/**
 * @file ssuvariables.cpp
 * @copyright 2013 Jolla Ltd.
 * @author Bernd Wachter <bwachter@lart.info>
 * @date 2013
 */

#include <QStringList>
#include <QRegExp>
#include <QStringRef>

#include "ssuvariables.h"
#include "ssulog.h"

#include "../constants.h"

SsuVariables::SsuVariables(): QObject() {

}

QString SsuVariables::defaultSection(SsuSettings *settings, QString section){
 QStringList parts = section.split("-");

 if (section.startsWith("var-"))
   parts.insert(1, "default");
 else
   parts.replace(0, "default");

 QString key = parts.join("-");

 if (settings->childGroups().contains(key))
   return key;
 else
   return "";
}

QString SsuVariables::resolveString(QString pattern, QHash<QString, QString> *variables, int recursionDepth){
  if (recursionDepth >= SSU_MAX_RECURSION){
    return "maximum-recursion-level-reached";
  }

  QRegExp regex("%\\\([^%]*\\\)", Qt::CaseSensitive, QRegExp::RegExp2);
  regex.setMinimal(true);

  int pos = 0;
  while ((pos = regex.indexIn(pattern, pos)) != -1){
    QString match = regex.cap(0);

    if (match.contains(":")){
      // variable is special, resolve before replacing
      QString variable = resolveVariable(match, variables);
      pattern.replace(match, variable);
      pos += variable.length();
    } else {
      // look up variable name in hashmap, and replace it with stored value,
      // if found, or ""
      QString variableName = match;
      variableName.remove(0,2);
      variableName.chop(1);
      if (variables->contains(variableName)){
        pattern.replace(match, variables->value(variableName));
        pos += variables->value(variableName).length();
      } else
        pattern.replace(match, "");
    }
  }

  // check if string still contains variables, and recurse
  if (regex.indexIn(pattern, 0) != -1)
    pattern = resolveString(pattern, variables, recursionDepth + 1);

  return pattern;
}

QString SsuVariables::resolveVariable(QString variable, QHash<QString, QString> *variables){
  QString variableValue = "";

  if (variable.endsWith(")"))
    variable.chop(1);
  if (variable.startsWith("%("))
    variable.remove(0,2);

  // hunt for your colon
  int magic = variable.indexOf(":");

  // seems you misplaced your colon
  if (magic == -1) return variable;

  QStringRef variableName(&variable, 0, magic);
  QStringRef variableSub(&variable, magic + 2, variable.length() - magic - 2);

  // Fill in variable value for later tests, if it exists
  if (variables->contains(variableName.toString()))
    variableValue = variables->value(variableName.toString());

  // find the operator who's after your colon
  QChar op;
  if (variable.length() > magic +1)
    op = variable.at(magic + 1);

  switch(op.toLatin1()){
    case '-':
      // substitute default value if variable is empty
      if (variableValue == "")
        return variableSub.toString();
      break;
    case '+':
      // substitute default value if variable is not empty
      if (variableValue != "")
        return variableSub.toString();
      break;
    case '=': {
      // %(%(foo):=bar?foobar|baz)
      // if foo == bar then return foobar, else baz
      QString sub = variableSub.toString();
      QString a = sub.left(sub.indexOf("?"));
      QString b = sub.right(sub.length() - sub.indexOf("?") - 1);
      if (b.indexOf("|") == -1)
        return b;
      if (variableName == a)
        return b.left(b.indexOf("|"));
      else
        return b.right(b.length() - b.indexOf("|") - 1);
    }
  }

  // no proper substitution found -> return default value
  return variableValue;
}

void SsuVariables::setSettings(SsuSettings *settings){
  m_settings = settings;
}

SsuSettings *SsuVariables::settings(){
  return m_settings;
}

/// @todo add override capability with an override-section in ssu.ini
QVariant SsuVariables::variable(QString section, const QString &key){
  if (m_settings != NULL)
    return variable(m_settings, section, key);
  else
    return QVariant();
}

QVariant SsuVariables::variable(SsuSettings *settings, QString section, const QString &key){
  QVariant value;

  value = readVariable(settings, section, key, 0);

