#include "png.hpp"

#include "../graphics/core/ImageData.hpp"
#include "../graphics/core/Texture.hpp"
#include "../files/files.hpp"
#include "../debug/Logger.hpp"

#include <iostream>
#include <GL/glew.h>

static debug::Logger logger("png-coder");

#ifndef _WIN32
#define LIBPNG
#endif

#ifdef LIBPNG
#include <png.h>

// returns 0 if all-right, 1 otherwise
int _png_write(const char* filename, uint width, uint height, const ubyte* data, bool alpha) {
    uint pixsize = alpha ? 4 : 3;

    // Open file for writing (binary mode)
    FILE* fp = fopen(filename, "wb");
    if (fp == nullptr) {
        logger.error() << "could not open file " << filename << " for writing";
        fclose(fp);
        return 1;
    }

    // Initialize write structure
    png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
    if (png_ptr == nullptr) {
        logger.error() << "could not allocate write struct";
        fclose(fp);
        return 1;
    }

    // Initialize info structure
    png_infop info_ptr = png_create_info_struct(png_ptr);
    if (info_ptr == nullptr) {
        logger.error() << "could not allocate info struct";
        fclose(fp);
        png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
        png_destroy_write_struct(&png_ptr, (png_infopp)nullptr);
        return 1;
        
    }

    // Setup Exception handling
    if (setjmp(png_jmpbuf(png_ptr))) {
        logger.error() << "error during png creation";
        fclose(fp);
        png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
        png_destroy_write_struct(&png_ptr, &info_ptr);
        return 1;
    }

    png_init_io(png_ptr, fp);

    // Write header (8 bit colour depth)
    png_set_IHDR(png_ptr, info_ptr, width, height,
            8, 
            alpha ? PNG_COLOR_TYPE_RGBA : 
                       PNG_COLOR_TYPE_RGB, 
            PNG_INTERLACE_NONE,
            PNG_COMPRESSION_TYPE_BASE, 
            PNG_FILTER_TYPE_BASE);

    png_write_info(png_ptr, info_ptr);

    auto row = std::make_unique<png_byte[]>(pixsize * width);
    // Write image data
    for (uint y = 0; y < height; y++) {
        for (uint x = 0; x < width; x++) {
            for (uint i = 0; i < pixsize; i++) {
                row[x * pixsize + i] = (png_byte)data[(y * width + x) * pixsize + i];
            }
        }
        png_write_row(png_ptr, row.get());
    }

    // End write
    png_write_end(png_ptr, nullptr);

    fclose(fp);
    png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
    png_destroy_write_struct(&png_ptr, &info_ptr);
    return 0;
}

std::unique_ptr<ImageData> _png_load(const char* file){
    FILE* fp = nullptr;
    if ((fp = fopen(file, "rb")) == nullptr) {
        return nullptr;
    }
    png_struct* png = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
    if (png == nullptr) {
        fclose(fp);
        return nullptr;
    }
    png_info* info = png_create_info_struct(png);
    if (info == nullptr) {
        png_destroy_read_struct(&png, (png_info**) nullptr, (png_info**) nullptr);
        fclose(fp);
        return nullptr;
    }
    png_info* end_info = png_create_info_struct(png);
    if (end_info == nullptr) {
        png_destroy_read_struct(&png, (png_info**) nullptr, (png_info**) nullptr);
        fclose(fp);
        return nullptr;
    }
    
    if (setjmp(png_jmpbuf(png))) {
        png_destroy_read_struct(&png, &info, &end_info);
        fclose(fp);
        return nullptr;
    }

    png_init_io(png, fp);
    png_read_info(png, info);

    int width      = png_get_image_width(png, info);
    int height     = png_get_image_height(png, info);
    png_byte color_type = png_get_color_type(png, info);
    int bit_depth  = png_get_bit_depth(png, info);

    if(bit_depth == 16)
        png_set_strip_16(png);

    if(color_type == PNG_COLOR_TYPE_PALETTE)
        png_set_palette_to_rgb(png);

    if(color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
        png_set_expand_gray_1_2_4_to_8(png);

    if(png_get_valid(png, info, PNG_INFO_tRNS))
        png_set_tRNS_to_alpha(png);

