Refactor parameters parsing

Introduce classes that encapsulate parameter names and parsing schemes
from command line and from environment variables.

src/app/options.cpp

@@ -47,32 +47,205 @@
 
 namespace
 {
-    bool isBoolEnvVarSetToTrue(const QProcessEnvironment &env, const QString &var)
+    // Base option class. Encapsulates name operations.
+    class Option
     {
-        QString val = env.value(var);
+    protected:
+        constexpr Option(const char *name, char shortcut = 0)
+            : m_name {name}
+            , m_shortcut {shortcut}
+        {
+        }
+
+        QString fullParameter() const
+        {
+            return QLatin1String("--") + QLatin1String(m_name);
+        }
+
+        QString shortcutParameter() const
+        {
+            return QLatin1String("-") + QLatin1Char(m_shortcut);
+        }
+
+        bool hasShortcut() const
+        {
+            return m_shortcut != 0;
+        }
+
+        QString envVarName() const
+        {
+            return QLatin1String("QBT_")
+                   + QString(QLatin1String(m_name)).toUpper().replace(QLatin1Char('-'), QLatin1Char('_'));
+        }
+
+        static QString padUsageText(const QString &usage)
+        {
+            const int TAB_WIDTH = 8;
+            QString res = QLatin1String("\t") + usage;
+            if (usage.size() < 2 * TAB_WIDTH)
+                return res + QLatin1String("\t\t");
+            else
+                return res + QLatin1String("\t");
+        }
+
+    private:
+        const char *m_name;
+        const char m_shortcut;
+    };
+
+    // Boolean option.
+    class BoolOption: protected Option
+    {
+    public:
+        constexpr BoolOption(const char *name, char shortcut = 0)
+            : Option {name, shortcut}
+        {
+        }
+
+        bool operator==(const QString &arg) const
+        {
+            return (hasShortcut() && ((arg.size() == 2) && (arg == shortcutParameter())))
+                   || (arg == fullParameter());
+        }
+
+        bool value(const QProcessEnvironment &env) const
+        {
+            QString val = env.value(envVarName());
             // we accept "1" and "true" (upper or lower cased) as boolean 'true' values
             return (val == QLatin1String("1") || val.toUpper() == QLatin1String("TRUE"));
         }
 
-    int readIntlEnvVar(const QProcessEnvironment &env, const QString &var, int defaultValue)
+        QString usage() const
         {
-        QString val = env.value(var);
+            QString res;
+            if (hasShortcut())
+                res += shortcutParameter() + QLatin1String(" | ");
+            res += fullParameter();
+            return padUsageText(res);
+        }
+    };
+
+    inline bool operator==(const QString &s, const BoolOption &o)
+    {
+        return o == s;
+    }
+
+    // Option with string value. May not have a shortcut
+    struct StringOption: protected Option
+    {
+    public:
+        constexpr StringOption(const char *name)
+            : Option {name, 0}
+        {
+        }
+
+        bool operator==(const QString &arg) const
+        {
+            return arg.startsWith(parameterAssignment());
+        }
+
+        QString value(const QString &arg) const
+        {
+            QStringList parts = arg.split(QLatin1Char('='));
+            if (parts.size() == 2)
+                return unquote(parts[1]);
+            throw CommandLineParameterError(QObject::tr("Parameter '%1' must follow syntax '%1=%2'",
+                                                        "e.g. Parameter '--webui-port' must follow syntax '--webui-port=value'")
+                                            .arg(fullParameter()).arg(QLatin1String("<value>")));
+        }
+
+        QString value(const QProcessEnvironment &env, const QString &defaultValue = QString()) const
+        {
+            QString val = env.value(envVarName());
+            return val.isEmpty() ? defaultValue : unquote(val);
+        }
+
+        QString usage(const QString &valueName) const
+        {
+            return padUsageText(parameterAssignment() + QLatin1Char('<') + valueName + QLatin1Char('>'));
+        }
+
+    private:
+        QString parameterAssignment() const
+        {
+            return fullParameter() + QLatin1Char('=');
+        }
+
+        static QString unquote(const QString &s)
+        {
+            auto isStringQuoted =
+                [](const QString &s, QChar quoteChar)
+                {
+                    return (s.startsWith(quoteChar) && s.endsWith(quoteChar));
+                };
+
+            if ((s.size() >= 2) && (isStringQuoted(s, QLatin1Char('\'')) || isStringQuoted(s, QLatin1Char('"'))))
+                return s.mid(1, s.size() - 2);
+            return s;
+        }
+    };
+
+    inline bool operator==(const QString &s, const StringOption &o)
+    {
+        return o == s;
+    }
+
+    // Option with integer value. May not have a shortcut
+    class IntOption: protected StringOption
+    {
+    public:
+        constexpr IntOption(const char *name)
+            : StringOption {name}
+        {
+        }
+
+        using StringOption::operator==;
+        using StringOption::usage;
+
+        int value(const QString &arg) const
+        {
+            QString val = StringOption::value(arg);
+            bool ok = false;
+            int res = val.toInt(&ok);
+            if (!ok)
+                throw CommandLineParameterError(QObject::tr("Parameter '%1' must follow syntax '%1=%2'",
+                                                            "e.g. Parameter '--webui-port' must follow syntax '--webui-port=<value>'")
+                                                .arg(fullParameter()).arg(QLatin1String("<integer value>")));
+            return res;
+        }
+
+        int value(const QProcessEnvironment &env, int defaultValue) const
+        {
+            QString val = env.value(envVarName());
             if (val.isEmpty()) return defaultValue;
+
             bool ok;
             int res = val.toInt(&ok);
             if (!ok) {
                 qDebug() << QObject::tr("Expected integer number in environment variable '%1', but got '%2'")
-                .arg(var).arg(val);
+                    .arg(envVarName()).arg(val);
                 return defaultValue;
             }
             return res;
         }
+    };
 
