// STL includes
#include <stdexcept>

// Qt includes 
#include <QHash>
#include <QStringList>
#include <QTextStream>
#include <QDebug>
#include <QSettings>
#include <QPointer>

// CTK includes
#include "ctkCommandLineParser.h"

namespace
{
// --------------------------------------------------------------------------
class CommandLineParserArgumentDescription
{
public:
  CommandLineParserArgumentDescription(
    const QString& longArg, const QString& longArgPrefix,
    const QString& shortArg, const QString& shortArgPrefix,
    QVariant::Type type, const QString& argHelp,
    const QVariant& defaultValue, bool ignoreRest,
    bool deprecated)
      : LongArg(longArg), LongArgPrefix(longArgPrefix),
      ShortArg(shortArg), ShortArgPrefix(shortArgPrefix),
      ArgHelp(argHelp), IgnoreRest(ignoreRest), NumberOfParametersToProcess(0),
      Deprecated(deprecated), DefaultValue(defaultValue), Value(type), ValueType(type)
  {
    if (defaultValue.isValid())
      {
      Value = defaultValue;
      }

    switch (type)
      {
      case QVariant::String:
        {
        NumberOfParametersToProcess = 1;
        RegularExpression = ".*";
        }
        break;
      case QVariant::Bool:
        {
        NumberOfParametersToProcess = 0;
        RegularExpression = "";
        }
        break;
      case QVariant::StringList:
        {
        NumberOfParametersToProcess = -1;
        RegularExpression = ".*";
        }
        break;
      case QVariant::Int:
        {
        NumberOfParametersToProcess = 1;
        RegularExpression = "-?[0-9]+";
        ExactMatchFailedMessage = "A negative or positive integer is expected.";
        }
        break;
      default:
        ExactMatchFailedMessage = QString("Type %1 not supported.").arg(static_cast<int>(type));
      }

  }

  ~CommandLineParserArgumentDescription(){}

  bool addParameter(const QString& value);

  QString helpText(int fieldWidth, const char charPad, const QString& settingsValue = "");

  QString LongArg;
  QString LongArgPrefix;
  QString ShortArg;
  QString ShortArgPrefix;
  QString ArgHelp;
  bool    IgnoreRest;
  int     NumberOfParametersToProcess;
  QString RegularExpression;
  QString ExactMatchFailedMessage;
  bool    Deprecated;

  QVariant       DefaultValue;
  QVariant       Value;
  QVariant::Type ValueType;
};

// --------------------------------------------------------------------------
bool CommandLineParserArgumentDescription::addParameter(const QString& value)
{
  if (!RegularExpression.isEmpty())
    {
    // Validate value
    QRegExp regexp(this->RegularExpression);
    if (!regexp.exactMatch(value))
      {
      return false;
      }
    }

  switch (Value.type())
    {
    case QVariant::String:
      {
      Value.setValue(value);
      }
      break;
    case QVariant::Bool:
      {
      Value.setValue(!QString::compare(value, "true", Qt::CaseInsensitive));
      }
      break;
    case QVariant::StringList:
      {
      if (Value.isNull())
        {
        QStringList list;
        list << value;
        Value.setValue(list);
        }
      else
        {
        QStringList list = Value.toStringList();
        list << value;
        Value.setValue(list);
        }
      }
      break;
    case QVariant::Int:
      {
      Value.setValue(value.toInt());
      }
      break;
    default:
      return false;
    }

  return true;
}

// --------------------------------------------------------------------------
QString CommandLineParserArgumentDescription::helpText(int fieldWidth, const char charPad,
                                                       const QString& settingsValue)
{
  QString text;
  QTextStream stream(&text);
  stream.setFieldAlignment(QTextStream::AlignLeft);
  stream.setPadChar(charPad);

