/*
Crafter®.Graphics
Copyright (C) 2026 Catcrafts®
catcrafts.net

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License version 3.0 as published by the Free Software Foundation;

This library 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
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
*/
export module Crafter.Graphics:UIHit;
import std;
import :UILength;
import :UIWidget;

export namespace Crafter::UI {
    // Find the topmost widget whose computedRect contains (x, y).
    // Children are visited in reverse order so later children (drawn on
    // top) win ties. Returns nullptr if the point is outside `root`.
    inline Widget* HitTest(Widget& root, float x, float y) {
        if (!root.computedRect.Contains(x, y)) return nullptr;

        // Search children in reverse — the last-added child is on top in
        // our draw order, so it wins overlapping hits.
        for (auto it = root.children_.rbegin(); it != root.children_.rend(); ++it) {
            if (Widget* hit = HitTest(**it, x, y); hit) return hit;
        }
        return &root;
    }

    // Dispatch a click at (x, y) to the topmost widget under the cursor,
    // bubbling to ancestors until one returns true (handled). The default
    // Widget::OnMouseClick returns false, so leaf widgets that don't care
    // automatically defer to their parents.
    inline void DispatchClick(Widget& root, float x, float y) {
        Widget* target = HitTest(root, x, y);
        while (target) {
            if (target->OnMouseClick(x, y)) return;
            target = target->parent;
        }
    }
}