Merge pull request #2670 from laanwj/2013_05_datadir

qt: allow user to choose data directory

6 files changed, 671 insertions, 44 deletions

diff --git a/bitcoin-qt.pro b/bitcoin-qt.pro
index c36e384673..e2dab18abf 100644
--- a/bitcoin-qt.pro
+++ b/bitcoin-qt.pro
@@ -214,7 +214,8 @@ HEADERS += src/qt/bitcoingui.h \
     src/leveldb.h \
     src/threadsafety.h \
     src/limitedmap.h \
-    src/qt/splashscreen.h
+    src/qt/splashscreen.h \
+    src/qt/intro.h
 
 SOURCES += src/qt/bitcoin.cpp \
     src/qt/bitcoingui.cpp \
@@ -284,7 +285,8 @@ SOURCES += src/qt/bitcoin.cpp \
     src/noui.cpp \
     src/leveldb.cpp \
     src/txdb.cpp \
-    src/qt/splashscreen.cpp
+    src/qt/splashscreen.cpp \
+    src/qt/intro.cpp
 
 RESOURCES += src/qt/bitcoin.qrc
 
@@ -298,7 +300,8 @@ FORMS += src/qt/forms/sendcoinsdialog.ui \
     src/qt/forms/sendcoinsentry.ui \
     src/qt/forms/askpassphrasedialog.ui \
     src/qt/forms/rpcconsole.ui \
-    src/qt/forms/optionsdialog.ui
+    src/qt/forms/optionsdialog.ui \
+    src/qt/forms/intro.ui
 
 contains(USE_QRCODE, 1) {
 HEADERS += src/qt/qrcodedialog.h
diff --git a/src/qt/bitcoin.cpp b/src/qt/bitcoin.cpp
index 76e88b36a7..b0c45d6863 100644
--- a/src/qt/bitcoin.cpp
+++ b/src/qt/bitcoin.cpp
@@ -15,6 +15,7 @@
 #include "ui_interface.h"
 #include "paymentserver.h"
 #include "splashscreen.h"
+#include "intro.h"
 
 #include <QMessageBox>
 #if QT_VERSION < 0x050000
@@ -24,6 +25,7 @@
 #include <QTimer>
 #include <QTranslator>
 #include <QLibraryInfo>
+#include <QSettings>
 
 #if defined(BITCOIN_NEED_QT_PLUGINS) && !defined(_BITCOIN_QT_PLUGINS_INCLUDED)
 #define _BITCOIN_QT_PLUGINS_INCLUDED
@@ -110,6 +112,46 @@ static void handleRunawayException(std::exception *e)
     exit(1);
 }
 
+/** Set up translations */
+static void initTranslations(QTranslator &qtTranslatorBase, QTranslator &qtTranslator, QTranslator &translatorBase, QTranslator &translator)
+{
+    QSettings settings;
+
+    // Get desired locale (e.g. "de_DE")
+    // 1) System default language
+    QString lang_territory = QLocale::system().name();
+    // 2) Language from QSettings
+    QString lang_territory_qsettings = settings.value("language", "").toString();
+    if(!lang_territory_qsettings.isEmpty())
+        lang_territory = lang_territory_qsettings;
+    // 3) -lang command line argument
+    lang_territory = QString::fromStdString(GetArg("-lang", lang_territory.toStdString()));
+
+    // Convert to "de" only by truncating "_DE"
+    QString lang = lang_territory;
+    lang.truncate(lang_territory.lastIndexOf('_'));
+
+    // Load language files for configured locale:
+    // - First load the translator for the base language, without territory
+    // - Then load the more specific locale translator
+
+    // Load e.g. qt_de.qm
+    if (qtTranslatorBase.load("qt_" + lang, QLibraryInfo::location(QLibraryInfo::TranslationsPath)))
+        QApplication::installTranslator(&qtTranslatorBase);
+
+    // Load e.g. qt_de_DE.qm
+    if (qtTranslator.load("qt_" + lang_territory, QLibraryInfo::location(QLibraryInfo::TranslationsPath)))
+        QApplication::installTranslator(&qtTranslator);
+
+    // Load e.g. bitcoin_de.qm (shortcut "de" needs to be defined in bitcoin.qrc)
+    if (translatorBase.load(lang, ":/translations/"))
+        QApplication::installTranslator(&translatorBase);
+
+    // Load e.g. bitcoin_de_DE.qm (shortcut "de_DE" needs to be defined in bitcoin.qrc)
+    if (translator.load(lang_territory, ":/translations/"))
+        QApplication::installTranslator(&translator);
+}
+
 #ifndef BITCOIN_QT_TEST
 int main(int argc, char *argv[])
 {
@@ -130,6 +172,22 @@ int main(int argc, char *argv[])
     // Register meta types used for QMetaObject::invokeMethod
     qRegisterMetaType< bool* >();
 