  QString shortAndLongArg;
  if (!this->ShortArg.isEmpty())
    {
    shortAndLongArg += QString("  %1%2").arg(this->ShortArgPrefix).arg(this->ShortArg);
    }

  if (!this->LongArg.isEmpty())
    {
    if (this->ShortArg.isEmpty())
      {
      shortAndLongArg.append("  ");
      }
    else
      {
      shortAndLongArg.append(", ");
      }

    shortAndLongArg += QString("%1%2").arg(this->LongArgPrefix).arg(this->LongArg);
    }

  if(!this->ArgHelp.isEmpty())
    {
    stream.setFieldWidth(fieldWidth);
    }

  stream  << shortAndLongArg;
  stream.setFieldWidth(0);
  stream << this->ArgHelp;
  if (!settingsValue.isNull())
    {
    stream << " (default: " << settingsValue << ")";
    }
  else if (!this->DefaultValue.isNull())
    {
    stream << " (default: " << this->DefaultValue.toString() << ")";
    }
  stream << "\n";
  return text;
}

}

// --------------------------------------------------------------------------
// ctkCommandLineParser::ctkInternal class

// --------------------------------------------------------------------------
class ctkCommandLineParser::ctkInternal
{
public:
  ctkInternal(QSettings* settings)
    : Debug(false), FieldWidth(0), UseQSettings(false),
      Settings(settings), MergeSettings(true), StrictMode(false)
  {}

  ~ctkInternal() { qDeleteAll(ArgumentDescriptionList); }
  
  CommandLineParserArgumentDescription* argumentDescription(const QString& argument);
  
  QList<CommandLineParserArgumentDescription*>                 ArgumentDescriptionList;
  QHash<QString, CommandLineParserArgumentDescription*>        ArgNameToArgumentDescriptionMap;
  QMap<QString, QList<CommandLineParserArgumentDescription*> > GroupToArgumentDescriptionListMap;
  
  QStringList UnparsedArguments; 
  QStringList ProcessedArguments;
  QString     ErrorString;
  bool        Debug;
  int         FieldWidth;
  QString     LongPrefix;
  QString     ShortPrefix;
  QString     CurrentGroup;
  bool        UseQSettings;
  QPointer<QSettings> Settings;
  QString     DisableQSettingsLongArg;
  QString     DisableQSettingsShortArg;
  bool        MergeSettings;
  bool        StrictMode;
};

// --------------------------------------------------------------------------
// ctkCommandLineParser::ctkInternal methods

// --------------------------------------------------------------------------
CommandLineParserArgumentDescription*
  ctkCommandLineParser::ctkInternal::argumentDescription(const QString& argument)
{
  QString unprefixedArg = argument;
  if (!LongPrefix.isEmpty() && argument.startsWith(LongPrefix))
    {
    // Case when (ShortPrefix + UnPrefixedArgument) matches LongPrefix
    if (argument == LongPrefix && !ShortPrefix.isEmpty() && argument.startsWith(ShortPrefix))
      {
      unprefixedArg = argument.mid(ShortPrefix.length());
      }
    else
      {
      unprefixedArg = argument.mid(LongPrefix.length());
      }
    }
  else if (!ShortPrefix.isEmpty() && argument.startsWith(ShortPrefix))
    {
    unprefixedArg = argument.mid(ShortPrefix.length());
    }
  else if (!LongPrefix.isEmpty() && !ShortPrefix.isEmpty())
    {
    return 0;
    }

  if (this->ArgNameToArgumentDescriptionMap.contains(unprefixedArg))
    {
    return this->ArgNameToArgumentDescriptionMap[unprefixedArg];
    }
  return 0;
}

// --------------------------------------------------------------------------
// ctkCommandLineParser methods

// --------------------------------------------------------------------------
ctkCommandLineParser::ctkCommandLineParser(QSettings* settings)
{
  this->Internal = new ctkInternal(settings);
}

// --------------------------------------------------------------------------
ctkCommandLineParser::~ctkCommandLineParser()
{
  delete this->Internal;
}

