#include "SdCardManager.h"
#include "scratchApi.h"

#include "linux/utility/utility.h"

#include "fsfw/ipc/MutexFactory.h"
#include "fsfw/serviceinterface/ServiceInterface.h"

#include <unistd.h>

#include <fstream>
#include <memory>
#include <filesystem>
#include <cstring>

SdCardManager* SdCardManager::factoryInstance = nullptr;

SdCardManager::SdCardManager() {
    waiter.events = POLLIN;
}

SdCardManager::~SdCardManager() {
}

void SdCardManager::create() {
    if(factoryInstance == nullptr) {
        factoryInstance = new SdCardManager();
    }
}

SdCardManager* SdCardManager::instance() {
    SdCardManager::create();
    return SdCardManager::factoryInstance;
}

ReturnValue_t SdCardManager::switchOnSdCard(sd::SdCard sdCard, bool doMountSdCard,
        SdStatusPair* statusPair) {
    ReturnValue_t result = HasReturnvaluesIF::RETURN_OK;
    std::unique_ptr<SdStatusPair> sdStatusPtr;
    if(statusPair == nullptr) {
        sdStatusPtr = std::make_unique<SdStatusPair>();
        statusPair = sdStatusPtr.get();
        result = getSdCardActiveStatus(*statusPair);
        if(result != HasReturnvaluesIF::RETURN_OK) {
            return result;
        }
    }

    // Not allowed, this function turns on one SD card
    if(sdCard == sd::SdCard::BOTH) {
        sif::warning << "SdCardManager::switchOffSdCard: API does not allow sd::SdStatus::BOTH"
                << std::endl;
        return HasReturnvaluesIF::RETURN_FAILED;
    }

    sd::SdStatus targetStatus;
    if(sdCard == sd::SdCard::SLOT_0) {
        targetStatus = statusPair->first;
    }
    else if(sdCard == sd::SdCard::SLOT_1) {
        targetStatus = statusPair->second;
    }
    else {
        // Should not happen
        targetStatus = sd::SdStatus::OFF;
    }

    auto switchCall = [&]() {
        if(targetStatus == sd::SdStatus::ON) {
            if(not doMountSdCard) {
                return ALREADY_ON;
            }
            else {
                return mountSdCard(sdCard);
            }
        }
        else if(targetStatus == sd::SdStatus::MOUNTED) {
            return ALREADY_MOUNTED;
        }
        else if(targetStatus == sd::SdStatus::OFF) {
            return setSdCardState(sdCard, true);
        }
        else {
            return HasReturnvaluesIF::RETURN_FAILED;
        }
    };

    result = switchCall();

    if(result != HasReturnvaluesIF::RETURN_OK or not doMountSdCard) {
        return result;
    }

    return mountSdCard(sdCard);
}

ReturnValue_t SdCardManager::switchOffSdCard(sd::SdCard sdCard, bool doUnmountSdCard,
        SdStatusPair* statusPair) {
    std::pair<sd::SdStatus, sd::SdStatus> active;
    ReturnValue_t result = getSdCardActiveStatus(active);
    if(result != HasReturnvaluesIF::RETURN_OK) {
        return result;
    }
    // Not allowed, this function turns off one SD card
    if(sdCard == sd::SdCard::BOTH) {
        sif::warning << "SdCardManager::switchOffSdCard: API does not allow sd::SdStatus::BOTH"
                << std::endl;
        return HasReturnvaluesIF::RETURN_FAILED;
    }
    if(sdCard == sd::SdCard::SLOT_0) {
        if(active.first == sd::SdStatus::OFF) {
            return ALREADY_OFF;
        }
    }
    else if(sdCard == sd::SdCard::SLOT_1) {
        if(active.second == sd::SdStatus::OFF) {
            return ALREADY_OFF;
        }
    }

    if(doUnmountSdCard) {
        result = unmountSdCard(sdCard);
        if(result != HasReturnvaluesIF::RETURN_OK) {
            return result;
        }
    }

