// Copyright IHY.
#pragma once

#include "CoreMinimal.h"
#include "OptimizerTypes.h"
#include "OptimizerGeometry.h"

/**
 * Recovered rigid (optionally mirrored/scaled) delta that maps CANONICAL-local geometry onto
 * MEMBER(sibling)-local geometry. Stored as a UE row-vector matrix: v_member = v_canon * CanonToMember.
 * This is exactly the D in the corrective formula W' = D * W.
 */
struct FOptDelta
{
	bool bValid = false;
	bool bIdentity = false;   // delta is (within tolerance) identity -> swap mesh, keep transform
	bool bMirrored = false;   // recovered rotation is improper (det < 0) -> negative-scale instance
	bool bScaled = false;     // uniform scale != 1 folded in
	double Scale = 1.0;
	double MaxDev = 0.0;      // worst per-vertex deviation under the delta, cm
	double Rms = 0.0;
	FMatrix CanonToMember = FMatrix::Identity;
};

namespace OptimizerMatcher
{
	/** Cheap bucket test: are these two fingerprints compatible enough to attempt recovery? */
	bool FingerprintCompatible(const FOptMeshGeom& A, const FOptMeshGeom& B, const FOptimizerScanSettings& Settings);

	/**
	 * Recover the delta mapping canonical-local (A) onto member-local (B). Both A.Positions and
	 * B.Positions must be populated. Returns false if no candidate passes verification.
	 */
	bool RecoverDelta(const FOptMeshGeom& A, const FOptMeshGeom& B, const FOptimizerScanSettings& Settings, FOptDelta& Out);
}