import {
	Box3,
	InstancedInterleavedBuffer,
	InterleavedBufferAttribute,
	Line3,
	MathUtils,
	Matrix4,
	Mesh,
	Sphere,
	Vector3,
	Vector4
} from 'three';
import { LineSegmentsGeometry } from '../lines/LineSegmentsGeometry.js';
import { LineMaterial } from '../lines/LineMaterial.js';

const _start = new Vector3();
const _end = new Vector3();

const _start4 = new Vector4();
const _end4 = new Vector4();

const _ssOrigin = new Vector4();
const _ssOrigin3 = new Vector3();
const _mvMatrix = new Matrix4();
const _line = new Line3();
const _closestPoint = new Vector3();

const _box = new Box3();
const _sphere = new Sphere();
const _clipToWorldVector = new Vector4();

class LineSegments2 extends Mesh {

	constructor( geometry = new LineSegmentsGeometry(), material = new LineMaterial( { color: Math.random() * 0xffffff } ) ) {

		super( geometry, material );

		this.type = 'LineSegments2';

	}

	// for backwards-compatability, but could be a method of LineSegmentsGeometry...

	computeLineDistances() {

		const geometry = this.geometry;

		const instanceStart = geometry.attributes.instanceStart;
		const instanceEnd = geometry.attributes.instanceEnd;
		const lineDistances = new Float32Array( 2 * instanceStart.count );

		for ( let i = 0, j = 0, l = instanceStart.count; i < l; i ++, j += 2 ) {

			_start.fromBufferAttribute( instanceStart, i );
			_end.fromBufferAttribute( instanceEnd, i );

			lineDistances[ j ] = ( j === 0 ) ? 0 : lineDistances[ j - 1 ];
			lineDistances[ j + 1 ] = lineDistances[ j ] + _start.distanceTo( _end );

		}

		const instanceDistanceBuffer = new InstancedInterleavedBuffer( lineDistances, 2, 1 ); // d0, d1

		geometry.setAttribute( 'instanceDistanceStart', new InterleavedBufferAttribute( instanceDistanceBuffer, 1, 0 ) ); // d0
		geometry.setAttribute( 'instanceDistanceEnd', new InterleavedBufferAttribute( instanceDistanceBuffer, 1, 1 ) ); // d1

		return this;

	}

	raycast( raycaster, intersects ) {

		if ( raycaster.camera === null ) {

			console.error( 'LineSegments2: "Raycaster.camera" needs to be set in order to raycast against LineSegments2.' );

		}

		const threshold = ( raycaster.params.Line2 !== undefined ) ? raycaster.params.Line2.threshold || 0 : 0;

		const ray = raycaster.ray;
		const camera = raycaster.camera;
		const projectionMatrix = camera.projectionMatrix;

		const matrixWorld = this.matrixWorld;
		const geometry = this.geometry;
		const material = this.material;
		const resolution = material.resolution;
		const lineWidth = material.linewidth + threshold;

		const instanceStart = geometry.attributes.instanceStart;
		const instanceEnd = geometry.attributes.instanceEnd;

		// camera forward is negative
		const near = - camera.near;

		// clip space is [ - 1, 1 ] so multiply by two to get the full
		// width in clip space
		const ssMaxWidth = 2.0 * Math.max( lineWidth / resolution.width, lineWidth / resolution.height );

		//

		// check if we intersect the sphere bounds
		if ( geometry.boundingSphere === null ) {

			geometry.computeBoundingSphere();

		}

		_sphere.copy( geometry.boundingSphere ).applyMatrix4( matrixWorld );
		const distanceToSphere = Math.max( camera.near, _sphere.distanceToPoint( ray.origin ) );

		// get the w component to scale the world space line width
		_clipToWorldVector.set( 0, 0, - distanceToSphere, 1.0 ).applyMatrix4( camera.projectionMatrix );
		_clipToWorldVector.multiplyScalar( 1.0 / _clipToWorldVector.w );
		_clipToWorldVector.applyMatrix4( camera.projectionMatrixInverse );

		// increase the sphere bounds by the worst case line screen space width
		const sphereMargin = Math.abs( ssMaxWidth / _clipToWorldVector.w ) * 0.5;
		_sphere.radius += sphereMargin;

		if ( raycaster.ray.intersectsSphere( _sphere ) === false ) {

			return;

		}

		//

		// check if we intersect the box bounds
		if ( geometry.boundingBox === null ) {

			geometry.computeBoundingBox();

		}

		_box.copy( geometry.boundingBox ).applyMatrix4( matrixWorld );
		const distanceToBox = Math.max( camera.near, _box.distanceToPoint( ray.origin ) );