    return setSdCardState(sdCard, false);
}

ReturnValue_t SdCardManager::setSdCardState(sd::SdCard sdCard, bool on) {
    using namespace std;
    string sdstring = "";
    string statestring = "";
    if(currentOp != Operations::IDLE) {
        return OP_ONGOING;
    }
    if(sdCard == sd::SdCard::SLOT_0) {
        sdstring = "0";
    }
    else if(sdCard == sd::SdCard::SLOT_1) {
        sdstring = "1";
    }
    if(on) {
        currentOp = Operations::SWITCHING_ON;
        statestring = "on";
    }
    else {
        currentOp = Operations::SWITCHING_OFF;
        statestring = "off";
    }
    ostringstream command;
    command << "q7hw sd set " << sdstring << " " << statestring;
    return handleCommand(command.str(), "SdCardManager::setSdCardState");
}

ReturnValue_t SdCardManager::getSdCardActiveStatus(SdStatusPair& active) {
    using namespace std;
    if(not filesystem::exists(SD_STATE_FILE)) {
        return STATUS_FILE_NEXISTS;
    }

    // Now the file should exist in any case. Still check whether it exists.
    fstream sdStatus(SD_STATE_FILE);
    if (not sdStatus.good()) {
        return STATUS_FILE_NEXISTS;
    }
    string line;
    uint8_t idx = 0;
    sd::SdCard currentSd = sd::SdCard::SLOT_0;
    // Process status file line by line
    while (std::getline(sdStatus, line)) {
        processSdStatusLine(active, line, idx, currentSd);
    }
    return HasReturnvaluesIF::RETURN_OK;
}

ReturnValue_t SdCardManager::mountSdCard(sd::SdCard sdCard) {
    using namespace std;
    if(currentOp != Operations::IDLE) {
        return OP_ONGOING;
    }
    if(sdCard == sd::SdCard::BOTH) {
        sif::warning << "SdCardManager::mountSdCard: API does not allow sd::SdStatus::BOTH"
                << std::endl;
        return HasReturnvaluesIF::RETURN_FAILED;
    }
    string mountDev;
    string mountPoint;
    if(sdCard == sd::SdCard::SLOT_0) {
        mountDev = SD_0_DEV_NAME;
        mountPoint = SD_0_MOUNT_POINT;
    }
    else if(sdCard == sd::SdCard::SLOT_1) {
        mountDev = SD_1_DEV_NAME;
        mountPoint = SD_1_MOUNT_POINT;
    }
    if(not filesystem::exists(mountDev)) {
        sif::warning << "SdCardManager::mountSdCard: Device file does not exists. Make sure to"
                " turn on the SD card" << std::endl;
        return MOUNT_ERROR;
    }

    string sdMountCommand = "mount " + mountDev + " " + mountPoint;
    return handleCommand(sdMountCommand, "SdCardManager::mountSdCard");
}

ReturnValue_t SdCardManager::unmountSdCard(sd::SdCard sdCard) {
    using namespace std;
    if(sdCard == sd::SdCard::BOTH) {
        sif::warning << "SdCardManager::unmountSdCard: API does not allow sd::SdStatus::BOTH"
                << std::endl;
        return HasReturnvaluesIF::RETURN_FAILED;
    }
    string mountPoint;
    if(sdCard == sd::SdCard::SLOT_0) {
        mountPoint = SD_0_MOUNT_POINT;
    }
    else if(sdCard == sd::SdCard::SLOT_1) {
        mountPoint = SD_1_MOUNT_POINT;
    }
    if(not filesystem::exists(mountPoint)) {
        sif::error << "SdCardManager::unmountSdCard: Default mount point " << mountPoint <<
                "does not exist" << std::endl;
        return UNMOUNT_ERROR;
    }
    if(filesystem::is_empty(mountPoint)) {
        // The mount point will always exist, but if it is empty, that is strong hint that
        // the SD card was not mounted properly. Still proceed with operation.
        sif::warning << "SdCardManager::unmountSdCard: Mount point is empty!" << std::endl;
    }
    string sdUnmountCommand = "umount " + mountPoint;
    return handleCommand(sdUnmountCommand, "SdCardManager::unmountSdCard");
}

