1 files changed, 434 insertions, 0 deletions
diff --git a/src/Classes/UHooks.pas b/src/Classes/UHooks.pas
new file mode 100644
index 00000000..f0ba3276
--- /dev/null
+++ b/src/Classes/UHooks.pas
@@ -0,0 +1,434 @@
+unit UHooks;
+
+{*********************
+  THookManager
+  Class for saving, managing and calling of Hooks.
+  Saves all hookable events and their subscribers
+*********************}
+interface
+
+{$IFDEF FPC}
+  {$MODE Delphi}
+{$ENDIF}
+
+{$I switches.inc}
+
+uses uPluginDefs,
+     SysUtils;
+
+type
+  //Record that saves info from Subscriber
+  PSubscriberInfo = ^TSubscriberInfo;
+  TSubscriberInfo = record
+    Self: THandle;  //ID of this Subscription (First Word: ID of Subscription; 2nd Word: ID of Hook)
+    Next: PSubscriberInfo; //Pointer to next Item in HookChain
+
+    Owner: Integer; //For Error Handling and Plugin Unloading.
+
+    //Here is s/t tricky
+    //To avoid writing of Wrapping Functions to Hook an Event with a Class
+    //We save a Normal Proc or a Method of a Class
+    Case isClass: boolean of
+      False: (Proc: TUS_Hook); //Proc that will be called on Event
+      True:  (ProcOfClass: TUS_Hook_of_Object);
+  end;
+
+  TEventInfo = record
+    Name: String[60];                  //Name of Event
+    FirstSubscriber:  PSubscriberInfo; //First subscriber in chain
+    LastSubscriber:   PSubscriberInfo; //Last " (for easier subscriber adding
+  end;
+
+  THookManager = class
+    private
+      Events: array of TEventInfo;
+      SpaceinEvents: Word; //Number of empty Items in Events Array. (e.g. Deleted Items)
+
+      Procedure FreeSubscriber(const EventIndex: Word; const Last, Cur: PSubscriberInfo);
+    public
+      constructor Create(const SpacetoAllocate: Word);
+
+      Function AddEvent (const EventName: PChar): THandle;
+      Function DelEvent (hEvent: THandle): Integer;
+
+      Function AddSubscriber (const EventName: PChar; const Proc: TUS_Hook = nil; const ProcOfClass: TUS_Hook_of_Object = nil): THandle;
+      Function DelSubscriber (const hSubscriber: THandle): Integer;
+
+      Function CallEventChain (const hEvent: THandle; const wParam: TwParam; lParam: TlParam): Integer;
+      Function EventExists (const EventName: PChar): Integer;
+
+      Procedure DelbyOwner(const Owner: Integer);
+  end;
+
+function HookTest(wParam: TwParam; lParam: TlParam): integer; stdcall;
+
+var
+  HookManager: THookManager;
+
+implementation
+uses
+  ULog,
+  UCore;
+
+//------------
+// Create - Creates Class and Set Standard Values
+//------------
+constructor THookManager.Create(const SpacetoAllocate: Word);
+var I: Integer;
+begin
+  inherited Create();
+
+  //Get the Space and "Zero" it
+  SetLength (Events, SpacetoAllocate);
+  For I := 0 to SpacetoAllocate-1 do
+    Events[I].Name[1] := chr(0);
+
+  SpaceinEvents := SpacetoAllocate;
+
+  {$IFDEF DEBUG}
+    debugWriteLn('HookManager: Succesful Created.');
+  {$ENDIF}
+end;
+
+//------------
+// AddEvent - Adds an Event and return the Events Handle or 0 on Failure
+//------------
+Function THookManager.AddEvent (const EventName: PChar): THandle;
+var I: Integer;
+begin
+  Result := 0;
+
+  if (EventExists(EventName) = 0) then
+  begin
+    If (SpaceinEvents > 0) then
+    begin
+      //There is already Space available
+      //Go Search it!
+      For I := 0 to High(Events) do
+        If (Events[I].Name[1] = chr(0)) then
+        begin //Found Space
+          Result := I;
+          Dec(SpaceinEvents);
+          Break;
+        end;
+
+      {$IFDEF DEBUG}
+        debugWriteLn('HookManager: Found Space for Event at Handle: ''' + InttoStr(Result+1) + '');
+      {$ENDIF}
+    end
+    else
+    begin //There is no Space => Go make some!
