/* Copyright(c) 2017-2019 Alejandro Sirgo Rica & Contributors
*
* This file is part of Kylin-Screenshot.
* 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 3 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, see <https://www.gnu.org/licenses/>.
*
*/

#include "commandlineparser.h"
#include <QApplication>
#include <QTextStream>

CommandLineParser::CommandLineParser() :
    m_description(qApp->applicationName())
{

}

namespace {

QTextStream out(stdout);
QTextStream err(stderr);

auto versionOption = CommandOption({"v", "version"},
                                   QStringLiteral("Displays version information"));
auto helpOption = CommandOption({"h", "help"},
                                QStringLiteral("Displays this help"));

QString optionsToString(const QList<CommandOption> &options,
                        const QList<CommandArgument> &arguments) {
    int size = 0; // track the largest size
    QStringList dashedOptionList;
    // save the dashed options and its size in order to print the description
    // of every option at the same horizontal character position.
    for (auto const &option: options) {
        QStringList dashedOptions = option.dashedNames();
        QString joinedDashedOptions = dashedOptions.join(QStringLiteral(", "));
        if (!option.valueName().isEmpty()) {
            joinedDashedOptions += QStringLiteral(" <%1>")
                    .arg(option.valueName());
        }
        if (joinedDashedOptions.length() > size) {
            size = joinedDashedOptions.length();
        }
        dashedOptionList << joinedDashedOptions;
    }
    // check the length of the arguments
    for (auto const &arg: arguments) {
        if(arg.name().length() > size)
            size = arg.name().length();
    }
    // generate the text
    QString result;
    if(!dashedOptionList.isEmpty()) {
        result += QLatin1String("Options:\n");
        QString linePadding = QStringLiteral(" ").repeated(size + 4).prepend("\n");
        for (int i = 0; i < options.length(); ++i) {
            result += QStringLiteral("  %1  %2\n")
                    .arg(dashedOptionList.at(i).leftJustified(size, ' '))
                    .arg(options.at(i).description()
                         .replace(QLatin1String("\n"), linePadding));
        }
        if (!arguments.isEmpty()) {
            result += QLatin1String("\n");
        }
    }
    if (!arguments.isEmpty()) {
        result += QLatin1String("Arguments:\n");
    }
    for (int i = 0; i < arguments.length(); ++i) {
        result += QStringLiteral("  %1  %2\n")
                .arg(arguments.at(i).name().leftJustified(size, ' '))
                .arg(arguments.at(i).description());
    }
    return result;
}

} // unnamed namespace

bool CommandLineParser::processArgs(const QStringList &args,
                                    QStringList::const_iterator &actualIt,
                                    Node * &actualNode)
{
    QString argument = *actualIt;
    bool ok = true;
    bool isValidArg = false;
    for (Node &n: actualNode->subNodes) {
        if (n.argument.name() == argument) {
            actualNode = &n;
            isValidArg = true;
            break;
        }
    }
    if (isValidArg) {
        auto nextArg = actualNode->argument;
        m_foundArgs.append(nextArg);
        // check next is help
        ++actualIt;
        ok = processIfOptionIsHelp(args, actualIt, actualNode);
        --actualIt;
    } else {
        ok = false;
        out << QStringLiteral("'%1' is not a valid argument.").arg(argument);
    }
    return ok;
}

bool CommandLineParser::processOptions(const QStringList &args,
                                       QStringList::const_iterator &actualIt,
                                       Node *const actualNode)
{
    QString arg = *actualIt;
    bool ok = true;
    // track values
    int equalsPos = arg.indexOf(QLatin1String("="));
    QString valueStr;
    if (equalsPos != -1) {
        valueStr = arg.mid(equalsPos +1); // right
        arg = arg.mid(0, equalsPos); // left
    }
    // check format -x --xx...
    bool isDoubleDashed = arg.startsWith(QLatin1String("--"));
    ok =  isDoubleDashed ? arg.length() > 3 :
                arg.length() == 2;
    if (!ok) {
        out << QStringLiteral("the option %1 has a wrong format.").arg(arg);
        return ok;
    }
    arg = isDoubleDashed ?
                arg.remove(0, 2) :
                arg.remove(0, 1);
    // get option
    auto endIt = actualNode->options.cend();
    auto optionIt = endIt;
    for (auto i = actualNode->options.cbegin(); i != endIt; ++i) {
        if ((*i).names().contains(arg)) {
            optionIt = i;
            break;
        }
    }
    if (optionIt == endIt) {
        QString argName = actualNode->argument.name();
        if (argName.isEmpty()) {
            argName = qApp->applicationName();
        }
        out << QStringLiteral("the option '%1' is not a valid option "
                         "for the argument '%2'.").arg(arg)
                .arg(argName);
        ok = false;
        return ok;
    }
    // check presence of values
    CommandOption option = *optionIt;
    bool requiresValue = !(option.valueName().isEmpty());
    if (!requiresValue && equalsPos != -1) {
        out << QStringLiteral("the option '%1' contains a '=' and it doesn't "
                         "require a value.").arg(arg);
        ok = false;
        return ok;
    } else if (requiresValue && valueStr.isEmpty()) {
        // find in the next
        if (actualIt+1 != args.cend()) {
            ++actualIt;
        } else {
            out << QStringLiteral("Expected value after the option '%1'.").arg(arg);
            ok = false;
            return ok;
        }
        valueStr = *actualIt;
    }
    // check the value correctness
    if (requiresValue) {
        ok = option.checkValue(valueStr);
        if (!ok) {
            QString err = option.errorMsg();
            if (!err.endsWith(QLatin1String(".")))
                err += QLatin1String(".");
            out << err;
            return ok;
        }
        option.setValue(valueStr);
    }
    m_foundOptions.append(option);
    return ok;
}

bool CommandLineParser::parse(const QStringList &args) {
    m_foundArgs.clear();
    m_foundOptions.clear();
    bool ok = true;
    Node *actualNode = &m_parseTree;
    auto it = ++args.cbegin();
    // check  version option
    QStringList dashedVersion = versionOption.dashedNames();
    if (m_withVersion && args.length() > 1 &&
            dashedVersion.contains(args.at(1)))
    {
        if (args.length() == 2) {
            printVersion();
            m_foundOptions << versionOption;
        } else {
            out << "Invalid arguments after the version option.";
            ok = false;
        }
        return ok;

