yadro-task/include/tapelib/filetape.h

#ifndef FILE_TAPE_H
#define FILE_TAPE_H

#include "tape.h"
#include <chrono>
#include <fstream>
#include <vector>

using std::chrono::milliseconds;

namespace tape {

/**
 * Strcuture for storing all possible settings for a file tape,
 * such as read dealy, write delay etc.
 */
struct FileTapeSettings {
    milliseconds read_delay;
    milliseconds write_delay;
    milliseconds seek_forward_delay;
    milliseconds seek_backwards_delay;
};

const static struct FileTapeSettings FT_DEFAULT_SETTINGS =
    FileTapeSettings{.read_delay = milliseconds(0),
                     .write_delay = milliseconds(0),
                     .seek_forward_delay = milliseconds(0),
                     .seek_backwards_delay = milliseconds(0)};

const static char FT_DELIMETER = '\n';

// uint32_t digits max count is 10
const static int FT_CELL_SIZE = 10;
const static int FT_SEEK_OFFSET = FT_CELL_SIZE + 1;

/**
 * Mock tape implementation that uses text files as data source.
 *
 * Simulates tape operations by artificially pausing the execution of some
 * methods using time intervals, specified in command line arguments or a
 * configuration file. Each cell is represented as a plain text 32-bit unsigned
 * int, padded to FT_CELL_SIZE with leading zeroes, separated by FT_DELIMETER.
 * Each cell MUST be FT_CELL_SIZE long to correctly implement write operation
 * without re-writing the entire file.
 *
 * Example of a valid file for a FileTape
 * - example.txt
 *   000000001
 *   000000034
 *   000001234
 *   123456789
 *   000000000
 */
class FileTape : public Tape {
  private:
    std::string file_name;
    std::fstream file;
    FileTapeSettings settings;
    bool tmp = false;

  public:
    /**
     * Creating copies of FileTape creates 2+ fstreams to one file, which
     * could introduce IO errors or data races if implemented incorrectly -
     * mark the copy constructor as deleted. Moving is fine.
     */
    FileTape(const FileTape &) = delete;
    FileTape(FileTape &&) noexcept = default;
    FileTape &operator=(const FileTape &) = delete;
    FileTape &operator=(FileTape &&tape) = default;

    /**
     * Initializes a new instance of FileTape that will open an existing file
     * with the specified name, already filled with data. File must be read and
     * write accessible.
     *
     * @param file_name Name of a file to be opened.
     * @param settings FileTape settings
     */
    FileTape(std::string file_name,
             FileTapeSettings settings = FT_DEFAULT_SETTINGS);

    /**
     * Initializes a new instance of FileTape that will create and open a file
     * with the specified name and fill it with *cells* amount of zeroed cells.
     * File must not exist and directory must be write accessible.
     *
     * Writing operations when filling file with zeroes will not introduce any
     * delay.
     *
     * @param size Size of a newly created FileTpae
     * @param file_name Name of a file to be created and opened
     * @param settings FileTape settings
     */
    FileTape(size_t cells, std::string file_name,
             FileTapeSettings settings = FT_DEFAULT_SETTINGS);

    /**
     * Initializes a new instance of FileTape that will create and open a file
     * with the specified name and fill it with zeroed cells - the amount of
     * cells will be the same as the specified FileTape.
     * File must not exist and directory must be write accessible.
     *
     * This is necessary in the situations when the FileTapse size is a bigger
     * than size_t max value. Seeking will not introduce delay during this
     * operation.
     *
     * @param same_size_as FileTape, the size of which will be carried over to
     * the new FileTape
     * @param file_name Name of a file to be created and opened
     * @param settings FileTape settings
     */
    FileTape(FileTape &same_size_as, std::string file_name,
             FileTapeSettings = FT_DEFAULT_SETTINGS);

    /**
     * Initializes a new instance of FileTape that will create and open a
     * temporary file and fill it with *cells* amount of zeroed cells.
     *
     * Writing operations when filling file with zeroes will not introduce any
     * delay.
     *
     * @param size Size of a newly created FileTape
     * @param settings FileTape settings
     */
    FileTape(size_t cells, FileTapeSettings settings = FT_DEFAULT_SETTINGS);

    /**
     * Initializes a new instance of FileTape that will create and open a
     * temporary file and fill it with zeroed cells -
     * the amount of cells will be the same as the specified FileTape. File must
     * not exist and directory must be write accessible.
     *
     * This is necessary in the situations when the FileTapse size is a bigger
     * than size_t max value. Seeking will not introduce delay during this
     * operation.
     *
     * @param same_size_as FileTape, the size of which will be carried over to
     * the new FileTape
     * @param file_name Name of a file to be created and opened
     * @param settings FileTape settings
     */
    FileTape(FileTape &same_size_as, FileTapeSettings = FT_DEFAULT_SETTINGS);

    /**
     * Initializes a new instance of FileTape that will create and open a
     * temporary file, and fill it with the data from the provided vector.
     *
     * Writing operations when copying vector to a FileTape will not have any
     * delay.
     * Use this constructor ONLY FOR TESTING. Do NOT use it to copy one
     * FileTape's data to another.
     *
     * @param data Vector of uint32 contents of which will be copied to FileTape
     * @param settings FileTape settings
     */
    FileTape(const std::vector<uint32_t> &data,
             FileTapeSettings settings = FT_DEFAULT_SETTINGS);

    /**
     * Advances the underlying fstream to a new line.
     *
     * @return false if empty line is reached, otherwise true.
     */
    bool seek_forward() override;

    /**
     * Rewinds the underlying fstream to a previous line.
     *
     * @return false if called from the first line of a file, otherwise true.
     */
    bool seek_backwards() override;

    /**
     * Reads and parses data from the current line.
     *
     * @return number from the line, or 0 if data can not be parsed.
     */
    uint32_t read() override;

    /**
     * Writes data to the current line.
     *
     * @param data Number, that should be written to the current line.
     */
    void write(uint32_t data) override;

    /**
     * Close the undetlying fstream, and, in case the FileTape is marked as
     * temporary (tmp is set to true), remove the temporary file
     */
    ~FileTape() override;

    // Define getters in header file since they are implicitly inlined

    bool is_tmp() const { return this->tmp; }

    const FileTapeSettings &get_settings() const { return this->settings; }

    const std::string &get_file_name() const { return this->file_name; }

    const std::fstream &get_file() const { return this->file; }
};

} // namespace tape

#endif // !FILE_TAPE_H