// basisu_gpu_texture.h
// Copyright (C) 2019 Binomial LLC. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#pragma once
#include "transcoder/basisu.h"
#include "basisu_etc.h"

namespace basisu
{
	// GPU texture image

	class gpu_image
	{
	public:
		enum { cMaxBlockSize = 12 };

		gpu_image()
		{
			clear();
		}

		gpu_image(texture_format fmt, uint32_t width, uint32_t height)
		{
			init(fmt, width, height);
		}

		void clear()
		{
			m_fmt = cInvalidTextureFormat;
			m_width = 0;
			m_height = 0;
			m_block_width = 0;
			m_block_height = 0;
			m_blocks_x = 0;
			m_blocks_y = 0;
			m_qwords_per_block = 0;
			m_blocks.clear();
		}

		inline texture_format get_format() const { return m_fmt; }
		
		// Width/height in pixels
		inline uint32_t get_pixel_width() const { return m_width; }
		inline uint32_t get_pixel_height() const { return m_height; }
		
		// Width/height in blocks, row pitch is assumed to be m_blocks_x.
		inline uint32_t get_blocks_x() const { return m_blocks_x; }
		inline uint32_t get_blocks_y() const { return m_blocks_y; }

		// Size of each block in pixels
		inline uint32_t get_block_width() const { return m_block_width; }
		inline uint32_t get_block_height() const { return m_block_height; }

		inline uint32_t get_qwords_per_block() const { return m_qwords_per_block; }
		inline uint32_t get_total_blocks() const { return m_blocks_x * m_blocks_y; }
		inline uint32_t get_bytes_per_block() const { return get_qwords_per_block() * sizeof(uint64_t); }
		inline uint32_t get_row_pitch_in_bytes() const { return get_bytes_per_block() * get_blocks_x(); }

		inline const uint64_vec &get_blocks() const { return m_blocks; }
		
		inline const uint64_t *get_ptr() const { return &m_blocks[0]; }
		inline uint64_t *get_ptr() { return &m_blocks[0]; }

		inline uint32_t get_size_in_bytes() const { return get_total_blocks() * get_qwords_per_block() * sizeof(uint64_t); }

		inline const void *get_block_ptr(uint32_t block_x, uint32_t block_y, uint32_t element_index = 0) const
		{
			assert(block_x < m_blocks_x && block_y < m_blocks_y);
			return &m_blocks[(block_x + block_y * m_blocks_x) * m_qwords_per_block + element_index];
		}

		inline void *get_block_ptr(uint32_t block_x, uint32_t block_y, uint32_t element_index = 0)
		{
			assert(block_x < m_blocks_x && block_y < m_blocks_y && element_index < m_qwords_per_block);
			return &m_blocks[(block_x + block_y * m_blocks_x) * m_qwords_per_block + element_index];
		}

		void init(texture_format fmt, uint32_t width, uint32_t height)
		{
			m_fmt = fmt;
			m_width = width;
			m_height = height;
			m_block_width = basisu::get_block_width(m_fmt);
			m_block_height = basisu::get_block_height(m_fmt);
			m_blocks_x = (m_width + m_block_width - 1) / m_block_width;
			m_blocks_y = (m_height + m_block_height - 1) / m_block_height;
			m_qwords_per_block = basisu::get_qwords_per_block(m_fmt);

			m_blocks.resize(0);
			m_blocks.resize(m_blocks_x * m_blocks_y * m_qwords_per_block);
		}

		bool unpack(image& img, bool pvrtc_wrap_addressing = true) const;
		
		void override_dimensions(uint32_t w, uint32_t h)
		{
			m_width = w;
			m_height = h;
		}

	private:
		texture_format m_fmt;
		uint32_t m_width, m_height, m_blocks_x, m_blocks_y, m_block_width, m_block_height, m_qwords_per_block;
		uint64_vec m_blocks;
	};

	typedef std::vector<gpu_image> gpu_image_vec;

	// KTX file writing

	bool create_ktx_texture_file(uint8_vec &ktx_data, const std::vector<gpu_image_vec>& gpu_images, bool cubemap_flag);
		
	bool write_compressed_texture_file(const char *pFilename, const std::vector<gpu_image_vec>& g, bool cubemap_flag);
	
	inline bool write_compressed_texture_file(const char *pFilename, const gpu_image_vec &g)
	{
		std::vector<gpu_image_vec> a;
		a.push_back(g);
		return write_compressed_texture_file(pFilename, a, false);
	}

	bool write_compressed_texture_file(const char *pFilename, const gpu_image &g);
	
	// GPU texture block unpacking

	void unpack_etc2_eac(const void *pBlock_bits, color_rgba *pPixels);
	bool unpack_bc1(const void *pBlock_bits, color_rgba *pPixels, bool set_alpha);
	void unpack_bc4(const void *pBlock_bits, uint8_t *pPixels, uint32_t stride);
	bool unpack_bc3(const void *pBlock_bits, color_rgba *pPixels);
	void unpack_bc5(const void *pBlock_bits, color_rgba *pPixels);
	bool unpack_bc7_mode6(const void *pBlock_bits, color_rgba *pPixels);
	bool unpack_bc7_mode5(const void* pBlock_bits, color_rgba* pPixels);
	void unpack_atc(const void* pBlock_bits, color_rgba* pPixels);

	// unpack_block() is only capable of unpacking texture data created by the transcoder. 
	// For some texture formats (like BC7, or ETC2) it's not a complete implementation.
	bool unpack_block(texture_format fmt, const void *pBlock, color_rgba *pPixels);
			
} // namespace basisu