/*
 * This source file is part of RmlUi, the HTML/CSS Interface Middleware
 *
 * For the latest information, see http://github.com/mikke89/RmlUi
 *
 * Copyright (c) 2008-2010 CodePoint Ltd, Shift Technology Ltd
 * Copyright (c) 2019 The RmlUi Team, and contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

#include "precompiled.h"
#include "../../Include/RmlUi/Core.h"
#include "../../Include/RmlUi/Core/TransformState.h"
#include "../../Include/RmlUi/Core/ElementUtilities.h"
#include <queue>
#include <limits>
#include "LayoutEngine.h"
#include "ElementStyle.h"

namespace Rml {
namespace Core {

// Builds and sets the box for an element.
static void SetBox(Element* element)
{
	Element* parent = element->GetParentNode();
	RMLUI_ASSERT(parent != nullptr);

	Vector2f containing_block = parent->GetBox().GetSize();
	containing_block.x -= parent->GetElementScroll()->GetScrollbarSize(ElementScroll::VERTICAL);
	containing_block.y -= parent->GetElementScroll()->GetScrollbarSize(ElementScroll::HORIZONTAL);

	Box box;
	LayoutEngine::BuildBox(box, containing_block, element);

	if (element->GetComputedValues().height.type != Style::Height::Auto)
		box.SetContent(Vector2f(box.GetSize().x, containing_block.y));

	element->SetBox(box);
}

// Positions an element relative to an offset parent.
static void SetElementOffset(Element* element, const Vector2f& offset)
{
	Vector2f relative_offset = element->GetParentNode()->GetBox().GetPosition(Box::CONTENT);
	relative_offset += offset;
	relative_offset.x += element->GetBox().GetEdge(Box::MARGIN, Box::LEFT);
	relative_offset.y += element->GetBox().GetEdge(Box::MARGIN, Box::TOP);

	element->SetOffset(relative_offset, element->GetParentNode());
}

Element* ElementUtilities::GetElementById(Element* root_element, const String& id)
{
	// Breadth first search on elements for the corresponding id
	typedef std::queue<Element*> SearchQueue;
	SearchQueue search_queue;
	search_queue.push(root_element);

	while (!search_queue.empty())
	{
		Element* element = search_queue.front();
		search_queue.pop();
		
		if (element->GetId() == id)
		{
			return element;
		}
		
		// Add all children to search
		for (int i = 0; i < element->GetNumChildren(); i++)
			search_queue.push(element->GetChild(i));
	}

	return nullptr;
}

void ElementUtilities::GetElementsByTagName(ElementList& elements, Element* root_element, const String& tag)
{
	// Breadth first search on elements for the corresponding id
	typedef std::queue< Element* > SearchQueue;
	SearchQueue search_queue;
	for (int i = 0; i < root_element->GetNumChildren(); ++i)
		search_queue.push(root_element->GetChild(i));

	while (!search_queue.empty())
	{
		Element* element = search_queue.front();
		search_queue.pop();

		if (element->GetTagName() == tag)
			elements.push_back(element);

		// Add all children to search.
		for (int i = 0; i < element->GetNumChildren(); i++)
			search_queue.push(element->GetChild(i));
	}
}

void ElementUtilities::GetElementsByClassName(ElementList& elements, Element* root_element, const String& class_name)
{
	// Breadth first search on elements for the corresponding id
	typedef std::queue< Element* > SearchQueue;
	SearchQueue search_queue;
	for (int i = 0; i < root_element->GetNumChildren(); ++i)
		search_queue.push(root_element->GetChild(i));

	while (!search_queue.empty())
	{
		Element* element = search_queue.front();
		search_queue.pop();

		if (element->IsClassSet(class_name))
			elements.push_back(element);

