/******************************************************************************
 * Spine Runtimes License Agreement
 * Last updated January 1, 2020. Replaces all prior versions.
 *
 * Copyright (c) 2013-2020, Esoteric Software LLC
 *
 * Integration of the Spine Runtimes into software or otherwise creating
 * derivative works of the Spine Runtimes is permitted under the terms and
 * conditions of Section 2 of the Spine Editor License Agreement:
 * http://esotericsoftware.com/spine-editor-license
 *
 * Otherwise, it is permitted to integrate the Spine Runtimes into software
 * or otherwise create derivative works of the Spine Runtimes (collectively,
 * "Products"), provided that each user of the Products must obtain their own
 * Spine Editor license and redistribution of the Products in any form must
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 * THE SPINE RUNTIMES ARE PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 *****************************************************************************/

module spine {

	/** Stores a bone's current pose.
	 *
	 * A bone has a local transform which is used to compute its world transform. A bone also has an applied transform, which is a
	 * local transform that can be applied to compute the world transform. The local transform and applied transform may differ if a
	 * constraint or application code modifies the world transform after it was computed from the local transform. */
	export class Bone implements Updatable {
		/** The bone's setup pose data. */
		data: BoneData;

		/** The skeleton this bone belongs to. */
		skeleton: Skeleton;

		/** The parent bone, or null if this is the root bone. */
		parent: Bone;

		/** The immediate children of this bone. */
		children = new Array<Bone>();

		/** The local x translation. */
		x = 0;

		/** The local y translation. */
		y = 0;

		/** The local rotation in degrees, counter clockwise. */
		rotation = 0;

		/** The local scaleX. */
		scaleX = 0;

		/** The local scaleY. */
		scaleY = 0;

		/** The local shearX. */
		shearX = 0;

		/** The local shearY. */
		shearY = 0;

		/** The applied local x translation. */
		ax = 0;

		/** The applied local y translation. */
		ay = 0;

		/** The applied local rotation in degrees, counter clockwise. */
		arotation = 0;

		/** The applied local scaleX. */
		ascaleX = 0;

		/** The applied local scaleY. */
		ascaleY = 0;

		/** The applied local shearX. */
		ashearX = 0;

		/** The applied local shearY. */
		ashearY = 0;

		/** If true, the applied transform matches the world transform. If false, the world transform has been modified since it was
	 	* computed and {@link #updateAppliedTransform()} must be called before accessing the applied transform. */
		appliedValid = false;

		/** Part of the world transform matrix for the X axis. If changed, {@link #appliedValid} should be set to false. */
		a = 0;

		/** Part of the world transform matrix for the Y axis. If changed, {@link #appliedValid} should be set to false. */
		b = 0;

		/** Part of the world transform matrix for the X axis. If changed, {@link #appliedValid} should be set to false. */
		c = 0;

		/** Part of the world transform matrix for the Y axis. If changed, {@link #appliedValid} should be set to false. */
		d = 0;

		/** The world X position. If changed, {@link #appliedValid} should be set to false. */
		worldY = 0;

		/** The world Y position. If changed, {@link #appliedValid} should be set to false. */
		worldX = 0;

		sorted = false;
		active = false;

		/** @param parent May be null. */
		constructor (data: BoneData, skeleton: Skeleton, parent: Bone) {
			if (data == null) throw new Error("data cannot be null.");
			if (skeleton == null) throw new Error("skeleton cannot be null.");
			this.data = data;
			this.skeleton = skeleton;
			this.parent = parent;
			this.setToSetupPose();
		}

		/** Returns false when the bone has not been computed because {@link BoneData#skinRequired} is true and the
	 	* {@link Skeleton#skin active skin} does not {@link Skin#bones contain} this bone. */
		isActive () {
			return this.active;
		}

		/** Same as {@link #updateWorldTransform()}. This method exists for Bone to implement {@link Updatable}. */
		update () {
			this.updateWorldTransformWith(this.x, this.y, this.rotation, this.scaleX, this.scaleY, this.shearX, this.shearY);
		}

		/** Computes the world transform using the parent bone and this bone's local transform.
		 *
		 * See {@link #updateWorldTransformWith()}. */
		updateWorldTransform () {
			this.updateWorldTransformWith(this.x, this.y, this.rotation, this.scaleX, this.scaleY, this.shearX, this.shearY);
		}

