/******************************************************************************
 * Spine Runtimes License Agreement
 * Last updated April 5, 2025. Replaces all prior versions.
 *
 * Copyright (c) 2013-2025, Esoteric Software LLC
 *
 * Integration of the Spine Runtimes into software or otherwise creating
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import { Bone } from "./Bone";
import { Inherit } from "./BoneData";
import { BoneLocal } from "./BoneLocal";
import { Physics } from "./Physics";
import { Skeleton } from "./Skeleton";
import { Update } from "./Update";
import { MathUtils, Vector2 } from "./Utils";

/** The applied pose for a bone. This is the {@link Bone} pose with constraints applied and the world transform computed by
 * {@link Skeleton#updateWorldTransform()}. */
export class BonePose extends BoneLocal implements Update {
	bone!: Bone;

	/** Part of the world transform matrix for the X axis. If changed, {@link updateLocalTransform()} should be called. */
	a = 0;

	/** Part of the world transform matrix for the Y axis. If changed, {@link updateLocalTransform()} should be called. */
	b = 0;

	/** Part of the world transform matrix for the X axis. If changed, {@link updateLocalTransform()} should be called. */
	c = 0;

	/** Part of the world transform matrix for the Y axis. If changed, {@link updateLocalTransform()} should be called. */
	d = 0;

	/** The world X position. If changed, {@link updateLocalTransform()} should be called. */
	worldY = 0;

	/** The world Y position. If changed, {@link updateLocalTransform()} should be called. */
	worldX = 0;

	world = 0;
	local = 0;

	/** Called by {@link Skeleton#updateCache()} to compute the world transform, if needed. */
	public update (skeleton: Skeleton, physics: Physics): void {
		if (this.world !== skeleton._update) this.updateWorldTransform(skeleton);
	}

	/** Computes the world transform using the parent bone's applied pose and this pose. Child bones are not updated.
	 * <p>
	 * See <a href="https://esotericsoftware.com/spine-runtime-skeletons#World-transforms">World transforms</a> in the Spine
	 * Runtimes Guide. */
	updateWorldTransform (skeleton: Skeleton): void {
		if (this.local === skeleton._update)
			this.updateLocalTransform(skeleton);
		else
			this.world = skeleton._update;

		let rotation = this.rotation;
		const scaleX = this.scaleX;
		const scaleY = this.scaleY;
		const shearX = this.shearX;
		const shearY = this.shearY;
		if (!this.bone.parent) { // Root bone.
			const sx = skeleton.scaleX, sy = skeleton.scaleY;
			const rx = (rotation + shearX) * MathUtils.degRad;
			const ry = (rotation + 90 + shearY) * MathUtils.degRad;
			this.a = Math.cos(rx) * scaleX * sx;
			this.b = Math.cos(ry) * scaleY * sx;
			this.c = Math.sin(rx) * scaleX * sy;
			this.d = Math.sin(ry) * scaleY * sy;
			this.worldX = this.x * sx + skeleton.x;
			this.worldY = this.y * sy + skeleton.y;
			return;
		}

		const parent = this.bone.parent.applied;
		let pa = parent.a, pb = parent.b, pc = parent.c, pd = parent.d;
		this.worldX = pa * this.x + pb * this.y + parent.worldX;
		this.worldY = pc * this.x + pd * this.y + parent.worldY;