    // These color_type don't have an alpha channel then fill it with 0xff.
    if(color_type == PNG_COLOR_TYPE_RGB ||
        color_type == PNG_COLOR_TYPE_GRAY ||
        color_type == PNG_COLOR_TYPE_PALETTE)
        png_set_filler(png, 0xFF, PNG_FILLER_AFTER);

    if(color_type == PNG_COLOR_TYPE_GRAY ||
     color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
        png_set_gray_to_rgb(png);

    png_read_update_info(png, info);

    int row_bytes = png_get_rowbytes(png, info);
    //color_type = png_get_color_type(png, info);
    // png_get_color_type returns 2 (RGB) but raster always have alpha channel
    // due to PNG_FILLER_AFTER

    color_type = 6;
    bit_depth  = png_get_bit_depth(png, info);

    std::unique_ptr<png_byte[]> image_data (new png_byte[row_bytes * height]);
    std::unique_ptr<png_byte*[]> row_pointers (new png_byte*[height]);
    for (int i = 0; i < height; ++i ) {
        row_pointers[height - 1 - i] = image_data.get() + i * row_bytes;
    }
    png_read_image(png, row_pointers.get());

    ImageFormat format = ImageFormat::rgba8888;
    switch (color_type) {
        case PNG_COLOR_TYPE_RGBA:
            format = ImageFormat::rgba8888;
            break;
        case PNG_COLOR_TYPE_RGB:
            format = ImageFormat::rgb888;
            break;
        default:
            logger.error() << "color type " << color_type << " is not supported!";
            png_destroy_read_struct(&png, &info, &end_info);
            fclose(fp);
            return nullptr;
    }
    auto image = std::make_unique<ImageData>(format, width, height, (void*)image_data.release());
    png_destroy_read_struct(&png, &info, &end_info);
    fclose(fp);
    return image;
}

#else
#include <spng.h>
#include <stdio.h>
#include <inttypes.h>

static const int SPNG_SUCCESS = 0;
//returns spng result code
int _png_write(const char* filename, uint width, uint height, const ubyte* data, bool alpha) {
    int fmt;
    int ret = 0;
    spng_ctx* ctx = nullptr;
    spng_ihdr ihdr = { 0 };
    uint pixsize = alpha ? 4 : 3;

    ctx = spng_ctx_new(SPNG_CTX_ENCODER);
    spng_set_option(ctx, SPNG_ENCODE_TO_BUFFER, 1);

    ihdr.width = width;
    ihdr.height = height;
    ihdr.color_type = alpha ? SPNG_COLOR_TYPE_TRUECOLOR_ALPHA : SPNG_COLOR_TYPE_TRUECOLOR;
    ihdr.bit_depth = 8;

    spng_set_ihdr(ctx, &ihdr);
    fmt = SPNG_FMT_PNG;
    ret = spng_encode_image(ctx, data, (size_t)width * (size_t)height * pixsize , fmt, SPNG_ENCODE_FINALIZE);
    if (ret != SPNG_SUCCESS) {
        logger.error() << "spng_encode_image() error: " << spng_strerror(ret);
        spng_ctx_free(ctx);
        return ret;
    }

    size_t png_size;
    void* png_buf = spng_get_png_buffer(ctx, &png_size, &ret);

    if (png_buf == nullptr) {
        logger.error() << "spng_get_png_buffer() error: " << spng_strerror(ret);
    }
    else {
        files::write_bytes(filename, (const unsigned char*)png_buf, png_size);
    }
    spng_ctx_free(ctx);
    return ret;
}

std::unique_ptr<ImageData> _png_load(const char* file){
    int r = 0;
    FILE *png = nullptr;
    char *pngbuf = nullptr;
    spng_ctx *ctx = nullptr;
    unsigned char *out = nullptr;

