionEnvironment struct {
	_objectEnvironment
	arguments *_object
	indexOfArgumentName map[string]string
}

func (runtime *_runtime) newFunctionEnvironment(outer _environment) *_functionEnvironment {
	return &_functionEnvironment{
		_objectEnvironment: _objectEnvironment{
			outer: outer,
			Object: runtime.newObject(),
		},
	}
}

func (self *_functionEnvironment) newReference(name string, strict bool) _reference {
	index, exists := self.indexOfArgumentName[name]
	if !exists {
		return self._objectEnvironment.newReference(name, strict)
	}
	return newArgumentReference(self.arguments, index, strict)
}

func (self *_functionEnvironment) HasBinding(name string) bool {
	_, exists := self.indexOfArgumentName[name]
	if exists {
		return true
	}
	return self.Object.HasProperty(name)
}

type _objectEnvironment struct {
	runtime *_runtime
    outer _environment
    Object *_object
	ProvideThis bool
}

func (runtime *_runtime) newObjectEnvironment() *_objectEnvironment {
    return &_objectEnvironment{
		runtime: runtime,
		outer: nil,
        Object: runtime.newBaseObject(),
    }
}

func (self *_objectEnvironment) HasBinding(name string) bool {
	return self.Object.HasProperty(name)
}

func (self *_objectEnvironment) CreateMutableBinding(name string, configure bool) {
	if self.Object.HasProperty(name) {
		panic(hereBeDragons())
	}
	self.Object._propertyStash.Write(name, UndefinedValue())
}

func (self *_objectEnvironment) SetMutableBinding(name string, value Value, strict bool) {
	self.Object.WriteValue(name, value, strict)
}

func (self *_objectEnvironment) GetBindingValue(name string, strict bool) Value {
	if self.Object.HasProperty(name) {
		return self.Object.Get(name)
	}
	if strict {
		panic(newReferenceError("Not Defined", name))
	}
	return UndefinedValue()
}

func (self *_objectEnvironment) DeleteBinding(name string) bool {
	return self.Object.Delete(name, false)
}

func (self *_objectEnvironment) ImplicitThisValue() *_object {
	if self.ProvideThis {
		return self.Object
	}
	return nil
}

func getIdentifierReference(environment _environment, name string, strict bool) _reference {
	if environment == nil {
		return newObjectReference(nil, name, strict)
	}
	if environment.HasBinding(name) {
		return environment.newReference(name, strict)
	}
	return getIdentifierReference(environment.Outer(), name, strict)
}

// ---

func (self *_objectEnvironment) Outer() _environment {
	return self.outer
}

func (self *_objectEnvironment) newObjectEnvironment(object *_object) *_objectEnvironment {
    return &_objectEnvironment{
		outer: self,
		Object: object,
	}
}

func (self *_objectEnvironment) newDeclarativeEnvironment() _environment {
    return self.runtime.newDeclarativeEnvironment(self)
}

func (self *_objectEnvironment) newReference(name string, strict bool) _reference {
	return newObjectReference(self.Object, name, strict)
}

func (self *_objectEnvironment) GetReference(name string) _reference {
	return getIdentifierReference(self, name, false)
}

func (self *_objectEnvironment) GetValue(name string, throw bool) Value {
	return self.GetBindingValue(name, throw)
}

func (self *_objectEnvironment) SetValue(name string, value Value, throw bool) {
	if !self.HasBinding(name) {
		self.CreateMutableBinding(name, true) // Configureable by default
	}
	self.SetMutableBinding(name, value, throw)
}