#include "UiWidget.hpp"

#include <algorithm>
#include <cmath>

#include "UiDebugBounds.hpp"

namespace jdi
{

	UiEventResult UiEventResult::Handled()
	{
		UiEventResult result;
		result.consumed = true;
		result.redraw = true;
		return result;
	}

	UiEventResult UiEventResult::Swallowed()
	{
		UiEventResult result;
		result.consumed = true;
		result.redraw = false;
		return result;
	}

	UiPaintContext UiPaintContext::WithClip(const gd::RectF& rect) const
	{
		UiPaintContext child = *this;
		gd::RectF intersection;
		if (UiRectIntersect(clip, rect, intersection))
		{
			child.clip = intersection;
		}
		else
		{
			child.clip = gd::RectF();
		}
		return child;
	}

	UiWidget::UiWidget() = default;

	UiWidget::~UiWidget()
	{
		// 子节点析构前先把"指向自己的根级状态"清掉：否则根的 m_capture / m_modal / m_hover
		// 会留下悬空指针（子节点被移除后又被派发事件 = 访问违例）。
		UiWidget* root = Root();
		if (root != nullptr && root != this)
		{
			if (root->m_capture == this)
			{
				root->m_capture = nullptr;
			}
			if (root->m_modal == this)
			{
				root->m_modal = nullptr;
			}
			if (root->m_hover == this)
			{
				root->m_hover = nullptr;
			}
		}
	}

	// ------------------------------------------------------------------
	// 树结构
	// ------------------------------------------------------------------

	UiWidget& UiWidget::AddChild(std::unique_ptr<UiWidget> child)
	{
		if (child == nullptr)
		{
			return *this;
		}
		UiWidget* raw = child.get();
		raw->m_parent = this;
		m_children.push_back(std::move(child));
		// 子节点的期望尺寸会影响自己 ⇒ 向上失效。
		InvalidateMeasure();
		return *this;
	}

	void UiWidget::RemoveChild(UiWidget* child)
	{
		if (child == nullptr)
		{
			return;
		}
		for (auto iterator = m_children.begin(); iterator != m_children.end(); ++iterator)
		{
			if (iterator->get() == child)
			{
				(*iterator)->m_parent = nullptr;
				m_children.erase(iterator);
				InvalidateMeasure();
				return;
			}
		}
	}

	UiWidget* UiWidget::Root()
	{
		UiWidget* node = this;
		while (node->m_parent != nullptr)
		{
			node = node->m_parent;
		}
		return node;
	}

	const UiWidget* UiWidget::Root() const
	{
		const UiWidget* node = this;
		while (node->m_parent != nullptr)
		{
			node = node->m_parent;
		}
		return node;
	}

	// ------------------------------------------------------------------
	// 布局
	// ------------------------------------------------------------------

	void UiWidget::InvalidateMeasure()
	{
		if (!m_measureValid)
		{
			// 已经失效 ⇒ 不必继续上溯（祖先此前也一定被失效过）。
			return;
		}
		m_measureValid = false;
		if (m_parent != nullptr)
		{
			m_parent->InvalidateMeasure();
		}
	}

	gd::SizeF UiWidget::Measure(const UiMeasureContext& ctx)
	{
		const gd::SizeF size = m_measureValid ? m_desiredSize : OnMeasure(ctx);
		m_desiredSize = size;
		m_measureValid = true;
		return m_desiredSize;
	}

	void UiWidget::Arrange(const gd::RectF& bounds)
	{
		m_bounds = bounds;
		OnArrange();
	}

	void UiWidget::MeasureChildren(const UiMeasureContext& ctx)
	{
		for (const std::unique_ptr<UiWidget>& child : m_children)
		{
			if (child == nullptr || !child->m_visible)
			{
				continue;
			}
			child->Measure(ctx);
		}
	}

	gd::SizeF UiWidget::ChildDesiredSize(std::size_t index) const
	{
		if (index >= m_children.size() || m_children[index] == nullptr)
		{
			return gd::SizeF(0.0f, 0.0f);
		}
		return m_children[index]->m_desiredSize;
	}

	// ------------------------------------------------------------------
	// 绘制
	// ------------------------------------------------------------------

	bool UiWidget::DirtyIntersects(const gd::RectF& dirty) const
	{
		gd::RectF intersection;
		return UiRectIntersect(dirty, m_bounds, intersection);
	}

	void UiWidget::Paint(UiPaintContext& ctx)
	{
		if (!m_visible || ctx.g == nullptr || !UiRectHasArea(m_bounds))
		{
			return;
		}