		switch (this.inherit) {
			case Inherit.Normal: {
				const rx = (rotation + shearX) * MathUtils.degRad;
				const ry = (rotation + 90 + shearY) * MathUtils.degRad;
				const la = Math.cos(rx) * scaleX;
				const lb = Math.cos(ry) * scaleY;
				const lc = Math.sin(rx) * scaleX;
				const ld = Math.sin(ry) * scaleY;
				this.a = pa * la + pb * lc;
				this.b = pa * lb + pb * ld;
				this.c = pc * la + pd * lc;
				this.d = pc * lb + pd * ld;
				return;
			}
			case Inherit.OnlyTranslation: {
				const rx = (rotation + shearX) * MathUtils.degRad;
				const ry = (rotation + 90 + shearY) * MathUtils.degRad;
				this.a = Math.cos(rx) * scaleX;
				this.b = Math.cos(ry) * scaleY;
				this.c = Math.sin(rx) * scaleX;
				this.d = Math.sin(ry) * scaleY;
				break;
			}
			case Inherit.NoRotationOrReflection: {
				let sx = 1 / skeleton.scaleX, sy = 1 / skeleton.scaleY;
				pa *= sx;
				pc *= sy;
				let s = pa * pa + pc * pc;
				let prx = 0;
				if (s > 0.0001) {
					s = Math.abs(pa * pd * sy - pb * sx * pc) / s;
					pb = pc * s;
					pd = pa * s;
					prx = MathUtils.atan2Deg(pc, pa);
				} else {
					pa = 0;
					pc = 0;
					prx = 90 - MathUtils.atan2Deg(pd, pb);
				}
				const rx = (rotation + shearX - prx) * MathUtils.degRad;
				const ry = (rotation + shearY - prx + 90) * MathUtils.degRad;
				const la = Math.cos(rx) * scaleX;
				const lb = Math.cos(ry) * scaleY;
				const lc = Math.sin(rx) * scaleX;
				const ld = Math.sin(ry) * scaleY;
				this.a = pa * la - pb * lc;
				this.b = pa * lb - pb * ld;
				this.c = pc * la + pd * lc;
				this.d = pc * lb + pd * ld;
				break;
			}
			case Inherit.NoScale:
			case Inherit.NoScaleOrReflection: {
				rotation *= MathUtils.degRad;
				const cos = Math.cos(rotation), sin = Math.sin(rotation);
				let za = (pa * cos + pb * sin) / skeleton.scaleX;
				let zc = (pc * cos + pd * sin) / skeleton.scaleY;
				let s = Math.sqrt(za * za + zc * zc);
				if (s > 0.00001) s = 1 / s;
				za *= s;
				zc *= s;
				s = Math.sqrt(za * za + zc * zc);
				if (this.inherit == Inherit.NoScale && (pa * pd - pb * pc < 0) != (skeleton.scaleX < 0 != skeleton.scaleY < 0)) s = -s;
				this.rotation = Math.PI / 2 + Math.atan2(zc, za);
				const zb = Math.cos(this.rotation) * s;
				const zd = Math.sin(this.rotation) * s;
				this.shearX *= MathUtils.degRad;
				this.shearY = (90 + shearY) * MathUtils.degRad;
				const la = Math.cos(this.shearX) * scaleX;
				const lb = Math.cos(this.shearY) * scaleY;
				const lc = Math.sin(this.shearX) * scaleX;
				const ld = Math.sin(this.shearY) * scaleY;
				this.a = za * la + zb * lc;
				this.b = za * lb + zb * ld;
				this.c = zc * la + zd * lc;
				this.d = zc * lb + zd * ld;
				break;
			}
		}
		this.a *= skeleton.scaleX;
		this.b *= skeleton.scaleX;
		this.c *= skeleton.scaleY;
		this.d *= skeleton.scaleY;
	}

	/** Computes the local transform values from the world transform.
	 * <p>
	 * If the world transform is modified (by a constraint, {@link #rotateWorld(float)}, etc) then this method should be called so
	 * the local transform matches the world transform. The local transform may be needed by other code (eg to apply another
	 * constraint).
	 * <p>
	 * Some information is ambiguous in the world transform, such as -1,-1 scale versus 180 rotation. The local transform after
	 * calling this method is equivalent to the local transform used to compute the world transform, but may not be identical. */
	public updateLocalTransform (skeleton: Skeleton): void {
		this.local = 0;
		this.world = skeleton._update;

		if (!this.bone.parent) {
			this.x = this.worldX - skeleton.x;
			this.y = this.worldY - skeleton.y;
			let a = this.a, b = this.b, c = this.c, d = this.d;
			this.rotation = MathUtils.atan2Deg(c, a);
			this.scaleX = Math.sqrt(a * a + c * c);
			this.scaleY = Math.sqrt(b * b + d * d);
			this.shearX = 0;
			this.shearY = MathUtils.atan2Deg(a * b + c * d, a * d - b * c);
			return;
		}

