#include "tftp.hpp"

/**
 * @brief tftp custom file functions to set the offset and read the data
 * @param[in,out] handle Custom file handles
 * @param[in] offset The offset to set
 * @param[in] whence The origin of the offset
 */
void tftp_custom_fseek(tftp_custom_file_t* handle, size_t offset, int whence) {
    switch (whence) {
        case SEEK_SET:
            handle->ofset = offset;
            break;
        case SEEK_CUR:
            handle->ofset += offset;
            break;
        case SEEK_END:
            break;
    }
    if (handle->ofset > handle->len) {
        handle->ofset = handle->len;
    }
}

/**
 * @brief tftp custom file functions to read the data
 *        auto rolling over the offset
 *        if the bytes to read is bigger than the remaining bytes
 *        it will read the remaining bytes and set the bytes to 0
 * @param[out] buf The buffer to write the data to
 * @param[in] bytes The number of bytes to read
 * @param[in,out] handle Custom file handles
 */
size_t tftp_custom_fread(void* buf, size_t bytes, tftp_custom_file_t* handle) {
    if (handle->ofset + bytes > handle->len) {
        bytes = handle->len - handle->ofset;
    }
    memcpy(buf, handle->data + handle->ofset, bytes);
    handle->ofset += bytes;
    ((char*)buf)[bytes] = '\0';
    if (handle->ofset > handle->len) {
        bytes = 0;
    }
    return bytes;
}