-    QString envVarNameForParameter(const char *parameterName)
+    inline bool operator==(const QString &s, const IntOption &o)
     {
-        return QLatin1String("QBT_") +
-               QString(QLatin1String(parameterName)).toUpper().replace(QLatin1Char('-'), QLatin1Char('_'));
+        return o == s;
     }
+
+    constexpr const BoolOption SHOW_HELP_OPTION = {"help", 'h'};
+    constexpr const BoolOption SHOW_VERSION_OPTION = {"version", 'v'};
+#ifdef DISABLE_GUI
+    constexpr const BoolOption DAEMON_OPTION = {"daemon", 'd'};
+#else
+    constexpr const BoolOption NO_SPLASH_OPTION = {"no-splash"};
+#endif
+    constexpr const IntOption WEBUI_PORT_OPTION = {"webui-port"};
+    constexpr const StringOption PROFILE_OPTION = {"profile"};
+    constexpr const StringOption CONFIGURATION_OPTION = {"configuration"};
+    constexpr const BoolOption PORTABLE_OPTION = {"portable"};
 }
 
 QBtCommandLineParameters::QBtCommandLineParameters(const QProcessEnvironment &env)
@@ -81,14 +254,14 @@ QBtCommandLineParameters::QBtCommandLineParameters(const QProcessEnvironment &en
     , showVersion(false)
 #endif
 #ifndef DISABLE_GUI
-    , noSplash(isBoolEnvVarSetToTrue(env, envVarNameForParameter("no-splash")))
+    , noSplash(NO_SPLASH_OPTION.value(env))
 #else
-    , shouldDaemonize(isBoolEnvVarSetToTrue(env, envVarNameForParameter("daemon")))
+    , shouldDaemonize(DAEMON_OPTION.value(env))
 #endif
-    , webUiPort(readIntlEnvVar(env, envVarNameForParameter("webui-port"), -1))
-    , profileDir(env.value(envVarNameForParameter("profile")))
-    , portableMode(isBoolEnvVarSetToTrue(env, envVarNameForParameter("portable")))
-    , configurationName(env.value(envVarNameForParameter("configuration")))
+    , webUiPort(WEBUI_PORT_OPTION.value(env, -1))
+    , profileDir(PROFILE_OPTION.value(env))
+    , portableMode(PORTABLE_OPTION.value(env))
+    , configurationName(CONFIGURATION_OPTION.value(env))
 {
 }
 