		// (1) 与脏区求交：**脏区为空表示"未知 ⇒ 全画"**。
		gd::RectF effectiveDirty = ctx.dirty;
		if (UiRectHasArea(effectiveDirty) && !DirtyIntersects(effectiveDirty))
		{
			// 本节点及其整棵子树都不在脏区内 ⇒ 直接跳过（这是本框架唯一真正省时间的机制）。
			return;
		}

		// (2) 裁剪 = 祖先裁剪切 ∩ （自身矩形外扩 1px）；脏区非空时再与脏区求交。
		//     ⚠️ 外扩 1px 是刻意设计的：边框/描边是**以矩形边界为中心**画的（`UiDrawRoundRect`
		//     的 1px 笔宽有一半在矩形外），严格按矩形裁剪会把外半侧切掉 ⇒ 控件看起来变细。
		//     这是与旧绘制代码保持“逐像素一致”的必要保证。
		UiPaintContext local = ctx;
		gd::RectF clip;
		if (!UiRectIntersect(ctx.clip, UiRectInflate(m_bounds, kUiClipBleed), clip))
		{
			return;		// 完全被祖先裁掉
		}
		if (UiRectHasArea(effectiveDirty))
		{
			gd::RectF clipWithDirty;
			if (!UiRectIntersect(clip, effectiveDirty, clipWithDirty))
			{
				return;
			}
			clip = clipWithDirty;
		}
		local.clip = clip;

		// (3) 收紧 GDI+ 裁剪。⚠️ 这里**只**约束 GDI+ 矢量绘制；GDI 绘制（`UiText` /
		//     `UiFillRect` 的快路径 / `UiDrawSolidLines`）**不受**该裁剪约束 ⇒ 派生类必须把
		//     `local.clip` 传给 `UiTextClipped` 一类带 `ETO_CLIPPED` 的辅助函数，
		//     否则文字会画到本节点之外（本项目"滚动时文字串到标题栏/工具栏"就是这类 BUG）。
		const int saveState = ctx.g->Save();
		ctx.g->SetClip(local.clip, gd::CombineModeIntersect);

		local.dirty = UiRectHasArea(effectiveDirty) ? clip : gd::RectF();
		OnPaint(local);

		// (4) 子节点：顺序 = z 序（末尾最上层），脏区向下取交集。
		for (const std::unique_ptr<UiWidget>& child : m_children)
		{
			if (child == nullptr)
			{
				continue;
			}
			UiPaintContext childContext = local;
			gd::RectF childClip;
			if (!UiRectIntersect(local.clip, UiRectInflate(child->m_bounds, kUiClipBleed), childClip))
			{
				continue;
			}
			childContext.clip = childClip;
			childContext.dirty = local.dirty;
			child->Paint(childContext);
		}

		ctx.g->Restore(saveState);
	}

	bool UiWidget::DispatchRedraw(UiEvent& event)
	{
		Dispatch(event);
		return UiRectHasArea(TakeDirty());
	}

	void UiWidget::CollectDebugBoxes(UiDebugBoxList& boxes, int depth) const
	{
		if (!m_visible || !UiRectHasArea(m_bounds))
		{
			// 不可见 / 未摆放的节点没有边界可画，其子树也不会被 `Paint` 画出来 ⇒ 一并跳过。
			return;
		}

		boxes.Add(m_bounds, depth);

		// 子节点按 z 序递归（末尾最上层）—— 与 `Paint` 的顺序一致，重叠时上层压住下层。
		for (const std::unique_ptr<UiWidget>& child : m_children)
		{
			if (child != nullptr)
			{
				child->CollectDebugBoxes(boxes, depth + 1);
			}
		}
	}

	void UiWidget::Invalidate(const gd::RectF& rect)
	{
		if (!UiRectHasArea(rect))
		{
			return;
		}
		m_dirty = UiRectUnion(m_dirty, rect);
		if (m_parent != nullptr)
		{
			// 向上冒泡的是"客户区坐标"的同一块矩形；父层只并集，**不清空**子节点的脏区。
			m_parent->Invalidate(rect);
		}
	}

	void UiWidget::InvalidateAll()
	{
		m_dirty = m_bounds;
		if (m_parent != nullptr)
		{
			m_parent->Invalidate(m_bounds);
		}
		for (const std::unique_ptr<UiWidget>& child : m_children)
		{
			if (child != nullptr)
			{
				child->InvalidateAll();
			}
		}
	}

	gd::RectF UiWidget::TakeDirty()
	{
		const gd::RectF dirty = m_dirty;
		m_dirty = gd::RectF();
		return dirty;
	}

	// ------------------------------------------------------------------
	// 事件
	// ------------------------------------------------------------------

	bool UiWidget::Contains(int x, int y) const
	{
		if (!m_visible || m_hitTransparent || !UiRectHasArea(m_bounds))
		{
			return false;
		}
		const float fx = static_cast<float>(x);
		const float fy = static_cast<float>(y);
		return fx >= m_bounds.X && fx < m_bounds.X + m_bounds.Width && fy >= m_bounds.Y &&
		       fy < m_bounds.Y + m_bounds.Height;
	}

