/******************************************************************************
 * 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
 * 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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 *****************************************************************************/

import { BoundingBoxAttachment } from "./attachments/BoundingBoxAttachment.js";
import type { Skeleton } from "./Skeleton.js";
import { type NumberArrayLike, Pool, Utils } from "./Utils.js";

/** Collects each visible {@link BoundingBoxAttachment} and computes the world vertices for its polygon. The polygon vertices are
 * provided along with convenience methods for doing hit detection. */
export class SkeletonBounds {

	/** The left edge of the axis aligned bounding box. */
	minX = 0;

	/** The bottom edge of the axis aligned bounding box. */
	minY = 0;

	/** The right edge of the axis aligned bounding box. */
	maxX = 0;

	/** The top edge of the axis aligned bounding box. */
	maxY = 0;

	/** The visible bounding boxes. */
	boundingBoxes = [] as BoundingBoxAttachment[];

	/** The world vertices for the bounding box polygons. */
	polygons = [] as NumberArrayLike[];

	private polygonPool = new Pool<NumberArrayLike>(() => {
		return Utils.newFloatArray(16);
	});

	/** Clears any previous polygons, finds all visible bounding box attachments, and computes the world vertices for each bounding
	 * box's polygon.
	 * @param updateAabb If true, the axis aligned bounding box containing all the polygons is computed. If false, the
	 *           SkeletonBounds AABB methods will always return true. */
	update (skeleton: Skeleton, updateAabb: boolean) {
		if (!skeleton) throw new Error("skeleton cannot be null.");
		const boundingBoxes = this.boundingBoxes;
		const polygons = this.polygons;
		const polygonPool = this.polygonPool;
		const slots = skeleton.slots;
		const slotCount = slots.length;

		boundingBoxes.length = 0;
		polygonPool.freeAll(polygons);
		polygons.length = 0;

		for (let i = 0; i < slotCount; i++) {
			const slot = slots[i];
			if (!slot.bone.active) continue;
			const attachment = slot.applied.attachment;
			if (attachment instanceof BoundingBoxAttachment) {
				boundingBoxes.push(attachment);

				let polygon = polygonPool.obtain();
				if (polygon.length !== attachment.worldVerticesLength) {
					polygon = Utils.newFloatArray(attachment.worldVerticesLength);
				}
				polygons.push(polygon);
				attachment.computeWorldVertices(skeleton, slot, 0, attachment.worldVerticesLength, polygon, 0, 2);
			}
		}

		if (updateAabb) {
			this.aabbCompute();
		} else {
			this.minX = Number.POSITIVE_INFINITY;
			this.minY = Number.POSITIVE_INFINITY;
			this.maxX = Number.NEGATIVE_INFINITY;
			this.maxY = Number.NEGATIVE_INFINITY;
		}
	}

	aabbCompute () {
		let minX = Number.POSITIVE_INFINITY, minY = Number.POSITIVE_INFINITY, maxX = Number.NEGATIVE_INFINITY, maxY = Number.NEGATIVE_INFINITY;
		const polygons = this.polygons;
		for (let i = 0, n = polygons.length; i < n; i++) {
			const polygon = polygons[i];
			const vertices = polygon;
			for (let ii = 0, nn = polygon.length; ii < nn; ii += 2) {
				const x = vertices[ii];
				const y = vertices[ii + 1];
				minX = Math.min(minX, x);
				minY = Math.min(minY, y);
				maxX = Math.max(maxX, x);
				maxY = Math.max(maxY, y);
			}
		}
		this.minX = minX;
		this.minY = minY;
		this.maxX = maxX;
		this.maxY = maxY;
	}

	/** Returns true if the axis aligned bounding box contains the point. */
	aabbContainsPoint (x: number, y: number) {
		return x >= this.minX && x <= this.maxX && y >= this.minY && y <= this.maxY;
	}

	/** Returns true if the axis aligned bounding box intersects the line segment. */
	aabbIntersectsSegment (x1: number, y1: number, x2: number, y2: number) {
		const minX = this.minX;
		const minY = this.minY;
		const maxX = this.maxX;
		const maxY = this.maxY;
		if ((x1 <= minX && x2 <= minX) || (y1 <= minY && y2 <= minY) || (x1 >= maxX && x2 >= maxX) || (y1 >= maxY && y2 >= maxY))
			return false;
		const m = (y2 - y1) / (x2 - x1);
		let y = m * (minX - x1) + y1;
		if (y > minY && y < maxY) return true;
		y = m * (maxX - x1) + y1;
		if (y > minY && y < maxY) return true;
		let x = (minY - y1) / m + x1;
		if (x > minX && x < maxX) return true;
		x = (maxY - y1) / m + x1;
		if (x > minX && x < maxX) return true;
		return false;
	}

