/*
 * SPDX-License-Identifier: GPL-3.0-or-later
 * SPDX-FileCopyrightText: 2020 Johan Ouwerkerk <jm.ouwerkerk@gmail.com>
 */
#include "accounts.h"

#include "../logging_p.h"

KEYSMITH_LOGGER(logger, ".model.accounts")

namespace model
{
qint64 millisecondsLeftForToken(const QDateTime &epoch, uint timeStep, const std::function<qint64(void)> &clock)
{
    QDateTime now = QDateTime::fromMSecsSinceEpoch(clock());
    if (!epoch.isValid() || !now.isValid() || timeStep == 0) {
        qCDebug(logger) << "Unable to compute milliseconds left: invalid arguments";
        return -1;
    }

    /*
     * Avoid integer overflow by casting to the wider type first before multiplying.
     * Not likely to happen 'in the wild', but good practice nevertheless
     */
    qint64 step = ((qint64)timeStep) * 1000LL;

    qint64 diff = epoch.msecsTo(now);

    /*
     * Compensate for the fact that % operator is not the same as mathematical mod in case diff is negative.
     * diff is negative when the given epoch is in the 'future' compared to the current clock value.
     */
    return diff < 0 ? -(diff % step) : step - (diff % step);
}

AccountView::AccountView(accounts::Account *model, QObject *parent)
    : QObject(parent)
    , m_model(model)
{
    QObject::connect(model, &accounts::Account::tokenChanged, this, &AccountView::tokenChanged);
    QObject::connect(this, &AccountView::remove, model, &accounts::Account::remove);
    QObject::connect(this, &AccountView::recompute, model, &accounts::Account::recompute);
    QObject::connect(this, &AccountView::advanceCounter, model, &accounts::Account::advanceCounter);
    QObject::connect(this, &AccountView::setCounter, model, &accounts::Account::setCounter);
}

bool AccountView::isHotp(void) const
{
    return m_model->algorithm() == accounts::Account::Hotp;
}

bool AccountView::isTotp(void) const
{
    return m_model->algorithm() == accounts::Account::Totp;
}

QString AccountView::name(void) const
{
    return m_model->name();
}

QString AccountView::token(void) const
{
    return m_model->token();
}

QString AccountView::issuer(void) const
{
    return m_model->issuer();
}

quint64 AccountView::counter(void) const
{
    return m_model->counter();
}

QDateTime AccountView::epoch(void) const
{
    return m_model->epoch();
}

uint AccountView::timeStep(void) const
{
    return m_model->timeStep();
}

uint AccountView::offset(void) const
{
    return m_model->offset().value_or(0);
}

int AccountView::tokenLength(void) const
{
    return m_model->tokenLength();
}

QString AccountView::hash(void) const
{
    switch (m_model->hash()) {
    case accounts::Account::Sha1:
        return QStringLiteral("SHA1");
    case accounts::Account::Sha256:
        return QStringLiteral("SHA256");
    case accounts::Account::Sha512:
        return QStringLiteral("SHA512");
    }
    return QString();
}

qint64 AccountView::millisecondsLeftForToken(void) const
{
    if (!isTotp()) {
        qCDebug(logger) << "Unable to compute milliseconds left for token, wrong account type:" << m_model->algorithm();
        return -1;
    }

    return model::millisecondsLeftForToken(m_model->epoch(), m_model->timeStep());
}

SimpleAccountListModel::SimpleAccountListModel(accounts::AccountStorage *storage, QObject *parent)
    : QAbstractListModel(parent)
    , m_storage(storage)
    , m_has_error(false)
    , m_index(QList<QString>())
{
    QObject::connect(storage, &accounts::AccountStorage::added, this, &SimpleAccountListModel::added);
    QObject::connect(storage, &accounts::AccountStorage::removed, this, &SimpleAccountListModel::removed);
    QObject::connect(storage, &accounts::AccountStorage::error, this, &SimpleAccountListModel::handleError);
    QObject::connect(storage, &accounts::AccountStorage::loaded, this, &SimpleAccountListModel::loadedChanged);

    beginResetModel();
    const auto accounts = m_storage->accounts();
    for (const QString &name : accounts) {
        populate(name, createView(name));
    }
    m_has_error = storage->hasError();
    endResetModel();
}