@@ -102,45 +275,37 @@ QBtCommandLineParameters parseCommandLine(const QStringList &args)
         if ((arg.startsWith("--") && !arg.endsWith(".torrent"))
             || (arg.startsWith("-") && (arg.size() == 2))) {
             // Parse known parameters
-            if ((arg == QLatin1String("-h")) || (arg == QLatin1String("--help"))) {
+            if ((arg == SHOW_HELP_OPTION)) {
                 result.showHelp = true;
             }
 #ifndef Q_OS_WIN
-            else if ((arg == QLatin1String("-v")) || (arg == QLatin1String("--version"))) {
+            else if (arg == SHOW_VERSION_OPTION) {
                 result.showVersion = true;
             }
 #endif
-            else if (arg.startsWith(QLatin1String("--webui-port="))) {
-                QStringList parts = arg.split(QLatin1Char('='));
-                if (parts.size() == 2) {
-                    bool ok = false;
-                    result.webUiPort = parts.last().toInt(&ok);
-                    if (!ok || (result.webUiPort < 1) || (result.webUiPort > 65535))
+            else if (arg == WEBUI_PORT_OPTION) {
+                result.webUiPort = WEBUI_PORT_OPTION.value(arg);
+                if ((result.webUiPort < 1) || (result.webUiPort > 65535))
                     throw CommandLineParameterError(QObject::tr("%1 must specify the correct port (1 to 65535).")
                                                     .arg(QLatin1String("--webui-port")));
             }
-            }
 #ifndef DISABLE_GUI
-            else if (arg == QLatin1String("--no-splash")) {
+            else if (arg == NO_SPLASH_OPTION) {
                 result.noSplash = true;
             }
 #else
-            else if ((arg == QLatin1String("-d")) || (arg == QLatin1String("--daemon"))) {
+            else if (arg == DAEMON_OPTION) {
                 result.shouldDaemonize = true;
             }
 #endif
-            else if (arg == QLatin1String("--profile")) {
-                QStringList parts = arg.split(QLatin1Char('='));
-                if (parts.size() == 2)
-                    result.profileDir = parts.last();
+            else if (arg == PROFILE_OPTION) {
+                result.profileDir = PROFILE_OPTION.value(arg);
             }
-            else if (arg == QLatin1String("--portable")) {
+            else if (arg == PORTABLE_OPTION) {
                 result.portableMode = true;
             }
-            else if (arg == QLatin1String("--configuration")) {
-                QStringList parts = arg.split(QLatin1Char('='));
-                if (parts.size() == 2)
-                    result.configurationName = parts.last();
+            else if (arg == CONFIGURATION_OPTION) {
+                result.configurationName = CONFIGURATION_OPTION.value(arg);
             }
             else {
                 // Unknown argument
@@ -185,20 +350,20 @@ QString makeUsage(const QString &prgName)
 
     stream << QObject::tr("Options:") << '\n';
 #ifndef Q_OS_WIN
-    stream << "\t-v | --version\t\t" << QObject::tr("Displays program version and exit") << '\n';
+    stream << SHOW_VERSION_OPTION.usage() << QObject::tr("Displays program version and exit") << '\n';
 #endif
-    stream << "\t-h | --help\t\t" << QObject::tr("Displays this help message and exit") << '\n';
-    stream << "\t--webui-port=<port>\t"
+    stream << SHOW_HELP_OPTION.usage() << QObject::tr("Displays this help message and exit") << '\n';
+    stream << WEBUI_PORT_OPTION.usage(QLatin1String("port"))
            << QObject::tr("Changes the Web UI port")
            << '\n';
 #ifndef DISABLE_GUI
-    stream << "\t--no-splash\t\t" << QObject::tr("Disable splash screen") << '\n';
+    stream << NO_SPLASH_OPTION.usage() << QObject::tr("Disable splash screen") << '\n';
 #else
-    stream << "\t-d | --daemon\t\t" << QObject::tr("Run in daemon-mode (background)") << '\n';
+    stream << DAEMON_OPTION.usage() << QObject::tr("Run in daemon-mode (background)") << '\n';
 #endif
-    stream << "\t--profile=<dir>\t\t" << QObject::tr("Store configuration files in <dir>") << '\n';
-    stream << "\t--portable\t\t" << QObject::tr("Shortcut for --profile=<exe dir>/profile") << '\n';
-    stream << "\t--configuration=<name>\t" << QObject::tr("Store configuration files in directories qBittorrent_<name>")
+    stream << PROFILE_OPTION.usage(QLatin1String("dir")) << QObject::tr("Store configuration files in <dir>") << '\n';
+    stream << PORTABLE_OPTION.usage() << QObject::tr("Shortcut for --profile=<exe dir>/profile") << '\n';
+    stream << CONFIGURATION_OPTION.usage(QLatin1String("name")) << QObject::tr("Store configuration files in directories qBittorrent_<name>")
            << '\n';
     stream << "\tfiles or urls\t\t" << QObject::tr("Downloads the torrents passed by the user") << '\n'
            << '\n';