		/** Computes the world transform using the parent bone and the specified local transform. Child bones are not updated.
		 *
		 * See [World transforms](http://esotericsoftware.com/spine-runtime-skeletons#World-transforms) in the Spine
		 * Runtimes Guide. */
		updateWorldTransformWith (x: number, y: number, rotation: number, scaleX: number, scaleY: number, shearX: number, shearY: number) {
			this.ax = x;
			this.ay = y;
			this.arotation = rotation;
			this.ascaleX = scaleX;
			this.ascaleY = scaleY;
			this.ashearX = shearX;
			this.ashearY = shearY;
			this.appliedValid = true;

			let parent = this.parent;
			if (parent == null) { // Root bone.
				let skeleton = this.skeleton;
				let rotationY = rotation + 90 + shearY;
				let sx = skeleton.scaleX;
				let sy = skeleton.scaleY;
				this.a = MathUtils.cosDeg(rotation + shearX) * scaleX * sx;
				this.b = MathUtils.cosDeg(rotationY) * scaleY * sx;
				this.c = MathUtils.sinDeg(rotation + shearX) * scaleX * sy;
				this.d = MathUtils.sinDeg(rotationY) * scaleY * sy;
				this.worldX = x * sx + skeleton.x;
				this.worldY = y * sy + skeleton.y;
				return;
			}

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

			switch (this.data.transformMode) {
			case TransformMode.Normal: {
				let rotationY = rotation + 90 + shearY;
				let la = MathUtils.cosDeg(rotation + shearX) * scaleX;
				let lb = MathUtils.cosDeg(rotationY) * scaleY;
				let lc = MathUtils.sinDeg(rotation + shearX) * scaleX;
				let ld = MathUtils.sinDeg(rotationY) * 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 TransformMode.OnlyTranslation: {
				let rotationY = rotation + 90 + shearY;
				this.a = MathUtils.cosDeg(rotation + shearX) * scaleX;
				this.b = MathUtils.cosDeg(rotationY) * scaleY;
				this.c = MathUtils.sinDeg(rotation + shearX) * scaleX;
				this.d = MathUtils.sinDeg(rotationY) * scaleY;
				break;
			}
			case TransformMode.NoRotationOrReflection: {
				let s = pa * pa + pc * pc;
				let prx = 0;
				if (s > 0.0001) {
					s = Math.abs(pa * pd - pb * pc) / s;
					pb = pc * s;
					pd = pa * s;
					prx = Math.atan2(pc, pa) * MathUtils.radDeg;
				} else {
					pa = 0;
					pc = 0;
					prx = 90 - Math.atan2(pd, pb) * MathUtils.radDeg;
				}
				let rx = rotation + shearX - prx;
				let ry = rotation + shearY - prx + 90;
				let la = MathUtils.cosDeg(rx) * scaleX;
				let lb = MathUtils.cosDeg(ry) * scaleY;
				let lc = MathUtils.sinDeg(rx) * scaleX;
				let ld = MathUtils.sinDeg(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 TransformMode.NoScale:
			case TransformMode.NoScaleOrReflection: {
				let cos = MathUtils.cosDeg(rotation);
				let sin = MathUtils.sinDeg(rotation);
				let za = (pa * cos + pb * sin) / this.skeleton.scaleX;
				let zc = (pc * cos + pd * sin) / this.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.data.transformMode == TransformMode.NoScale
					&& (pa * pd - pb * pc < 0) != (this.skeleton.scaleX < 0 != this.skeleton.scaleY < 0)) s = -s;
				let r = Math.PI / 2 + Math.atan2(zc, za);
				let zb = Math.cos(r) * s;
				let zd = Math.sin(r) * s;
				let la = MathUtils.cosDeg(shearX) * scaleX;
				let lb = MathUtils.cosDeg(90 + shearY) * scaleY;
				let lc = MathUtils.sinDeg(shearX) * scaleX;
				let ld = MathUtils.sinDeg(90 + 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 *= this.skeleton.scaleX;
			this.b *= this.skeleton.scaleX;
			this.c *= this.skeleton.scaleY;
			this.d *= this.skeleton.scaleY;
		}

		/** Sets this bone's local transform to the setup pose. */
		setToSetupPose () {
			let data = this.data;
			this.x = data.x;
			this.y = data.y;
			this.rotation = data.rotation;
			this.scaleX = data.scaleX;
			this.scaleY = data.scaleY;
			this.shearX = data.shearX;
			this.shearY = data.shearY;
		}

		/** The world rotation for the X axis, calculated using {@link #a} and {@link #c}. */
		getWorldRotationX () {
			return Math.atan2(this.c, this.a) * MathUtils.radDeg;
		}

		/** The world rotation for the Y axis, calculated using {@link #b} and {@link #d}. */
		getWorldRotationY () {
			return Math.atan2(this.d, this.b) * MathUtils.radDeg;
		}