AccountView *SimpleAccountListModel::createView(const QString &name)
{
    accounts::Account *existingAccount = m_storage->get(name);
    if (!existingAccount) {
        qCDebug(logger) << "Account storage did not yield a valid account object for account name";
        return nullptr;
    }

    return new AccountView(existingAccount, this);
}

void SimpleAccountListModel::populate(const QString &name, AccountView *account)
{
    if (!account) {
        qCDebug(logger) << "Not populating account without a valid account view object";
        return;
    }

    m_index.append(name);
    m_accounts[name] = account;
    Q_EMIT account->recompute();
}

bool SimpleAccountListModel::error(void) const
{
    return m_has_error;
}

void SimpleAccountListModel::setError(bool markAsError)
{
    if (!markAsError && m_storage->hasError()) {
        m_storage->clearError();
    }

    if (markAsError != m_has_error) {
        m_has_error = markAsError;
        Q_EMIT errorChanged();
    }
}

void SimpleAccountListModel::handleError(void)
{
    setError(true);
}

bool SimpleAccountListModel::loaded(void) const
{
    return m_storage->isLoaded();
}

accounts::Account::Hash SimpleAccountListModel::toHash(TOTPAlgorithms value)
{
    switch (value) {
    case TOTPAlgorithms::Sha1:
        return accounts::Account::Hash::Sha1;
    case TOTPAlgorithms::Sha256:
        return accounts::Account::Hash::Sha256;
    case TOTPAlgorithms::Sha512:
        return accounts::Account::Hash::Sha512;
    default:
        Q_ASSERT_X(false, Q_FUNC_INFO, "Unknown/unsupported totp algorithm value");
        return accounts::Account::Hash::Sha1;
    }
}

void SimpleAccountListModel::addAccount(AccountInput *input)
{
    if (!input) {
        qCDebug(logger) << "Not adding account, no input provided";
        return;
    }
    input->createNewAccount(m_storage);
}

QHash<int, QByteArray> SimpleAccountListModel::roleNames(void) const
{
    QHash<int, QByteArray> roles;
    roles[NonStandardRoles::AccountRole] = "account";
    return roles;
}

QVariant SimpleAccountListModel::data(const QModelIndex &account, int role) const
{
    if (!account.isValid()) {
        qCDebug(logger) << "Not returning any data, model index is invalid";
        return QVariant();
    }

    int accountIndex = account.row();
    if (accountIndex < 0 || m_index.size() < accountIndex) {
        qCDebug(logger) << "Not returning any data, model index is out of bounds:" << accountIndex << "model size is:" << m_index.size();
        return QVariant();
    }

    if (role != NonStandardRoles::AccountRole) {
        qCDebug(logger) << "Not returning any data, unknown role:" << role;
        return QVariant();
    }

    const QString accountName = m_index.at(accountIndex);
    auto model = m_accounts.value(accountName, nullptr);
    if (!model) {
        qCDebug(logger) << "Not returning any data, unable to find associated account for:" << accountIndex;
        return QVariant();
    }

    return QVariant::fromValue(model);
}

int SimpleAccountListModel::rowCount(const QModelIndex &parent) const
{
    return parent.isValid() ? 0 : m_index.size();
}

void SimpleAccountListModel::added(const QString &account)
{
    auto newAccount = createView(account);
    if (!newAccount) {
        qCDebug(logger) << "Unable to handle added account: unable to construct account view object";
        return;
    }

    if (m_accounts.contains(account)) {
        qCDebug(logger) << "Added account already/still part of the model: requesting removal of the old one from the model first";
        removed(account);
    }

    int accountIndex = m_index.size();
    qCDebug(logger) << "Adding (new) account to the model at position:" << accountIndex;

    beginInsertRows(QModelIndex(), accountIndex, accountIndex);
    populate(account, newAccount);
    endInsertRows();
}

void SimpleAccountListModel::removed(const QString &account)
{
    int accountIndex = m_index.indexOf(account);
    if (accountIndex < 0) {
        qCDebug(logger) << "Unable to handle account removal: account not part of the model";
        return;
    }

    AccountView *v = nullptr;

    qCDebug(logger) << "Removing (old) account from the model at position:" << accountIndex;
    beginRemoveRows(QModelIndex(), accountIndex, accountIndex);
    m_index.remove(accountIndex);
    v = m_accounts.take(account);
    endRemoveRows();

    if (v) {
        v->deleteLater();
    }
}

bool SimpleAccountListModel::isAccountStillAvailable(const QString &name, const QString &issuer) const
{
    return m_storage && m_storage->isAccountStillAvailable(name, issuer);
}

AccountNameValidator::AccountNameValidator(QObject *parent)
    : QValidator(parent)
    , m_validateAvailability(true)
    , m_issuer(std::nullopt)
    , m_accounts(nullptr)
    , m_delegate(nullptr)
{
}

bool AccountNameValidator::validateAvailability(void) const
{
    return m_validateAvailability;
}

void AccountNameValidator::setValidateAvailability(bool enabled)
{
    if (enabled != m_validateAvailability) {
        m_validateAvailability = enabled;
        Q_EMIT validateAvailabilityChanged();
    }
}