// --------------------------------------------------------------------------
QHash<QString, QVariant> ctkCommandLineParser::parseArguments(const QStringList& arguments,
                                                              bool* ok)
{
  // Reset
  this->Internal->UnparsedArguments.clear();
  this->Internal->ProcessedArguments.clear();
  this->Internal->ErrorString.clear();
  foreach (CommandLineParserArgumentDescription* desc,
           this->Internal->ArgumentDescriptionList)
    {
    desc->Value = QVariant(desc->ValueType);
    if (desc->DefaultValue.isValid())
      {
      desc->Value = desc->DefaultValue;
      }
    }

  bool error = false;
  bool ignoreRest = false;
  bool useSettings = this->Internal->UseQSettings;
  CommandLineParserArgumentDescription * currentArgDesc = 0;
  QList<CommandLineParserArgumentDescription*> parsedArgDescriptions;
  for(int i = 1; i < arguments.size(); ++i)
    {
    QString argument = arguments.at(i);
    if (this->Internal->Debug) { qDebug() << "Processing" << argument; }

    // should argument be ignored ?
    if (ignoreRest)
      {
      if (this->Internal->Debug)
        {
        qDebug() << "  Skipping: IgnoreRest flag was been set";
        }
      this->Internal->UnparsedArguments << argument;
      continue;
      }

    // Skip if the argument does not start with the defined prefix
    if (!(argument.startsWith(this->Internal->LongPrefix)
      || argument.startsWith(this->Internal->ShortPrefix)))
      {
      if (this->Internal->StrictMode)
        {
        this->Internal->ErrorString = QString("Unknown argument %1").arg(argument);
        error = true;
        break;
        }
      if (this->Internal->Debug)
        {
        qDebug() << "  Skipping: It does not start with the defined prefix";
        }
      this->Internal->UnparsedArguments << argument;
      continue;
      }

    // Skip if argument has already been parsed ...
    if (this->Internal->ProcessedArguments.contains(argument))
      {
      if (this->Internal->StrictMode)
        {
        this->Internal->ErrorString = QString("Argument %1 already processed !").arg(argument);
        error = true;
        break;
        }
      if (this->Internal->Debug)
        {
        qDebug() << "  Skipping: Already processed !";
        }
      continue;
      }

    // Retrieve corresponding argument description
    currentArgDesc = this->Internal->argumentDescription(argument);

    // Is there a corresponding argument description ?
    if (currentArgDesc)
      {
      // If the argument is deprecated, print the help text but continue processing
      if (currentArgDesc->Deprecated)
        {
        qWarning().nospace() << "Deprecated argument " << argument << ": "  << currentArgDesc->ArgHelp;
        }
      else
        {
        parsedArgDescriptions.push_back(currentArgDesc);
        }

      // Is the argument the special "disable QSettings" argument?
      if ((!currentArgDesc->LongArg.isEmpty() && currentArgDesc->LongArg == this->Internal->DisableQSettingsLongArg)
        || (!currentArgDesc->ShortArg.isEmpty() && currentArgDesc->ShortArg == this->Internal->DisableQSettingsShortArg))
        {
        useSettings = false;
        }

      this->Internal->ProcessedArguments << currentArgDesc->ShortArg << currentArgDesc->LongArg;
      int numberOfParametersToProcess = currentArgDesc->NumberOfParametersToProcess;
      ignoreRest = currentArgDesc->IgnoreRest;
      if (this->Internal->Debug && ignoreRest)
        {
        qDebug() << "  IgnoreRest flag is True";
        }