    png = fopen(file, "rb");
    if (png == nullptr){
        logger.error() << "could not to open file " << file;
        return nullptr;
    }

    fseek(png, 0, SEEK_END);
    long siz_pngbuf = ftell(png);
    rewind(png);
    if(siz_pngbuf < 1) {
        fclose(png);
        logger.error() << "could not to read file " << file;
        return nullptr;
    }
    pngbuf = new char[siz_pngbuf];
    if(fread(pngbuf, siz_pngbuf, 1, png) != 1){ //check of read elements count
        fclose(png);
        delete[] pngbuf;
        logger.error() << "fread() failed: " << file;
        return nullptr;
    }
    fclose(png); // <- finally closing file
    ctx = spng_ctx_new(0);
    if (ctx == nullptr){
        delete[] pngbuf;
        logger.error() << "spng_ctx_new() failed";
        return nullptr;
    }
    r = spng_set_crc_action(ctx, SPNG_CRC_USE, SPNG_CRC_USE);
    if (r != SPNG_SUCCESS){
        delete[] pngbuf;
        spng_ctx_free(ctx);
        logger.error() << "spng_set_crc_action(): " << spng_strerror(r);
        return nullptr;
    }
    r = spng_set_png_buffer(ctx, pngbuf, siz_pngbuf);
    if (r != SPNG_SUCCESS){
        delete[] pngbuf;
        spng_ctx_free(ctx);
        logger.error() << "spng_set_png_buffer(): " << spng_strerror(r);
        return nullptr;
    }

    spng_ihdr ihdr;
    r = spng_get_ihdr(ctx, &ihdr);
    if (r != SPNG_SUCCESS){
        delete[] pngbuf;
        spng_ctx_free(ctx);
        logger.error() << "spng_get_ihdr(): " << spng_strerror(r);
        return nullptr;
    }

    size_t out_size;
    r = spng_decoded_image_size(ctx, SPNG_FMT_RGBA8, &out_size);
    if (r != SPNG_SUCCESS){
        delete[] pngbuf;
        spng_ctx_free(ctx);
        logger.error() << "spng_decoded_image_size(): " << spng_strerror(r);
        return nullptr;
    }
    out = new unsigned char[out_size];
    r = spng_decode_image(ctx, out, out_size, SPNG_FMT_RGBA8, 0);
    if (r != SPNG_SUCCESS){
        delete[] out;
        delete[] pngbuf;
        spng_ctx_free(ctx);
        logger.error() << "spng_decode_image(): " << spng_strerror(r);
        return nullptr;
    }

    unsigned char* flipped = new unsigned char[out_size];

    for (size_t i = 0; i < ihdr.height; i+=1){
        size_t rowsize = ihdr.width*4;
        for (size_t j = 0; j < rowsize; j++){
            flipped[(ihdr.height-i-1)*rowsize+j] = out[i*rowsize+j];
        }
    }
    delete[] out; // <- finally delete out // no, delete spng usage

    auto image = std::make_unique<ImageData>(ImageFormat::rgba8888, ihdr.width, ihdr.height, (void*)flipped);

    delete[] pngbuf;
    spng_ctx_free(ctx);

    return image;
}
#endif

std::unique_ptr<ImageData> png::load_image(const std::string& filename) {
    auto image = _png_load(filename.c_str());
    if (image == nullptr) {
        throw std::runtime_error("could not load image "+filename);
    }
    return image;
}

std::unique_ptr<Texture> png::load_texture(const std::string& filename) {
    auto image = load_image(filename);
    auto texture = Texture::from(image.get());
    texture->setNearestFilter();
    return texture;
}

void png::write_image(const std::string& filename, const ImageData* image) {
    _png_write(
        filename.c_str(), 
        image->getWidth(), 
        image->getHeight(), 
        (const ubyte*)image->getData(), 
        image->getFormat() == ImageFormat::rgba8888
    );
}
