#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>

// Таблица CRC32 для полинома 0xEDB88320 (IEEE 802.3)
static const uint32_t crc32_table[256] = {
        0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F,
        0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
        0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2,
        0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
        0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
        0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
        0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
        0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
        0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423,
        0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
        0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106,
        0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
        0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
        0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
        0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
        0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
        0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7,
        0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
        0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA,
        0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
        0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81,
        0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
        0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84,
        0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
        0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
        0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
        0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E,
        0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
        0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55,
        0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
        0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28,
        0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
        0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F,
        0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
        0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
        0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
        0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69,
        0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
        0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
        0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
        0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693,
        0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
        0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
};

// Структура для параметров командной строки
typedef struct {
    char *filename;
    int write_crc;      // Флаг: записывать CRC в файл
    int verify_crc;     // Флаг: проверять CRC
    int show_only;      // Флаг: только показать CRC без записи
    int split;          // Флаг: разрезать файл
    int verbose;        // Флаг: подробный вывод
    long split_offset;  // Смещение для разрезания (в байтах)
    char *output1;      // Имя первого выходного файла
    char *output2;      // Имя второго выходного файла
} ProgramOptions;

// Прототипы функций
void print_usage(const char *program_name);
int parse_arguments(int argc, char *argv[], ProgramOptions *options);
uint32_t calculate_crc32(const uint8_t *data, uint32_t len);
uint32_t calculate_file_crc32_without_last4(const char *filename, int verbose);
uint32_t calculate_file_crc32_full(const char *filename, int verbose);
int write_crc32_to_file(const char *filename, uint32_t crc_value, int verbose);
int verify_crc32(const char *filename, int verbose);
int split_bin_file(const char *input_file, long offset, const char *output1, const char *output2, int verbose);

/**
 * @brief Вычисляет CRC32 (IEEE 802.3) для блока данных в памяти
 */
uint32_t calculate_crc32(const uint8_t *data, uint32_t len) {
    uint32_t crc = 0xFFFFFFFF;

    for (uint32_t i = 0; i < len; i++) {
        crc = (crc >> 8) ^ crc32_table[(crc ^ data[i]) & 0xFF];
    }

    return crc ^ 0xFFFFFFFF;
}

/**
 * @brief Вычисляет CRC32 для файла, исключая последние 4 байта
 * Используется для записи и проверки CRC
 */
uint32_t calculate_file_crc32_without_last4(const char *filename, int verbose) {
    FILE *file = NULL;
    uint8_t *buffer = NULL;
    long file_size = 0;
    uint32_t crc = 0;

    file = fopen(filename, "rb");
    if (file == NULL) {
        perror("Failed to open file");
        return 0;
    }

    // Получаем размер файла
    if (fseek(file, 0, SEEK_END) != 0) {
        perror("Failed to seek to end");
        fclose(file);
        return 0;
    }

    file_size = ftell(file);

    if (file_size < 4) {
        fprintf(stderr, "File size (%ld bytes) is less than 4 bytes\n", file_size);
        fclose(file);
        return 0;
    }

    long data_size = file_size - 4; // Размер данных без последних 4 байт

    if (verbose) {
        printf("File size: %ld bytes\n", file_size);
        printf("Data size for CRC calculation (without last 4 bytes): %ld bytes\n", data_size);
    }

    // Выделяем память под данные
    buffer = (uint8_t*)malloc(data_size);
    if (buffer == NULL && data_size > 0) {
        perror("Failed to allocate memory");
        fclose(file);
        return 0;
    }

    // Возвращаемся в начало
    if (fseek(file, 0, SEEK_SET) != 0) {
        perror("Failed to seek to beginning");
        free(buffer);
        fclose(file);
        return 0;
    }

    // Читаем данные (все, кроме последних 4 байт)
    if (data_size > 0) {
        size_t bytes_read = fread(buffer, 1, data_size, file);
        if (bytes_read != data_size) {
            fprintf(stderr, "Failed to read file data. Read %zu bytes, expected %ld bytes\n",
                    bytes_read, data_size);
            free(buffer);
            fclose(file);
            return 0;
        }
    }