+    // Application identification (must be set before OptionsModel is initialized,
+    // as it is used to locate QSettings)
+    QApplication::setOrganizationName("Bitcoin");
+    QApplication::setOrganizationDomain("bitcoin.org");
+    if (GetBoolArg("-testnet", false)) // Separate UI settings for testnet
+        QApplication::setApplicationName("Bitcoin-Qt-testnet");
+    else
+        QApplication::setApplicationName("Bitcoin-Qt");
+
+    // Now that QSettings are accessible, initialize translations
+    QTranslator qtTranslatorBase, qtTranslator, translatorBase, translator;
+    initTranslations(qtTranslatorBase, qtTranslator, translatorBase, translator);
+
+    // User language is set up: pick a data directory
+    Intro::pickDataDirectory();
+
     // Do this early as we don't want to bother initializing if we are just calling IPC
     // ... but do it after creating app, so QCoreApplication::arguments is initialized:
     if (PaymentServer::ipcSendCommandLine())
@@ -142,53 +200,15 @@ int main(int argc, char *argv[])
     // ... then bitcoin.conf:
     if (!boost::filesystem::is_directory(GetDataDir(false)))
     {
-        // This message can not be translated, as translation is not initialized yet
-        // (which not yet possible because lang=XX can be overridden in bitcoin.conf in the data directory)
-        QMessageBox::critical(0, "Bitcoin",
-                              QString("Error: Specified data directory \"%1\" does not exist.").arg(QString::fromStdString(mapArgs["-datadir"])));
+        QMessageBox::critical(0, QObject::tr("Bitcoin"),
+                              QObject::tr("Error: Specified data directory \"%1\" does not exist.").arg(QString::fromStdString(mapArgs["-datadir"])));
         return 1;
     }
     ReadConfigFile(mapArgs, mapMultiArgs);
 
-    // Application identification (must be set before OptionsModel is initialized,
-    // as it is used to locate QSettings)
-    QApplication::setOrganizationName("Bitcoin");
-    QApplication::setOrganizationDomain("bitcoin.org");
-    if (GetBoolArg("-testnet", false)) // Separate UI settings for testnet
-        QApplication::setApplicationName("Bitcoin-Qt-testnet");
-    else
-        QApplication::setApplicationName("Bitcoin-Qt");
-
     // ... then GUI settings:
     OptionsModel optionsModel;
 
