import { BufferGeometry } from '../core/BufferGeometry';

import { Vector3 } from '../math/Vector3';

import { Vector2 } from '../math/Vector2';

import { BufferAttribute } from '../core/BufferAttribute';

import { _Math } from '../math/Math';

/**

* @author Mugen87 / https://github.com/Mugen87

*/

// points - to create a closed torus, one must use a set of points

// like so: [ a, b, c, d, a ], see first is the same as last.

// segments - the number of circumference segments to create

// phiStart - the starting radian

// phiLength - the radian (0 to 2PI) range of the lathed section

// 2PI is a closed lathe, less than 2PI is a portion.

function LatheBufferGeometry( points, segments, phiStart, phiLength ) {

BufferGeometry.call( this );

this.type = 'LatheBufferGeometry';

this.parameters = {

points: points,

segments: segments,

phiStart: phiStart,

phiLength: phiLength

};

segments = Math.floor( segments ) || 12;

phiStart = phiStart || 0;

phiLength = phiLength || Math.PI * 2;

// clamp phiLength so it's in range of [ 0, 2PI ]

phiLength = _Math.clamp( phiLength, 0, Math.PI * 2 );

// these are used to calculate buffer length

var vertexCount = ( segments + 1 ) * points.length;

var indexCount = segments * points.length * 2 * 3;

// buffers

var indices = new BufferAttribute( new ( indexCount > 65535 ? Uint32Array : Uint16Array )( indexCount ) , 1 );

var vertices = new BufferAttribute( new Float32Array( vertexCount * 3 ), 3 );

var uvs = new BufferAttribute( new Float32Array( vertexCount * 2 ), 2 );

// helper variables

var index = 0, indexOffset = 0, base;

var inverseSegments = 1.0 / segments;

var vertex = new Vector3();

var uv = new Vector2();

var i, j;

// generate vertices and uvs

for ( i = 0; i <= segments; i ++ ) {

var phi = phiStart + i * inverseSegments * phiLength;

var sin = Math.sin( phi );

var cos = Math.cos( phi );

for ( j = 0; j <= ( points.length - 1 ); j ++ ) {

// vertex

vertex.x = points[ j ].x * sin;

vertex.y = points[ j ].y;

vertex.z = points[ j ].x * cos;

vertices.setXYZ( index, vertex.x, vertex.y, vertex.z );

// uv

uv.x = i / segments;

uv.y = j / ( points.length - 1 );

uvs.setXY( index, uv.x, uv.y );

// increase index

index ++;

}

}

// generate indices

for ( i = 0; i < segments; i ++ ) {

for ( j = 0; j < ( points.length - 1 ); j ++ ) {

base = j + i * points.length;

// indices

var a = base;

var b = base + points.length;

var c = base + points.length + 1;

var d = base + 1;

// face one

indices.setX( indexOffset, a ); indexOffset++;

indices.setX( indexOffset, b ); indexOffset++;

indices.setX( indexOffset, d ); indexOffset++;

// face two

indices.setX( indexOffset, b ); indexOffset++;

indices.setX( indexOffset, c ); indexOffset++;

indices.setX( indexOffset, d ); indexOffset++;

}

}

// build geometry

this.setIndex( indices );

this.addAttribute( 'position', vertices );

this.addAttribute( 'uv', uvs );

// generate normals

this.computeVertexNormals();

// if the geometry is closed, we need to average the normals along the seam.

// because the corresponding vertices are identical (but still have different UVs).

if( phiLength === Math.PI * 2 ) {

var normals = this.attributes.normal.array;

var n1 = new Vector3();

var n2 = new Vector3();

var n = new Vector3();

// this is the buffer offset for the last line of vertices

base = segments * points.length * 3;

for( i = 0, j = 0; i < points.length; i ++, j += 3 ) {

// select the normal of the vertex in the first line

n1.x = normals[ j + 0 ];

n1.y = normals[ j + 1 ];

n1.z = normals[ j + 2 ];

// select the normal of the vertex in the last line

n2.x = normals[ base + j + 0 ];

n2.y = normals[ base + j + 1 ];

n2.z = normals[ base + j + 2 ];

// average normals

n.addVectors( n1, n2 ).normalize();

// assign the new values to both normals

normals[ j + 0 ] = normals[ base + j + 0 ] = n.x;

normals[ j + 1 ] = normals[ base + j + 1 ] = n.y;

normals[ j + 2 ] = normals[ base + j + 2 ] = n.z;

} // next row

}

}

LatheBufferGeometry.prototype = Object.create( BufferGeometry.prototype );

LatheBufferGeometry.prototype.constructor = LatheBufferGeometry;

export { LatheBufferGeometry };