    // Вычисляем CRC
    if (data_size > 0) {
        crc = calculate_crc32(buffer, data_size);
    } else {
        crc = calculate_crc32(NULL, 0);
    }

    free(buffer);
    fclose(file);

    return crc;
}

/**
 * @brief Вычисляет CRC32 для всего файла (включая последние 4 байта)
 * Используется только для показа CRC
 */
uint32_t calculate_file_crc32_full(const char *filename, int verbose) {
    FILE *file = NULL;
    uint8_t *buffer = NULL;
    long file_size = 0;
    uint32_t crc = 0;

    file = fopen(filename, "rb");
    if (file == NULL) {
        perror("Failed to open file");
        return 0;
    }

    if (fseek(file, 0, SEEK_END) != 0) {
        perror("Failed to seek to end");
        fclose(file);
        return 0;
    }

    file_size = ftell(file);
    if (verbose) {
        printf("File size: %ld bytes\n", file_size);
    }

    if (file_size <= 0) {
        fprintf(stderr, "File is empty\n");
        fclose(file);
        return 0;
    }

    buffer = (uint8_t*)malloc(file_size);
    if (buffer == NULL) {
        perror("Failed to allocate memory");
        fclose(file);
        return 0;
    }

    if (fseek(file, 0, SEEK_SET) != 0) {
        perror("Failed to seek to beginning");
        free(buffer);
        fclose(file);
        return 0;
    }

    size_t bytes_read = fread(buffer, 1, file_size, file);
    if (bytes_read != file_size) {
        fprintf(stderr, "Failed to read entire file\n");
        free(buffer);
        fclose(file);
        return 0;
    }

    crc = calculate_crc32(buffer, file_size);

    free(buffer);
    fclose(file);

    return crc;
}

/**
 * @brief Записывает размер данных и CRC32 в файл
 * Размер данных (file_size - 4) записывается по смещению 256 байт от конца файла
 * CRC32 записывается в последние 4 байта файла
 */
int write_crc32_to_file(const char *filename, uint32_t crc_value, int verbose) {
    FILE *file = NULL;
    long file_size;
    long data_size;
    int result = 0;

    file = fopen(filename, "rb+");
    if (file == NULL) {
        perror("Failed to open file for writing");
        return -1;
    }

    // Получаем размер файла
    if (fseek(file, 0, SEEK_END) != 0) {
        perror("Failed to seek to end");
        fclose(file);
        return -1;
    }

    file_size = ftell(file);
    if (file_size < 4) {
        fprintf(stderr, "File size (%ld bytes) is less than 4 bytes\n", file_size);
        fclose(file);
        return -1;
    }

    data_size = file_size - 4; // Размер данных без CRC

    if (verbose) {
        printf("File size: %ld bytes\n", file_size);
        printf("Data size (without CRC): %ld bytes (0x%lX)\n", data_size, data_size);
        printf("CRC value: 0x%08X (%u)\n", crc_value, crc_value);
    }

    // ==============================================
    // 1. Записываем размер данных по смещению 256 байт от конца файла
    // ==============================================
    long data_size_offset = file_size - 256; // Позиция для размера данных (ровно 256 байт от конца)

    // Проверяем, что позиция не отрицательная и не перекрывается с CRC
    if (data_size_offset < 0) {
        fprintf(stderr, "Warning: File too small, cannot write data size at offset 256 from end\n");
        fprintf(stderr, "File size: %ld bytes, need at least 256 bytes\n", file_size);
        if (verbose) {
            printf("Skipping data size write (file too small)\n");
        }
    } else if (data_size_offset + 4 > file_size - 4) {
        fprintf(stderr, "Warning: Data size position overlaps with CRC area\n");
        fprintf(stderr, "Data size would be at %ld, CRC at %ld\n", data_size_offset, file_size - 4);
        if (verbose) {
            printf("Skipping data size write (overlap detected)\n");
        }
    } else {
        // Перемещаемся на позицию для записи размера данных
        if (fseek(file, data_size_offset, SEEK_SET) != 0) {
            perror("Failed to seek to data size position");
            result = -1;
            goto cleanup;
        }