ReturnValue_t SdCardManager::sanitizeState(SdStatusPair* statusPair, sd::SdCard prefSdCard) {
    std::unique_ptr<SdStatusPair> sdStatusPtr;
    if(prefSdCard == sd::SdCard::NONE) {
        ReturnValue_t result = getPreferredSdCard(prefSdCard);
        if(result != HasReturnvaluesIF::RETURN_OK) {}
    }
    if(statusPair == nullptr) {
        sdStatusPtr = std::make_unique<SdStatusPair>();
        statusPair = sdStatusPtr.get();
        getSdCardActiveStatus(*statusPair);
    }

    if(statusPair->first == sd::SdStatus::ON) {
        return mountSdCard(prefSdCard);
    }

    return switchOnSdCard(prefSdCard, true, statusPair);
}

void SdCardManager::processSdStatusLine(std::pair<sd::SdStatus, sd::SdStatus> &active,
        std::string& line, uint8_t& idx, sd::SdCard& currentSd) {
    using namespace std;
    istringstream iss(line);
    string word;
    bool slotLine = false;
    bool mountLine = false;
    while(iss >> word) {
        if (word == "Slot") {
            slotLine = true;
        }
        if(word == "Mounted") {
            mountLine = true;
        }

        if(slotLine) {
            if (word == "1:") {
                currentSd = sd::SdCard::SLOT_1;
            }

            if(word == "on") {
                if(currentSd == sd::SdCard::SLOT_0) {
                    active.first = sd::SdStatus::ON;
                }
                else {
                    active.second = sd::SdStatus::ON;
                }
            }
            else if (word == "off") {
                if(currentSd == sd::SdCard::SLOT_0) {
                    active.first = sd::SdStatus::OFF;
                }
                else {
                    active.second = sd::SdStatus::OFF;
                }
            }
        }

        if(mountLine) {
            if(currentSd == sd::SdCard::SLOT_0) {
                active.first = sd::SdStatus::MOUNTED;
            }
            else {
                active.second = sd::SdStatus::MOUNTED;
            }
        }

        if(idx > 5) {
            sif::warning << "SdCardManager::sdCardActive: /tmp/sd_status.txt has more than 6 "
                    "lines and might be invalid!" << std::endl;
        }
    }
    idx++;
}

ReturnValue_t SdCardManager::getPreferredSdCard(sd::SdCard& sdCard) const {
    uint8_t prefSdCard = 0;
    ReturnValue_t result = scratch::readNumber(scratch::PREFERED_SDC_KEY, prefSdCard);
    if(result != HasReturnvaluesIF::RETURN_OK) {
        return result;
    }
    sdCard = static_cast<sd::SdCard>(prefSdCard);
    return HasReturnvaluesIF::RETURN_OK;
}

ReturnValue_t SdCardManager::setPreferredSdCard(sd::SdCard sdCard) {
    if(sdCard == sd::SdCard::BOTH) {
        return HasReturnvaluesIF::RETURN_FAILED;
    }
    return scratch::writeNumber(scratch::PREFERED_SDC_KEY, static_cast<uint8_t>(sdCard));
}

ReturnValue_t SdCardManager::updateSdCardStateFile() {
    // Use q7hw utility and pipe the command output into the state file
    std::string updateCmd = "q7hw sd info all > " + std::string(SD_STATE_FILE);
    int result = std::system(updateCmd.c_str());
    if(result == 0) {
        return HasReturnvaluesIF::RETURN_OK;
    }
    sif::warning << "SdCardManager::updateSdCardStateFile: system call failed with code " <<
            result << std::endl;
    return HasReturnvaluesIF::RETURN_FAILED;
}

std::string SdCardManager::getCurrentMountPrefix(sd::SdCard prefSdCard) {
    if(prefSdCard == sd::SdCard::NONE) {
        ReturnValue_t result = getPreferredSdCard(prefSdCard);
        if(result != HasReturnvaluesIF::RETURN_OK) {
            return SD_0_MOUNT_POINT;
        }
    }
    if(prefSdCard == sd::SdCard::SLOT_0) {
        return SD_0_MOUNT_POINT;
    }
    else {
        return SD_1_MOUNT_POINT;
    }
}