		const parent = this.bone.parent.applied;
		let pa = parent.a, pb = parent.b, pc = parent.c, pd = parent.d;
		let pid = 1 / (pa * pd - pb * pc);
		let ia = pd * pid, ib = pb * pid, ic = pc * pid, id = pa * pid;
		let dx = this.worldX - parent.worldX, dy = this.worldY - parent.worldY;
		this.x = (dx * ia - dy * ib);
		this.y = (dy * id - dx * ic);

		let ra, rb, rc, rd;
		if (this.inherit == Inherit.OnlyTranslation) {
			ra = this.a;
			rb = this.b;
			rc = this.c;
			rd = this.d;
		} else {
			switch (this.inherit) {
				case Inherit.NoRotationOrReflection: {
					let s = Math.abs(pa * pd - pb * pc) / (pa * pa + pc * pc);
					pb = -pc * skeleton.scaleX * s / skeleton.scaleY;
					pd = pa * skeleton.scaleY * s / skeleton.scaleX;
					pid = 1 / (pa * pd - pb * pc);
					ia = pd * pid;
					ib = pb * pid;
					break;
				}
				case Inherit.NoScale:
				case Inherit.NoScaleOrReflection:
					let r = this.rotation * MathUtils.degRad, cos = Math.cos(r), sin = Math.sin(r);
					pa = (pa * cos + pb * sin) / skeleton.scaleX;
					pc = (pc * cos + pd * sin) / skeleton.scaleY;
					let s = Math.sqrt(pa * pa + pc * pc);
					if (s > 0.00001) s = 1 / s;
					pa *= s;
					pc *= s;
					s = Math.sqrt(pa * pa + pc * pc);
					if (this.inherit == Inherit.NoScale && pid < 0 != (skeleton.scaleX < 0 != skeleton.scaleY < 0)) s = -s;
					r = MathUtils.PI / 2 + Math.atan2(pc, pa);
					pb = Math.cos(r) * s;
					pd = Math.sin(r) * s;
					pid = 1 / (pa * pd - pb * pc);
					ia = pd * pid;
					ib = pb * pid;
					ic = pc * pid;
					id = pa * pid;
			}
			ra = ia * this.a - ib * this.c;
			rb = ia * this.b - ib * this.d;
			rc = id * this.c - ic * this.a;
			rd = id * this.d - ic * this.b;
		}

		this.shearX = 0;
		this.scaleX = Math.sqrt(ra * ra + rc * rc);
		if (this.scaleX > 0.0001) {
			let det = ra * rd - rb * rc;
			this.scaleY = det / this.scaleX;
			this.shearY = -MathUtils.atan2Deg(ra * rb + rc * rd, det);
			this.rotation = MathUtils.atan2Deg(rc, ra);
		} else {
			this.scaleX = 0;
			this.scaleY = Math.sqrt(rb * rb + rd * rd);
			this.shearY = 0;
			this.rotation = 90 - MathUtils.atan2Deg(rd, rb);
		}
	}

	/** If the world transform has been modified and the local transform no longer matches, {@link #updateLocalTransform(Skeleton)}
	 * is called. */
	public validateLocalTransform (skeleton: Skeleton): void {
		if (this.local === skeleton._update) this.updateLocalTransform(skeleton);
	}

	modifyLocal (skeleton: Skeleton): void {
		if (this.local === skeleton._update) this.updateLocalTransform(skeleton);
		this.world = 0;
		this.resetWorld(skeleton._update);
	}

	modifyWorld (update: number): void {
		this.local = update;
		this.world = update;
		this.resetWorld(update);
	}

	resetWorld (update: number): void {
		const children = this.bone.children;
		for (let i = 0, n = children.length; i < n; i++) {
			const child = children[i].applied;
			if (child.world === update) {
				child.world = 0;
				child.local = 0;
				child.resetWorld(update);
			}
		}
	}