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

		/** Computes the applied transform values from the world transform. This allows the applied transform to be accessed after the
		 * world transform has been modified (by a constraint, {@link #rotateWorld()}, etc).
		 *
		 * If {@link #updateWorldTransform()} has been called for a bone and {@link #appliedValid} is false, then
		 * {@link #updateAppliedTransform()} must be called before accessing the applied transform.
		 *
		 * Some information is ambiguous in the world transform, such as -1,-1 scale versus 180 rotation. The applied transform after
		 * calling this method is equivalent to the local tranform used to compute the world transform, but may not be identical. */
		updateAppliedTransform () {
			this.appliedValid = true;
			let parent = this.parent;
			if (parent == null) {
				this.ax = this.worldX;
				this.ay = this.worldY;
				this.arotation = Math.atan2(this.c, this.a) * MathUtils.radDeg;
				this.ascaleX = Math.sqrt(this.a * this.a + this.c * this.c);
				this.ascaleY = Math.sqrt(this.b * this.b + this.d * this.d);
				this.ashearX = 0;
				this.ashearY = Math.atan2(this.a * this.b + this.c * this.d, this.a * this.d - this.b * this.c) * MathUtils.radDeg;
				return;
			}
			let pa = parent.a, pb = parent.b, pc = parent.c, pd = parent.d;
			let pid = 1 / (pa * pd - pb * pc);
			let dx = this.worldX - parent.worldX, dy = this.worldY - parent.worldY;
			this.ax = (dx * pd * pid - dy * pb * pid);
			this.ay = (dy * pa * pid - dx * pc * pid);
			let ia = pid * pd;
			let id = pid * pa;
			let ib = pid * pb;
			let ic = pid * pc;
			let ra = ia * this.a - ib * this.c;
			let rb = ia * this.b - ib * this.d;
			let rc = id * this.c - ic * this.a;
			let rd = id * this.d - ic * this.b;
			this.ashearX = 0;
			this.ascaleX = Math.sqrt(ra * ra + rc * rc);
			if (this.ascaleX > 0.0001) {
				let det = ra * rd - rb * rc;
				this.ascaleY = det / this.ascaleX;
				this.ashearY = Math.atan2(ra * rb + rc * rd, det) * MathUtils.radDeg;
				this.arotation = Math.atan2(rc, ra) * MathUtils.radDeg;
			} else {
				this.ascaleX = 0;
				this.ascaleY = Math.sqrt(rb * rb + rd * rd);
				this.ashearY = 0;
				this.arotation = 90 - Math.atan2(rd, rb) * MathUtils.radDeg;
			}
		}

		/** Transforms a point from world coordinates to the bone's local coordinates. */
		worldToLocal (world: Vector2) {
			let a = this.a, b = this.b, c = this.c, d = this.d;
			let invDet = 1 / (a * d - b * c);
			let x = world.x - this.worldX, y = world.y - this.worldY;
			world.x = (x * d * invDet - y * b * invDet);
			world.y = (y * a * invDet - x * c * invDet);
			return world;
		}

		/** Transforms a point from the bone's local coordinates to world coordinates. */
		localToWorld (local: Vector2) {
			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 world rotation to a local rotation. */
		worldToLocalRotation (worldRotation: number) {
			let sin = MathUtils.sinDeg(worldRotation), cos = MathUtils.cosDeg(worldRotation);
			return Math.atan2(this.a * sin - this.c * cos, this.d * cos - this.b * sin) * MathUtils.radDeg + this.rotation - this.shearX;
		}

		/** Transforms a local rotation to a world rotation. */
		localToWorldRotation (localRotation: number) {
			localRotation -= this.rotation - this.shearX;
			let sin = MathUtils.sinDeg(localRotation), cos = MathUtils.cosDeg(localRotation);
			return Math.atan2(cos * this.c + sin * this.d, cos * this.a + sin * this.b) * MathUtils.radDeg;
		}

		/** Rotates the world transform the specified amount and sets {@link #appliedValid} to false.
		 * {@link #updateWorldTransform()} will need to be called on any child bones, recursively, and any constraints reapplied. */
		rotateWorld (degrees: number) {
			let a = this.a, b = this.b, c = this.c, d = this.d;
			let cos = MathUtils.cosDeg(degrees), sin = MathUtils.sinDeg(degrees);
			this.a = cos * a - sin * c;
			this.b = cos * b - sin * d;
			this.c = sin * a + cos * c;
			this.d = sin * b + cos * d;
			this.appliedValid = false;
		}
	}
}