SdCardManager::OpStatus SdCardManager::checkCurrentOp(Operations &currentOp) {
    currentOp = this->currentOp;
    switch(currentOpStatus) {
    case(OpStatus::IDLE):
    case(OpStatus::FAIL):
    case(OpStatus::TIMEOUT):
    case(OpStatus::SUCCESS):{
        break;
    }
    case(OpStatus::ONGOING): {
        int result = poll(&waiter, 1, 0);
        switch(result) {
        case(0): {
            // No data available
            break;
        }
        case(1): {
            if (waiter.revents & POLLIN) {
                ssize_t readBytes = read(opFileNum, readBuf.data(), readBuf.size());
                if(readBytes == 0) {
                    // Should not happen..
                    sif::warning << "SdCardManager::checkCurrentOp: 0 bytes read" << std::endl;
                }
                else if(readBytes > 0) {
                    sif::info << currentCmd << " | " << readBuf.data() << std::endl;
                }
                else {
                    sif::error << "SdCardManager::checkCurrentOp: Error code " << errno <<
                            ": " << strerror(errno) << std::endl;
                    return OpStatus::FAIL;
                }
            }
            else if (waiter.revents & POLLERR) {
                sif::warning << "SdCardManager::checkCurrentOp: Poll error.." << std::endl;
            }
            else if(waiter.revents & POLLHUP) {
                int result = pclose(opFile);
                if(result != 0) {
                    sif::error << "SdCardManager::setSdCardState: pclose failed with code " <<
                            result << ": " << strerror(result) << std::endl;
                }
                opFile = nullptr;
                opFileNum = 0;
                currentOp = Operations::IDLE;
                return OpStatus::SUCCESS;
            }
            break;
        }
        default: {
            sif::error << "SdCardManager::checkCurrentOp: Unexpected returnvalue " << result <<
                    "for poll call" << std::endl;
            break;
        }
        }
    }
    }
    return currentOpStatus;
}

void SdCardManager::resetState() {
    currentOp = Operations::IDLE;
    currentOpStatus = OpStatus::IDLE;
    currentOpSdCard = sd::SdCard::NONE;
}

void  SdCardManager::setBlocking(bool blocking) {
    this->blocking = blocking;
    if(not blocking) {
        currentOp = Operations::IDLE;
        currentOpStatus = OpStatus::IDLE;
    }
}

ReturnValue_t SdCardManager::handleCommand(std::string cmd, std::string funcName) {
    currentCmd = cmd;
    opFile = popen(currentCmd.c_str(), "r");
    if(opFile == nullptr) {
        return POPEN_CALL_ERROR;
    }
    if(blocking) {
        return handleBlockingOperation(funcName);
    }
    else {
        opFileNum = fileno(opFile);
        waiter.fd = opFileNum;
    }
    return HasReturnvaluesIF::RETURN_OK;
}

ReturnValue_t SdCardManager::handleBlockingOperation(std::string funcName) {
    while(fgets(readBuf.data(), readBuf.size(), opFile) != nullptr) {
        sif::info << currentCmd << " | " << readBuf.data() << std::endl;
    }
    int result = pclose(opFile);
    if(result != 0) {
        sif::error << "SdCardManager::setSdCardState: pclose failed with code " <<
                result << ": " << strerror(result) << std::endl;
        return HasReturnvaluesIF::RETURN_FAILED;
    }
    return HasReturnvaluesIF::RETURN_OK;
}