/***************************************************************************
 *   Copyright (C) 2006 Hans van Leeuwen <hanz@hanz.nl>                    *
 *   Copyright (C) 2008-2010 Armin Berres <armin@space-based.de>           *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA          *
 ***************************************************************************/

#include <memory>
#include <sys/resource.h>

#include <KAboutData>
#include <KLocalizedString>
#include <KMessageBox>
#include <KPasswordDialog>
#include <kwallet.h>

#include <QApplication>
#include <QCommandLineOption>
#include <QCommandLineParser>
#include <QDesktopWidget>
#include <QInputDialog>
#include <QLoggingCategory>
#include <QPointer>
#include <QRegularExpression>
#include <QTextStream>

Q_LOGGING_CATEGORY(LOG_KSSHASKPASS, "ksshaskpass")

enum Type {
    TypePassword,
    TypeClearText,
    TypeConfirm,
};

// Try to understand what we're asked for by parsing the phrase. Unfortunately, sshaskpass interface does not
// include any saner methods to pass the action or the name of the keyfile. Fortunately, openssh and git
// has no i18n, so this should work for all languages as long as the string is unchanged.
static void parsePrompt(const QString &prompt, QString &identifier, bool &ignoreWallet, enum Type &type)
{
    QRegularExpressionMatch match;

    // openssh sshconnect2.c
    // Case: password for authentication on remote ssh server
    match = QRegularExpression(QStringLiteral("^(.*@.*)'s password( \\(JPAKE\\))?: $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypePassword;
        ignoreWallet = false;
        return;
    }

    // openssh sshconnect2.c
    // Case: password change request
    match = QRegularExpression(QStringLiteral("^(Enter|Retype) (.*@.*)'s (old|new) password: $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(2);
        type = TypePassword;
        ignoreWallet = true;
        return;
    }

    // openssh sshconnect2.c and sshconnect1.c
    // Case: asking for passphrase for a certain keyfile
    match = QRegularExpression(QStringLiteral("^Enter passphrase for( RSA)? key '(.*)': $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(2);
        type = TypePassword;
        ignoreWallet = false;
        return;
    }

    // openssh ssh-add.c
    // Case: asking for passphrase for a certain keyfile for the first time => we should try a password from the wallet
    match = QRegularExpression(QStringLiteral("^Enter passphrase for (.*?)( \\(will confirm each use\\))?: $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypePassword;
        ignoreWallet = false;
        return;
    }

    // openssh ssh-add.c
    // Case: re-asking for passphrase for a certain keyfile => probably we've tried a password from the wallet, no point
    // in trying it again
    match = QRegularExpression(QStringLiteral("^Bad passphrase, try again for (.*?)( \\(will confirm each use\\))?: $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypePassword;
        ignoreWallet = true;
        return;
    }

    // openssh ssh-pkcs11.c
    // Case: asking for PIN for some token label
    match = QRegularExpression(QStringLiteral("Enter PIN for '(.*)': $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypePassword;
        ignoreWallet = false;
        return;
    }

    // openssh mux.c
    match = QRegularExpression(QStringLiteral("^(Allow|Terminate) shared connection to (.*)\\? $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(2);
        type = TypeConfirm;
        ignoreWallet = true;
        return;
    }

    // openssh mux.c
    match = QRegularExpression(QStringLiteral("^Open (.* on .*)?$")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypeConfirm;
        ignoreWallet = true;
        return;
    }

    // openssh mux.c
    match = QRegularExpression(QStringLiteral("^Allow forward to (.*:.*)\\? $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypeConfirm;
        ignoreWallet = true;
        return;
    }

    // openssh mux.c
    match = QRegularExpression(QStringLiteral("^Disable further multiplexing on shared connection to (.*)? $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypeConfirm;
        ignoreWallet = true;
        return;
    }

    // openssh ssh-agent.c
    match = QRegularExpression(QStringLiteral("^Allow use of key (.*)?\\nKey fingerprint .*\\.$")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypeConfirm;
        ignoreWallet = true;
        return;
    }