        // Записываем размер данных в little-endian порядке (4 байта для 32-битного размера)
        uint8_t size_bytes[4];
        size_bytes[0] = (data_size >> 0) & 0xFF;
        size_bytes[1] = (data_size >> 8) & 0xFF;
        size_bytes[2] = (data_size >> 16) & 0xFF;
        size_bytes[3] = (data_size >> 24) & 0xFF;

        size_t bytes_written = fwrite(size_bytes, 1, 4, file);
        if (bytes_written != 4) {
            fprintf(stderr, "Failed to write data size to file\n");
            result = -1;
            goto cleanup;
        }

        if (verbose) {
            printf("\nData size written: %ld bytes (0x%lX)\n", data_size, data_size);
            printf("  Position: %ld (0x%lX) bytes from start\n", data_size_offset, data_size_offset);
            printf("  Distance from end: %ld bytes (exactly 256 bytes)\n", file_size - data_size_offset);
            printf("  Bytes written (LE 32-bit): %02X %02X %02X %02X\n",
                   size_bytes[0], size_bytes[1], size_bytes[2], size_bytes[3]);
        }
    }

    // ==============================================
    // 2. Записываем CRC в последние 4 байта файла
    // ==============================================
    if (fseek(file, file_size - 4, SEEK_SET) != 0) {
        perror("Failed to seek to CRC position");
        result = -1;
        goto cleanup;
    }

    // Записываем CRC в little-endian порядке
    uint8_t crc_bytes[4];
    crc_bytes[0] = (crc_value >> 0) & 0xFF;
    crc_bytes[1] = (crc_value >> 8) & 0xFF;
    crc_bytes[2] = (crc_value >> 16) & 0xFF;
    crc_bytes[3] = (crc_value >> 24) & 0xFF;

    size_t bytes_written = fwrite(crc_bytes, 1, 4, file);
    if (bytes_written != 4) {
        fprintf(stderr, "Failed to write CRC to file\n");
        result = -1;
        goto cleanup;
    }

    if (verbose) {
        printf("\nCRC32 value written: 0x%08X (%u)\n", crc_value, crc_value);
        printf("  Position: %ld-%ld (last 4 bytes)\n", file_size - 4, file_size - 1);
        printf("  Bytes written (LE): %02X %02X %02X %02X\n",
               crc_bytes[0], crc_bytes[1], crc_bytes[2], crc_bytes[3]);
        printf("Byte order: little-endian (LSB first)\n");
    }

    cleanup:
    fclose(file);
    return result;
}

/**
 * @brief Проверяет CRC32, сравнивая вычисленное значение с сохраненным
 * Также опционально проверяет сохраненный размер данных
 */
int verify_crc32(const char *filename, int verbose) {
    FILE *file = NULL;
    long file_size;
    long stored_data_size = 0;
    uint32_t calculated_crc = 0;
    uint32_t stored_crc = 0;
    int verify_size = 1; // Флаг проверки размера

    file = fopen(filename, "rb");
    if (file == NULL) {
        perror("Failed to open file");
        return -1;
    }

    if (fseek(file, 0, SEEK_END) != 0) {
        perror("Failed to seek to end");
        fclose(file);
        return -1;
    }

    file_size = ftell(file);
    if (file_size < 4) {
        fprintf(stderr, "File size (%ld bytes) is less than 4 bytes\n", file_size);
        fclose(file);
        return -1;
    }

    if (verbose) {
        printf("File size: %ld bytes\n", file_size);
    }

    // ==============================================
    // 1. Читаем сохраненный размер данных (опционально)
    // ==============================================
    long data_size_offset = file_size - 256; // Позиция размера данных (256 байт от конца)
    if (data_size_offset >= 0 && data_size_offset + 4 <= file_size - 4) {
        if (fseek(file, data_size_offset, SEEK_SET) != 0) {
            perror("Failed to seek to stored data size");
            verify_size = 0;
        } else {
            uint8_t size_bytes[4];
            size_t bytes_read = fread(size_bytes, 1, 4, file);
            if (bytes_read == 4) {
                stored_data_size = (long)size_bytes[0] << 0 |
                                   (long)size_bytes[1] << 8 |
                                   (long)size_bytes[2] << 16 |
                                   (long)size_bytes[3] << 24;

                if (verbose) {
                    printf("\nStored data size: %ld bytes (0x%lX) at offset %ld\n",
                           stored_data_size, stored_data_size, data_size_offset);
                    printf("  Distance from end: %ld bytes (exactly 256 bytes)\n", file_size - data_size_offset);
                    printf("  Bytes read (LE 32-bit): %02X %02X %02X %02X\n",
                           size_bytes[0], size_bytes[1], size_bytes[2], size_bytes[3]);
                }
            } else {
                verify_size = 0;
                if (verbose) {
                    printf("Failed to read stored data size (expected 4 bytes, got %zu)\n", bytes_read);
                }
            }
        }
    } else {
        verify_size = 0;
        if (verbose) {
            printf("\nNo valid data size stored at offset 256 bytes from end\n");
            printf("  File size: %ld, would need at least %ld bytes\n", file_size, 256 + 4);
        }
    }

