import { RGBAFormat, FloatType } from '../constants.js';
import { Bone } from './Bone.js';
import { Matrix4 } from '../math/Matrix4.js';
import { DataTexture } from '../textures/DataTexture.js';
import * as MathUtils from '../math/MathUtils.js';

const _offsetMatrix = /*@__PURE__*/ new Matrix4();
const _identityMatrix = /*@__PURE__*/ new Matrix4();

class Skeleton {
	constructor(bones = [], boneInverses = []) {
		this.uuid = MathUtils.generateUUID();

		this.bones = bones.slice(0);
		this.boneInverses = boneInverses;
		this.boneMatrices = null;

		this.boneTexture = null;
		this.boneTextureSize = 0;

		this.frame = -1;

		this.init();
	}

	init() {
		const bones = this.bones;
		const boneInverses = this.boneInverses;

		this.boneMatrices = new Float32Array(bones.length * 16);

		// calculate inverse bone matrices if necessary

		if (boneInverses.length === 0) {
			this.calculateInverses();
		} else {
			// handle special case

			if (bones.length !== boneInverses.length) {
				console.warn('THREE.Skeleton: Number of inverse bone matrices does not match amount of bones.');

				this.boneInverses = [];

				for (let i = 0, il = this.bones.length; i < il; i++) {
					this.boneInverses.push(new Matrix4());
				}
			}
		}
	}

	calculateInverses() {
		this.boneInverses.length = 0;

		for (let i = 0, il = this.bones.length; i < il; i++) {
			const inverse = new Matrix4();

			if (this.bones[i]) {
				inverse.copy(this.bones[i].matrixWorld).invert();
			}

			this.boneInverses.push(inverse);
		}
	}

	pose() {
		// recover the bind-time world matrices

		for (let i = 0, il = this.bones.length; i < il; i++) {
			const bone = this.bones[i];

			if (bone) {
				bone.matrixWorld.copy(this.boneInverses[i]).invert();
			}
		}

		// compute the local matrices, positions, rotations and scales

		for (let i = 0, il = this.bones.length; i < il; i++) {
			const bone = this.bones[i];

			if (bone) {
				if (bone.parent && bone.parent.isBone) {
					bone.matrix.copy(bone.parent.matrixWorld).invert();
					bone.matrix.multiply(bone.matrixWorld);
				} else {
					bone.matrix.copy(bone.matrixWorld);
				}

				bone.matrix.decompose(bone.position, bone.quaternion, bone.scale);
			}
		}
	}

	update() {
		const bones = this.bones;
		const boneInverses = this.boneInverses;
		const boneMatrices = this.boneMatrices;
		const boneTexture = this.boneTexture;

		// flatten bone matrices to array

		for (let i = 0, il = bones.length; i < il; i++) {
			// compute the offset between the current and the original transform

			const matrix = bones[i] ? bones[i].matrixWorld : _identityMatrix;

			_offsetMatrix.multiplyMatrices(matrix, boneInverses[i]);
			_offsetMatrix.toArray(boneMatrices, i * 16);
		}

		if (boneTexture !== null) {
			boneTexture.needsUpdate = true;
		}
	}

	clone() {
		return new Skeleton(this.bones, this.boneInverses);
	}

	computeBoneTexture() {
		// layout (1 matrix = 4 pixels)
		//      RGBA RGBA RGBA RGBA (=> column1, column2, column3, column4)
		//  with  8x8  pixel texture max   16 bones * 4 pixels =  (8 * 8)
		//       16x16 pixel texture max   64 bones * 4 pixels = (16 * 16)
		//       32x32 pixel texture max  256 bones * 4 pixels = (32 * 32)
		//       64x64 pixel texture max 1024 bones * 4 pixels = (64 * 64)

		let size = Math.sqrt(this.bones.length * 4); // 4 pixels needed for 1 matrix
		size = MathUtils.ceilPowerOfTwo(size);
		size = Math.max(size, 4);

		const boneMatrices = new Float32Array(size * size * 4); // 4 floats per RGBA pixel
		boneMatrices.set(this.boneMatrices); // copy current values

		const boneTexture = new DataTexture(boneMatrices, size, size, RGBAFormat, FloatType);
		boneTexture.needsUpdate = true;

		this.boneMatrices = boneMatrices;
		this.boneTexture = boneTexture;
		this.boneTextureSize = size;

		return this;
	}

	getBoneByName(name) {
		for (let i = 0, il = this.bones.length; i < il; i++) {
			const bone = this.bones[i];

			if (bone.name === name) {
				return bone;
			}
		}

		return undefined;
	}

	dispose() {
		if (this.boneTexture !== null) {
			this.boneTexture.dispose();

			this.boneTexture = null;
		}
	}

	fromJSON(json, bones) {
		this.uuid = json.uuid;

		for (let i = 0, l = json.bones.length; i < l; i++) {
			const uuid = json.bones[i];
			let bone = bones[uuid];

			if (bone === undefined) {
				console.warn('THREE.Skeleton: No bone found with UUID:', uuid);
				bone = new Bone();
			}

			this.bones.push(bone);
			this.boneInverses.push(new Matrix4().fromArray(json.boneInverses[i]));
		}

		this.init();

		return this;
	}

	toJSON() {
		const data = {
			metadata: {
				version: 4.5,
				type: 'Skeleton',
				generator: 'Skeleton.toJSON',
			},
			bones: [],
			boneInverses: [],
		};

		data.uuid = this.uuid;

		const bones = this.bones;
		const boneInverses = this.boneInverses;

		for (let i = 0, l = bones.length; i < l; i++) {
			const bone = bones[i];
			data.bones.push(bone.uuid);

			const boneInverse = boneInverses[i];
			data.boneInverses.push(boneInverse.toArray());
		}

		return data;
	}
}

export { Skeleton };