      // Is the number of parameters associated with the argument being processed known ?
      if (numberOfParametersToProcess == 0)
        {
        currentArgDesc->addParameter("true");
        }
      else if (numberOfParametersToProcess > 0)
        {
        QString missingParameterError =
            "Argument %1 has %2 value(s) associated whereas exacly %3 are expected.";
        for(int j=1; j <= numberOfParametersToProcess; ++j)
          {
          if (i + j >= arguments.size())
            {
            this->Internal->ErrorString = 
                missingParameterError.arg(argument).arg(j-1).arg(numberOfParametersToProcess);
            if (this->Internal->Debug) { qDebug() << this->Internal->ErrorString; }
            if (ok) { *ok = false; }
            return QHash<QString, QVariant>();
            }
          QString parameter = arguments.at(i + j);
          if (this->Internal->Debug)
            {
            qDebug() << "  Processing parameter" << j << ", value:" << parameter;
            }
          if (this->argumentAdded(parameter))
            {
            this->Internal->ErrorString =
                missingParameterError.arg(argument).arg(j-1).arg(numberOfParametersToProcess);
            if (this->Internal->Debug) { qDebug() << this->Internal->ErrorString; }
            if (ok) { *ok = false; }
            return QHash<QString, QVariant>();
            }
          if (!currentArgDesc->addParameter(parameter))
            {
            this->Internal->ErrorString = QString(
                "Value(s) associated with argument %1 are incorrect. %2").
                arg(argument).arg(currentArgDesc->ExactMatchFailedMessage);

            if (this->Internal->Debug) { qDebug() << this->Internal->ErrorString; }
            if (ok) { *ok = false; }
            return QHash<QString, QVariant>();
            }
          }
        // Update main loop increment
        i = i + numberOfParametersToProcess;
        }
      else if (numberOfParametersToProcess == -1)
        {
        if (this->Internal->Debug)
          {
          qDebug() << "  Proccessing StringList ...";
          }
        int j = 1;
        while(j + i < arguments.size())
          {
          if (this->argumentAdded(arguments.at(j + i)))
            {
            if (this->Internal->Debug)
              {
              qDebug() << "  No more parameter for" << argument;
              }
            break;
            }
          QString parameter = arguments.at(j + i);
          if (this->Internal->Debug)
            {
            qDebug() << "  Processing parameter" << j << ", value:" << parameter;
            }
          if (!currentArgDesc->addParameter(parameter))
            {
            this->Internal->ErrorString = QString(
                "Value(s) associated with argument %1 are incorrect. %2").
                arg(argument).arg(currentArgDesc->ExactMatchFailedMessage);

            if (this->Internal->Debug) { qDebug() << this->Internal->ErrorString; }
            if (ok) { *ok = false; }
            return QHash<QString, QVariant>();
            }
          j++;
          }
        // Update main loop increment
        i = i + j;
        }
      }
    else
      {
      if (this->Internal->StrictMode)
        {
        this->Internal->ErrorString = QString("Unknown argument %1").arg(argument);
        error = true;
        break;
        }
      if (this->Internal->Debug)
        {
        qDebug() << "  Skipping: Unknown argument";
        }
      this->Internal->UnparsedArguments << argument;
      }
    }

  if (ok)
    {
    *ok = !error;
    }

  QSettings* settings = 0;
  if (this->Internal->UseQSettings && useSettings)
    {
    if (this->Internal->Settings)
      {
      settings = this->Internal->Settings;
      }
    else
      {
      // Use a default constructed QSettings instance
      settings = new QSettings();
      }
    }

  QHash<QString, QVariant> parsedArguments;
  QListIterator<CommandLineParserArgumentDescription*> it(this->Internal->ArgumentDescriptionList);
  while (it.hasNext())
    {
    QString key;
    CommandLineParserArgumentDescription* desc = it.next();
    if (!desc->LongArg.isEmpty())
      {
      key = desc->LongArg;
      }
    else
      {
      key = desc->ShortArg;
      }

    if (parsedArgDescriptions.contains(desc))
      {
      // The argument was supplied on the command line, so use the given value

      if (this->Internal->MergeSettings && settings)
        {
        // Merge with QSettings
        QVariant settingsVal = settings->value(key);

        if (desc->ValueType == QVariant::StringList &&
            settingsVal.canConvert(QVariant::StringList))
          {
          QStringList stringList = desc->Value.toStringList();
          stringList.append(settingsVal.toStringList());
          parsedArguments.insert(key, stringList);
          }
        else
          {
          // do a normal insert
          parsedArguments.insert(key, desc->Value);
          }
        }
      else
        {
        // No merging, just insert all user values
        parsedArguments.insert(key, desc->Value);
        }
      }
    else
      {
      if (settings)
        {
        // If there is a valid QSettings entry for the argument, use the value
        QVariant settingsVal = settings->value(key, desc->Value);
        if (!settingsVal.isNull())
          {
          parsedArguments.insert(key, settingsVal);
          }
        }
      else
        {
        // Just insert the arguments with valid default values
        if (!desc->Value.isNull())
          {
          parsedArguments.insert(key, desc->Value);
          }
        }
      }
    }