    // ==============================================
    // 2. Читаем сохраненный CRC из последних 4 байт
    // ==============================================
    if (fseek(file, file_size - 4, SEEK_SET) != 0) {
        perror("Failed to seek to stored CRC");
        fclose(file);
        return -1;
    }

    uint8_t crc_bytes[4];
    size_t bytes_read = fread(crc_bytes, 1, 4, file);
    if (bytes_read != 4) {
        fprintf(stderr, "Failed to read stored CRC\n");
        fclose(file);
        return -1;
    }

    stored_crc = (uint32_t)crc_bytes[0] << 0 |
                 (uint32_t)crc_bytes[1] << 8 |
                 (uint32_t)crc_bytes[2] << 16 |
                 (uint32_t)crc_bytes[3] << 24;

    fclose(file);

    // Вычисляем CRC для данных (без последних 4 байт)
    calculated_crc = calculate_file_crc32_without_last4(filename, verbose);
    if (calculated_crc == 0) {
        fprintf(stderr, "Failed to calculate CRC\n");
        return -1;
    }

    long actual_data_size = file_size - 4;

    // Всегда выводим значения CRC при проверке
    printf("\n╔════════════════════════════════════════════════════════════╗\n");
    printf("║                    CRC32 Verification                       ║\n");
    printf("╠════════════════════════════════════════════════════════════╣\n");
    printf("║ Stored CRC     : 0x%08X (%10u)                        ║\n", stored_crc, stored_crc);
    printf("║ Calculated CRC : 0x%08X (%10u)                        ║\n", calculated_crc, calculated_crc);

    if (verify_size && stored_data_size > 0) {
        printf("╠════════════════════════════════════════════════════════════╣\n");
        printf("║ Stored data size   : %12ld bytes (0x%lX)              ║\n", stored_data_size, stored_data_size);
        printf("║ Actual data size   : %12ld bytes (0x%lX)              ║\n", actual_data_size, actual_data_size);
    }

    printf("╚════════════════════════════════════════════════════════════╝\n");

    int crc_valid = (calculated_crc == stored_crc);
    int size_valid = 1;

    if (verify_size && stored_data_size > 0) {
        size_valid = (actual_data_size == stored_data_size);
    }

    if (crc_valid && size_valid) {
        printf("\n✓ VERIFIED: CRC matches and data size is correct! File integrity check passed.\n");
        return 0;
    } else if (crc_valid && !size_valid) {
        printf("\n⚠ WARNING: CRC matches but data size mismatch!\n");
        printf("  Stored size: %ld, Actual size: %ld, Difference: %ld\n",
               stored_data_size, actual_data_size, actual_data_size - stored_data_size);
        return 1;
    } else if (!crc_valid && size_valid) {
        printf("\n✗ MISMATCH: File is corrupted! CRC does not match (data size OK).\n");
        printf("  Difference: 0x%08X\n", calculated_crc ^ stored_crc);
        return 1;
    } else {
        printf("\n✗ MISMATCH: File is corrupted! Both CRC and data size are incorrect!\n");
        printf("  CRC difference: 0x%08X\n", calculated_crc ^ stored_crc);
        if (verify_size && stored_data_size > 0) {
            printf("  Size difference: %ld bytes\n", actual_data_size - stored_data_size);
        }
        return 1;
    }
}

/**
 * @brief Разрезает BIN файл на два файла по указанному смещению
 */
int split_bin_file(const char *input_file, long offset, const char *output1, const char *output2, int verbose) {
    FILE *fin = NULL;
    FILE *fout1 = NULL;
    FILE *fout2 = NULL;
    uint8_t *buffer = NULL;
    long file_size = 0;
    long bytes_to_copy1 = 0;
    long bytes_to_copy2 = 0;
    size_t bytes_read, bytes_written;
    int result = 0;

    // Открываем входной файл
    fin = fopen(input_file, "rb");
    if (fin == NULL) {
        perror("Failed to open input file");
        return -1;
    }

