/*
 * 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/.
 */

#include "BitmapFontAtlasGenerator.hpp"
#include "Base/Logger.hpp"

namespace OpenVulkano::Scene
{
	void BitmapFontAtlasGenerator::GenerateAtlas(const std::string& fontFile, const std::set<uint32_t>& charset,
	                                             const std::optional<std::string>& pngOutput)
	{
		Generate(fontFile, charset, pngOutput);
	}

	void BitmapFontAtlasGenerator::GenerateAtlas(const Array<char>& fontData, const std::set<uint32_t>& charset,
	                                             const std::optional<std::string>& pngOutput)
	{
		Generate(fontData, charset, pngOutput);
	}

	void BitmapFontAtlasGenerator::Generate(const std::variant<std::string, Array<char>>& source,
	                                        const std::set<uint32_t>& chset,
	                                        const std::optional<std::string>& pngOutput)
	{
		if (chset.empty())
		{
			Logger::APP->info("Charset is empty. Nothing to generate.");
			return;
		}

		m_atlasData = std::make_shared<AtlasData>();
		const auto& [lib, face] = FontAtlasGeneratorBase::InitFreetype(source);
		if (m_pixelSizeConfig.isPixelSize)
		{
			FT_Set_Pixel_Sizes(face.get(), 0, m_pixelSizeConfig.size);
		}
		else
		{
			const float pixelSize = (m_pixelSizeConfig.size * m_pixelSizeConfig.dpi) / 72.0f;
			FT_Set_Pixel_Sizes(face.get(), 0, pixelSize);
		}

		auto [allGlyphs, area] = InitGlyphsForPacking(chset, face);
		const double atlasWidth = ceil(sqrt(area));
		std::vector<Shelf> shelves = Shelf::CreateShelves(atlasWidth, allGlyphs, face);
		uint32_t atlasHeight = 0;
		std::for_each(shelves.begin(), shelves.end(), [&](const Shelf& shelf) { atlasHeight += shelf.GetHeight(); });
		const Math::Vector2ui atlasResolution = { atlasWidth, atlasHeight };

		// same as in msdfgen lib by default. see import-font.h for reference
		// TODO: probably also support keeping coordinates as the integer values native to the font file
		// but since some algorithms have already been implemented for EM_NORMALIZED mode, currently there is no support for default font metrics (ints)
		// The coordinates will be normalized to the em size, i.e. 1 = 1 em
		const double scaleFactor = (1. / face->units_per_EM);
		SetupAtlasData(atlasResolution, face->height * scaleFactor, FontAtlasType::BITMAP);

		size_t loadedGlyphs = 0;
		for (const GlyphForPacking& glyph : allGlyphs)
		{
			FT_Error error = FT_Load_Char(face.get(), glyph.code, FT_LOAD_RENDER);
			if (error)
			{
				Logger::SCENE->error("FT_Load_Char for codepoint {} has failed. {}", glyph.code,
				                     GetFreetypeErrorDescription(error));
				continue;
			}

			FT_GlyphSlot slot = face->glyph;
			for (int row = 0; row < slot->bitmap.rows; row++)
			{
				std::memcpy(&m_atlasData->img->data[glyph.firstGlyphByteInAtlas + row * atlasResolution.x],
				            &slot->bitmap.buffer[(slot->bitmap.rows - 1 - row) * slot->bitmap.pitch],
				            slot->bitmap.width);
			}

			GlyphInfo& glyphInfo = m_atlasData->glyphs[glyph.code];
			const Math::Vector2d glyphMetrics = { slot->metrics.width * scaleFactor,
				                                  slot->metrics.height * scaleFactor };
			const Math::Vector2d glyphBearing = { slot->metrics.horiBearingX * scaleFactor,
				                                  slot->metrics.horiBearingY * scaleFactor };
			Math::AABB glyphAtlasAABB(Math::Vector3f(glyph.atlasPos.x, glyph.atlasPos.y, 0), Math::Vector3f(glyph.atlasPos.x + slot->bitmap.width, glyph.atlasPos.y + slot->bitmap.rows, 0));
			SetGlyphData(glyphInfo, glyphBearing, glyphMetrics, glyphAtlasAABB, slot->advance.x * scaleFactor);
			loadedGlyphs++;
		}

		if (pngOutput)
		{
			SavePng(*pngOutput);
		}
		Logger::SCENE->debug("Created atlas with {} glyphs, {} glyphs could not be loaded", loadedGlyphs, chset.size() - loadedGlyphs);
	}

	std::pair<std::vector<GlyphForPacking>, double> 
		BitmapFontAtlasGenerator::InitGlyphsForPacking(const std::set<uint32_t>& chset, const FtFaceRecPtr& face)
	{
		FT_Error error = 0;
		double area = 0;
		std::vector<GlyphForPacking> allGlyphs;
		allGlyphs.reserve(chset.size());
		for (uint32_t codepoint : chset)
		{
			error = FT_Load_Char(face.get(), codepoint, FT_LOAD_RENDER);
			if (error)
			{
				Logger::SCENE->error("FT_Load_Char for codepoint {} has failed. {}", codepoint,
				                     GetFreetypeErrorDescription(error));
				continue;
			}
			FT_GlyphSlot slot = face->glyph;
			GlyphForPacking& glyph = allGlyphs.emplace_back(codepoint, Math::Vector2ui(slot->bitmap.width, slot->bitmap.rows));
			area += slot->bitmap.rows * slot->bitmap.width;
		}
		std::sort(allGlyphs.begin(), allGlyphs.end(),
		          [](const GlyphForPacking& a, const GlyphForPacking& b) { return a.size.y > b.size.y; });
		return { allGlyphs, area };
	}
}