	UiWidget* UiWidget::HitTestDeep(int x, int y)
	{
		if (!Contains(x, y))
		{
			return nullptr;
		}
		// 反 z 序：末尾（最上层）优先。
		for (auto iterator = m_children.rbegin(); iterator != m_children.rend(); ++iterator)
		{
			if (*iterator == nullptr)
			{
				continue;
			}
			if (UiWidget* hit = (*iterator)->HitTestDeep(x, y))
			{
				return hit;
			}
		}
		return this;
	}

	UiEventResult UiWidget::Dispatch(UiEvent& event)
	{
		UiWidget* root = Root();
		if (root == nullptr)
		{
			return UiEventResult();
		}

		const bool mouseEvent = (event.kind == UiEventKind::MOUSE_MOVE ||
		                         event.kind == UiEventKind::MOUSE_DOWN ||
		                         event.kind == UiEventKind::MOUSE_UP ||
		                         event.kind == UiEventKind::MOUSE_DOUBLE_CLICK ||
		                         event.kind == UiEventKind::MOUSE_WHEEL ||
		                         event.kind == UiEventKind::QUERY_CURSOR);

		// (1) 捕获优先：拖拽期间所有鼠标事件直接投给捕获者（与 Windows `SetCapture` 同义）。
		if (mouseEvent && root->m_capture != nullptr)
		{
			return root->m_capture->OnEvent(event);
		}

		// (2) 模态：只向模态子树派发（菜单/拾色器等浮层）。
		if (root->m_modal != nullptr)
		{
			return root->m_modal->DispatchAlongHitPath(event);
		}

		// (3) 悬停链（只在根节点维护：鼠标移动会改变悬停者）。
		if (event.kind == UiEventKind::MOUSE_MOVE || event.kind == UiEventKind::MOUSE_LEAVE)
		{
			root->UpdateHover(event.x, event.y);
		}

		// (4) 键盘/字符：沿焦点链派发（无焦点时交给根，保证宿主级快捷键仍可用）。
		if (event.kind == UiEventKind::KEY_DOWN || event.kind == UiEventKind::CHAR)
		{
			UiWidget* node = (root->m_focus != nullptr) ? root->m_focus : root;
			for (; node != nullptr; node = node->m_parent)
			{
				UiEventResult result = node->OnEvent(event);
				if (result.consumed)
				{
					return result;
				}
			}
			return UiEventResult();
		}

		return DispatchAlongHitPath(event);
	}

	void UiWidget::CollectHitChain(int x, int y, std::vector<UiWidget*>& chain)
	{
		if (!Contains(x, y))
		{
			return;
		}
		chain.push_back(this);
		// 反 z 序：末尾（最上层）优先；只进入**真正命中**的那一个子节点。
		for (auto iterator = m_children.rbegin(); iterator != m_children.rend(); ++iterator)
		{
			if (*iterator == nullptr)
			{
				continue;
			}
			if ((*iterator)->Contains(x, y))
			{
				(*iterator)->CollectHitChain(x, y, chain);
				return;
			}
		}
	}

	UiEventResult UiWidget::DispatchAlongHitPath(UiEvent& event)
	{
		if (!m_visible)
		{
			return UiEventResult();
		}

		const bool positional = (event.kind == UiEventKind::MOUSE_MOVE ||
		                         event.kind == UiEventKind::MOUSE_DOWN ||
		                         event.kind == UiEventKind::MOUSE_UP ||
		                         event.kind == UiEventKind::MOUSE_DOUBLE_CLICK ||
		                         event.kind == UiEventKind::MOUSE_WHEEL ||
		                         event.kind == UiEventKind::QUERY_CURSOR);

		if (!positional)
		{
			// 非位置事件（理论上已被 `Dispatch` 分流）：自身优先，再逐个子节点。
			UiEventResult result = OnEvent(event);
			if (result.consumed)
			{
				return result;
			}
			for (const std::unique_ptr<UiWidget>& child : m_children)
			{
				if (child == nullptr || !child->m_visible)
				{
					continue;
				}
				result = child->DispatchAlongHitPath(event);
				if (result.consumed)
				{
					return result;
				}
			}
			return UiEventResult();
		}

		std::vector<UiWidget*> chain;
		CollectHitChain(event.x, event.y, chain);
		if (chain.empty())
		{
			return UiEventResult();
		}