    // Получаем размер файла
    if (fseek(fin, 0, SEEK_END) != 0) {
        perror("Failed to seek to end");
        fclose(fin);
        return -1;
    }
    file_size = ftell(fin);
    rewind(fin);

    printf("\n--- Splitting file ---\n");
    printf("Input file: %s\n", input_file);
    printf("File size: %ld bytes (0x%lX)\n", file_size, file_size);
    printf("Split offset: %ld bytes (0x%lX)\n", offset, offset);

    // Проверяем смещение
    if (offset <= 0) {
        fprintf(stderr, "Error: Split offset must be positive (got %ld)\n", offset);
        fclose(fin);
        return -1;
    }

    if (offset >= file_size) {
        fprintf(stderr, "Error: Split offset (%ld) is greater than or equal to file size (%ld)\n",
                offset, file_size);
        fclose(fin);
        return -1;
    }

    bytes_to_copy1 = offset;
    bytes_to_copy2 = file_size - offset;

    printf("First part size: %ld bytes (0x%lX)\n", bytes_to_copy1, bytes_to_copy1);
    printf("Second part size: %ld bytes (0x%lX)\n", bytes_to_copy2, bytes_to_copy2);
    printf("Output file 1: %s\n", output1);
    printf("Output file 2: %s\n", output2);

    // Открываем выходные файлы
    fout1 = fopen(output1, "wb");
    if (fout1 == NULL) {
        perror("Failed to create output file 1");
        fclose(fin);
        return -1;
    }

    fout2 = fopen(output2, "wb");
    if (fout2 == NULL) {
        perror("Failed to create output file 2");
        fclose(fin);
        fclose(fout1);
        return -1;
    }

    // Выделяем буфер для чтения/записи (1 МБ)
    const size_t buffer_size = 1024 * 1024;
    buffer = (uint8_t*)malloc(buffer_size);
    if (buffer == NULL) {
        perror("Failed to allocate buffer");
        fclose(fin);
        fclose(fout1);
        fclose(fout2);
        return -1;
    }

    // Копируем первую часть
    if (verbose) {
        printf("\nCopying first part (%ld bytes)...\n", bytes_to_copy1);
    }

    long remaining = bytes_to_copy1;
    long progress_step = bytes_to_copy1 / 10;
    long next_progress = progress_step;

    while (remaining > 0) {
        size_t to_read = (remaining < buffer_size) ? remaining : buffer_size;
        bytes_read = fread(buffer, 1, to_read, fin);
        if (bytes_read != to_read) {
            fprintf(stderr, "Error reading input file (first part)\n");
            result = -1;
            goto cleanup;
        }

        bytes_written = fwrite(buffer, 1, bytes_read, fout1);
        if (bytes_written != bytes_read) {
            fprintf(stderr, "Error writing to output file 1\n");
            result = -1;
            goto cleanup;
        }

        remaining -= bytes_read;

        if (verbose && progress_step > 0 && remaining <= next_progress) {
            int percent = (int)((bytes_to_copy1 - remaining) * 100 / bytes_to_copy1);
            printf("  Progress: %d%% (%ld bytes remaining)...\n", percent, remaining);
            next_progress -= progress_step;
        }
    }

    // Копируем вторую часть
    if (verbose) {
        printf("Copying second part (%ld bytes)...\n", bytes_to_copy2);
    }

    remaining = bytes_to_copy2;
    progress_step = bytes_to_copy2 / 10;
    next_progress = bytes_to_copy2 - progress_step;

    while (remaining > 0) {
        size_t to_read = (remaining < buffer_size) ? remaining : buffer_size;
        bytes_read = fread(buffer, 1, to_read, fin);
        if (bytes_read != to_read) {
            fprintf(stderr, "Error reading input file (second part)\n");
            result = -1;
            goto cleanup;
        }

        bytes_written = fwrite(buffer, 1, bytes_read, fout2);
        if (bytes_written != bytes_read) {
            fprintf(stderr, "Error writing to output file 2\n");
            result = -1;
            goto cleanup;
        }

        remaining -= bytes_read;

        if (verbose && progress_step > 0 && remaining <= next_progress) {
            int percent = (int)((bytes_to_copy2 - remaining) * 100 / bytes_to_copy2);
            printf("  Progress: %d%% (%ld bytes remaining)...\n", percent, remaining);
            next_progress -= progress_step;
        }
    }

    printf("\n✓ File split successfully!\n");
    printf("  Part 1: %s (%ld bytes)\n", output1, bytes_to_copy1);
    printf("  Part 2: %s (%ld bytes)\n", output2, bytes_to_copy2);

    cleanup:
    free(buffer);
    fclose(fin);
    fclose(fout1);
    fclose(fout2);