    // openssh sshconnect.c
    match = QRegularExpression(QStringLiteral("^Add key (.*) \\(.*\\) to agent\\?$")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypeConfirm;
        ignoreWallet = true;
        return;
    }

    // git imap-send.c
    // Case: asking for password by git imap-send
    match = QRegularExpression(QStringLiteral("^Password \\((.*@.*)\\): $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypePassword;
        ignoreWallet = false;
        return;
    }

    // git credential.c
    // Case: asking for username by git without specifying any other information
    match = QRegularExpression(QStringLiteral("^Username: $")).match(prompt);
    if (match.hasMatch()) {
        identifier = QString();
        type = TypeClearText;
        ignoreWallet = true;
        return;
    }

    // git credential.c
    // Case: asking for password by git without specifying any other information
    match = QRegularExpression(QStringLiteral("^Password: $")).match(prompt);
    if (match.hasMatch()) {
        identifier = QString();
        type = TypePassword;
        ignoreWallet = true;
        return;
    }

    // git credential.c
    // Case: asking for username by git for some identifier
    match = QRegularExpression(QStringLiteral("^Username for '(.*)': $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypeClearText;
        ignoreWallet = false;
        return;
    }

    // git credential.c
    // Case: asking for password by git for some identifier
    match = QRegularExpression(QStringLiteral("^Password for '(.*)': $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypePassword;
        ignoreWallet = false;
        return;
    }

    // Case: username extraction from git-lfs
    match = QRegularExpression(QStringLiteral("^Username for \"(.*?)\"$")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypeClearText;
        ignoreWallet = false;
        return;
    }

    // Case: password extraction from git-lfs
    match = QRegularExpression(QStringLiteral("^Password for \"(.*?)\"$")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypePassword;
        ignoreWallet = false;
        return;
    }

    // Case: password extraction from mercurial, see bug 380085
    match = QRegularExpression(QStringLiteral("^(.*?)'s password: $")).match(prompt);
    if (match.hasMatch()) {
        identifier = match.captured(1);
        type = TypePassword;
        ignoreWallet = false;
        return;
    }

    // Nothing matched; either it was called by some sort of a script with a custom prompt (i.e. not ssh-add), or
    // strings we're looking for were broken. Issue a warning and continue without identifier.
    qCWarning(LOG_KSSHASKPASS) << "Unable to parse phrase" << prompt;
}

int main(int argc, char **argv)
{
    QGuiApplication::setAttribute(Qt::AA_UseHighDpiPixmaps, true);

    QApplication app(argc, argv);
    KLocalizedString::setApplicationDomain("ksshaskpass");

    // TODO update it.
    KAboutData about(QStringLiteral("ksshaskpass"),
                     i18n("Ksshaskpass"),
                     QStringLiteral(PROJECT_VERSION),
                     i18n("KDE version of ssh-askpass"),
                     KAboutLicense::GPL,
                     i18n("(c) 2006 Hans van Leeuwen\n(c) 2008-2010 Armin Berres\n(c) 2013 Pali Rohár"),
                     i18n("Ksshaskpass allows you to interactively prompt users for a passphrase for ssh-add"),
                     QStringLiteral("https://commits.kde.org/ksshaskpass"),
                     QStringLiteral("armin@space-based.de"));

    about.addAuthor(i18n("Armin Berres"), i18n("Current author"), QStringLiteral("armin@space-based.de"));
    about.addAuthor(i18n("Hans van Leeuwen"), i18n("Original author"), QStringLiteral("hanz@hanz.nl"));
    about.addAuthor(i18n("Pali Rohár"), i18n("Contributor"), QStringLiteral("pali.rohar@gmail.com"));
    about.addAuthor(i18n("Armin Berres"), i18n("Current author"), QStringLiteral("armin@space-based.de"), QString());
    about.addAuthor(i18n("Hans van Leeuwen"), i18n("Original author"), QStringLiteral("hanz@hanz.nl"), QString());
    about.addAuthor(i18n("Pali Rohár"), i18n("Contributor"), QStringLiteral("pali.rohar@gmail.com"), QString());
    KAboutData::setApplicationData(about);