	/** Returns true if the axis aligned bounding box intersects the axis aligned bounding box of the specified bounds. */
	aabbIntersectsSkeleton (bounds: SkeletonBounds) {
		return this.minX < bounds.maxX && this.maxX > bounds.minX && this.minY < bounds.maxY && this.maxY > bounds.minY;
	}

	/** Returns the first bounding box attachment that contains the point, or null. When doing many checks, it is usually more
	 * efficient to only call this method if {@link #aabbContainsPoint(float, float)} returns true. */
	containsPoint (x: number, y: number): BoundingBoxAttachment | null {
		const polygons = this.polygons;
		for (let i = 0, n = polygons.length; i < n; i++)
			if (this.containsPointPolygon(polygons[i], x, y)) return this.boundingBoxes[i];
		return null;
	}

	/** Returns true if the polygon contains the point. */
	containsPointPolygon (polygon: NumberArrayLike, x: number, y: number) {
		const vertices = polygon;
		const nn = polygon.length;

		let prevIndex = nn - 2;
		let inside = false;
		for (let ii = 0; ii < nn; ii += 2) {
			const vertexY = vertices[ii + 1];
			const prevY = vertices[prevIndex + 1];
			if ((vertexY < y && prevY >= y) || (prevY < y && vertexY >= y)) {
				const vertexX = vertices[ii];
				if (vertexX + (y - vertexY) / (prevY - vertexY) * (vertices[prevIndex] - vertexX) < x) inside = !inside;
			}
			prevIndex = ii;
		}
		return inside;
	}

	/** Returns the first bounding box attachment that contains any part of the line segment, or null. When doing many checks, it
	 * is usually more efficient to only call this method if {@link #aabbIntersectsSegment()} returns
	 * true. */
	intersectsSegment (x1: number, y1: number, x2: number, y2: number) {
		const polygons = this.polygons;
		for (let i = 0, n = polygons.length; i < n; i++)
			if (this.intersectsSegmentPolygon(polygons[i], x1, y1, x2, y2)) return this.boundingBoxes[i];
		return null;
	}

	/** Returns true if the polygon contains any part of the line segment. */
	intersectsSegmentPolygon (polygon: NumberArrayLike, x1: number, y1: number, x2: number, y2: number) {
		const vertices = polygon;
		const nn = polygon.length;

		const width12 = x1 - x2, height12 = y1 - y2;
		const det1 = x1 * y2 - y1 * x2;
		let x3 = vertices[nn - 2], y3 = vertices[nn - 1];
		for (let ii = 0; ii < nn; ii += 2) {
			const x4 = vertices[ii], y4 = vertices[ii + 1];
			const det2 = x3 * y4 - y3 * x4;
			const width34 = x3 - x4, height34 = y3 - y4;
			const det3 = width12 * height34 - height12 * width34;
			const x = (det1 * width34 - width12 * det2) / det3;
			if (((x >= x3 && x <= x4) || (x >= x4 && x <= x3)) && ((x >= x1 && x <= x2) || (x >= x2 && x <= x1))) {
				const y = (det1 * height34 - height12 * det2) / det3;
				if (((y >= y3 && y <= y4) || (y >= y4 && y <= y3)) && ((y >= y1 && y <= y2) || (y >= y2 && y <= y1))) return true;
			}
			x3 = x4;
			y3 = y4;
		}
		return false;
	}

	/** Returns the polygon for the specified bounding box, or null. */
	getPolygon (boundingBox: BoundingBoxAttachment) {
		if (!boundingBox) throw new Error("boundingBox cannot be null.");
		const index = this.boundingBoxes.indexOf(boundingBox);
		return index === -1 ? null : this.polygons[index];
	}

	/** The width of the axis aligned bounding box. */
	getWidth () {
		return this.maxX - this.minX;
	}

	/** The height of the axis aligned bounding box. */
	getHeight () {
		return this.maxY - this.minY;
	}
}