-    // Get desired locale (e.g. "de_DE") from command line or use system locale
-    QString lang_territory = QString::fromStdString(GetArg("-lang", QLocale::system().name().toStdString()));
-    QString lang = lang_territory;
-    // Convert to "de" only by truncating "_DE"
-    lang.truncate(lang_territory.lastIndexOf('_'));
-
-    QTranslator qtTranslatorBase, qtTranslator, translatorBase, translator;
-    // Load language files for configured locale:
-    // - First load the translator for the base language, without territory
-    // - Then load the more specific locale translator
-
-    // Load e.g. qt_de.qm
-    if (qtTranslatorBase.load("qt_" + lang, QLibraryInfo::location(QLibraryInfo::TranslationsPath)))
-        app.installTranslator(&qtTranslatorBase);
-
-    // Load e.g. qt_de_DE.qm
-    if (qtTranslator.load("qt_" + lang_territory, QLibraryInfo::location(QLibraryInfo::TranslationsPath)))
-        app.installTranslator(&qtTranslator);
-
-    // Load e.g. bitcoin_de.qm (shortcut "de" needs to be defined in bitcoin.qrc)
-    if (translatorBase.load(lang, ":/translations/"))
-        app.installTranslator(&translatorBase);
-
-    // Load e.g. bitcoin_de_DE.qm (shortcut "de_DE" needs to be defined in bitcoin.qrc)
-    if (translator.load(lang_territory, ":/translations/"))
-        app.installTranslator(&translator);
-
     // Subscribe to global signals from core
     uiInterface.ThreadSafeMessageBox.connect(ThreadSafeMessageBox);
     uiInterface.ThreadSafeAskFee.connect(ThreadSafeAskFee);
diff --git a/src/qt/forms/intro.ui b/src/qt/forms/intro.ui
new file mode 100644
index 0000000000..0f6ae5a7d0
--- /dev/null
+++ b/src/qt/forms/intro.ui
@@ -0,0 +1,266 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>Intro</class>
+ <widget class="QDialog" name="Intro">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>674</width>
+    <height>363</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Welcome</string>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <widget class="QLabel" name="label_2">
+     <property name="styleSheet">
+      <string notr="true">QLabel { font-style:italic; }</string>
+     </property>
+     <property name="text">
+      <string>Welcome to Bitcoin-Qt.</string>
+     </property>
+     <property name="wordWrap">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <spacer name="verticalSpacer_4">
+     <property name="orientation">
+      <enum>Qt::Vertical</enum>
+     </property>
+     <property name="sizeType">
+      <enum>QSizePolicy::Minimum</enum>
+     </property>
+     <property name="sizeHint" stdset="0">
+      <size>
+       <width>20</width>
+       <height>15</height>
+      </size>
+     </property>
+    </spacer>
+   </item>
+   <item>
+    <widget class="QLabel" name="label_4">
+     <property name="text">
+      <string>As this is the first time the program is launched, you can choose where Bitcoin-Qt will store its data.</string>
+     </property>
+     <property name="wordWrap">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QLabel" name="sizeWarningLabel">
+     <property name="text">
+      <string>Bitcoin-Qt will download and store a copy of the Bitcoin block chain. At least %1GB of data will be stored in this directory, and it will grow over time. The wallet will also be stored in this directory.</string>
+     </property>
+     <property name="wordWrap">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QRadioButton" name="dataDirDefault">
+     <property name="text">
+      <string>Use the default data directory</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QRadioButton" name="dataDirCustom">
+     <property name="text">
+      <string>Use a custom data directory:</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout">
+     <property name="spacing">
+      <number>0</number>
+     </property>
+     <property name="sizeConstraint">
+      <enum>QLayout::SetDefaultConstraint</enum>
+     </property>
+     <item>
+      <spacer name="horizontalSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeType">
+        <enum>QSizePolicy::Fixed</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>60</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <layout class="QVBoxLayout" name="verticalLayout_2">
+       <property name="sizeConstraint">
+        <enum>QLayout::SetDefaultConstraint</enum>
+       </property>
+       <item>
+        <layout class="QHBoxLayout" name="horizontalLayout_2">