QString AccountNameValidator::issuer(void) const
{
    return m_issuer ? *m_issuer : QStringLiteral(":: WARNING: dummy invalid issuer; this is meant as a write-only property anyway ::");
}

void AccountNameValidator::setIssuer(const QString &issuer)
{
    if (m_issuer && issuer == *m_issuer) {
        qCDebug(logger) << "Ignoring new issuer: same as the current issuer";
        return;
    }

    m_issuer.emplace(issuer);
    Q_EMIT issuerChanged();
}

QValidator::State AccountNameValidator::validate(QString &input, int &pos) const
{
    QValidator::State result = m_delegate.validate(input, pos);
    if (!m_validateAvailability) {
        qCDebug(logger) << "Not validating account availability: explicitly disabled";
        return result;
    }

    if (!m_accounts) {
        qCDebug(logger) << "Unable to validate account name: missing accounts model object";
        return QValidator::Invalid;
    }

    if (!m_issuer) {
        qCDebug(logger) << "Unable to validate account name: missing issuer";
        return QValidator::Invalid;
    }

    return result != QValidator::Acceptable || m_accounts->isAccountStillAvailable(input, *m_issuer) ? result : QValidator::Intermediate;
}

void AccountNameValidator::fixup(QString &input) const
{
    m_delegate.fixup(input);
}

SimpleAccountListModel *AccountNameValidator::accounts(void) const
{
    return m_accounts;
}

void AccountNameValidator::setAccounts(SimpleAccountListModel *accounts)
{
    if (!accounts) {
        qCDebug(logger) << "Ignoring new accounts model: not a valid object";
        return;
    }

    m_accounts = accounts;
    Q_EMIT accountsChanged();
}

SortedAccountsListModel::SortedAccountsListModel(QObject *parent)
    : QSortFilterProxyModel(parent)
{
}

void SortedAccountsListModel::setSourceModel(QAbstractItemModel *sourceModel)
{
    SimpleAccountListModel *model = qobject_cast<SimpleAccountListModel *>(sourceModel);
    if (!model) {
        qCDebug(logger) << "Not setting source model: it is not an accounts list model!";
        return;
    }

    QSortFilterProxyModel::setSourceModel(sourceModel);
    qCDebug(logger) << "Updating properties & resorting the model";
    setSortRole(SimpleAccountListModel::NonStandardRoles::AccountRole);
    setDynamicSortFilter(true);
    setSortLocaleAware(true);
    sort(0);
}

bool SortedAccountsListModel::lessThan(const QModelIndex &source_left, const QModelIndex &source_right) const
{
    QAbstractItemModel *source = sourceModel();
    Q_ASSERT_X(source, Q_FUNC_INFO, "should have a source model at this point");

    const SimpleAccountListModel *model = qobject_cast<const SimpleAccountListModel *>(source);
    // useless junk: implement sorting as no-op: claim equality between left & right
    if (!model) {
        qCDebug(logger) << "Short-circuiting lessThan operator: source model is not an accounts list model!";
        return false;
    }

    const QVariant leftValue = model->data(source_left, SimpleAccountListModel::NonStandardRoles::AccountRole);
    const QVariant rightValue = model->data(source_right, SimpleAccountListModel::NonStandardRoles::AccountRole);

    const AccountView *leftAccount = leftValue.isNull() ? nullptr : leftValue.value<AccountView *>();
    const AccountView *rightAccount = rightValue.isNull() ? nullptr : rightValue.value<AccountView *>();

    // useless junk: implement sorting as no-op: claim left == right
    if (!leftAccount && !rightAccount) {
        qCDebug(logger) << "Short-circuiting lessThan operator: both source model indices do not point to accounts";
        return false;
    }

    // Sort actual accounts before useless junk: claim left >= right
    if (!leftAccount) {
        qCDebug(logger) << "Short-circuiting lessThan operator: left source model index does not point to an account";
        return false;
    }

    // Sort actual accounts before useless junk: claim left < right
    if (!rightAccount) {
        qCDebug(logger) << "Short-circuiting lessThan operator: right source model index does not point to an account";
        return true;
    }

    const QString leftIssuer = leftAccount->issuer();
    const QString rightIssuer = rightAccount->issuer();

    // both issuers are null: sort by account name
    if (leftIssuer.isNull() && rightIssuer.isNull()) {
        return leftAccount->name().localeAwareCompare(rightAccount->name()) < 0;
    }

    // Sort accounts without issuer to the top: claim left < right
    if (leftIssuer.isNull()) {
        return true;
    }

    // Sort accounts without issuer to the top: claim left >= right
    if (rightIssuer.isNull()) {
        return false;
    }

    // actual sorting by account issuer, then name
    int issuer = leftIssuer.localeAwareCompare(rightIssuer);
    return issuer == 0 ? leftAccount->name().localeAwareCompare(rightAccount->name()) < 0 : issuer < 0;
}
}

#include "moc_accounts.cpp"