/*

 * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#pragma once

#include <LibJS/Runtime/Completion.h>

#include <LibJS/Runtime/DeclarativeEnvironment.h>

namespace JS {

class FunctionEnvironment final : public DeclarativeEnvironment {

    JS_ENVIRONMENT(FunctionEnvironment, DeclarativeEnvironment);

    JS_DECLARE_ALLOCATOR(FunctionEnvironment);

public:

    enum class ThisBindingStatus : u8 {

        Lexical,

        Initialized,

        Uninitialized,

    };

    virtual ~FunctionEnvironment() override = default;

    ThisBindingStatus this_binding_status() const { return m_this_binding_status; }

    void set_this_binding_status(ThisBindingStatus status) { m_this_binding_status = status; }

    ECMAScriptFunctionObject& function_object() { return *m_function_object; }

    ECMAScriptFunctionObject const& function_object() const { return *m_function_object; }

    void set_function_object(ECMAScriptFunctionObject& function) { m_function_object = &function; }

    Value new_target() const { return m_new_target; }

    void set_new_target(Value new_target)

    {

        VERIFY(!new_target.is_empty());

        m_new_target = new_target;

    }

    // Abstract operations

    ThrowCompletionOr<Value> get_super_base() const;

    bool has_super_binding() const;

    virtual bool has_this_binding() const override;

    virtual ThrowCompletionOr<Value> get_this_binding(VM&) const override;

    ThrowCompletionOr<Value> bind_this_value(VM&, Value);

private:

    explicit FunctionEnvironment(Environment* parent_environment);

    virtual bool is_function_environment() const override { return true; }

    virtual void visit_edges(Visitor&) override;

    Value m_this_value;                                                           // [[ThisValue]]

    ThisBindingStatus m_this_binding_status { ThisBindingStatus::Uninitialized }; // [[ThisBindingStatus]]

    GCPtr<ECMAScriptFunctionObject> m_function_object;                            // [[FunctionObject]]

    Value m_new_target { js_undefined() };                                        // [[NewTarget]]

};

template<>

inline bool Environment::fast_is<FunctionEnvironment>() const { return is_function_environment(); }

}