#pragma once

#include "CoreMinimal.h"
#include "WingServer.h"
#include "WingHandler.h"
#include "WingFetcher.h"
#include "WingUtils.h"
#include "Engine/Blueprint.h"
#include "EdGraph/EdGraph.h"
#include "EdGraph/EdGraphNode.h"
#include "EdGraph/EdGraphPin.h"
#include "Blueprint_Diff.generated.h"


// ---------------------------------------------------------------------------
// ---------------------------------------------------------------------------
// ---------------------------------------------------------------------------

UCLASS()
class UWing_Blueprint_Diff : public UObject, public IWingHandler
{
	GENERATED_BODY()

public:
	UPROPERTY(meta=(Description="First blueprint package path"))
	FString BlueprintA;

	UPROPERTY(meta=(Description="Second blueprint package path"))
	FString BlueprintB;

	UPROPERTY(meta=(Optional, Description="Filter to a specific graph name"))
	FString Graph;

	virtual FString GetDescription() const override
	{
		return TEXT("Structural diff between two different Blueprints. Compares nodes, "
			"connections, and variables across graphs. Use for comparing variants, "
			"finding divergence after copy-paste, or auditing consistency.");
	}

	virtual void Handle() override
	{
		// Load both blueprints
		WingFetcher FA;
		UBlueprint* BPA = FA.Asset(BlueprintA).Cast<UBlueprint>();
		if (!BPA) return;

		WingFetcher FB;
		UBlueprint* BPB = FB.Asset(BlueprintB).Cast<UBlueprint>();
		if (!BPB) return;

		// Gather graphs, optionally filtering by name
		auto GatherGraphs = [this](UBlueprint* BP) -> TArray<UEdGraph*>
		{
			TArray<UEdGraph*> Graphs;
			for (UEdGraph* G : BP->UbergraphPages)
			{
				if (!G) continue;
				if (!Graph.IsEmpty() && !WingUtils::Identifies(Graph, G)) continue;
				Graphs.Add(G);
			}
			for (UEdGraph* G : BP->FunctionGraphs)
			{
				if (!G) continue;
				if (!Graph.IsEmpty() && !WingUtils::Identifies(Graph, G)) continue;
				Graphs.Add(G);
			}
			return Graphs;
		};

		TArray<UEdGraph*> GraphsA = GatherGraphs(BPA);
		TArray<UEdGraph*> GraphsB = GatherGraphs(BPB);

		// Build graph name maps
		TMap<FString, UEdGraph*> GraphMapA, GraphMapB;
		for (UEdGraph* G : GraphsA) GraphMapA.Add(WingUtils::FormatName(G), G);
		for (UEdGraph* G : GraphsB) GraphMapB.Add(WingUtils::FormatName(G), G);

		// Find all unique graph names
		TSet<FString> AllGraphNames;
		for (auto& Pair : GraphMapA) AllGraphNames.Add(Pair.Key);
		for (auto& Pair : GraphMapB) AllGraphNames.Add(Pair.Key);

		int32 TotalDiffs = 0;

		for (const FString& GraphName : AllGraphNames)
		{
			UEdGraph** pGA = GraphMapA.Find(GraphName);
			UEdGraph** pGB = GraphMapB.Find(GraphName);

			if (!pGA)
			{
				UWingServer::Printf(TEXT("Graph %s: only in B (%d nodes)\n"), *GraphName, (*pGB)->Nodes.Num());
				TotalDiffs++;
				continue;
			}
			if (!pGB)
			{
				UWingServer::Printf(TEXT("Graph %s: only in A (%d nodes)\n"), *GraphName, (*pGA)->Nodes.Num());
				TotalDiffs++;
				continue;
			}

			// Both exist -- compare nodes
			UEdGraph* GA = *pGA;
			UEdGraph* GB = *pGB;

			// Build node title maps for matching
			TMap<FString, TArray<UEdGraphNode*>> NodesA, NodesB;
			for (UEdGraphNode* N : GA->Nodes)
			{
				if (!N) continue;
				NodesA.FindOrAdd(WingUtils::FormatName(N)).Add(N);
			}
			for (UEdGraphNode* N : GB->Nodes)
			{
				if (!N) continue;
				NodesB.FindOrAdd(WingUtils::FormatName(N)).Add(N);
			}

			// Nodes only in A
			TArray<FString> OnlyInA;
			for (auto& Pair : NodesA)
			{
				int32 CountA = Pair.Value.Num();
				int32 CountB = 0;
				if (auto* pArr = NodesB.Find(Pair.Key)) CountB = pArr->Num();
				if (CountA > CountB)
					OnlyInA.Add(FString::Printf(TEXT("  %s (x%d)"), *Pair.Key, CountA - CountB));
			}

