#pragma once

#include "CoreMinimal.h"

/** How a part of the arm moves. Generated into Player/Arm/ArmLayout.inl by Tools/blender/export_arm.py. */
enum class EDescentArmJoint : uint8
{
	Fixed,   // RA_Root: the shoulder anchor, does not move itself
	Ball,    // RA_UpperArm: the shoulder, yaw / pitch / roll
	Hinge,   // RA_Forearm (elbow) and RA_Hand (wrist flex): one rotation about JointAxis
	Roll,    // RA_Wrist: rotation about the forearm axis
	Slide,   // RA_PistonRod: translation along JointAxis
	Finger,  // a phalanx: one rotation about JointAxis (curl)
};

/** One row of the generated table: a segment of the arm. Centimetres, Unreal axes, arm at rest. */
struct FDescentArmPartDef
{
	/** Blender object name = component name: "RA_UpperArm", "RA_Index_2", ... */
	const TCHAR* Name;
	/** Index of the parent row in the table, -1 for the root. */
	int32 ParentIndex;
	/** Asset under /Game/Player/Arm/ ("SM_Arm_Hand"); empty for the root, which has no mesh. */
	const TCHAR* MeshAsset;
	EDescentArmJoint Joint;
	/** Where the part's joint is, in the parent's frame (cm). */
	FVector LocalOffsetCm;
	/** The part's orientation at rest, relative to the parent. */
	FQuat RestRotation;
	/** Hinge / roll / finger: FQuat(JointAxis, +angle) is the model's positive rotation. Slide: the +distance direction. In the part's own frame. */
	FVector JointAxis;
	/** Fingers: the curl about JointAxis already built into the rest rotation (degrees). 0 for the thumb root. */
	double RestCurlDeg;
	/** Where the joint is at rest in arm space (cm), for tests: the parent chain must land exactly here. */
	FVector PivotRestCm;
	/** Bounds of the part's mesh in its own frame (cm). */
	FVector LocalBoundsMinCm;
	FVector LocalBoundsMaxCm;
	int32 Triangles;
};

/** Index of each part in the generated table (the order is fixed by export_arm.py; a test compares the names). */
enum class EDescentArmPart : uint8
{
	Root, UpperArm, Forearm, PistonRod, Wrist, Hand,
	Thumb1, Thumb2, Thumb3, Index1, Index2, Index3, Middle1, Middle2, Middle3, Ring1, Ring2, Ring3, Pinky1, Pinky2, Pinky3,
	Count
};

/** Fingers in the order of every per-finger array. */
enum class EDescentArmFinger : uint8 { Thumb, Index, Middle, Ring, Pinky, Count };

namespace Descent::Arm
{
	constexpr int32 PartCount = static_cast<int32>(EDescentArmPart::Count);
	constexpr int32 FingerCount = static_cast<int32>(EDescentArmFinger::Count);

	/** The generated table. */
	THEDESCENT_API TConstArrayView<FDescentArmPartDef> Parts();
	THEDESCENT_API const FDescentArmPartDef& Def(EDescentArmPart Part);

	/** Phalanx 1..3 (Joint 0..2) of a finger. */
	inline EDescentArmPart FingerPart(int32 Finger, int32 Joint)
	{
		return static_cast<EDescentArmPart>(static_cast<int32>(EDescentArmPart::Thumb1) + Finger * 3 + Joint);
	}

	/** Mesh folder: /Game/Player/Arm/ */
	THEDESCENT_API const TCHAR* MeshFolder();

	/** Measured by the export. */
	THEDESCENT_API double ShoulderToElbowCm();
	THEDESCENT_API double ElbowToHandPivotCm();      // elbow to the hand's flex axis
	THEDESCENT_API double HandPivotToFingertipCm();  // at the pose the model was authored in
	THEDESCENT_API double ShoulderToFingertipCm();
	/** True when the exported geometry is a right arm (it is; the export says so from the palm / thumb analysis). */
	THEDESCENT_API bool ModelIsRightArm();
}