    // Если произошла ошибка, удаляем созданные файлы
    if (result != 0) {
        printf("\nError occurred, removing output files...\n");
        remove(output1);
        remove(output2);
    }

    return result;
}

/**
 * @brief Выводит справку
 */
void print_usage(const char *program_name) {
    printf("\nCRC32 Tool for BIN files\n");
    printf("========================\n\n");
    printf("Usage: %s [OPTIONS] <filename>\n\n", program_name);
    printf("Options:\n");
    printf("  -w, --write          Calculate CRC32 from all except last 4 bytes\n");
    printf("                       and write it to last 4 bytes\n");
    printf("  -c, --check          Verify CRC32 by comparing with stored value\n");
    printf("  -s, --show-only      Calculate and display CRC32 of entire file\n");
    printf("  --split <offset>     Split file into two parts at specified offset (bytes)\n");
    printf("  -1, --output1 <file> Output filename for first part (with --split)\n");
    printf("  -2, --output2 <file> Output filename for second part (with --split)\n");
    printf("  -v, --verbose        Show detailed information\n");
    printf("  -h, --help           Show this help\n");
    printf("\nExamples:\n");
    printf("  %s -s firmware.bin                # Show CRC32 of entire file\n", program_name);
    printf("  %s -w firmware.bin                # Write CRC32 to last 4 bytes\n", program_name);
    printf("  %s -c firmware.bin                # Verify CRC32\n", program_name);
    printf("  %s --split 4096 firmware.bin      # Split at offset 4096 bytes\n", program_name);
    printf("  %s --split 0x1000 firmware.bin    # Split at offset 0x1000 (hex)\n", program_name);
    printf("  %s --split 8192 -1 part1.bin -2 part2.bin firmware.bin\n", program_name);
    printf("  %s -v --split 1024 firmware.bin   # Split with verbose output\n", program_name);
    printf("\nNote:\n");
    printf("  For -w and -c operations, CRC is calculated from the first\n");
    printf("  (file_size - 4) bytes, ignoring the last 4 bytes.\n");
    printf("  Data size (file_size - 4) is written at offset 256 bytes from end.\n");
    printf("  For split operation, offset can be specified in decimal or hex (0x prefix).\n");
    printf("  If output filenames are not specified, default names will be used:\n");
    printf("  <input>_part1.bin and <input>_part2.bin\n");
    printf("\n");
}

/**
 * @brief Разбирает аргументы командной строки
 */
int parse_arguments(int argc, char *argv[], ProgramOptions *options) {
    int option_index = 0;
    int c;

    static struct option long_options[] = {
            {"write",      no_argument,       0, 'w'},
            {"check",      no_argument,       0, 'c'},
            {"show-only",  no_argument,       0, 's'},
            {"split",      required_argument, 0, 1000},
            {"output1",    required_argument, 0, 1001},
            {"output2",    required_argument, 0, 1002},
            {"verbose",    no_argument,       0, 'v'},
            {"help",       no_argument,       0, 'h'},
            {0, 0, 0, 0}
    };

    memset(options, 0, sizeof(ProgramOptions));

    // Инициализация имен выходных файлов
    options->output1 = NULL;
    options->output2 = NULL;
    options->split_offset = 0;

    // Поддержка коротких опций: -1 и -2 для output1/output2
    while ((c = getopt_long(argc, argv, "wcsvh1:2:", long_options, &option_index)) != -1) {
        switch (c) {
            case 'w':
                options->write_crc = 1;
                break;
            case 'c':
                options->verify_crc = 1;
                break;
            case 's':
                options->show_only = 1;
                break;
            case 'v':
                options->verbose = 1;
                break;
            case 'h':
                print_usage(argv[0]);
                return -1;
            case '1':  // Короткая опция -1 для output1
                options->output1 = strdup(optarg);
                break;
            case '2':  // Короткая опция -2 для output2
                options->output2 = strdup(optarg);
                break;
            case 1000: // --split
                options->split = 1;
                // Поддержка шестнадцатеричных чисел
                if (optarg[0] == '0' && (optarg[1] == 'x' || optarg[1] == 'X')) {
                    options->split_offset = strtol(optarg, NULL, 16);
                } else {
                    options->split_offset = strtol(optarg, NULL, 10);
                }
                break;
            case 1001: // --output1
                options->output1 = strdup(optarg);
                break;
            case 1002: // --output2
                options->output2 = strdup(optarg);
                break;
            case '?':
                return -1;
        }
    }

