Add registerUriScheme() to qx-system

lib/core/include/qx/core/qx-system.h

@@ -25,6 +25,8 @@ QX_CORE_EXPORT SystemError cleanKillProcess(quint32 processId);
 QX_CORE_EXPORT SystemError forceKillProcess(quint32 processId);
 
 QX_CORE_EXPORT bool enforceSingleInstance(QString uniqueAppId);
+
+QX_CORE_EXPORT bool registerUriScheme(const QString& scheme, const QString& command);
 }
 
 #endif // QX_SYSTEM_H

lib/core/src/qx-system.cpp

@@ -123,4 +123,17 @@ bool processIsRunning(quint32 processId) { return processName(processId).isNull(
  *  changed in future revisions once set.
  */
 
+/*!
+ *  @fn bool registerUriScheme(const QString& scheme, const QString& command)
+ *
+ *  Registers the custom URI scheme @a scheme with the system. The scheme is configued so that
+ *  when a URL that uses the scheme is followed, the command @a command will be executed with
+ *  the scheme URL automatically passed as the last argument.
+ *
+ *  @a scheme cannot contains whitespace.
+ *
+ *  @note On Linux this function only works for distibutions that can utilize FreeDesktop
+ *  XDG Desktop Entries.
+ */
+
 }

lib/core/src/qx-system_linux.cpp

@@ -13,6 +13,9 @@
 #include <QFile>
 #include <QDir>
 #include <QDirIterator>
+#include <QSettings>
+#include <QProcess>
+#include <QStandardPaths>
 
 // Inner-component Includes
 #include <qx/core/qx-regularexpression.h>
@@ -297,4 +300,40 @@ bool enforceSingleInstance(QString uniqueAppId)
     return true;
 }
 
+bool registerUriScheme(const QString& scheme, const QString& command)
+{
+    if(scheme.contains(QChar::Space))
+        return false;
+
+    // Get desktop entry path
+    QString XDG_DATA_HOME = QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation);
+    QString dEntryFilename = scheme + u"-scheme-handler.desktop"_s;
+    QString dEntryPath = XDG_DATA_HOME + u"/applications/"_s + dEntryFilename;
+    QString xSchemeHandler = u"x-scheme-handler/"_s + scheme;
+
+    // Create desktop entry
+    QSettings de(dEntryPath, QSettings::IniFormat);
+    de.beginGroup(u"Desktop Entry"_s);
+    de.setValue(u"Type"_s, u"Application"_s);
+    de.setValue(u"Name"_s, scheme.toUpper() + u" Scheme Handler"_s);
+    de.setValue(u"Exec"_s, command + u" %u"_s); // %u is already passed as single param, no need for quotes
+    de.setValue(u"StartupNotify"_s, u"false"_s);
+    de.setValue(u"MimeType"_s, xSchemeHandler);
+    de.endGroup();
+
+    de.sync();
+    if(de.status() != QSettings::NoError)
+        return false;
+
+    // Register MIME type
+    QProcess xdgMime;
+    xdgMime.setProgram(u"xdg-mime"_s);
+    xdgMime.setArguments({u"default"_s, dEntryFilename, xSchemeHandler});
+    xdgMime.setStandardOutputFile(QProcess::nullDevice());
+    xdgMime.setStandardErrorFile(QProcess::nullDevice());
+    xdgMime.start();
+
+    return xdgMime.waitForFinished(3000) && xdgMime.exitStatus() == xdgMime.NormalExit && xdgMime.exitCode() == 0;
+}
+
 }

lib/core/src/qx-system_win.cpp

@@ -5,6 +5,7 @@
 #include <QFile>
 #include <QDir>
 #include <QDirIterator>
+#include <QSettings>
 
 // Extra-component Includes
 #include "qx/core/qx-integrity.h"
@@ -223,4 +224,26 @@ bool enforceSingleInstance(QString uniqueAppId)
     return createMutex(hashId);
 }
 
+bool registerUriScheme(const QString& scheme, const QString& command)
+{
+    if(scheme.contains(QChar::Space))
+        return false;
+
+    // Set registry keys
+    QSettings schemeKey(u"HKEY_CLASSES_ROOT\\"_s + scheme, QSettings::NativeFormat);
+    schemeKey.setValue(u"."_s, u"URL:"_s + scheme + u" Protocol"_s);
+    schemeKey.setValue("URL Protocol", "");
+    schemeKey.setValue(u"shell\\open\\command"_s, command + uR"( "%1")"_s);
+
+    // Save and return status
+    schemeKey.sync();
+    return schemeKey.status() == QSettings::NoError;
+
+    /* NOTE: The Microsoft specification recommends adding a DefaultIcon key to these entries
+     * with an executable based icon path, though I'm not sure if/how that's actually
+     * used. If that is ever added, we should check if adding an icon to the desktop entry
+     * of the Linux equivalent has an appreciable effect as well.
+     */
+}
+
 }