		// 自最深的命中节点向上冒泡：命中者优先，未消费才交给祖先（合法的"兜底"语义）。
		for (UiWidget* node : chain)
		{
			if (event.kind == UiEventKind::QUERY_CURSOR)
			{
				if (HCURSOR cursor = node->OnQueryCursor(event.x, event.y))
				{
					event.cursor = cursor;
					return UiEventResult::Swallowed();
				}
				continue;
			}
			UiEventResult result = node->OnEvent(event);
			if (result.consumed)
			{
				return result;
			}
		}
		if (event.kind == UiEventKind::QUERY_CURSOR && event.cursor != nullptr)
		{
			return UiEventResult::Swallowed();
		}
		return UiEventResult();
	}

	void UiWidget::UpdateHover(int x, int y)
	{
		UiWidget* target = (m_visible) ? HitTestDeep(x, y) : nullptr;
		if (target == m_hover)
		{
			return;
		}
		UiWidget* previous = m_hover;
		m_hover = target;
		if (previous != nullptr)
		{
			previous->m_hovered = false;
			previous->OnHoverChanged(false);
			previous->Invalidate(previous->m_bounds);
		}
		if (target != nullptr)
		{
			target->m_hovered = true;
			target->m_hoverX = x;
			target->m_hoverY = y;
			target->OnHoverChanged(true);
			target->Invalidate(target->m_bounds);
		}
	}

	// ------------------------------------------------------------------
	// 交互仲裁
	// ------------------------------------------------------------------

	void UiWidget::CaptureMouse()
	{
		UiWidget* root = Root();
		if (root != nullptr)
		{
			root->m_capture = this;
		}
	}

	void UiWidget::ReleaseMouse()
	{
		UiWidget* root = Root();
		if (root != nullptr && root->m_capture == this)
		{
			root->m_capture = nullptr;
		}
	}

	UiWidget* UiWidget::MouseCaptureWidget() const
	{
		const UiWidget* root = Root();
		return (root != nullptr) ? root->m_capture : nullptr;
	}

	void UiWidget::SetModal(bool modal)
	{
		UiWidget* root = Root();
		if (root == nullptr)
		{
			return;
		}
		if (modal)
		{
			root->m_modal = this;
		}
		else if (root->m_modal == this)
		{
			root->m_modal = nullptr;
		}
	}

	UiWidget* UiWidget::ModalWidget() const
	{
		const UiWidget* root = Root();
		return (root != nullptr) ? root->m_modal : nullptr;
	}

	UiWidget* UiWidget::HoverWidget() const
	{
		const UiWidget* root = Root();
		return (root != nullptr) ? root->m_hover : nullptr;
	}

	bool UiWidget::HoverPoint(int& x, int& y) const
	{
		if (!m_hovered)
		{
			return false;
		}
		x = m_hoverX;
		y = m_hoverY;
		return true;
	}

	void UiWidget::RequestFocus()
	{
		UiWidget* root = Root();
		if (root == nullptr || root->m_focus == this)
		{
			return;
		}
		if (root->m_focus != nullptr)
		{
			root->m_focus->Invalidate(root->m_focus->m_bounds);
		}
		root->m_focus = this;
		Invalidate(m_bounds);
	}

	void UiWidget::ReleaseFocus()
	{
		UiWidget* root = Root();
		if (root != nullptr && root->m_focus == this)
		{
			root->m_focus = nullptr;
			Invalidate(m_bounds);
		}
	}

	UiWidget* UiWidget::FocusWidget() const
	{
		const UiWidget* root = Root();
		return (root != nullptr) ? root->m_focus : nullptr;
	}

	// ------------------------------------------------------------------
	// 动画
	// ------------------------------------------------------------------

	bool UiWidget::AdvanceAnimation(std::int64_t nowMs)
	{
		bool active = AdvanceAnimationSelf(nowMs);
		for (const std::unique_ptr<UiWidget>& child : m_children)
		{
			if (child != nullptr && child->AdvanceAnimation(nowMs))
			{
				active = true;
			}
		}
		return active;
	}

	bool UiWidget::AnimationActive() const
	{
		if (AnimationActiveSelf())
		{
			return true;
		}
		for (const std::unique_ptr<UiWidget>& child : m_children)
		{
			if (child != nullptr && child->AnimationActive())
			{
				return true;
			}
		}
		return false;
	}

	// ------------------------------------------------------------------
	// 缓存键
	// ------------------------------------------------------------------

	std::uint64_t UiWidget::BaseContentKey() const
	{
		std::uint64_t key = 0xCBF29CE484222325ull;
		key = UiMixKeyFloat(key, m_bounds.X);
		key = UiMixKeyFloat(key, m_bounds.Y);
		key = UiMixKeyFloat(key, m_bounds.Width);
		key = UiMixKeyFloat(key, m_bounds.Height);
		key = UiMixKey(key, m_visible ? 1u : 0u);
		return key;
	}

} // namespace jdi