+      Result := Length(Events);
+      SetLength(Events, Result + 1);
+    end;
+
+    //Set Events Data
+    Events[Result].Name := EventName;
+    Events[Result].FirstSubscriber := nil;
+    Events[Result].LastSubscriber := nil;
+
+    //Handle is Index + 1
+    Inc(Result);
+
+    {$IFDEF DEBUG}
+    debugWriteLn('HookManager: Add Event succesful: ''' + EventName + '');
+    {$ENDIF}
+  end
+  {$IFDEF DEBUG}
+  else
+    debugWriteLn('HookManager: Trying to ReAdd Event: ''' + EventName + '');
+  {$ENDIF}
+end;
+
+//------------
+// DelEvent - Deletes an Event by Handle Returns False on Failure
+//------------
+Function THookManager.DelEvent (hEvent: THandle): Integer;
+var
+  Cur, Last: PSubscriberInfo;
+begin
+  hEvent := hEvent - 1; //Arrayindex is Handle - 1
+  Result := -1;
+
+
+  If (Length(Events) > hEvent) AND (Events[hEvent].Name[1] <> chr(0)) then
+  begin //Event exists
+    //Free the Space for all Subscribers
+    Cur := Events[hEvent].FirstSubscriber;
+
+    While (Cur <> nil) do
+    begin
+      Last := Cur;
+      Cur  := Cur.Next;
+      FreeMem(Last, SizeOf(TSubscriberInfo));
+    end;
+
+    {$IFDEF DEBUG}
+      debugWriteLn('HookManager: Removed Event succesful: ''' + Events[hEvent].Name + '');
+    {$ENDIF}
+
+    //Free the Event
+    Events[hEvent].Name[1] := chr(0);
+    Inc(SpaceinEvents); //There is one more space for new events
+  end
+
+  {$IFDEF DEBUG}
+  else
+    debugWriteLn('HookManager: Try to Remove not Existing Event. Handle: ''' + InttoStr(hEvent) + '');
+  {$ENDIF}
+end;
+
+//------------
+// AddSubscriber - Adds an Subscriber to the Event by Name
+// Returns Handle of the Subscribtion or 0 on Failure
+//------------
+Function THookManager.AddSubscriber (const EventName: PChar; const Proc: TUS_Hook; const ProcOfClass: TUS_Hook_of_Object): THandle;
+var
+  EventHandle: THandle;
+  EventIndex:  Cardinal;
+  Cur:   PSubscriberInfo;
+begin
+  Result := 0;
+
+  If (@Proc <> nil) or (@ProcOfClass <> nil) then
+  begin
+    EventHandle := EventExists(EventName);
+
+    If (EventHandle <> 0) then
+    begin
+      EventIndex := EventHandle - 1;
+      
+      //Get Memory
+      GetMem(Cur, SizeOf(TSubscriberInfo));
+
+      //Fill it with Data
+      Cur.Next := nil;
+
+      //Add Owner
+      Cur.Owner := Core.CurExecuted;
+
+      If (@Proc = nil) then
+      begin //Use the ProcofClass Method
+        Cur.isClass := True;
+        Cur.ProcOfClass := ProcofClass;
+      end
+      else //Use the normal Proc
+      begin
+        Cur.isClass := False;
+        Cur.Proc := Proc;
+      end;
+
+      //Create Handle (1st Word: Handle of Event; 2nd Word: unique ID
+      If (Events[EventIndex].LastSubscriber = nil) then
+      begin
+        If (Events[EventIndex].FirstSubscriber = nil) then
+        begin
+          Result := (EventHandle SHL 16);
+          Events[EventIndex].FirstSubscriber := Cur;
+        end
+        Else
+        begin
+          Result := Events[EventIndex].FirstSubscriber.Self + 1;
+        end;
+      end
+      Else
+      begin
+        Result := Events[EventIndex].LastSubscriber.Self + 1;
+        Events[EventIndex].LastSubscriber.Next := Cur;
+      end;
+
+      Cur.Self := Result;
+
+      //Add to Chain
+      Events[EventIndex].LastSubscriber := Cur;
+
+      {$IFDEF DEBUG}
+          debugWriteLn('HookManager: Add Subscriber to Event ''' + Events[EventIndex].Name + ''' succesful. Handle: ''' + InttoStr(Result) + ''' Owner: ' + InttoStr(Cur.Owner));
+      {$ENDIF}
+    end;
+  end;
+end;
+
+//------------
+// FreeSubscriber - Helper for DelSubscriber. Prevents Loss of Chain Items. Frees Memory.
+//------------
+Procedure THookManager.FreeSubscriber(const EventIndex: Word; const Last, Cur: PSubscriberInfo);
+begin
+  //Delete from Chain
+  If (Last <> nil) then
+  begin
+    Last.Next := Cur.Next;
+  end
+  else  //Was first Popup
+  begin
+    Events[EventIndex].FirstSubscriber := Cur.Next;
+  end;
+
+  //Was this Last subscription ?
+  If (Cur = Events[EventIndex].LastSubscriber) then
+  begin //Change Last Subscriber
+    Events[EventIndex].LastSubscriber := Last;
+  end;
+
+  //Free Space:
+  FreeMem(Cur, SizeOf(TSubscriberInfo));
+end;
+
+//------------
+// DelSubscriber - Deletes a Subscribtion by Handle, return non Zero on Failure
+//------------
+Function THookManager.DelSubscriber (const hSubscriber: THandle): Integer;
+var
+  EventIndex: Cardinal;
+  Cur, Last: PSubscriberInfo;
+begin
+  Result := -1;
+  EventIndex := ((hSubscriber AND (High(THandle) xor High(Word))) SHR 16) - 1;
+
+  //Existing Event ?
