#include "bmp.hpp"

#include <fstream>
#include <iostream>

// 将RGB24格式像素数据封装为BMP图像
bool write_bmp(const char* filename, uint8_t* data, int32_t width,
               int32_t height) {
    BMPFileHeader file_header = {0};
    BMPInfoHeader info_header = {0};
    std::ofstream ofs(filename, std::ios::binary);
    if (!ofs) {
        std::cerr << "Failed to create file: " << filename << std::endl;
        return false;
    }
    // BMP文件头
    file_header.type = 0x4D42;  // BM
    file_header.size =
        sizeof(BMPFileHeader) + sizeof(BMPInfoHeader) + width * height * 3;
    file_header.offset = sizeof(BMPFileHeader) + sizeof(BMPInfoHeader);
    ofs.write(reinterpret_cast<char*>(&file_header), sizeof(file_header));

    // BMP位图信息头
    info_header.size = sizeof(BMPInfoHeader);
    info_header.width = width;
    info_header.height = height;
    info_header.planes = 1;
    info_header.bit_count = 24;
    info_header.size_image = width * height * 3;
    ofs.write(reinterpret_cast<char*>(&info_header), sizeof(info_header));

    // 像素数据
    int32_t row_size = (((width + 1) * 3) / 4) * 4;  // 行字节数，必须为4的倍数
    uint8_t* row_data = new uint8_t[row_size];
    for (int32_t y = height - 1; y >= 0; --y) {  // BMP图像的行是从下往上存储的
        for (int32_t x = 0; x < width; ++x) {
            row_data[x * 3 + 2] = data[(y * width + x) * 3 + 0];  // B
            row_data[x * 3 + 1] = data[(y * width + x) * 3 + 1];  // G
            row_data[x * 3 + 0] = data[(y * width + x) * 3 + 2];  // R
        }
        ofs.write(reinterpret_cast<char*>(row_data), row_size);
    }
    delete[] row_data;
    ofs.close();
    return true;
}