  // If we created a default QSettings instance, delete it
  if (settings && !this->Internal->Settings)
    {
    delete settings;
    }

  return parsedArguments;
}

// -------------------------------------------------------------------------
QHash<QString, QVariant> ctkCommandLineParser::parseArguments(int argc, char** argv, bool* ok)
{
  QStringList arguments;

  // Create a QStringList of arguments
  for(int i = 0; i < argc; ++i)
    {
    arguments << argv[i];
    }

  return this->parseArguments(arguments, ok);
}

// -------------------------------------------------------------------------
QString ctkCommandLineParser::errorString() const
{
  return this->Internal->ErrorString;
}

// -------------------------------------------------------------------------
const QStringList& ctkCommandLineParser::unparsedArguments() const
{
  return this->Internal->UnparsedArguments;
}

// --------------------------------------------------------------------------
void ctkCommandLineParser::addArgument(const QString& longarg, const QString& shortarg,
                                       QVariant::Type type, const QString& argHelp,
                                       const QVariant& defaultValue, bool ignoreRest,
                                       bool deprecated)
{
  Q_ASSERT_X(!(longarg.isEmpty() && shortarg.isEmpty()), "addArgument",
             "both long and short argument names are empty");
  if (longarg.isEmpty() && shortarg.isEmpty()) { return; }

  Q_ASSERT_X(!defaultValue.isValid() || defaultValue.type() == type, "addArgument",
             "defaultValue type does not match");
  if (defaultValue.isValid() && defaultValue.type() != type)
    throw std::logic_error("The QVariant type of defaultValue does not match the specified type");

  /* Make sure it's not already added */
  bool added = this->Internal->ArgNameToArgumentDescriptionMap.contains(longarg);
  Q_ASSERT_X(!added, "addArgument", "long argument already added");
  if (added) { return; }

  added = this->Internal->ArgNameToArgumentDescriptionMap.contains(shortarg);
  Q_ASSERT_X(!added, "addArgument", "short argument already added");
  if (added) { return; }

  CommandLineParserArgumentDescription* argDesc =
    new CommandLineParserArgumentDescription(longarg, this->Internal->LongPrefix,
                                             shortarg, this->Internal->ShortPrefix, type,
                                             argHelp, defaultValue, ignoreRest, deprecated);

  int argWidth = 0;
  if (!longarg.isEmpty())
    {
    this->Internal->ArgNameToArgumentDescriptionMap[longarg] = argDesc;
    argWidth += longarg.length() + this->Internal->LongPrefix.length();
    }
  if (!shortarg.isEmpty())
    {
    this->Internal->ArgNameToArgumentDescriptionMap[shortarg] = argDesc;
    argWidth += shortarg.length() + this->Internal->ShortPrefix.length() + 2;
    }
  argWidth += 5;

  // Set the field width for the arguments
  if (argWidth > this->Internal->FieldWidth)
    {
    this->Internal->FieldWidth = argWidth;
    }

  this->Internal->ArgumentDescriptionList << argDesc;
  this->Internal->GroupToArgumentDescriptionListMap[this->Internal->CurrentGroup] << argDesc;
}

// --------------------------------------------------------------------------
void ctkCommandLineParser::addDeprecatedArgument(
    const QString& longarg, const QString& shortarg, const QString& argHelp)
{
  addArgument(longarg, shortarg, QVariant::StringList, argHelp, QVariant(), false, true);
}