+         <item>
+          <widget class="QLineEdit" name="dataDirectory"/>
+         </item>
+         <item>
+          <widget class="QPushButton" name="ellipsisButton">
+           <property name="sizePolicy">
+            <sizepolicy hsizetype="Minimum" vsizetype="Fixed">
+             <horstretch>0</horstretch>
+             <verstretch>0</verstretch>
+            </sizepolicy>
+           </property>
+           <property name="maximumSize">
+            <size>
+             <width>30</width>
+             <height>16777215</height>
+            </size>
+           </property>
+           <property name="text">
+            <string notr="true">…</string>
+           </property>
+           <property name="autoDefault">
+            <bool>false</bool>
+           </property>
+          </widget>
+         </item>
+        </layout>
+       </item>
+       <item>
+        <spacer name="verticalSpacer_3">
+         <property name="orientation">
+          <enum>Qt::Vertical</enum>
+         </property>
+         <property name="sizeType">
+          <enum>QSizePolicy::Fixed</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>20</width>
+           <height>5</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+       <item>
+        <widget class="QLabel" name="freeSpace">
+         <property name="sizePolicy">
+          <sizepolicy hsizetype="Preferred" vsizetype="Expanding">
+           <horstretch>1</horstretch>
+           <verstretch>0</verstretch>
+          </sizepolicy>
+         </property>
+         <property name="text">
+          <string/>
+         </property>
+         <property name="wordWrap">
+          <bool>true</bool>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <spacer name="verticalSpacer_2">
+         <property name="orientation">
+          <enum>Qt::Vertical</enum>
+         </property>
+         <property name="sizeType">
+          <enum>QSizePolicy::Fixed</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>20</width>
+           <height>5</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+       <item>
+        <widget class="QLabel" name="errorMessage">
+         <property name="sizePolicy">
+          <sizepolicy hsizetype="Preferred" vsizetype="Expanding">
+           <horstretch>0</horstretch>
+           <verstretch>0</verstretch>
+          </sizepolicy>
+         </property>
+         <property name="textFormat">
+          <enum>Qt::RichText</enum>
+         </property>
+         <property name="wordWrap">
+          <bool>true</bool>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <spacer name="verticalSpacer">
+     <property name="orientation">
+      <enum>Qt::Vertical</enum>
+     </property>
+     <property name="sizeHint" stdset="0">
+      <size>
+       <width>20</width>
+       <height>40</height>
+      </size>
+     </property>
+    </spacer>
+   </item>
+   <item>
+    <widget class="QDialogButtonBox" name="buttonBox">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="standardButtons">
+      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources/>
+ <connections>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>accepted()</signal>
+   <receiver>Intro</receiver>
+   <slot>accept()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>248</x>
+     <y>254</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>157</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>rejected()</signal>
+   <receiver>Intro</receiver>
+   <slot>reject()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>316</x>
+     <y>260</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>286</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+ </connections>
+</ui>
diff --git a/src/qt/guiutil.cpp b/src/qt/guiutil.cpp
index 88a6e7226e..3d1e91efdc 100644
--- a/src/qt/guiutil.cpp
+++ b/src/qt/guiutil.cpp
@@ -500,7 +500,8 @@ HelpMessageBox::HelpMessageBox(QWidget *parent) :
     uiOptions = tr("UI options") + ":\n" +
         "  -lang=<lang>           " + tr("Set language, for example \"de_DE\" (default: system locale)") + "\n" +
         "  -min                   " + tr("Start minimized") + "\n" +
-        "  -splash                " + tr("Show splash screen on startup (default: 1)") + "\n";
+        "  -splash                " + tr("Show splash screen on startup (default: 1)") + "\n" +
+        "  -choosedatadir         " + tr("Choose data directory on startup (default: 0)") + "\n";
 