  // first check if the value is defined in the main section, and fall back
  // to default sections
  if (value.type() == QMetaType::UnknownType){
    QString dSection = defaultSection(settings, section);
    if (!dSection.isEmpty())
      value = readVariable(settings, dSection, key, 0, false);
  }

  return value;
}

void SsuVariables::variableSection(QString section, QHash<QString, QString> *storageHash){
  if (m_settings != NULL)
    variableSection(m_settings, section, storageHash);
}

void SsuVariables::variableSection(SsuSettings *settings, QString section, QHash<QString, QString> *storageHash){

  QString dSection = defaultSection(settings, section);
  if (dSection.isEmpty())
    readSection(settings, section, storageHash, 0);
  else {
    readSection(settings, dSection, storageHash, 0);
    readSection(settings, section, storageHash, 0, false);
  }
}

// resolve a configuration section, recursively following all 'variables' sections.
// variables which exist in more than one section will get overwritten when discovered
// again
// the section itself gets evaluated at the end, again having a chance to overwrite variables
void SsuVariables::readSection(SsuSettings *settings, QString section,
                               QHash<QString, QString> *storageHash, int recursionDepth,
                               bool logOverride){
  if (recursionDepth >= SSU_MAX_RECURSION){
    SsuLog::instance()->print(LOG_WARNING,
                              QString("Maximum recursion depth for resolving section %1 from %2")
                                      .arg(section)
                                      .arg(settings->fileName()));
    return;
  }

  if (settings->contains(section + "/variables")){
    // child should log unless the parent is a default section
    bool childLogOverride = true;
    if (section.startsWith("default-") || section.startsWith("var-default-"))
      childLogOverride = false;

    QStringList sections = settings->value(section + "/variables").toStringList();
    foreach(const QString &section, sections){
      if (section.startsWith("var-"))
        readSection(settings, section, storageHash, recursionDepth + 1, childLogOverride);
      else
        readSection(settings, "var-" + section, storageHash,
                    recursionDepth + 1, childLogOverride);
    }
  }

  settings->beginGroup(section);
  if (settings->group() != section)
    return;

  QStringList locals;
  if (settings->contains("local"))
    locals = settings->value("local").toStringList();

  QStringList keys = settings->allKeys();
  foreach (const QString &key, keys){
    // local variable
    if (key.startsWith("_"))
        continue;

    if (locals.contains(key))
      continue;

    if (key == "variables" || key == "local")
      continue;

    if (storageHash->contains(key) && logOverride){
      SsuLog::instance()->print(LOG_DEBUG,
                                QString("Variable %1 overwritten from %2::%3")
                                .arg(key)
                                .arg(settings->fileName())
                                .arg(section));
    }
    storageHash->insert(key, settings->value(key).toString());
  }
  settings->endGroup();
}

QVariant SsuVariables::readVariable(SsuSettings *settings, QString section, const QString &key,
                                    int recursionDepth, bool logOverride){
  QVariant value;

  if (recursionDepth >= SSU_MAX_RECURSION){
    SsuLog::instance()->print(LOG_WARNING,
                              QString("Maximum recursion depth for resolving %1 from %2::%3")
                                      .arg(key)
                                      .arg(settings->fileName())
                                      .arg(section));
    return value;
  }

  // variables directly in the section take precedence
  if (settings->contains(section + "/" + key)){
    return settings->value(section + "/" + key);
  }

  /// @todo add logging for overrides
  if (settings->contains(section + "/variables")){
    // child should log unless the parent is a default section
    bool childLogOverride = true;
    if (section.startsWith("default-") || section.startsWith("var-default-"))
      childLogOverride = false;

    QStringList sections = settings->value(section + "/variables").toStringList();
    foreach(const QString &section, sections){
      if (section.startsWith("var-"))
        value = readVariable(settings, section, key, recursionDepth + 1, childLogOverride);
      else
        value = readVariable(settings, "var-" + section, key,
                    recursionDepth + 1, childLogOverride);
    }
  }

  return value;
}