/*
 * Copyright (C) 2017  Christopher J. Howard
 *
 * This file is part of Antkeeper Source Code.
 *
 * Antkeeper Source Code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Antkeeper Source Code 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Antkeeper Source Code.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "ui.hpp"
#include "../application.hpp"

// UI callbacks
void menuPrint(Application* application, const std::string& string)
{
	std::cout << string << std::endl;
}

UIElement::UIElement():
	parent(nullptr),
	anchor(Anchor::TOP_LEFT),
	layerOffset(0),
	layer(0),
	origin(0.0f),
	translation(0.0f),
	rotation(0.0f),
	dimensions(0.0f),
	position(0.0f),
	bounds(position, position),
	tintColor(1.0f),
	color(tintColor),
	visible(true),
	active(true),
	mouseOver(false),
	mouseOverCallback(nullptr),
	mouseOutCallback(nullptr),
	mouseMovedCallback(nullptr),
	mousePressedCallback(nullptr),
	mouseReleasedCallback(nullptr)
{}

UIElement::~UIElement()
{}

void UIElement::update()
{	
	// Calculate position
	if (parent != nullptr)
	{
		// Calculate world-space position
		Vector2 anchorPoint = parent->position + parent->dimensions * anchor - dimensions * anchor;
		position = anchorPoint + origin + translation;
		
		// Calculate layer
		layer = parent->layer + 1 + layerOffset;
		
		// Calculate color
		color = parent->color * tintColor;
	}
	else
	{
		position = origin + translation;
		layer = layerOffset;
		color = tintColor;
	}
	
	// Calculate bounds
	bounds.setMin(position);
	bounds.setMax(position + dimensions);
	
	// Update children
	for (UIElement* child: children)
	{
		child->update();
	}
}

void UIElement::addChild(UIElement* element)
{
	children.push_back(element);
	element->parent = this;
}

void UIElement::removeChild(UIElement* element)
{
	for (auto it = children.begin(); it != children.end(); ++it)
	{
		if (*it == element)
		{
			children.erase(it);
			return;
		}
	}
}

void UIElement::setMouseOverCallback(std::function<void()> callback)
{
	mouseOverCallback = callback;
}

void UIElement::setMouseOutCallback(std::function<void()> callback)
{
	mouseOutCallback = callback;
}

void UIElement::setMouseMovedCallback(std::function<void(int, int)> callback)
{
	mouseMovedCallback = callback;
}

void UIElement::setMousePressedCallback(std::function<void(int, int, int)> callback)
{
	mousePressedCallback = callback;
}

void UIElement::setMouseReleasedCallback(std::function<void(int, int, int)> callback)
{
	mouseReleasedCallback = callback;
}

void UIElement::mouseMoved(int x, int y)
{
	if (!active)
	{
		return;
	}
	
	if (bounds.contains(Vector2(x, y)))
	{
		if (!mouseOver)
		{
			mouseOver = true;
			if (mouseOverCallback)
			{
				mouseOverCallback();
			}
		}
		
		if (mouseMovedCallback)
		{
			mouseMovedCallback(x, y);
		}
	}
	else if (mouseOver)
	{
		mouseOver = false;
		if (mouseOutCallback)
		{
			mouseOutCallback();
		}
	}
	
	for (UIElement* child: children)
	{
		child->mouseMoved(x, y);
	}
}

void UIElement::mouseButtonPressed(int button, int x, int y)
{
	if (!active)
	{
		return;
	}
	
	if (bounds.contains(Vector2(x, y)))
	{
		if (mousePressedCallback)
		{
			mousePressedCallback(button, x, y);
		}
		
		for (UIElement* child: children)
		{
			child->mouseButtonPressed(button, x, y);
		}
	}
}

void UIElement::mouseButtonReleased(int button, int x, int y)
{
	if (!active)
	{
		return;
	}
	
	if (bounds.contains(Vector2(x, y)))
	{
		if (mouseReleasedCallback)
		{
			mouseReleasedCallback(button, x , y);
		}
		
		for (UIElement* child: children)
		{
			child->mouseButtonReleased(button, x, y);
		}
	}
}

UILabel::UILabel():
	font(nullptr)
{}

UILabel::~UILabel()
{}

void UILabel::setFont(Font* font)
{
	this->font = font;
	material.texture = font->getTexture();
	calculateDimensions();
}

void UILabel::setText(const std::string& text)
{
	this->text = text;
	calculateDimensions();
}

void UILabel::calculateDimensions()
{
	if (font != nullptr && !text.empty())
	{
		float width = font->getWidth(text.c_str());
		float height = font->getMetrics().getHeight();
		setDimensions(Vector2(width, height));
	}
	else
	{
		setDimensions(Vector2(0.0f));
	}
}

UIImage::UIImage():
	textureBounds(Vector2(0.0f), Vector2(1.0f))
{}

UIImage::~UIImage()
{}

void UIBatcher::batch(BillboardBatch* result, const UIElement* ui)
{
	// Create list of visible UI elements
	std::list<const UIElement*> elements;
	queueElements(&elements, ui);
	
	// Sort UI elements according to layer and texture
	elements.sort([](const UIElement* a, const UIElement* b)
	{
		if (a->getLayer() < b->getLayer())
		{
			return true;
		}
		else if (b->getLayer() < a->getLayer())
		{
			return false;
		}
		
		return (a->getMaterial()->texture < b->getMaterial()->texture);
	});
	
	// Clear previous ranges
	
	result->removeRanges();
	