	/** The world rotation for the X axis, calculated using {@link a} and {@link c}. */
	public getWorldRotationX (): number {
		return MathUtils.atan2Deg(this.c, this.a);
	}

	/** The world rotation for the Y axis, calculated using {@link b} and {@link d}. */
	public getWorldRotationY (): number {
		return MathUtils.atan2Deg(this.d, this.b);
	}

	/** The magnitude (always positive) of the world scale X, calculated using {@link a} and {@link c}. */
	public getWorldScaleX (): number {
		return Math.sqrt(this.a * this.a + this.c * this.c);
	}

	/** The magnitude (always positive) of the world scale Y, calculated using {@link b} and {@link d}. */
	public getWorldScaleY (): number {
		return Math.sqrt(this.b * this.b + this.d * this.d);
	}

	// public Matrix3 getWorldTransform (Matrix3 worldTransform) {
	// 	if (worldTransform == null) throw new IllegalArgumentException("worldTransform cannot be null.");
	// 	float[] val = worldTransform.val;
	// 	val[M00] = a;
	// 	val[M01] = b;
	// 	val[M10] = c;
	// 	val[M11] = d;
	// 	val[M02] = worldX;
	// 	val[M12] = worldY;
	// 	val[M20] = 0;
	// 	val[M21] = 0;
	// 	val[M22] = 1;
	// 	return worldTransform;
	// }

	/** Transforms a point from world coordinates to the bone's local coordinates. */
	public worldToLocal (world: Vector2): Vector2 {
		if (world == null) throw new Error("world cannot be null.");
		let det = this.a * this.d - this.b * this.c;
		let x = world.x - this.worldX, y = world.y - this.worldY;
		world.x = (x * this.d - y * this.b) / det;
		world.y = (y * this.a - x * this.c) / det;
		return world;
	}

	/** Transforms a point from the bone's local coordinates to world coordinates. */
	public localToWorld (local: Vector2): Vector2 {
		if (local == null) throw new Error("local cannot be null.");
		let x = local.x, y = local.y;
		local.x = x * this.a + y * this.b + this.worldX;
		local.y = x * this.c + y * this.d + this.worldY;
		return local;
	}

	/** Transforms a point from world coordinates to the parent bone's local coordinates. */
	public worldToParent (world: Vector2): Vector2 {
		if (world == null) throw new Error("world cannot be null.");
		return this.bone.parent == null ? world : this.bone.parent.applied.worldToLocal(world);
	}

	/** Transforms a point from the parent bone's coordinates to world coordinates. */
	public parentToWorld (world: Vector2): Vector2 {
		if (world == null) throw new Error("world cannot be null.");
		return this.bone.parent == null ? world : this.bone.parent.applied.localToWorld(world);
	}

	/** Transforms a world rotation to a local rotation. */
	public worldToLocalRotation (worldRotation: number): number {
		worldRotation *= MathUtils.degRad;
		let sin = Math.sin(worldRotation), cos = Math.cos(worldRotation);
		return MathUtils.atan2Deg(this.a * sin - this.c * cos, this.d * cos - this.b * sin) + this.rotation - this.shearX;
	}

	/** Transforms a local rotation to a world rotation. */
	localToWorldRotation (localRotation: number): number {
		localRotation = (localRotation - this.rotation - this.shearX) * MathUtils.degRad;
		let sin = Math.sin(localRotation), cos = Math.cos(localRotation);
		return MathUtils.atan2Deg(cos * this.c + sin * this.d, cos * this.a + sin * this.b);
	}

	/** Rotates the world transform the specified amount.
	 * <p>
	 * After changes are made to the world transform, {@link updateLocalTransform} should be called on this bone and any
	 * child bones, recursively. */
	rotateWorld (degrees: number) {
		degrees *= MathUtils.degRad;
		const sin = Math.sin(degrees), cos = Math.cos(degrees);
		const ra = this.a, rb = this.b;
		this.a = cos * ra - sin * this.c;
		this.b = cos * rb - sin * this.d;
		this.c = sin * ra + cos * this.c;
		this.d = sin * rb + cos * this.d;
	}
}