		// Add all children to search.
		for (int i = 0; i < element->GetNumChildren(); i++)
			search_queue.push(element->GetChild(i));
	}
}

float ElementUtilities::GetDensityIndependentPixelRatio(Element * element)
{
	Context* context = element->GetContext();
	if (context == nullptr)
		return 1.0f;

	return context->GetDensityIndependentPixelRatio();
}

// Returns the width of a string rendered within the context of the given element.
int ElementUtilities::GetStringWidth(Element* element, const String& string)
{
	FontFaceHandle font_face_handle = element->GetFontFaceHandle();
	if (font_face_handle == 0)
		return 0;

	return GetFontEngineInterface()->GetStringWidth(font_face_handle, string);
}

void ElementUtilities::BindEventAttributes(Element* element)
{
	// Check for and instance the on* events
	for (const auto& pair: element->GetAttributes())
	{
		if (pair.first.size() > 2 && pair.first[0] == 'o' && pair.first[1] == 'n')
		{
			EventListener* listener = Factory::InstanceEventListener(pair.second.Get<String>(), element);
			if (listener)
				element->AddEventListener(pair.first.substr(2), listener, false);
		}
	}
}
	
// Generates the clipping region for an element.
bool ElementUtilities::GetClippingRegion(Vector2i& clip_origin, Vector2i& clip_dimensions, Element* element)
{
	clip_origin = Vector2i(-1, -1);
	clip_dimensions = Vector2i(-1, -1);
	
	int num_ignored_clips = element->GetClippingIgnoreDepth();
	if (num_ignored_clips < 0)
		return false;

	// Search through the element's ancestors, finding all elements that clip their overflow and have overflow to clip.
	// For each that we find, we combine their clipping region with the existing clipping region, and so build up a
	// complete clipping region for the element.
	Element* clipping_element = element->GetParentNode();

	while (clipping_element != nullptr)
	{
		// Merge the existing clip region with the current clip region if we aren't ignoring clip regions.
		if (num_ignored_clips == 0 && clipping_element->IsClippingEnabled())
		{
			// Ignore nodes that don't clip.
			if (clipping_element->GetClientWidth() < clipping_element->GetScrollWidth()
				|| clipping_element->GetClientHeight() < clipping_element->GetScrollHeight())
			{				
				Vector2f element_origin_f = clipping_element->GetAbsoluteOffset(Box::CONTENT);
				Vector2f element_dimensions_f = clipping_element->GetBox().GetSize(Box::CONTENT);
				
				Vector2i element_origin(Math::RealToInteger(element_origin_f.x), Math::RealToInteger(element_origin_f.y));
				Vector2i element_dimensions(Math::RealToInteger(element_dimensions_f.x), Math::RealToInteger(element_dimensions_f.y));
				
				if (clip_origin == Vector2i(-1, -1) && clip_dimensions == Vector2i(-1, -1))
				{
					clip_origin = element_origin;
					clip_dimensions = element_dimensions;
				}
				else
				{
					Vector2i top_left(Math::Max(clip_origin.x, element_origin.x),
									  Math::Max(clip_origin.y, element_origin.y));
					
					Vector2i bottom_right(Math::Min(clip_origin.x + clip_dimensions.x, element_origin.x + element_dimensions.x),
										  Math::Min(clip_origin.y + clip_dimensions.y, element_origin.y + element_dimensions.y));
					
					clip_origin = top_left;
					clip_dimensions.x = Math::Max(0, bottom_right.x - top_left.x);
					clip_dimensions.y = Math::Max(0, bottom_right.y - top_left.y);
				}
			}
		}

		// If this region is meant to clip and we're skipping regions, update the counter.
		if (num_ignored_clips > 0)
		{
			if (clipping_element->IsClippingEnabled())
				num_ignored_clips--;
		}

		// Determine how many clip regions this ancestor ignores, and inherit the value. If this region ignores all
		// clipping regions, then we do too.
		int clipping_element_ignore_clips = clipping_element->GetClippingIgnoreDepth();
		if (clipping_element_ignore_clips < 0)
			break;
		
		num_ignored_clips = Math::Max(num_ignored_clips, clipping_element_ignore_clips);