    if (optind >= argc) {
        fprintf(stderr, "Error: No filename specified.\n");
        print_usage(argv[0]);
        return -1;
    }

    options->filename = argv[optind];

    // Подсчет количества выбранных режимов
    int mode_count = options->write_crc + options->verify_crc + options->show_only + options->split;
    if (mode_count > 1) {
        fprintf(stderr, "Error: Cannot use multiple modes simultaneously\n");
        return -1;
    }

    // Если режим не выбран, по умолчанию show-only
    if (mode_count == 0) {
        options->show_only = 1;
    }

    // Проверка параметров для split
    if (options->split) {
        if (options->split_offset <= 0) {
            fprintf(stderr, "Error: Invalid split offset (must be > 0)\n");
            return -1;
        }

        // Генерация имен выходных файлов, если не указаны
        if (options->output1 == NULL) {
            char *default_name = malloc(strlen(options->filename) + 10);
            sprintf(default_name, "%s_part1.bin", options->filename);
            options->output1 = default_name;
        }

        if (options->output2 == NULL) {
            char *default_name = malloc(strlen(options->filename) + 10);
            sprintf(default_name, "%s_part2.bin", options->filename);
            options->output2 = default_name;
        }
    }

    return 0;
}

/**
 * @brief Главная функция
 */
int main(int argc, char *argv[]) {
    ProgramOptions options;
    uint32_t crc_value;
    int result = 0;

    if (parse_arguments(argc, argv, &options) != 0) {
        return 1;
    }

    if (options.show_only) {
        // Показать CRC всего файла
        printf("\n--- CRC32 of %s ---\n", options.filename);
        crc_value = calculate_file_crc32_full(options.filename, options.verbose);
        if (crc_value == 0) {
            fprintf(stderr, "Failed to calculate CRC32\n");
            return 1;
        }
        printf("\nCRC32 (full file): 0x%08X (%u)\n", crc_value, crc_value);

    }
    else if (options.write_crc) {
        // Записать CRC
        printf("\n--- Writing CRC32 to %s ---\n", options.filename);

        if (options.verbose) {
            printf("\nStep 1: Calculating CRC32 from first (file_size - 4) bytes...\n");
        }

        crc_value = calculate_file_crc32_without_last4(options.filename, options.verbose);
        if (crc_value == 0) {
            fprintf(stderr, "Failed to calculate CRC32\n");
            return 1;
        }

        // Всегда выводим вычисленное CRC при записи
        printf("\n╔════════════════════════════════════════╗\n");
        printf("║         CRC32 Calculation              ║\n");
        printf("╠════════════════════════════════════════╣\n");
        printf("║ Calculated CRC : 0x%08X (%10u) ║\n", crc_value, crc_value);
        printf("╚════════════════════════════════════════╝\n");

        if (options.verbose) {
            printf("\nStep 2: Writing CRC and data size to file...\n");
        }

        result = write_crc32_to_file(options.filename, crc_value, options.verbose);
        if (result != 0) {
            fprintf(stderr, "Failed to write CRC32\n");
            return 1;
        }

        printf("\n✓ CRC32 successfully written to file\n");

        // Опционально: проверим сразу после записи
        if (options.verbose) {
            printf("\n--- Verifying after write ---\n");
            verify_crc32(options.filename, 0);
        }

    }
    else if (options.verify_crc) {
        // Проверить CRC
        printf("\n--- Verifying CRC32 for %s ---\n", options.filename);
        result = verify_crc32(options.filename, options.verbose);
    }
    else if (options.split) {
        // Разрезать файл
        result = split_bin_file(options.filename, options.split_offset,
                                options.output1, options.output2, options.verbose);

        // Освобождаем память для имен выходных файлов
        if (options.output1 != NULL) free(options.output1);
        if (options.output2 != NULL) free(options.output2);
    }

    return result;
}