	// Batch UI elements
	for (const UIElement* element: elements)
	{
		batchElement(result, element);
	}
	
	// Update batch
	result->update();
}

void UIBatcher::queueElements(std::list<const UIElement*>* elements, const UIElement* element) const
{
	if (element->isVisible())
	{
		elements->push_back(element);
		
		for (std::size_t i = 0; i < element->getChildCount(); ++i)
		{
			queueElements(elements, element->getChild(i));
		}
	}
}

BillboardBatch::Range* UIBatcher::getRange(BillboardBatch* result, const UIElement* element) const
{
	BillboardBatch::Range* range = nullptr;
	
	if (!result->getRangeCount())
	{
		// Create initial range
		range = result->addRange();
		range->material = (Material*)element->getMaterial();
		range->start = 0;
		range->length = 0;
	}
	else
	{
		range = result->getRange(result->getRangeCount() - 1);
		
		const UIMaterial* material = static_cast<UIMaterial*>(range->material);
		
		if (material->texture != element->getMaterial()->texture)
		{
			// Create new range for the element
			range = result->addRange();
			BillboardBatch::Range* precedingRange = result->getRange(result->getRangeCount() - 2);
			range->material = (Material*)element->getMaterial();
			range->start = precedingRange->start + precedingRange->length;
			range->length = 0;
		}
	}
	
	return range;
}

void UIBatcher::batchElement(BillboardBatch* result, const UIElement* element)
{	
	switch (element->getElementType())
	{
		case UIElement::Type::LABEL:
			batchLabel(result, static_cast<const UILabel*>(element));
			break;
		
		case UIElement::Type::IMAGE:
			batchImage(result, static_cast<const UIImage*>(element));
			break;
		
		case UIElement::Type::CONTAINER:
			break;
		
		default:
			break;
	}
}

void UIBatcher::batchLabel(BillboardBatch* result, const UILabel* label)
{
	if (label->getFont() != nullptr && !label->getText().empty())
	{
		// Get range
		BillboardBatch::Range* range = getRange(result, label);
		
		// Pixel-perfect
		Vector3 origin = Vector3((int)label->getPosition().x, (int)label->getPosition().y, label->getLayer() * 0.01f);
		
		// Print billboards
		const Font* font = label->getFont();
		std::size_t index = range->start + range->length;
		std::size_t count = 0;
		font->puts(result, origin, label->getText().c_str(), label->getColor(), index, &count);
		
		// Increment range length
		range->length += count;
	}
}

void UIBatcher::batchImage(BillboardBatch* result, const UIImage* image)
{
	// Get range
	BillboardBatch::Range* range = getRange(result, image);
	
	// Pixel-perfect
	//Vector3 translation = Vector3((int)(image->getPosition().x + image->getDimensions().x * 0.5f), (int)(image->getPosition().y + image->getDimensions().y * 0.5f), image->getLayer() * 0.01f);
	
	Vector3 translation = Vector3(image->getPosition() + image->getDimensions() * 0.5f, image->getLayer() * 0.01f);
	
	// Create billboard
	std::size_t index = range->start + range->length;
	Billboard* billboard = result->getBillboard(index);
	billboard->setDimensions(image->getDimensions());
	billboard->setTranslation(translation);
	
	if (image->getRotation() != 0.0f)
	{
		billboard->setRotation(glm::angleAxis(image->getRotation(), Vector3(0, 0, -1.0f)));
	}
	
	billboard->setTextureCoordinates(image->getTextureBounds().getMin(), image->getTextureBounds().getMax());
	billboard->setTintColor(image->getColor());
	
	// Increment range length
	++(range->length);
}

MenuItem::MenuItem(Menu* parent, std::size_t index):
	parent(parent),
	index(index),
	selected(false),
	selectedCallback(nullptr),
	deselectedCallback(nullptr),
	activatedCallback(nullptr)
{}

void MenuItem::select()
{
	if (!selected)
	{
		selected = true;
		
		if (selectedCallback != nullptr)
		{
			selectedCallback();
		}
	}
}

void MenuItem::deselect()
{
	if (selected)
	{
		selected = false;
		
		if (deselectedCallback != nullptr)
		{
			deselectedCallback();
		}
	}
}

void MenuItem::activate()
{
	if (activatedCallback != nullptr)
	{
		activatedCallback();
	}
}

void MenuItem::setSelectedCallback(std::function<void()> callback)
{
	this->selectedCallback = callback = callback;
}

void MenuItem::setDeselectedCallback(std::function<void()> callback)
{
	this->deselectedCallback = callback;
}

void MenuItem::setActivatedCallback(std::function<void()> callback)
{
	this->activatedCallback = callback;
}

Menu::Menu():
	enteredCallback(nullptr),
	exitedCallback(nullptr)
{}

Menu::~Menu()
{
	for (MenuItem* item: items)
	{
		delete item;
	}
}

void Menu::enter()
{
	if (enteredCallback != nullptr)
	{
		enteredCallback();
	}
}

void Menu::exit()
{
	if (exitedCallback != nullptr)
	{
		exitedCallback();
	}
}

MenuItem* Menu::addItem()
{
	MenuItem* item = new MenuItem(this, items.size());
	items.push_back(item);
	return item;
}

void Menu::removeItems()
{
	for (MenuItem* item: items)
	{
		delete item;
	}
	items.clear();
}

void Menu::setEnteredCallback(std::function<void()> callback)
{
	this->enteredCallback = callback;
}

void Menu::setExitedCallback(std::function<void()> callback)
{
	this->exitedCallback = callback;
}