     setWindowTitle(tr("Bitcoin-Qt"));
     setTextFormat(Qt::PlainText);
diff --git a/src/qt/intro.cpp b/src/qt/intro.cpp
new file mode 100644
index 0000000000..51f3c812e4
--- /dev/null
+++ b/src/qt/intro.cpp
@@ -0,0 +1,270 @@
+#include "intro.h"
+#include "ui_intro.h"
+#include "util.h"
+
+#include <QFileDialog>
+#include <QSettings>
+#include <QMessageBox>
+
+#include <boost/filesystem.hpp>
+
+/* Minimum free space (in bytes) needed for data directory */
+static const uint64 GB_BYTES = 1000000000LL;
+static const uint64 BLOCK_CHAIN_SIZE = 10LL * GB_BYTES;
+
+/* Check free space asynchronously to prevent hanging the UI thread.
+
+   Up to one request to check a path is in flight to this thread; when the check()
+   function runs, the current path is requested from the associated Intro object.
+   The reply is sent back through a signal.
+
+   This ensures that no queue of checking requests is built up while the user is
+   still entering the path, and that always the most recently entered path is checked as
+   soon as the thread becomes available.
+*/
+class FreespaceChecker : public QObject
+{
+    Q_OBJECT
+public:
+    FreespaceChecker(Intro *intro);
+
+    enum Status {
+        ST_OK,
+        ST_ERROR
+    };
+
+public slots:
+    void check();
+
+signals:
+    void reply(int status, const QString &message, quint64 available);
+
+private:
+    Intro *intro;
+};
+
+#include "intro.moc"
+
+FreespaceChecker::FreespaceChecker(Intro *intro)
+{
+    this->intro = intro;
+}
+
+void FreespaceChecker::check()
+{
+    namespace fs = boost::filesystem;
+    QString dataDirStr = intro->getPathToCheck();
+    fs::path dataDir = fs::path(dataDirStr.toStdString());
+    uint64 freeBytesAvailable = 0;
+    int replyStatus = ST_OK;
+    QString replyMessage = tr("A new data directory will be created.");
+
+    /* Find first parent that exists, so that fs::space does not fail */
+    fs::path parentDir = dataDir;
+    while(parentDir.has_parent_path() && !fs::exists(parentDir))
+    {
+        parentDir = parentDir.parent_path();
+    }
+
+    try {
+        freeBytesAvailable = fs::space(parentDir).available;
+        if(fs::exists(dataDir))
+        {
+            if(fs::is_directory(dataDir))
+            {
+                QString separator = QDir::toNativeSeparators("/");
+                replyStatus = ST_OK;
+                replyMessage = tr("Directory already exists. Add <code>%1name</code> if you intend to create a new directory here.").arg(separator);
+            } else {
+                replyStatus = ST_ERROR;
+                replyMessage = tr("Path already exists, and is not a directory.");
+            }
+        }
+    } catch(fs::filesystem_error &e)
+    {
+        /* Parent directory does not exist or is not accessible */
+        replyStatus = ST_ERROR;
+        replyMessage = tr("Cannot create data directory here.");
+    }
+    emit reply(replyStatus, replyMessage, freeBytesAvailable);
+}
+
+
+Intro::Intro(QWidget *parent) :
+    QDialog(parent),
+    ui(new Ui::Intro),
+    thread(0),
+    signalled(false)
+{
+    ui->setupUi(this);
+    ui->sizeWarningLabel->setText(ui->sizeWarningLabel->text().arg(BLOCK_CHAIN_SIZE/GB_BYTES));
+    startThread();
+}
+
+Intro::~Intro()
+{
+    delete ui;
+    /* Ensure thread is finished before it is deleted */
+    emit stopThread();
+    thread->wait();
+}
+
+QString Intro::getDataDirectory()
+{
+    return ui->dataDirectory->text();
+}
+
+void Intro::setDataDirectory(const QString &dataDir)
+{
+    ui->dataDirectory->setText(dataDir);
+    if(dataDir == getDefaultDataDirectory())
+    {
+        ui->dataDirDefault->setChecked(true);
+        ui->dataDirectory->setEnabled(false);
+        ui->ellipsisButton->setEnabled(false);
+    } else {
+        ui->dataDirCustom->setChecked(true);
+        ui->dataDirectory->setEnabled(true);
+        ui->ellipsisButton->setEnabled(true);
+    }
+}
+
+QString Intro::getDefaultDataDirectory()
+{
+    return QString::fromStdString(GetDefaultDataDir().string());
+}
+
+void Intro::pickDataDirectory()
+{
+    namespace fs = boost::filesystem;;
+    QSettings settings;
+    /* If data directory provided on command line, no need to look at settings
+       or show a picking dialog */
+    if(!GetArg("-datadir", "").empty())
+        return;
+    /* 1) Default data directory for operating system */
+    QString dataDir = getDefaultDataDirectory();
+    /* 2) Allow QSettings to override default dir */
+    dataDir = settings.value("strDataDir", dataDir).toString();
+
+    if(!fs::exists(dataDir.toStdString()) || GetBoolArg("-choosedatadir", false))
+    {
+        /* If current default data directory does not exist, let the user choose one */
+        Intro intro;
+        intro.setDataDirectory(dataDir);
+        while(true)
+        {
+            if(!intro.exec())
+            {
+                /* Cancel clicked */
+                exit(0);
+            }
+            dataDir = intro.getDataDirectory();
+            try {
+                fs::create_directory(dataDir.toStdString());