+  If (EventIndex < Length(Events)) AND (Events[EventIndex].Name[1] <> chr(0)) then
+  begin
+    Result := -2; //Return -1 on not existing Event, -2 on not existing Subscription
+
+    //Search for Subscription
+    Cur := Events[EventIndex].FirstSubscriber;
+    Last := nil;
+
+    //go through the chain ...
+    While (Cur <> nil) do
+    begin
+      If (Cur.Self = hSubscriber) then
+      begin  //Found Subscription we searched for
+        FreeSubscriber(EventIndex, Last, Cur);
+
+        {$IFDEF DEBUG}
+          debugWriteLn('HookManager: Del Subscriber from Event ''' + Events[EventIndex].Name + ''' succesful. Handle: ''' + InttoStr(hSubscriber) + '');
+        {$ENDIF}
+
+        //Set Result and Break the Loop
+        Result := 0;
+        Break;
+      end;
+
+      Last := Cur;
+      Cur := Cur.Next;
+    end;
+
+  end;
+end;
+
+
+//------------
+// CallEventChain - Calls the Chain of a specified EventHandle
+// Returns: -1: Handle doesn't Exist, 0 Chain is called until the End
+//------------
+Function THookManager.CallEventChain (const hEvent: THandle; const wParam: TwParam; lParam: TlParam): Integer;
+var
+  EventIndex: Cardinal;
+  Cur: PSubscriberInfo;
+  CurExecutedBackup: Integer; //backup of Core.CurExecuted Attribute
+begin
+  Result := -1;
+  EventIndex := hEvent - 1;
+
+  If ((EventIndex <= High(Events)) AND (Events[EventIndex].Name[1] <> chr(0))) then
+  begin //Existing Event
+    //Backup CurExecuted
+    CurExecutedBackup := Core.CurExecuted;
+
+    //Start calling the Chain !!!11
+    Cur := Events[EventIndex].FirstSubscriber;
+    Result := 0;
+    //Call Hooks until the Chain is at the End or breaked
+    While ((Cur <> nil) AND (Result = 0)) do
+    begin
+      //Set CurExecuted
+      Core.CurExecuted := Cur.Owner;
+      if (Cur.isClass) then
+        Result := Cur.ProcOfClass(wParam, lParam)
+      else
+        Result := Cur.Proc(wParam, lParam);
+
+      Cur := Cur.Next;
+    end;
+
+    //Restore CurExecuted
+    Core.CurExecuted := CurExecutedBackup;
+  end;
+
+  {$IFDEF DEBUG}
+    debugWriteLn('HookManager: Called Chain from Event ''' + Events[EventIndex].Name + ''' succesful. Result: ''' + InttoStr(Result) + '');
+  {$ENDIF}
+end;
+
+//------------
+// EventExists - Returns non Zero if an Event with the given Name exists
+//------------
+Function THookManager.EventExists (const EventName: PChar): Integer;
+var
+  I: Integer;
+  Name: String[60];
+begin
+  Result := 0;
+  //If (Length(EventName) <
+  Name := String(EventName);
+
+  //Sure not to search for empty space
+  If (Name[1] <> chr(0)) then
+  begin
+    //Search for Event
+    For I := 0 to High(Events) do
+      If (Events[I].Name = Name) then
+      begin //Event found
+        Result := I + 1;
+        Break;
+      end;
+  end;
+end;
+
+//------------
+// DelbyOwner - Dels all Subscriptions by a specific Owner. (For Clean Plugin/Module unloading)
+//------------
+Procedure THookManager.DelbyOwner(const Owner: Integer);
+var
+  I: Integer;
+  Cur, Last: PSubscriberInfo;
+begin
+  //Search for Owner in all Hooks Chains
+  For I := 0 to High(Events) do
+  begin
+    If (Events[I].Name[1] <> chr(0)) then
+    begin
+      
+      Last := nil;
+      Cur  := Events[I].FirstSubscriber;
+      //Went Through Chain
+      While (Cur <> nil) do
+      begin
+        If (Cur.Owner = Owner) then
+        begin //Found Subscription by Owner -> Delete
+          FreeSubscriber(I, Last, Cur);
+          If (Last <> nil) then
+            Cur := Last.Next
+          else
+            Cur := Events[I].FirstSubscriber;
+        end
+        Else
+        begin
+          //Next Item:
+          Last := Cur;
+          Cur := Cur.Next;
+        end;
+      end;
+    end;
+  end;
+end;
+
+
+function HookTest(wParam: TwParam; lParam: TlParam): integer; stdcall;
+begin
+  Result := 0; //Don't break the chain
+  Core.ShowMessage(CORE_SM_INFO, PChar(String(PChar(Pointer(lParam))) + ': ' + String(PChar(Pointer(wParam)))));
+end;
+
+end.