		// get the w component to scale the world space line width
		_clipToWorldVector.set( 0, 0, - distanceToBox, 1.0 ).applyMatrix4( camera.projectionMatrix );
		_clipToWorldVector.multiplyScalar( 1.0 / _clipToWorldVector.w );
		_clipToWorldVector.applyMatrix4( camera.projectionMatrixInverse );

		// increase the sphere bounds by the worst case line screen space width
		const boxMargin = Math.abs( ssMaxWidth / _clipToWorldVector.w ) * 0.5;
		_box.max.x += boxMargin;
		_box.max.y += boxMargin;
		_box.max.z += boxMargin;
		_box.min.x -= boxMargin;
		_box.min.y -= boxMargin;
		_box.min.z -= boxMargin;

		if ( raycaster.ray.intersectsBox( _box ) === false ) {

			return;

		}

		//

		// pick a point 1 unit out along the ray to avoid the ray origin
		// sitting at the camera origin which will cause "w" to be 0 when
		// applying the projection matrix.
		ray.at( 1, _ssOrigin );

		// ndc space [ - 1.0, 1.0 ]
		_ssOrigin.w = 1;
		_ssOrigin.applyMatrix4( camera.matrixWorldInverse );
		_ssOrigin.applyMatrix4( projectionMatrix );
		_ssOrigin.multiplyScalar( 1 / _ssOrigin.w );

		// screen space
		_ssOrigin.x *= resolution.x / 2;
		_ssOrigin.y *= resolution.y / 2;
		_ssOrigin.z = 0;

		_ssOrigin3.copy( _ssOrigin );

		_mvMatrix.multiplyMatrices( camera.matrixWorldInverse, matrixWorld );

		for ( let i = 0, l = instanceStart.count; i < l; i ++ ) {

			_start4.fromBufferAttribute( instanceStart, i );
			_end4.fromBufferAttribute( instanceEnd, i );

			_start4.w = 1;
			_end4.w = 1;

			// camera space
			_start4.applyMatrix4( _mvMatrix );
			_end4.applyMatrix4( _mvMatrix );

			// skip the segment if it's entirely behind the camera
			var isBehindCameraNear = _start4.z > near && _end4.z > near;
			if ( isBehindCameraNear ) {

				continue;

			}

			// trim the segment if it extends behind camera near
			if ( _start4.z > near ) {

				const deltaDist = _start4.z - _end4.z;
				const t = ( _start4.z - near ) / deltaDist;
				_start4.lerp( _end4, t );

			} else if ( _end4.z > near ) {

				const deltaDist = _end4.z - _start4.z;
				const t = ( _end4.z - near ) / deltaDist;
				_end4.lerp( _start4, t );

			}

			// clip space
			_start4.applyMatrix4( projectionMatrix );
			_end4.applyMatrix4( projectionMatrix );

			// ndc space [ - 1.0, 1.0 ]
			_start4.multiplyScalar( 1 / _start4.w );
			_end4.multiplyScalar( 1 / _end4.w );

			// screen space
			_start4.x *= resolution.x / 2;
			_start4.y *= resolution.y / 2;

			_end4.x *= resolution.x / 2;
			_end4.y *= resolution.y / 2;

			// create 2d segment
			_line.start.copy( _start4 );
			_line.start.z = 0;

			_line.end.copy( _end4 );
			_line.end.z = 0;

			// get closest point on ray to segment
			const param = _line.closestPointToPointParameter( _ssOrigin3, true );
			_line.at( param, _closestPoint );

			// check if the intersection point is within clip space
			const zPos = MathUtils.lerp( _start4.z, _end4.z, param );
			const isInClipSpace = zPos >= - 1 && zPos <= 1;

			const isInside = _ssOrigin3.distanceTo( _closestPoint ) < lineWidth * 0.5;

			if ( isInClipSpace && isInside ) {

				_line.start.fromBufferAttribute( instanceStart, i );
				_line.end.fromBufferAttribute( instanceEnd, i );

				_line.start.applyMatrix4( matrixWorld );
				_line.end.applyMatrix4( matrixWorld );

				const pointOnLine = new Vector3();
				const point = new Vector3();

				ray.distanceSqToSegment( _line.start, _line.end, point, pointOnLine );

				intersects.push( {

					point: point,
					pointOnLine: pointOnLine,
					distance: ray.origin.distanceTo( point ),

					object: this,
					face: null,
					faceIndex: i,
					uv: null,
					uv2: null,

				} );

			}

		}

	}

}

LineSegments2.prototype.LineSegments2 = true;

export { LineSegments2 };