    QCommandLineParser parser;
    about.setupCommandLine(&parser);
    parser.addOption(QCommandLineOption(QStringList() << QStringLiteral("+[prompt]"), i18nc("Name of a prompt for a password", "Prompt")));

    parser.process(app);
    about.processCommandLine(&parser);

    const QString walletFolder = app.applicationName();
    QString dialog = i18n("Please enter passphrase"); // Default dialog text.
    QString identifier;
    QString item;
    bool ignoreWallet = false;
    enum Type type = TypePassword;

    // Parse commandline arguments
    if (!parser.positionalArguments().isEmpty()) {
        dialog = parser.positionalArguments().at(0);
        parsePrompt(dialog, identifier, ignoreWallet, type);
    }

    // Open KWallet to see if an item was previously stored
    WId winId = QApplication::desktop()->winId();
    std::unique_ptr<KWallet::Wallet> wallet(ignoreWallet ? nullptr : KWallet::Wallet::openWallet(KWallet::Wallet::NetworkWallet(), winId));

    if ((!ignoreWallet) && (!identifier.isNull()) && wallet.get() && wallet->hasFolder(walletFolder)) {
        wallet->setFolder(walletFolder);

        wallet->readPassword(identifier, item);

        if (item.isEmpty()) {
            // There was a bug in previous versions of ksshaskpass that caused it to create keys with single quotes
            // around the identifier and even older versions have an extra space appended to the identifier.
            // key file name. Try these keys too, and, if there's a match, ensure that it's properly
            // replaced with proper one.
            for (auto templ : QStringList{QStringLiteral("'%0'"), QStringLiteral("%0 "), QStringLiteral("'%0' ")}) {
                const QString keyFile = templ.arg(identifier);
                wallet->readPassword(keyFile, item);
                if (!item.isEmpty()) {
                    qCWarning(LOG_KSSHASKPASS) << "Detected legacy key for " << identifier << ", enabling workaround";
                    wallet->renameEntry(keyFile, identifier);
                    break;
                }
            }
        }
    }

    if (!item.isEmpty()) {
        QTextStream(stdout) << item;
        return 0;
    }

    // Item could not be retrieved from wallet. Open dialog
    switch (type) {
    case TypeConfirm: {
        if (KMessageBox::questionYesNo(nullptr, dialog, i18n("Ksshaskpass")) != KMessageBox::Yes) {
            // dialog has been canceled
            return 1;
        }
        item = QStringLiteral("yes\n");
        break;
    }
    case TypeClearText:
        // Should use a dialog with visible input, but KPasswordDialog doesn't support that and
        // other available dialog types don't have a "Keep" checkbox.
        /* fallthrough */
    case TypePassword: {
        // create the password dialog, but only show "Enable Keep" button, if the wallet is open
        KPasswordDialog::KPasswordDialogFlag flag(KPasswordDialog::NoFlags);
        if (wallet.get()) {
            flag = KPasswordDialog::ShowKeepPassword;
        }
        QPointer<KPasswordDialog> kpd = new KPasswordDialog(nullptr, flag);

        kpd->setPrompt(dialog);
        kpd->setWindowTitle(i18n("Ksshaskpass"));
        // We don't want to dump core when the password dialog is shown, because it could contain the entered password.
        // KPasswordDialog::disableCoreDumps() seems to be gone in KDE 4 -- do it manually
        struct rlimit rlim;
        rlim.rlim_cur = rlim.rlim_max = 0;
        setrlimit(RLIMIT_CORE, &rlim);

        if (kpd->exec() == QDialog::Accepted) {
            item = kpd->password();
            // If "Enable Keep" is enabled, open/create a folder in KWallet and store the password.
            if ((!identifier.isNull()) && wallet.get() && kpd->keepPassword()) {
                if (!wallet->hasFolder(walletFolder)) {
                    wallet->createFolder(walletFolder);
                }
                wallet->setFolder(walletFolder);
                wallet->writePassword(identifier, item);
            }
        } else {
            // dialog has been canceled
            return 1;
        }
        break;
    }
    }

    QTextStream out(stdout);
    out << item << "\n";
    return 0;
}