		// Climb the tree to this region's parent.
		clipping_element = clipping_element->GetParentNode();
	}
	
	return clip_dimensions.x >= 0 && clip_dimensions.y >= 0;
}

// Sets the clipping region from an element and its ancestors.
bool ElementUtilities::SetClippingRegion(Element* element, Context* context)
{	
	Rml::Core::RenderInterface* render_interface = nullptr;
	if (element)
	{
		render_interface = element->GetRenderInterface();
		if (!context)
			context = element->GetContext();
	}
	else if (context)
	{
		render_interface = context->GetRenderInterface();
		if (!render_interface)
			render_interface = GetRenderInterface();
	}

	if (!render_interface || !context)
		return false;
	
	Vector2i clip_origin = { -1, -1 };
	Vector2i clip_dimensions = { -1, -1 };
	bool clip = element && GetClippingRegion(clip_origin, clip_dimensions, element);
	
	Vector2i current_origin = { -1, -1 };
	Vector2i current_dimensions = { -1, -1 };
	bool current_clip = context->GetActiveClipRegion(current_origin, current_dimensions);
	if (current_clip != clip || (clip && (clip_origin != current_origin || clip_dimensions != current_dimensions)))
	{
		context->SetActiveClipRegion(clip_origin, clip_dimensions);
		ApplyActiveClipRegion(context, render_interface);
	}

	return true;
}

void ElementUtilities::ApplyActiveClipRegion(Context* context, RenderInterface* render_interface)
{
	if (render_interface == nullptr)
		return;
	
	Vector2i origin;
	Vector2i dimensions;
	bool clip_enabled = context->GetActiveClipRegion(origin, dimensions);

	render_interface->EnableScissorRegion(clip_enabled);
	if (clip_enabled)
	{
		render_interface->SetScissorRegion(origin.x, origin.y, dimensions.x, dimensions.y);
	}
}

// Formats the contents of an element.
bool ElementUtilities::FormatElement(Element* element, const Vector2f& containing_block)
{
	LayoutEngine layout_engine;
	return layout_engine.FormatElement(element, containing_block);
}

// Generates the box for an element.
void ElementUtilities::BuildBox(Box& box, const Vector2f& containing_block, Element* element, bool inline_element)
{
	LayoutEngine::BuildBox(box, containing_block, element, inline_element);
}

// Sizes an element, and positions it within its parent offset from the borders of its content area.
bool ElementUtilities::PositionElement(Element* element, const Vector2f& offset, PositionAnchor anchor)
{
	Element* parent = element->GetParentNode();
	if (parent == nullptr)
		return false;

	SetBox(element);

	Vector2f containing_block = element->GetParentNode()->GetBox().GetSize(Box::CONTENT);
	Vector2f element_block = element->GetBox().GetSize(Box::MARGIN);

	Vector2f resolved_offset = offset;

	if (anchor & RIGHT)
		resolved_offset.x = containing_block.x - (element_block.x + offset.x);

	if (anchor & BOTTOM)
		resolved_offset.y = containing_block.y - (element_block.y + offset.y);

	SetElementOffset(element, resolved_offset);

	return true;
}

bool ElementUtilities::ApplyTransform(Element &element)
{
	RenderInterface *render_interface = element.GetRenderInterface();
	if (!render_interface)
		return false;

	static SmallUnorderedMap<RenderInterface*, const Matrix4f*> previous_matrix;

	const Matrix4f*& old_transform = previous_matrix.emplace(render_interface, nullptr).first->second;
	const Matrix4f* new_transform = nullptr;

	if (auto state = element.GetTransformState())
		new_transform = state->GetTransform();

	// Only changed transforms are submitted.
	if (old_transform != new_transform)
	{
		render_interface->SetTransform(new_transform);
		old_transform = new_transform;
	}

	return true;
}

}
}