VCS[git], CodePaster: Add support for applying patches.

Modify CodePaster::fetch to do a mimetype detection on the
content, create a filename with the matching extension and
open that file.
This gives correct syntax highlighting  and makes "Save as"
more convenient. Keep the file around and delete on exit.

Modify patch mimetype with some content detection (higher priority
than C++).

Add a "current patch file" to the VCSBasePlugin::State. Add "Apply
patch" to git with whitespace fix.

src/plugins/cpaster/cpasterplugin.cpp

@@ -43,13 +43,18 @@
 #include <coreplugin/actionmanager/command.h>
 #include <coreplugin/coreconstants.h>
 #include <coreplugin/editormanager/editormanager.h>
+#include <coreplugin/mimedatabase.h>
 #include <coreplugin/icore.h>
 #include <coreplugin/messagemanager.h>
 #include <coreplugin/uniqueidmanager.h>
+#include <utils/qtcassert.h>
 #include <texteditor/itexteditor.h>
 
 #include <QtCore/QtPlugin>
 #include <QtCore/QDebug>
+#include <QtCore/QDir>
+#include <QtCore/QFileInfo>
+#include <QtCore/QTemporaryFile>
 #include <QtGui/QAction>
 #include <QtGui/QApplication>
 #include <QtGui/QClipboard>
@@ -130,6 +135,16 @@ void CodepasterPlugin::extensionsInitialized()
 {
 }
 
+void CodepasterPlugin::shutdown()
+{
+    // Delete temporary, fetched files
+    foreach(const QString &fetchedSnippet, m_fetchedSnippets) {
+        QFile file(fetchedSnippet);
+        if (file.exists())
+            file.remove();
+    }
+}
+
 void CodepasterPlugin::post()
 {
     IEditor* editor = EditorManager::instance()->currentEditor();
@@ -250,18 +265,100 @@ void CodepasterPlugin::finishPost(const QString &link)
                                                            m_settingsPage->displayOutput());
 }
 
+// Extract the characters that can be used for a file name from a title
+// "CodePaster.com-34" -> "CodePastercom34".
+static inline QString filePrefixFromTitle(const QString &title)
+{
+    QString rc;
+    const int titleSize = title.size();
+    rc.reserve(titleSize);
+    for (int i = 0; i < titleSize; i++)
+        if (title.at(i).isLetterOrNumber())
+            rc.append(title.at(i));
+    if (rc.isEmpty())
+        rc = QLatin1String("qtcreator");
+    return rc;
+}
+
+// Return a temp file pattern with extension or not
+static inline QString tempFilePattern(const QString &prefix,
+                                      const QString &extension = QString())
+{
+    // Get directory
+    QString pattern = QDir::tempPath();
+    if (!pattern.endsWith(QDir::separator()))
+        pattern.append(QDir::separator());
+    // Prefix, placeholder, extension
+    pattern += prefix;
+    pattern += QLatin1String("_XXXXXX");
+    if (!extension.isEmpty()) {
+       pattern += QLatin1Char('.');
+       pattern += extension;
+    }
+    return pattern;
+}
+
+typedef QSharedPointer<QTemporaryFile> TemporaryFilePtr;
+
+// Write an a temporary file.
+TemporaryFilePtr writeTemporaryFile(const QString &namePattern,
+                                    const QString &contents,
+                                    QString *errorMessage)
+{
+    TemporaryFilePtr tempFile(new QTemporaryFile(namePattern));
+    if (!tempFile->open()) {
+        *errorMessage = QString::fromLatin1("Unable to open temporary file %1").arg(tempFile->errorString());
+        return TemporaryFilePtr();
+    }
+    tempFile->write(contents.toUtf8());
+    tempFile->close();
+    return tempFile;
+}
+
 void CodepasterPlugin::finishFetch(const QString &titleDescription,
                                    const QString &content,
                                    bool error)
 {
-    QString title = titleDescription;
+    Core::MessageManager *messageManager = ICore::instance()->messageManager();
+    // Failure?
     if (error) {
-        ICore::instance()->messageManager()->printToOutputPane(content, true);
-    } else {
-        EditorManager* manager = EditorManager::instance();
-        IEditor* editor = manager->openEditorWithContents(Core::Constants::K_DEFAULT_TEXT_EDITOR_ID, &title, content);
-        manager->activateEditor(editor);
+        messageManager->printToOutputPane(content, true);
+        return;
     }
+    // Write the file out and do a mime type detection on the content. Note
+    // that for the initial detection, there must not be a suffix
+    // as we want mime type detection to trigger on the content and not on
+    // higher-prioritized suffixes.
+    const QString filePrefix = filePrefixFromTitle(titleDescription);
+    QString errorMessage;
+    TemporaryFilePtr tempFile = writeTemporaryFile(tempFilePattern(filePrefix), content, &errorMessage);
+    if (tempFile.isNull()) {
+        messageManager->printToOutputPane(errorMessage);
+        return;
+    }
+    // If the mime type has a preferred suffix (cpp/h/patch...), use that for
+    // the temporary file. This is to make it more convenient to "Save as"
+    // for the user and also to be able to tell a patch or diff in the VCS plugins
+    // by looking at the file name of FileManager::currentFile() without expensive checking.
+    if (const Core::MimeType mimeType = Core::ICore::instance()->mimeDatabase()->findByFile(QFileInfo(tempFile->fileName()))) {
+        const QString preferredSuffix = mimeType.preferredSuffix();
+        if (!preferredSuffix.isEmpty()) {
+            tempFile = writeTemporaryFile(tempFilePattern(filePrefix, preferredSuffix), content, &errorMessage);
+            if (tempFile.isNull()) {
+                messageManager->printToOutputPane(errorMessage);
+                return;
+            }
+        }
+    }
+    // Keep the file and store in list of files to be removed.
+    tempFile->setAutoRemove(false);
+    const QString fileName = tempFile->fileName();
+    m_fetchedSnippets.push_back(fileName);
+    // Open editor with title.
+    Core::IEditor* editor = EditorManager::instance()->openEditor(fileName);
+    QTC_ASSERT(editor, return)
+    editor->setDisplayName(titleDescription);
+    EditorManager::instance()->activateEditor(editor);
 }
 
 Q_EXPORT_PLUGIN(CodepasterPlugin)