CGUISetting.h

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/* Copyright (C) 2021 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_CGUISETTINGS
#define INCLUDED_CGUISETTINGS

#include "ps/CStr.h"
#include "scriptinterface/ScriptForward.h"


class IGUIObject;

/**
 * This setting interface allows GUI objects to call setting function functions without having to know the setting type.
 * This is fact is used for setting the value from a JS value or XML value (string) and when deleting the setting,
 * when the type of the setting value is not known in advance.
 */
class IGUISetting
{
public:
    NONCOPYABLE(IGUISetting);
    IGUISetting(const CStr& name, IGUIObject* owner);

    /**
     * Parses the given string and assigns to the setting value. Used for parsing XML attributes.
     */
    bool FromString(const CStrW& value, const bool sendMessage);

    /**
     * Parses the given JS::Value using Script::FromJSVal and assigns it to the setting data.
     */
    bool FromJSVal(const ScriptRequest& rq, JS::HandleValue value, const bool sendMessage);

    /**
     * Converts the setting data to a JS::Value using Script::ToJSVal.
     */
    virtual void ToJSVal(const ScriptRequest& rq, JS::MutableHandleValue value) = 0;

protected:
    IGUISetting(IGUISetting&& o);
    virtual ~IGUISetting() = default;

    virtual bool DoFromString(const CStrW& value) = 0;
    virtual bool DoFromJSVal(const ScriptRequest& rq, JS::HandleValue value) = 0;

    /**
     * Triggers the IGUIObject logic when a setting changes.
     * This should be called by derived classes when something externally visible changes,
     * unless overloaded to provide similar behaviour.
     */
    virtual void OnSettingChange(const CStr& setting, bool sendMessage);

    /**
     * Return the name of the setting, from JS.
     */
    virtual CStr GetName() const = 0;

    /**
     * The object that stores this setting.
     */
    IGUIObject& m_pObject;
};

/**
 * Wraps a T. Makes sure the appropriate setting functions are called when modifying T,
 * and likewise makes sure that JS/xml settings affect T appropriately,
 * while being as transparent as possible to use from C++ code.
 */
template<typename T>
class CGUISimpleSetting : public IGUISetting
{
public:
    template<typename... Args>
    CGUISimpleSetting(IGUIObject* pObject, const CStr& Name, Args&&... args)
        : IGUISetting(Name, pObject), m_Name(Name), m_Setting(args...)
    {}
    NONCOPYABLE(CGUISimpleSetting);
    MOVABLE(CGUISimpleSetting);

    operator const T&() const { return m_Setting; }
    const T& operator*() const { return m_Setting; }
    const T* operator->() const { return &m_Setting; }

    /**
     * 'Uglified' getter when you want direct access without triggering messages.
     */
    T& GetMutable() { return m_Setting; }

    /**
     * 'Uglified' operator=, so that SendMessage is explicit.
     */
    void Set(T value, bool sendMessage)
    {
        m_Setting = std::move(value);
        OnSettingChange(m_Name, sendMessage);
    }

protected:
    CStr GetName() const override
    {
        return m_Name;
    }

    bool DoFromString(const CStrW& value) override;
    bool DoFromJSVal(const ScriptRequest& rq, JS::HandleValue value) override;
    void ToJSVal(const ScriptRequest& rq, JS::MutableHandleValue value) override;

    const CStr m_Name;
    T m_Setting;
};

#endif // INCLUDED_CGUISETTINGS