+                break;
+            } catch(fs::filesystem_error &e) {
+                QMessageBox::critical(0, QObject::tr("Bitcoin"),
+                                      QObject::tr("Error: Specified data directory \"%1\" can not be created.").arg(dataDir));
+                /* fall through, back to choosing screen */
+            }
+        }
+
+        settings.setValue("strDataDir", dataDir);
+    }
+    SoftSetArg("-datadir", dataDir.toStdString());
+}
+
+void Intro::setStatus(int status, const QString &message, quint64 bytesAvailable)
+{
+    switch(status)
+    {
+    case FreespaceChecker::ST_OK:
+        ui->errorMessage->setText(message);
+        ui->errorMessage->setStyleSheet("");
+        break;
+    case FreespaceChecker::ST_ERROR:
+        ui->errorMessage->setText(tr("Error") + ": " + message);
+        ui->errorMessage->setStyleSheet("QLabel { color: #800000 }");
+        break;
+    }
+    /* Indicate number of bytes available */
+    if(status == FreespaceChecker::ST_ERROR)
+    {
+        ui->freeSpace->setText("");
+    } else {
+        QString freeString = QString::number(bytesAvailable/GB_BYTES) + tr("GB of free space available");
+        if(bytesAvailable < BLOCK_CHAIN_SIZE)
+        {
+            freeString += " " + tr("(of %1GB needed)").arg(BLOCK_CHAIN_SIZE/GB_BYTES);
+            ui->freeSpace->setStyleSheet("QLabel { color: #800000 }");
+        } else {
+            ui->freeSpace->setStyleSheet("");
+        }
+        ui->freeSpace->setText(freeString+".");
+    }
+    /* Don't allow confirm in ERROR state */
+    ui->buttonBox->button(QDialogButtonBox::Ok)->setEnabled(status != FreespaceChecker::ST_ERROR);
+}
+
+void Intro::on_dataDirectory_textChanged(const QString &dataDirStr)
+{
+    /* Disable OK button until check result comes in */
+    ui->buttonBox->button(QDialogButtonBox::Ok)->setEnabled(false);
+    checkPath(dataDirStr);
+}
+
+void Intro::on_ellipsisButton_clicked()
+{
+    QString dir = QFileDialog::getExistingDirectory(0, "Choose data directory", ui->dataDirectory->text());
+    if(!dir.isEmpty())
+        ui->dataDirectory->setText(dir);
+}
+
+void Intro::on_dataDirDefault_clicked()
+{
+    setDataDirectory(getDefaultDataDirectory());
+}
+
+void Intro::on_dataDirCustom_clicked()
+{
+    ui->dataDirectory->setEnabled(true);
+    ui->ellipsisButton->setEnabled(true);
+}
+
+void Intro::startThread()
+{
+    thread = new QThread(this);
+    FreespaceChecker *executor = new FreespaceChecker(this);
+    executor->moveToThread(thread);
+
+    connect(executor, SIGNAL(reply(int,QString,quint64)), this, SLOT(setStatus(int,QString,quint64)));
+    connect(this, SIGNAL(requestCheck()), executor, SLOT(check()));
+    /*  make sure executor object is deleted in its own thread */
+    connect(this, SIGNAL(stopThread()), executor, SLOT(deleteLater()));
+    connect(this, SIGNAL(stopThread()), thread, SLOT(quit()));
+
+    thread->start();
+}
+
+void Intro::checkPath(const QString &dataDir)
+{
+    mutex.lock();
+    pathToCheck = dataDir;
+    if(!signalled)
+    {
+        signalled = true;
+        emit requestCheck();
+    }
+    mutex.unlock();
+}
+
+QString Intro::getPathToCheck()
+{
+    QString retval;
+    mutex.lock();
+    retval = pathToCheck;
+    signalled = false; /* new request can be queued now */
+    mutex.unlock();
+    return retval;
+}
diff --git a/src/qt/intro.h b/src/qt/intro.h
new file mode 100644
index 0000000000..b246c65a82
--- /dev/null
+++ b/src/qt/intro.h
@@ -0,0 +1,67 @@
+#ifndef INTRO_H
+#define INTRO_H
+
+#include <QDialog>
+#include <QThread>
+#include <QMutex>
+
+namespace Ui {
+class Intro;
+}
+class FreespaceChecker;
+
+/** Introduction screen (pre-GUI startup).
+  Allows the user to choose a data directory,
+  in which the wallet and block chain will be stored.
+ */
+class Intro : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit Intro(QWidget *parent = 0);
+    ~Intro();
+
+    QString getDataDirectory();
+    void setDataDirectory(const QString &dataDir);
+
+    /**
+     * Determine data directory. Let the user choose if the current one doesn't exist.
+     *
+     * @note do NOT call global GetDataDir() before calling this function, this
+     * will cause the wrong path to be cached.
+     */
+    static void pickDataDirectory();
+
+    /**
+     * Determine default data directory for operating system.
+     */
+    static QString getDefaultDataDirectory();
+signals:
+    void requestCheck();
+    void stopThread();
+
+public slots:
+    void setStatus(int status, const QString &message, quint64 bytesAvailable);
+
+private slots:
+    void on_dataDirectory_textChanged(const QString &arg1);
+    void on_ellipsisButton_clicked();
+    void on_dataDirDefault_clicked();
+    void on_dataDirCustom_clicked();
+
+private:
+    Ui::Intro *ui;
+    QThread *thread;
+    QMutex mutex;
+    bool signalled;
+    QString pathToCheck;
+
+    void startThread();
+    void checkPath(const QString &dataDir);
+    QString getPathToCheck();
+
+    friend class FreespaceChecker;
+};
+
+#endif // INTRO_H