AI: extract pathfinding special actions and rules to separate files

AI/VCAI/Pathfinding/Rules/AIPreviousNodeRule.cpp

@@ -0,0 +1,47 @@
+/*
+* AIPreviousNodeRule.cpp, part of VCMI engine
+*
+* Authors: listed in file AUTHORS in main folder
+*
+* License: GNU General Public License v2.0 or later
+* Full text of license available in license.txt file, in main folder
+*
+*/
+#include "StdInc.h"
+#include "AIPreviousNodeRule.h"
+
+namespace AIPathfinding
+{
+	AIPreviousNodeRule::AIPreviousNodeRule(std::shared_ptr<AINodeStorage> nodeStorage)
+		: nodeStorage(nodeStorage)
+	{
+	}
+
+	void AIPreviousNodeRule::process(
+		const PathNodeInfo & source,
+		CDestinationNodeInfo & destination,
+		const PathfinderConfig * pathfinderConfig,
+		CPathfinderHelper * pathfinderHelper) const
+	{
+		if(source.node->action == CGPathNode::ENodeAction::BLOCKING_VISIT || source.node->action == CGPathNode::ENodeAction::VISIT)
+		{
+			// we can not directly bypass objects, we need to interact with them first
+			destination.node->theNodeBefore = source.node;
+#ifdef VCMI_TRACE_PATHFINDER
+			logAi->trace(
+				"Link src node %s to destination node %s while bypassing visitable obj",
+				source.coord.toString(),
+				destination.coord.toString());
+#endif
+			return;
+		}
+
+		auto aiSourceNode = nodeStorage->getAINode(source.node);
+
+		if(aiSourceNode->specialAction)
+		{
+			// there is some action on source tile which should be performed before we can bypass it
+			destination.node->theNodeBefore = source.node;
+		}
+	}
+}