Git: Show detached HEAD in branches view when applicable

Fixes: QTCREATORBUG-21311
Change-Id: Ia4297d23a965d83ea2814bd1e41f35a3017b8e9b
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/git/branchmodel.cpp

@@ -161,6 +161,13 @@ public:
         return n;
     }
 
+    BranchNode *prepend(BranchNode *n)
+    {
+        n->parent = this;
+        children.prepend(n);
+        return n;
+    }
+
     QStringList childrenNames() const
     {
         if (children.count() > 0) {
@@ -206,7 +213,9 @@ public:
     QString workingDirectory;
     BranchNode *rootNode;
     BranchNode *currentBranch = nullptr;
+    BranchNode *headNode = nullptr;
     QString currentSha;
+    QDateTime currentDateTime;
     QStringList obsoleteLocalBranches;
     bool oldBranchesIncluded = false;
 };
@@ -340,7 +349,7 @@ Qt::ItemFlags BranchModel::flags(const QModelIndex &index) const
     if (!node)
         return Qt::NoItemFlags;
     Qt::ItemFlags res = Qt::ItemIsSelectable | Qt::ItemIsEnabled;
-    if (node->isLeaf() && node->isLocal() && index.column() == 0)
+    if (node != d->headNode && node->isLeaf() && node->isLocal() && index.column() == 0)
         res |= Qt::ItemIsEditable;
     return res;
 }
@@ -355,7 +364,9 @@ void BranchModel::clear()
         d->rootNode->children.takeLast();
 
     d->currentSha.clear();
+    d->currentDateTime = QDateTime();
     d->currentBranch = nullptr;
+    d->headNode = nullptr;
     d->obsoleteLocalBranches.clear();
 }
 
@@ -368,7 +379,7 @@ bool BranchModel::refresh(const QString &workingDirectory, QString *errorMessage
         return true;
     }
 
-    d->currentSha = d->client->synchronousTopRevision(workingDirectory);
+    d->currentSha = d->client->synchronousTopRevision(workingDirectory, &d->currentDateTime);
     const QStringList args = {"--format=%(objectname)\t%(refname)\t%(upstream:short)\t"
                               "%(*objectname)\t%(committerdate:raw)\t%(*committerdate:raw)"};
     QString output;
@@ -387,6 +398,12 @@ bool BranchModel::refresh(const QString &workingDirectory, QString *errorMessage
             d->currentBranch = nullptr;
         setCurrentBranch();
     }
+    if (!d->currentBranch) {
+        BranchNode *local = d->rootNode->children.at(LocalBranches);
+        d->currentBranch = d->headNode = new BranchNode(tr("Detached HEAD"), "HEAD", QString(),
+                                                        d->currentDateTime);
+        local->prepend(d->headNode);
+    }
 
     endResetModel();
 
@@ -458,6 +475,8 @@ QString BranchModel::fullName(const QModelIndex &idx, bool includePrefix) const
     BranchNode *node = indexToNode(idx);
     if (!node || !node->isLeaf())
         return QString();
+    if (node == d->headNode)
+        return QString("HEAD");
     return node->fullName(includePrefix).join('/');
 }
 
@@ -490,12 +509,20 @@ bool BranchModel::hasTags() const
     return d->rootNode->children.count() > Tags;
 }
 
+bool BranchModel::isHead(const QModelIndex &idx) const
+{
+    if (!idx.isValid())
+        return false;
+    BranchNode *node = indexToNode(idx);
+    return node == d->headNode;
+}
+
 bool BranchModel::isLocal(const QModelIndex &idx) const
 {
     if (!idx.isValid())
         return false;
     BranchNode *node = indexToNode(idx);
-    return node->isLocal();
+    return node == d->headNode ? false : node->isLocal();
 }
 
 bool BranchModel::isLeaf(const QModelIndex &idx) const

src/plugins/git/branchmodel.h

@@ -72,6 +72,7 @@ public:
     QString sha(const QModelIndex &idx) const;
     QDateTime dateTime(const QModelIndex &idx) const;
     bool hasTags() const;
+    bool isHead(const QModelIndex &idx) const;
     bool isLocal(const QModelIndex &idx) const;
     bool isLeaf(const QModelIndex &idx) const;
     bool isTag(const QModelIndex &idx) const;

src/plugins/git/branchview.cpp

@@ -298,12 +298,12 @@ bool BranchView::add()
         trackedBranch = m_model->fullName(trackedIndex);
     }
     const bool isLocal = m_model->isLocal(trackedIndex);
-    const bool isTag = m_model->isTag(trackedIndex);
+    const bool isTracked = !m_model->isHead(trackedIndex) && !m_model->isTag(trackedIndex);
 
     const QStringList localNames = m_model->localBranchNames();
 
     QString suggestedName;
-    if (!isTag) {
+    if (isTracked) {
         const QString suggestedNameBase = trackedBranch.mid(trackedBranch.lastIndexOf('/') + 1);
         suggestedName = suggestedNameBase;
         int i = 2;
@@ -315,7 +315,7 @@ bool BranchView::add()
 
     BranchAddDialog branchAddDialog(localNames, true, this);
     branchAddDialog.setBranchName(suggestedName);
-    branchAddDialog.setTrackedBranchName(isTag ? QString() : trackedBranch, !isLocal);
+    branchAddDialog.setTrackedBranchName(isTracked ? trackedBranch : QString(), !isLocal);
 
     if (branchAddDialog.exec() == QDialog::Accepted) {
         QModelIndex idx = m_model->addBranch(branchAddDialog.branchName(), branchAddDialog.track(), trackedIndex);

src/plugins/git/gitclient.cpp

@@ -1557,14 +1557,20 @@ bool GitClient::synchronousRevParseCmd(const QString &workingDirectory, const QS
 }
 
 // Retrieve head revision
-QString GitClient::synchronousTopRevision(const QString &workingDirectory)
+QString GitClient::synchronousTopRevision(const QString &workingDirectory, QDateTime *dateTime)
 {
-    QString revision;
-    QString errorMessage;
-    if (!synchronousRevParseCmd(workingDirectory, HEAD, &revision, &errorMessage))
+    const QStringList arguments = {"show", "-s", "--pretty=format:%H:%ct", HEAD};
+    const SynchronousProcessResponse resp = vcsFullySynchronousExec(
+                workingDirectory, arguments, silentFlags);
+    if (resp.result != SynchronousProcessResponse::Finished)
         return QString();
-
-    return revision;
+    const QStringList output = resp.stdOut().trimmed().split(':');
+    if (dateTime && output.size() > 1) {
+        bool ok = false;
+        const qint64 timeT = output.at(1).toLongLong(&ok);
+        *dateTime = ok ? QDateTime::fromSecsSinceEpoch(timeT) : QDateTime();
+    }
+    return output.first();
 }
 
 void GitClient::synchronousTagsForCommit(const QString &workingDirectory, const QString &revision,

src/plugins/git/gitclient.h

@@ -234,7 +234,7 @@ public:
     QString synchronousTopic(const QString &workingDirectory) const;
     bool synchronousRevParseCmd(const QString &workingDirectory, const QString &ref,
                                 QString *output, QString *errorMessage = nullptr) const;
-    QString synchronousTopRevision(const QString &workingDirectory);
+    QString synchronousTopRevision(const QString &workingDirectory, QDateTime *dateTime = nullptr);
     void synchronousTagsForCommit(const QString &workingDirectory, const QString &revision,
                                   QString &precedes, QString &follows) const;
     bool isRemoteCommit(const QString &workingDirectory, const QString &commit);