eive-obsw/bsp_q7s/memory/SdCardManager.h

#ifndef BSP_Q7S_MEMORY_SDCARDACCESSMANAGER_H_
#define BSP_Q7S_MEMORY_SDCARDACCESSMANAGER_H_

#include "definitions.h"
#include "returnvalues/classIds.h"

#include "fsfw/returnvalues/HasReturnvaluesIF.h"

#include <cstdint>
#include <utility>
#include <string>
#include <optional>

class MutexIF;

/**
 * @brief   Manages handling of SD cards like switching them on or off or getting the current
 *          state
 */
class SdCardManager {
    friend class SdCardAccess;
public:
    using SdStatusPair = std::pair<sd::SdStatus, sd::SdStatus>;

    static constexpr uint8_t INTERFACE_ID = CLASS_ID::SD_CARD_MANAGER;

    static constexpr ReturnValue_t ALREADY_ON =
            HasReturnvaluesIF::makeReturnCode(INTERFACE_ID, 0);
    static constexpr ReturnValue_t ALREADY_MOUNTED  =
            HasReturnvaluesIF::makeReturnCode(INTERFACE_ID, 1);
    static constexpr ReturnValue_t ALREADY_OFF =
            HasReturnvaluesIF::makeReturnCode(INTERFACE_ID, 2);
    static constexpr ReturnValue_t STATUS_FILE_NEXISTS =
            HasReturnvaluesIF::makeReturnCode(INTERFACE_ID, 10);
    static constexpr ReturnValue_t STATUS_FILE_FORMAT_INVALID =
            HasReturnvaluesIF::makeReturnCode(INTERFACE_ID, 11);
    static constexpr ReturnValue_t MOUNT_ERROR =
            HasReturnvaluesIF::makeReturnCode(INTERFACE_ID, 12);
    static constexpr ReturnValue_t UNMOUNT_ERROR =
            HasReturnvaluesIF::makeReturnCode(INTERFACE_ID, 13);
    static constexpr ReturnValue_t SYSTEM_CALL_ERROR =
            HasReturnvaluesIF::makeReturnCode(INTERFACE_ID, 14);

    // C++17 does not support constexpr std::string yet
    static constexpr char SD_0_DEV_NAME[] = "/dev/mmcblk0p1";
    static constexpr char SD_1_DEV_NAME[] = "/dev/mmcblk1p1";
    static constexpr char SD_0_MOUNT_POINT[] = "/mnt/sd0";
    static constexpr char SD_1_MOUNT_POINT[] = "/mnt/sd1";
    static constexpr char SD_STATE_FILE[] = "/tmp/sd_status.txt";

    virtual ~SdCardManager();

    static void create();

    /**
     * Returns the single instance of the SD card manager.
     */
    static SdCardManager* instance();

    /**
     * Set the preferred SD card which will determine which SD card will be used as the primary
     * SD card in hot redundant and cold redundant mode. This function will not switch the
     * SD cards which are currently on and mounted, this needs to be implemented by
     * an upper layer by using #switchOffSdCard , #switchOnSdCard and #updateSdCardStateFile
     * @param sdCard
     * @return
     */
    ReturnValue_t setPreferredSdCard(sd::SdCard sdCard);

    /**
     * Get the currently configured preferred SD card
     * @param sdCard
     * @return
     */
    ReturnValue_t getPreferredSdCard(sd::SdCard& sdCard) const;

    /**
     * Switch on the specified SD card.
     * @param sdCard
     * @param doMountSdCard     Mount the SD card after switching it on, which is necessary
     *                          to use it
     * @param statusPair        If the status pair is already available, it can be passed here
     * @return - RETURN_OK on success, ALREADY_ON if it is already on,
     *           SYSTEM_CALL_ERROR on system error
     */
    ReturnValue_t switchOnSdCard(sd::SdCard sdCard, bool doMountSdCard = true,
            SdStatusPair* statusPair = nullptr);

    /**
     * Switch off the specified SD card.
     * @param sdCard
     * @param doUnmountSdCard   Unmount the SD card before switching the card off, which makes
     *                          the operation safer
     * @param statusPair        If the status pair is already available, it can be passed here
     * @return - RETURN_OK on success, ALREADY_ON if it is already on,
     *           SYSTEM_CALL_ERROR on system error
     */
    ReturnValue_t switchOffSdCard(sd::SdCard sdCard, bool doUnmountSdCard = true,
            SdStatusPair* statusPair = nullptr);

    /**
     * Update the state file or creates one if it does not exist. You need to call this
     * function before calling #sdCardActive
     * @return - RETURN_OK if the state file was updated successfully
     *         - SYSTEM_CALL_ERROR if the call to create the status file failed
     */
    ReturnValue_t updateSdCardStateFile();

    /**
     * Get the state of the SD cards. If the state file does not exist, this function will
     * take care of updating it. If it does not, the function will use the state file to get
     * the status of the SD cards and set the field of the provided boolean pair.
     * @param active Pair of booleans, where the first entry is the state of the first SD card
     * and the second one the state of the second SD card
     * @return - RETURN_OK if the state was read successfully
     *         - STATUS_FILE_FORMAT_INVALID if there was an issue with the state file. The user
     *           should call #updateSdCardStateFile again in that case
     *         - STATUS_FILE_NEXISTS if the status file does not exist
     */
    ReturnValue_t getSdCardActiveStatus(SdStatusPair& active);

    /**
     * Mount the specified SD card. This is necessary to use it.
     * @param sdCard
     * @return
     */
    ReturnValue_t mountSdCard(sd::SdCard sdCard);
    /**
     * Unmount the specified SD card. This is recommended before switching it off. The SD card
     * can't be used after it has been unmounted.
     * @param sdCard
     * @return
     */
    ReturnValue_t unmountSdCard(sd::SdCard sdCard);

    /**
     * In case that there is a discrepancy between the preferred SD card and the currently
     * mounted one, this function will sanitize the state by attempting to mount the
     * currently preferred SD card. If the caller already has state information, it can be
     * passed into the function.
     * @param statusPair    Current SD card status capture with #getSdCardActiveStatus
     * @param prefSdCard    Preferred SD card captured with #getPreferredSdCard
     * @throws std::bad_alloc if one of the two arguments was a nullptr and an allocation failed
     * @return
     */
    ReturnValue_t sanitizeState(SdStatusPair* statusPair = nullptr,
            sd::SdCard prefSdCard = sd::SdCard::NONE);

    /**
     * If sd::SdCard::NONE is passed as an argument, this funtion will get the currently
     * preferred SD card from the scratch buffer.
     * @param prefSdCardPtr
     * @return
     */
    std::string getCurrentMountPrefix(sd::SdCard prefSdCardPtr = sd::SdCard::NONE);
private:
    SdCardManager();

    ReturnValue_t setSdCardState(sd::SdCard sdCard, bool on);

    void processSdStatusLine(SdStatusPair& active, std::string& line, uint8_t& idx,
            sd::SdCard& currentSd);

    std::string currentPrefix;

    static SdCardManager* factoryInstance;
};

#endif /* BSP_Q7S_MEMORY_SDCARDACCESSMANAGER_H_ */