/******************************************************************************
 * Spine Runtimes License Agreement
 * Last updated September 24, 2021. Replaces all prior versions.
 *
 * Copyright (c) 2013-2021, 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
 * include this license and copyright notice.
 *
 * THE SPINE RUNTIMES ARE PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL ESOTERIC SOFTWARE LLC BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES,
 * BUSINESS INTERRUPTION, OR LOSS OF USE, DATA, OR PROFITS) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THE SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *****************************************************************************/

import { Slot } from "../Slot";
import { NumberArrayLike, Utils } from "../Utils";

/** The base class for all attachments. */
export abstract class Attachment {
	name: string;

	constructor (name: string) {
		if (!name) throw new Error("name cannot be null.");
		this.name = name;
	}

	abstract copy (): Attachment;
}

/** Base class for an attachment with vertices that are transformed by one or more bones and can be deformed by a slot's
 * {@link Slot#deform}. */
export abstract class VertexAttachment extends Attachment {
	private static nextID = 0;

	/** The unique ID for this attachment. */
	id = VertexAttachment.nextID++;

	/** The bones which affect the {@link #getVertices()}. The array entries are, for each vertex, the number of bones affecting
	 * the vertex followed by that many bone indices, which is the index of the bone in {@link Skeleton#bones}. Will be null
	 * if this attachment has no weights. */
	bones: Array<number> | null = null;

	/** The vertex positions in the bone's coordinate system. For a non-weighted attachment, the values are `x,y`
	 * entries for each vertex. For a weighted attachment, the values are `x,y,weight` entries for each bone affecting
	 * each vertex. */
	vertices: NumberArrayLike = [];

	/** The maximum number of world vertex values that can be output by
	 * {@link #computeWorldVertices()} using the `count` parameter. */
	worldVerticesLength = 0;

	/** Timelines for the timeline attachment are also applied to this attachment.
	 * May be null if no attachment-specific timelines should be applied. */
	timelineAttachment: Attachment = this;

	constructor (name: string) {
		super(name);
	}

	/** Transforms the attachment's local {@link #vertices} to world coordinates. If the slot's {@link Slot#deform} is
	 * not empty, it is used to deform the vertices.
	 *
	 * See [World transforms](http://esotericsoftware.com/spine-runtime-skeletons#World-transforms) in the Spine
	 * Runtimes Guide.
	 * @param start The index of the first {@link #vertices} value to transform. Each vertex has 2 values, x and y.
	 * @param count The number of world vertex values to output. Must be <= {@link #worldVerticesLength} - `start`.
	 * @param worldVertices The output world vertices. Must have a length >= `offset` + `count` *
	 *           `stride` / 2.
	 * @param offset The `worldVertices` index to begin writing values.
	 * @param stride The number of `worldVertices` entries between the value pairs written. */
	computeWorldVertices (slot: Slot, start: number, count: number, worldVertices: NumberArrayLike, offset: number, stride: number) {
		count = offset + (count >> 1) * stride;
		let skeleton = slot.bone.skeleton;
		let deformArray = slot.deform;
		let vertices = this.vertices;
		let bones = this.bones;
		if (!bones) {
			if (deformArray.length > 0) vertices = deformArray;
			let bone = slot.bone;
			let x = bone.worldX;
			let y = bone.worldY;
			let a = bone.a, b = bone.b, c = bone.c, d = bone.d;
			for (let v = start, w = offset; w < count; v += 2, w += stride) {
				let vx = vertices[v], vy = vertices[v + 1];
				worldVertices[w] = vx * a + vy * b + x;
				worldVertices[w + 1] = vx * c + vy * d + y;
			}
			return;
		}
		let v = 0, skip = 0;
		for (let i = 0; i < start; i += 2) {
			let n = bones[v];
			v += n + 1;
			skip += n;
		}
		let skeletonBones = skeleton.bones;
		if (deformArray.length == 0) {
			for (let w = offset, b = skip * 3; w < count; w += stride) {
				let wx = 0, wy = 0;
				let n = bones[v++];
				n += v;
				for (; v < n; v++, b += 3) {
					let bone = skeletonBones[bones[v]];
					let vx = vertices[b], vy = vertices[b + 1], weight = vertices[b + 2];
					wx += (vx * bone.a + vy * bone.b + bone.worldX) * weight;
					wy += (vx * bone.c + vy * bone.d + bone.worldY) * weight;
				}
				worldVertices[w] = wx;
				worldVertices[w + 1] = wy;
			}
		} else {
			let deform = deformArray;
			for (let w = offset, b = skip * 3, f = skip << 1; w < count; w += stride) {
				let wx = 0, wy = 0;
				let n = bones[v++];
				n += v;
				for (; v < n; v++, b += 3, f += 2) {
					let bone = skeletonBones[bones[v]];
					let vx = vertices[b] + deform[f], vy = vertices[b + 1] + deform[f + 1], weight = vertices[b + 2];
					wx += (vx * bone.a + vy * bone.b + bone.worldX) * weight;
					wy += (vx * bone.c + vy * bone.d + bone.worldY) * weight;
				}
				worldVertices[w] = wx;
				worldVertices[w + 1] = wy;
			}
		}
	}

	/** Does not copy id (generated) or name (set on construction). **/
	copyTo (attachment: VertexAttachment) {
		if (this.bones) {
			attachment.bones = new Array<number>(this.bones.length);
			Utils.arrayCopy(this.bones, 0, attachment.bones, 0, this.bones.length);
		} else
			attachment.bones = null;

		if (this.vertices) {
			attachment.vertices = Utils.newFloatArray(this.vertices.length);
			Utils.arrayCopy(this.vertices, 0, attachment.vertices, 0, this.vertices.length);
		}

		attachment.worldVerticesLength = this.worldVerticesLength;
		attachment.timelineAttachment = this.timelineAttachment;
	}
}