Allow renaming file via `set --script …`

This allows doing what the GUI renaming utilitiy does on the command-line.
If only renaming is wanted

README.md

@@ -369,12 +369,13 @@ Here are some Bash examples which illustrate getting and setting tag information
     - The script needs to be ECMAScript as supported by the Qt framework.
     - This feature requires the tag editor to be configured with Qt QML as JavaScript provider at
       compile time. Checkout the build instructions under "Building with Qt GUI" for details.
-    - The script needs to export a `main()` function. This function gets executed for every file and
-      passed an object representing this file as first argument.
+    - The script needs to export a `main()` function. This function is invoked for every file and
+      passed an object representing the current file as first argument.
     - Checkout the file `testfiles/set-tags.js` in this repository for an example that applies basic
       fixes and tries to fetch lyrics and cover art.
-    - The option `--pedantic debug` is not required but useful for debugging. You may also add
-      `--script-settings dryRun=1` and use that setting within the script as shown in the example.
+    - For debugging, the option `--pedantic debug` is very useful. You may also add
+      `--script-settings dryRun=1` and check for that setting within the script as shown in the
+      mentioned example script.
     - Common tag fields are exposed as object properties as shown in the mentioned example.
         - Only properties for fields that are supported by the tag are added to the "fields" object.
         - Adding properties of unsupported fields manually does not work; those will just be ignored.
@@ -394,6 +395,11 @@ Here are some Bash examples which illustrate getting and setting tag information
     - The script is executed before any other modifications are applied. So if you also specify
       values as usual (via `--values`) then these values have precedence over values set by the
       script.
+    - It is also possible to rename the file (via e.g. `file.rename(newPath)`). This will be done
+      immediately and also if `main()` returns a falsy value (so it is possible to only rename a
+      file without modifying it by returning a falsy value). If the specified path is relative, it
+      is interpreted relative to current directory of the file (and *not* to the current working
+      directory of the tag editor).
 
 ##### Further useful commands
 * Let the tag editor return with a non-zero exit code even if only non-fatal problems have been encountered

cli/mainfeatures.cpp

@@ -494,6 +494,7 @@ public:
 private:
     static void addWarnings(Diagnostics &diag, const std::string &context, const QList<QQmlError> &warnings);
 
+    const SetTagInfoArgs &args;
     int argc;
     QCoreApplication app;
     Diagnostics diag;
@@ -510,7 +511,8 @@ private:
  * - Logs status/problems directly in accordance with other parts of the CLI.
  */
 JavaScriptProcessor::JavaScriptProcessor(const SetTagInfoArgs &args)
-    : argc(0)
+    : args(args)
+    , argc(0)
     , app(argc, nullptr)
     , utility(new UtilityObject(&engine))
 {
@@ -567,7 +569,7 @@ JavaScriptProcessor::JavaScriptProcessor(const SetTagInfoArgs &args)
  */
 QJSValue JavaScriptProcessor::callMain(MediaFileInfo &mediaFileInfo, Diagnostics &diag)
 {
-    auto fileInfoObject = MediaFileInfoObject(mediaFileInfo, diag, &engine);
+    auto fileInfoObject = MediaFileInfoObject(mediaFileInfo, diag, &engine, args.quietArg.isPresent());
     auto fileInfoObjectValue = engine.newQObject(&fileInfoObject);
     auto context = argsToString("executing JavaScript for ", mediaFileInfo.fileName());
     utility->setDiag(&context, &diag);

cli/scriptapi.cpp

@@ -20,6 +20,8 @@
 
 #include <c++utilities/conversion/binaryconversion.h>
 #include <c++utilities/conversion/conversionexception.h>
+#include <c++utilities/conversion/stringbuilder.h>
+#include <c++utilities/io/path.h>
 
 #include <qtutilities/misc/compat.h>
 
@@ -33,6 +35,7 @@
 #include <QJSValueIterator>
 #include <QRegularExpression>
 
+#include <filesystem>
 #include <iostream>
 #include <limits>
 #include <type_traits>
@@ -558,11 +561,13 @@ void TagObject::applyChanges()
     }
 }
 
-MediaFileInfoObject::MediaFileInfoObject(TagParser::MediaFileInfo &mediaFileInfo, TagParser::Diagnostics &diag, QJSEngine *engine, QObject *parent)
+MediaFileInfoObject::MediaFileInfoObject(
+    TagParser::MediaFileInfo &mediaFileInfo, TagParser::Diagnostics &diag, QJSEngine *engine, bool quiet, QObject *parent)
     : QObject(parent)
     , m_f(mediaFileInfo)
     , m_diag(diag)
     , m_engine(engine)
+    , m_quiet(quiet)
 {
 }
 
@@ -621,4 +626,27 @@ void MediaFileInfoObject::applyChanges()
     }
 }
 
+bool MediaFileInfoObject::rename(const QString &newPath)
+{
+    const auto from = m_f.path();
+    const auto fromNative = std::filesystem::path(CppUtilities::makeNativePath(from));
+    const auto toRelUtf8 = newPath.toUtf8();
+    const auto toRelView = CppUtilities::PathStringView(toRelUtf8.data(), static_cast<std::size_t>(toRelUtf8.size()));
+    const auto toNative = fromNative.parent_path().append(CppUtilities::makeNativePath(toRelView));
+    const auto toView = CppUtilities::extractNativePath(toNative.native());
+    try {
+        m_f.stream().close();
+        std::filesystem::rename(fromNative, toNative);
+        m_f.reportPathChanged(toView);
+        m_f.stream().open(m_f.path(), std::ios_base::in | std::ios_base::out | std::ios_base::binary);
+    } catch (const std::runtime_error &e) {
+        m_diag.emplace_back(TagParser::DiagLevel::Critical, e.what(), CppUtilities::argsToString("renaming \"", from, "\" to \"", toView));
+        return false;
+    }
+    if (!m_quiet) {
+        std::cout << " - Renamed \"" << from << "\" to \"" << toView << "\"\n";
+    }
+    return true;
+}
+
 } // namespace Cli

cli/scriptapi.h

@@ -193,7 +193,8 @@ class MediaFileInfoObject : public QObject {
     Q_PROPERTY(QList<TagObject *> tags READ tags)
 
 public:
-    explicit MediaFileInfoObject(TagParser::MediaFileInfo &mediaFileInfo, TagParser::Diagnostics &diag, QJSEngine *engine, QObject *parent = nullptr);
+    explicit MediaFileInfoObject(
+        TagParser::MediaFileInfo &mediaFileInfo, TagParser::Diagnostics &diag, QJSEngine *engine, bool quiet, QObject *parent = nullptr);
     ~MediaFileInfoObject() override;
 
     TagParser::MediaFileInfo &fileInfo();
@@ -207,12 +208,14 @@ public:
 
 public Q_SLOTS:
     void applyChanges();
+    bool rename(const QString &newPath);
 
 private:
     TagParser::MediaFileInfo &m_f;
     TagParser::Diagnostics &m_diag;
     QJSEngine *m_engine;
     QList<TagObject *> m_tags;
+    bool m_quiet;
 };
 
 inline TagParser::MediaFileInfo &MediaFileInfoObject::fileInfo()