    }
    // check  help option
    ok = processIfOptionIsHelp(args, it, actualNode);
    // process the other args
    for (; it != args.cend() && ok; ++it) {
        const QString &value = *it;
        if (value.startsWith(QLatin1String("-"))) {
            ok = processOptions(args, it, actualNode);

        } else {
            ok = processArgs(args, it, actualNode);
        }
    }
    if (!ok && !m_generalErrorMessage.isEmpty()) {
        out << QStringLiteral(" %1\n").arg(m_generalErrorMessage);
    }
    return ok;
}

CommandOption CommandLineParser::addVersionOption() {
    m_withVersion = true;
    return versionOption;
}

CommandOption CommandLineParser::addHelpOption() {
    m_withHelp = true;
    return helpOption;
}

bool CommandLineParser::AddArgument(const CommandArgument &arg,
                                    const CommandArgument &parent)
{
    bool res = true;
    Node *n = findParent(parent);
    if (n == nullptr) {
        res = false;
    } else {
        Node child;
        child.argument = arg;
        n->subNodes.append(child);
    }
    return res;
}

bool CommandLineParser::AddOption(const CommandOption &option,
                                  const CommandArgument &parent)
{
    bool res = true;
    Node *n = findParent(parent);
    if (n == nullptr) {
        res = false;
    } else {
        n->options.append(option);
    }
    return res;
}

bool CommandLineParser::AddOptions(const QList<CommandOption> &options,
                                   const CommandArgument &parent)
{
    bool res = true;
    for (auto const &option: options) {
        if (!AddOption(option, parent)) {
            res = false;
            break;
        }
    }
    return res;
}

void CommandLineParser::setGeneralErrorMessage(const QString &msg) {
    m_generalErrorMessage = msg;
}

void CommandLineParser::setDescription(const QString &description) {
    m_description = description;
}

bool CommandLineParser::isSet(const CommandArgument &arg) const {
    return m_foundArgs.contains(arg);
}


bool CommandLineParser::isSet(const CommandOption &option) const {
    return m_foundOptions.contains(option);
}

QString CommandLineParser::value(const CommandOption &option) const {
    QString value = option.value();
    for (const CommandOption &fOption: m_foundOptions) {
        if (option == fOption) {
            value = fOption.value();
            break;
        }
    }
    return value;
}

void CommandLineParser::printVersion() {
    out << "kylin-screenshot " << qApp->applicationVersion() << "\nCompiled with Qt "
        << static_cast<QString>(QT_VERSION_STR) << "\n";
}

void CommandLineParser::printHelp(QStringList args, const Node *node) {
    args.removeLast(); // remove the help, it's always the last
    QString helpText;
    // add usage info
    QString argName = node->argument.name();
    if (argName.isEmpty()) {
        argName = qApp->applicationName();
    }
    QString argText = node->subNodes.isEmpty() ? "" : "[arguments]";
    helpText += QStringLiteral("Usage: %1 [%2-options] %3\n\n")
            .arg(args.join(QStringLiteral(" ")))
            .arg(argName).arg(argText);
    // add command options and subarguments
    QList<CommandArgument> subArgs;
    for (const Node &n: node->subNodes)
        subArgs.append(n.argument);
    auto modifiedOptions = node->options;
    if (m_withHelp)
        modifiedOptions << helpOption;
    if (m_withVersion && node == &m_parseTree) {
        modifiedOptions << versionOption;
    }
    helpText += optionsToString(modifiedOptions, subArgs);
    // print it
    out << helpText;
}

CommandLineParser::Node* CommandLineParser::findParent(
        const CommandArgument &parent)
{
    if (parent == CommandArgument()) {
        return &m_parseTree;
    }
    //find the parent in the subNodes recursively
    Node *res = nullptr;
    for (auto i = m_parseTree.subNodes.begin();
        i != m_parseTree.subNodes.end(); ++i)
    {
        res = recursiveParentSearch(parent, *i);
        if (res != nullptr) {
            break;
        }
    }
    return res;
}

CommandLineParser::Node* CommandLineParser::recursiveParentSearch(
        const CommandArgument &parent, Node &node) const
{
    Node * res = nullptr;
    if (node.argument == parent) {
        res = &node;
    } else {
        for (auto i = node.subNodes.begin(); i != node.subNodes.end(); ++i){
            res = recursiveParentSearch(parent, *i);
            if (res != nullptr) {
                break;
            }
        }
    }
    return res;
}

bool CommandLineParser::processIfOptionIsHelp(
        const QStringList &args,
        QStringList::const_iterator &actualIt,
        Node * &actualNode)
{
    bool ok = true;
    auto dashedHelpNames = helpOption.dashedNames();
    if (m_withHelp && actualIt != args.cend() &&
            dashedHelpNames.contains(*actualIt))
    {
        if (actualIt+1 == args.cend()) {
            m_foundOptions << helpOption;
            printHelp(args, actualNode);
            actualIt++;
        } else {
            out << "Invalid arguments after the help option.";
            ok = false;
        }
    }
    return ok;
}