			// Nodes only in B
			TArray<FString> OnlyInB;
			for (auto& Pair : NodesB)
			{
				int32 CountB = Pair.Value.Num();
				int32 CountA = 0;
				if (auto* pArr = NodesA.Find(Pair.Key)) CountA = pArr->Num();
				if (CountB > CountA)
					OnlyInB.Add(FString::Printf(TEXT("  %s (x%d)"), *Pair.Key, CountB - CountA));
			}

			// Connection diff
			auto MakeConnKey = [](UEdGraphPin* SrcPin, UEdGraphPin* TgtPin) -> FString
			{
				return FString::Printf(TEXT("%s|%s|%s|%s"),
					*WingUtils::FormatName(SrcPin->GetOwningNode()), *WingUtils::FormatName(SrcPin),
					*WingUtils::FormatName(TgtPin->GetOwningNode()), *WingUtils::FormatName(TgtPin));
			};

			auto GatherConnections = [&MakeConnKey](UEdGraph* G) -> TSet<FString>
			{
				TSet<FString> Conns;
				for (UEdGraphNode* N : G->Nodes)
				{
					if (!N) continue;
					for (UEdGraphPin* Pin : N->Pins)
					{
						if (!Pin || Pin->Direction != EGPD_Output) continue;
						for (UEdGraphPin* Linked : Pin->LinkedTo)
						{
							if (!Linked || !Linked->GetOwningNode()) continue;
							Conns.Add(MakeConnKey(Pin, Linked));
						}
					}
				}
				return Conns;
			};

			TSet<FString> ConnectionsA = GatherConnections(GA);
			TSet<FString> ConnectionsB = GatherConnections(GB);

			TArray<FString> ConnsOnlyInA, ConnsOnlyInB;
			for (const FString& Key : ConnectionsA)
				if (!ConnectionsB.Contains(Key))
					ConnsOnlyInA.Add(FString::Printf(TEXT("  %s"), *Key));
			for (const FString& Key : ConnectionsB)
				if (!ConnectionsA.Contains(Key))
					ConnsOnlyInB.Add(FString::Printf(TEXT("  %s"), *Key));

			bool bIdentical = OnlyInA.IsEmpty() && OnlyInB.IsEmpty() && ConnsOnlyInA.IsEmpty() && ConnsOnlyInB.IsEmpty();

			if (bIdentical)
			{
				UWingServer::Printf(TEXT("Graph %s: identical (%d nodes)\n"), *GraphName, GA->Nodes.Num());
				continue;
			}

			TotalDiffs++;
			UWingServer::Printf(TEXT("Graph %s: different (A=%d nodes, B=%d nodes)\n"), *GraphName, GA->Nodes.Num(), GB->Nodes.Num());

			if (!OnlyInA.IsEmpty())
			{
				UWingServer::Print(TEXT("  Nodes only in A:\n"));
				for (const FString& Line : OnlyInA) UWingServer::Printf(TEXT("  %s\n"), *Line);
			}
			if (!OnlyInB.IsEmpty())
			{
				UWingServer::Print(TEXT("  Nodes only in B:\n"));
				for (const FString& Line : OnlyInB) UWingServer::Printf(TEXT("  %s\n"), *Line);
			}
			if (!ConnsOnlyInA.IsEmpty())
			{
				UWingServer::Print(TEXT("  Connections only in A:\n"));
				for (const FString& Line : ConnsOnlyInA) UWingServer::Printf(TEXT("  %s\n"), *Line);
			}
			if (!ConnsOnlyInB.IsEmpty())
			{
				UWingServer::Print(TEXT("  Connections only in B:\n"));
				for (const FString& Line : ConnsOnlyInB) UWingServer::Printf(TEXT("  %s\n"), *Line);
			}
		}

		// Compare variables
		TSet<FString> VarNamesA, VarNamesB;
		for (const FBPVariableDescription& V : BPA->NewVariables) VarNamesA.Add(WingUtils::FormatName(V));
		for (const FBPVariableDescription& V : BPB->NewVariables) VarNamesB.Add(WingUtils::FormatName(V));

		TArray<FString> VarsOnlyInA, VarsOnlyInB;
		for (const FString& Name : VarNamesA)
			if (!VarNamesB.Contains(Name))
				VarsOnlyInA.Add(Name);
		for (const FString& Name : VarNamesB)
			if (!VarNamesA.Contains(Name))
				VarsOnlyInB.Add(Name);

		if (!VarsOnlyInA.IsEmpty())
		{
			UWingServer::Print(TEXT("Variables only in A:\n"));
			for (const FString& Name : VarsOnlyInA) UWingServer::Printf(TEXT("  %s\n"), *Name);
			TotalDiffs += VarsOnlyInA.Num();
		}
		if (!VarsOnlyInB.IsEmpty())
		{
			UWingServer::Print(TEXT("Variables only in B:\n"));
			for (const FString& Name : VarsOnlyInB) UWingServer::Printf(TEXT("  %s\n"), *Name);
			TotalDiffs += VarsOnlyInB.Num();
		}

		UWingServer::Printf(TEXT("Total differences: %d\n"), TotalDiffs);
	}
};