/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#pragma once

#include "Math/Math.hpp"
#include "Scene/FreetypeHelper.hpp"
#include <vector>
#include <optional>

namespace OpenVulkano::Scene
{
	struct GlyphForPacking
	{
		uint32_t code;
		Math::Vector2i size;
		Math::Vector2d atlasPos;
		size_t firstGlyphByteInAtlas;
	};

	struct Shelf
	{
		inline static std::vector<Shelf> CreateShelves(uint32_t atlasWidth, std::vector<GlyphForPacking>& glyphs,
		                                        const FtFaceRecPtr& face);

		Shelf(uint32_t width, uint32_t height) : m_width(width), m_height(height), m_remainingWidth(width) {}
		bool HasSpaceForGlyph(uint32_t glyphWidth, uint32_t glyphHeight) const
		{
			return m_remainingWidth >= glyphWidth && m_height >= glyphHeight;
		}
		uint32_t GetWidth() const { return m_width; }
		uint32_t GetHeight() const { return m_height; }
		uint32_t GetNextGlyphPos() const { return m_nextGlyphPos; };
		uint32_t GetOccupiedSize() const { return ((m_width - m_remainingWidth) * m_height); }
		std::optional<uint32_t> AddGlyph(uint32_t glyphWidth, uint32_t glyphHeight)
		{
			if (!HasSpaceForGlyph(glyphWidth, glyphHeight))
			{
				return {};
			}
			uint32_t insertionPos = m_nextGlyphPos;
			m_nextGlyphPos += glyphWidth;
			m_remainingWidth -= glyphWidth;
			return insertionPos;
		}

	private:
		uint32_t m_width;
		uint32_t m_height;
		uint32_t m_remainingWidth;
		uint32_t m_nextGlyphPos = 0;
	};

	std::vector<Shelf> Shelf::CreateShelves(uint32_t atlasWidth, std::vector<GlyphForPacking>& glyphs,
																					const FtFaceRecPtr& face)
	{
		std::vector<Shelf> shelves;
		for (GlyphForPacking& glyph : glyphs)
		{
			FT_Error error = FT_Load_Char(face.get(), glyph.code, FT_LOAD_RENDER);
			if (error)
			{
				continue;
			}

			FT_GlyphSlot slot = face->glyph;
			bool needNewShelf = true;
			uint32_t totalPrevShelvesHeight = 0;
			for (Shelf& shelf : shelves)
			{
				if (std::optional<uint32_t> insertionPosX = shelf.AddGlyph(glyph.size.x, glyph.size.y))
				{
					glyph.firstGlyphByteInAtlas = *insertionPosX + (totalPrevShelvesHeight * atlasWidth);
					glyph.atlasPos.x = *insertionPosX;
					glyph.atlasPos.y = totalPrevShelvesHeight;
					needNewShelf = false;
					break;
				}
				totalPrevShelvesHeight += shelf.GetHeight();
			}

			if (needNewShelf)
			{
				shelves.emplace_back(atlasWidth, glyph.size.y);
				shelves.back().AddGlyph(glyph.size.x, glyph.size.y);
				glyph.firstGlyphByteInAtlas = totalPrevShelvesHeight * atlasWidth;
				glyph.atlasPos.x = 0;
				glyph.atlasPos.y = totalPrevShelvesHeight;
			}
		}
		return shelves;
	}
}