#pragma once
#include "creeper-qt/utility/trait/widget.hh"
#include "creeper-qt/utility/wrapper/common.hh"
#include "creeper-qt/utility/wrapper/property.hh"

namespace creeper::group::internal {

template <typename F, typename T>
concept foreach_invoke_item_trait = requires {
    { std::invoke(std::declval<F>(), std::declval<T const&>()) } -> widget_pointer_trait;
};

template <typename F, typename T>
concept foreach_apply_item_trait = requires {
    { std::apply(std::declval<F>(), std::declval<T const&>()) } -> widget_pointer_trait;
};

template <typename F, typename T>
concept foreach_item_trait = foreach_invoke_item_trait<F, T> || foreach_apply_item_trait<F, T>;

template <typename R, typename F>
concept foreach_invoke_ranges_trait = foreach_item_trait<F, std::ranges::range_value_t<R>>;

template <layout_trait T, widget_trait W>
struct Group : public T {
    using T::T;
    std::vector<W*> widgets;

    template <std::ranges::range R, typename F>
        requires foreach_invoke_ranges_trait<R, F>
    constexpr auto compose(const R& ranges, F&& f, Qt::Alignment a = {}) noexcept -> void {
        for (const auto& item : ranges) {
            using ItemT = decltype(item);

            auto widget_pointer = (W*) {};

            if constexpr (foreach_invoke_item_trait<F, ItemT>)
                widget_pointer = std::invoke(f, item);

            else if constexpr (foreach_apply_item_trait<F, ItemT>)
                widget_pointer = std::apply(f, item);

            if (widget_pointer != nullptr) {
                T::addWidget(widget_pointer, 0, a);
                widgets.push_back(widget_pointer);
            }
        }
    }
    auto foreach_(this auto&& self, auto&& f) noexcept
        requires std::invocable<decltype(f), W&>
    {
        for (auto widget : self.widgets)
            std::invoke(f, *widget);
    }
};

};

namespace creeper::group::pro {

using Token = common::Token<internal::Group<QLayout, QWidget>>;

/// @note
/// 一种典型的用法，委托构造时，所传函数只能接受常量引用，
/// 放心使用 auto，类型是可以被推导出来的
///
/// group::pro::Compose {
///     std::array {
///         std::tuple(1, "xxxxxx"),
///         ......
///     },
///     [](auto index, auto text) {
///         return new TextButton { ... };
///     },
/// }
///
template <typename R, typename F>
    requires internal::foreach_invoke_ranges_trait<R, F>
struct Compose : Token {
    const R& ranges;
    F method;
    Qt::Alignment alignment;

    explicit Compose(const R& r, F f, Qt::Alignment a = {}) noexcept
        : ranges { r }
        , method { std::move(f) }
        , alignment { a } { }

    auto apply(auto& self) noexcept -> void { //
        self.compose(ranges, std::move(method), alignment);
    }
};

/// @note
/// 函数参数是组件的引用:
///
/// group::pro::Foreach { [](Widget& button) { ... } },
///
template <typename F>
    requires(!std::invocable<F>)
struct Foreach : Token {
    F function;

    explicit Foreach(F&& f) noexcept
        : function { std::forward<F>(f) } { }

    auto apply(auto& self) const noexcept {
        // 很遗憾，Qt 占用了 foreach 这个单词
        self.foreach_(std::move(function));
    }
};

template <class T>
concept trait = std::derived_from<T, Token>;

CREEPER_DEFINE_CHECKER(trait)
};
namespace creeper {

template <layout_trait T, widget_trait W>
using Group =
    Declarative<group::internal::Group<T, W>, CheckerOr<group::pro::checker, typename T::Checker>>;

}