Rework MODE/RPL_CHANMODEIS handling for trailing args (#1661)

Some servers may send a colon even if the last parameter doesn't need it, currently this leads to issues with permission/mode tracking, as the core doesn't handle the colon properly.

This fix replaces reconstructing the parameter string with just passing a vector of the relevant parameters to CChan::SetModes() and adds overrides for CChan::SetModes() and CChan::ModeChange() that accept the vector instead.

Clean up uses of old CModeMessage::GetModes()

include/znc/Chan.h

@@ -76,8 +76,22 @@ class CChan : private CCoreTranslationMixin {
                const CString& sHost);
 
     // Modes
+    /// @deprecated Use SetModes(CString, VCString)
     void SetModes(const CString& s);
+    /**
+     * Set the current modes for this channel
+     * @param sModes The mode characters being changed
+     * @param vsModeParams The parameters for the modes to be set
+     */
+    void SetModes(const CString& sModes, const VCString& vsModeParams);
+    /// @deprecated Use ModeChange(CString, VCString, CNick*)
     void ModeChange(const CString& sModes, const CNick* OpNick = nullptr);
+    /**
+     * Handle changing the modes on a channel
+     * @param sModes The mode string (eg. +ovbs-pbo)
+     * @param vsModeParams The parameters for the mode string
+     */
+    void ModeChange(const CString& sModes,const VCString& vsModeParams, const CNick* OpNick = nullptr);
     bool AddMode(char cMode, const CString& sArg);
     bool RemMode(char cMode);
     CString GetModeString() const;

include/znc/Message.h

@@ -121,6 +121,18 @@ class CMessage {
     void SetCommand(const CString& sCommand);
 
     const VCString& GetParams() const { return m_vsParams; }
+
+    /**
+     * Get a subset of the message parameters
+     *
+     * This allows accessing a vector of a specific range of parameters,
+     * allowing easy inline use, such as `pChan->SetModes(Message.GetParam(2), Message.GetParamsSplit(3));`
+     *
+     * @param uIdx The index of the first parameter to retrieve
+     * @param uLen How many parameters to retrieve
+     * @return A VCString containing the retrieved parameters
+     */
+    VCString GetParamsSplit(unsigned int uIdx, unsigned int uLen = -1) const;
     void SetParams(const VCString& vsParams);
 
     /// @deprecated use GetParamsColon() instead.
@@ -257,7 +269,14 @@ REGISTER_ZNC_MESSAGE(CJoinMessage);
 
 class CModeMessage : public CTargetMessage {
   public:
+    /// @deprecated Use GetModeList() and GetModeParams()
     CString GetModes() const { return GetParamsColon(1).TrimPrefix_n(":"); }
+
+    CString GetModeList() const { return GetParam(1); };
+
+    VCString GetModeParams() const { return GetParamsSplit(2); };
+
+    bool HasModes() const { return !GetModeList().empty(); };
 };
 REGISTER_ZNC_MESSAGE(CModeMessage);