// --------------------------------------------------------------------------
bool ctkCommandLineParser::setExactMatchRegularExpression(
    const QString& argument, const QString& expression, const QString& exactMatchFailedMessage)
{
  CommandLineParserArgumentDescription * argDesc =
      this->Internal->argumentDescription(argument);
  if (!argDesc)
    {
    return false;
    }

  if (argDesc->Value.type() == QVariant::Bool)
    {
    return false;
    }
  argDesc->RegularExpression = expression;
  argDesc->ExactMatchFailedMessage = exactMatchFailedMessage;
  return true;
}

// --------------------------------------------------------------------------
int ctkCommandLineParser::fieldWidth() const
{
  return this->Internal->FieldWidth;
}

// --------------------------------------------------------------------------
void ctkCommandLineParser::beginGroup(const QString& description)
{
  this->Internal->CurrentGroup = description;
}

// --------------------------------------------------------------------------
void ctkCommandLineParser::endGroup()
{
  this->Internal->CurrentGroup.clear();
}

// --------------------------------------------------------------------------
void ctkCommandLineParser::enableSettings(const QString& disableLongArg, const QString& disableShortArg)
{
  this->Internal->UseQSettings = true;
  this->Internal->DisableQSettingsLongArg = disableLongArg;
  this->Internal->DisableQSettingsShortArg = disableShortArg;
}

// --------------------------------------------------------------------------
void ctkCommandLineParser::mergeSettings(bool merge)
{
  this->Internal->MergeSettings = merge;
}

// --------------------------------------------------------------------------
bool ctkCommandLineParser::settingsEnabled() const
{
  return this->Internal->UseQSettings;
}

// --------------------------------------------------------------------------
QString ctkCommandLineParser::helpText(const char charPad) const
{
  QString text;
  QTextStream stream(&text);

  QList<CommandLineParserArgumentDescription*> deprecatedArgs;

  // Loop over grouped argument descriptions
  QMapIterator<QString, QList<CommandLineParserArgumentDescription*> > it(
      this->Internal->GroupToArgumentDescriptionListMap);
  while(it.hasNext())
    {
    it.next();
    if (!it.key().isEmpty())
      {
      stream << "\n" << it.key() << "\n";
      }
    foreach(CommandLineParserArgumentDescription* argDesc, it.value())
      {
      if (argDesc->Deprecated)
        {
        deprecatedArgs << argDesc;
        }
      else
        {
        // Extract associated value from settings if any
        QString settingsValue;
        if (this->Internal->Settings)
          {
          QString key;
          if (!argDesc->LongArg.isEmpty())
            {
            key = argDesc->LongArg;
            }
          else
            {
            key = argDesc->ShortArg;
            }
          settingsValue = this->Internal->Settings->value(key).toString();
          }
        stream << argDesc->helpText(this->Internal->FieldWidth, charPad, settingsValue);
        }
      }
    }

  if (!deprecatedArgs.empty())
    {
    stream << "\nDeprecated arguments:\n";
    foreach(CommandLineParserArgumentDescription* argDesc, deprecatedArgs)
      {
      stream << argDesc->helpText(this->Internal->FieldWidth, charPad);
      }
    }

  return text;
}

// --------------------------------------------------------------------------
bool ctkCommandLineParser::argumentAdded(const QString& argument) const
{
  return this->Internal->ArgNameToArgumentDescriptionMap.contains(argument);
}

// --------------------------------------------------------------------------
bool ctkCommandLineParser::argumentParsed(const QString& argument) const
{
  return this->Internal->ProcessedArguments.contains(argument);
}

// --------------------------------------------------------------------------
void ctkCommandLineParser::setArgumentPrefix(const QString& longPrefix, const QString& shortPrefix)
{
  this->Internal->LongPrefix = longPrefix;
  this->Internal->ShortPrefix = shortPrefix;
}

// --------------------------------------------------------------------------
void ctkCommandLineParser::setStrictModeEnabled(bool strictMode)
{
  this->Internal->StrictMode = strictMode;
}