spk_combo_box.hpp

#pragma once
 
#include <any>
#include <cstddef>
#include <cstdint>
#include <limits>
#include <memory>
#include <optional>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>
 
#include "structure/design_pattern/spk_contract_provider.hpp"
#include "structure/widget/spk_frame.hpp"
#include "structure/widget/spk_linear_layout.hpp"
#include "structure/widget/spk_push_button.hpp"
#include "structure/widget/spk_scrollable_area.hpp"
#include "structure/widget/spk_widget.hpp"
 
namespace spk
{
    class ComboBox : public spk::Widget
    {
    private:
        class Item : public spk::Widget
        {
        private:
            spk::PushButton _button;
 
        protected:
            void _onGeometryChange() override;
 
        public:
            Item(const std::wstring &p_name, spk::Widget *p_parent);
 
            void setText(const std::wstring &p_text);
            spk::PushButton::Contract subscribe(const spk::PushButton::Job &p_job);
        };
 
        class ListContent : public spk::Widget
        {
        private:
            spk::VerticalLayout _layout;
            std::vector<std::unique_ptr<Item>> _items;
 
        protected:
            void _onGeometryChange() override;
 
        public:
            ListContent(const std::wstring &p_name, spk::Widget *p_parent);
 
            Item &addItem(const std::wstring &p_name, const std::wstring &p_text);
            void removeItem(size_t p_index);
            void clear();
            spk::Vector2UInt maxItemMinimal() const;
        };
 
        class Popup : public spk::Widget
        {
        private:
            spk::Frame _background;
            spk::ScrolableArea<ListContent> _scrollArea;
            std::optional<uint32_t> _maxHeight;
            ComboBox *_owner = nullptr;
 
            void _refreshContentGeometry();
            uint32_t _resolveHeight(uint32_t p_contentHeight) const;
 
        protected:
            void _onGeometryChange() override;
 
        public:
            Popup(const std::wstring &p_name, spk::Widget *p_parent);
 
            ListContent &content();
            const ListContent &content() const;
            spk::Vector2UInt backgroundPadding() const;
            void updateContentGeometry();
 
            void setOwner(ComboBox *p_owner);
            void setMaxPopupHeight(uint32_t p_height);
            uint32_t maxPopupHeight() const;
            uint32_t resolvedHeight(uint32_t p_contentHeight) const;
            void setScrollBarWidth(size_t p_scrollBarWidth);
            size_t scrollBarWidth() const;
        };
 
        struct Entry
        {
            std::wstring text;
            std::any value;
        };
 
        spk::PushButton _displayButton;
        Popup _popup;
        spk::Widget *_popupParent = nullptr;
        std::vector<Entry> _entries;
        std::optional<size_t> _currentIndex;
        bool _isPopupOpen = false;
        spk::PushButton::Contract _displayContract;
        std::vector<spk::PushButton::Contract> _itemContracts;
        spk::Vector2Int _popupOffset{0, 2};
        spk::Vector2UInt _maxEntryMinimal = spk::Vector2UInt::Zero;
 
        void _refreshPopupGeometry();
        void _setPopupOpen(bool p_open);
        void _refreshDisplay();
        void _addEntry(const std::wstring &p_text, std::any p_value);
        void _selectIndex(size_t p_index);
        void _updateMaxEntryMinimal();
        void _refreshSizeHint();
        bool _needsPopupVerticalScrollBar() const;
 
    protected:
        void _onGeometryChange() override;
 
    public:
        ComboBox(const std::wstring &p_name, spk::Widget *p_parent);

        template <typename TValue>
        void addElement(const std::wstring &p_text, TValue &&p_value)
        {
            _addEntry(p_text, std::any(std::forward<TValue>(p_value)));
        }

        const std::wstring &currentText() const;

        template <typename TValue>
        TValue currentValue() const
        {
            if (_currentIndex.has_value() == false)
            {
                throw std::runtime_error("ComboBox has no current value.");
            }
 
            return std::any_cast<TValue>(_entries[_currentIndex.value()].value);
        }

        void selectElement(const std::wstring &p_text);
        void selectElement(size_t p_index);
        void removeElement(const std::wstring &p_text);
        void removeElement(size_t p_index);
        void openPopup();

        Popup &popup();
        const Popup &popup() const;
    };
}