/**
 * Description: A THREE loader for STL ASCII files, as created by Solidworks and other CAD programs.
 *
 * Supports both binary and ASCII encoded files, with automatic detection of type.
 *
 * The loader returns a non-indexed buffer geometry.
 *
 * Limitations:
 *  Binary decoding supports "Magics" color format (http://en.wikipedia.org/wiki/STL_(file_format)#Color_in_binary_STL).
 *  There is perhaps some question as to how valid it is to always assume little-endian-ness.
 *  ASCII decoding assumes file is UTF-8.
 *
 * Usage:
 *  const loader = new STLLoader();
 *  loader.load( './models/stl/slotted_disk.stl', function ( geometry ) {
 *    scene.add( new THREE.Mesh( geometry ) );
 *  });
 *
 * For binary STLs geometry might contain colors for vertices. To use it:
 *  // use the same code to load STL as above
 *  if (geometry.hasColors) {
 *    material = new THREE.MeshPhongMaterial({ opacity: geometry.alpha, vertexColors: true });
 *  } else { .... }
 *  const mesh = new THREE.Mesh( geometry, material );
 *
 * For ASCII STLs containing multiple solids, each solid is assigned to a different group.
 * Groups can be used to assign a different color by defining an array of materials with the same length of
 * geometry.groups and passing it to the Mesh constructor:
 *
 * const mesh = new THREE.Mesh( geometry, material );
 *
 * For example:
 *
 *  const materials = [];
 *  const nGeometryGroups = geometry.groups.length;
 *
 *  const colorMap = ...; // Some logic to index colors.
 *
 *  for (let i = 0; i < nGeometryGroups; i++) {
 *
 *		const material = new THREE.MeshPhongMaterial({
 *			color: colorMap[i],
 *			wireframe: false
 *		});
 *
 *  }
 *
 *  materials.push(material);
 *  const mesh = new THREE.Mesh(geometry, materials);
 */

import * as THREE from 'three';

export class STLLoader extends THREE.Loader {
  constructor(manager) {
    super(manager);
  }

  load(url, onLoad, onProgress, onError) {
    const scope = this;
    const loader = new THREE.FileLoader(this.manager);
    loader.setPath(this.path);
    loader.setResponseType('arraybuffer');
    loader.setRequestHeader(this.requestHeader);
    loader.setWithCredentials(this.withCredentials);
    loader.load(
      url,
      function (text) {
        try {
          onLoad(scope.parse(text));
        } catch (e) {
          if (onError) {
            onError(e);
          } else {
            console.error(e);
          }

          scope.manager.itemError(url);
        }
      },
      onProgress,
      onError
    );
  }

  parse(data) {
    function isBinary(data) {
      const reader = new DataView(data);
      const face_size = (32 / 8) * 3 + (32 / 8) * 3 * 3 + 16 / 8;
      const n_faces = reader.getUint32(80, true);
      const expect = 80 + 32 / 8 + n_faces * face_size;

      if (expect === reader.byteLength) {
        return true;
      } // An ASCII STL data must begin with 'solid ' as the first six bytes.
      // However, ASCII STLs lacking the SPACE after the 'd' are known to be
      // plentiful.  So, check the first 5 bytes for 'solid'.
      // Several encodings, such as UTF-8, precede the text with up to 5 bytes:
      // https://en.wikipedia.org/wiki/Byte_order_mark#Byte_order_marks_by_encoding
      // Search for "solid" to start anywhere after those prefixes.
      // US-ASCII ordinal values for 's', 'o', 'l', 'i', 'd'

      const solid = [115, 111, 108, 105, 100];

      for (let off = 0; off < 5; off++) {
        // If "solid" text is matched to the current offset, declare it to be an ASCII STL.
        if (matchDataViewAt(solid, reader, off)) return false;
      } // Couldn't find "solid" text at the beginning; it is binary STL.

      return true;
    }

    function matchDataViewAt(query, reader, offset) {
      // Check if each byte in query matches the corresponding byte from the current offset
      for (let i = 0, il = query.length; i < il; i++) {
        if (query[i] !== reader.getUint8(offset + i, false)) return false;
      }

      return true;
    }

    function parseBinary(data) {
      const reader = new DataView(data);
      const faces = reader.getUint32(80, true);
      let r,
        g,
        b,
        hasColors = false,
        colors;
      let defaultR, defaultG, defaultB, alpha; // process STL header
      // check for default color in header ("COLOR=rgba" sequence).

      for (let index = 0; index < 80 - 10; index++) {
        if (
          reader.getUint32(index, false) == 0x434f4c4f &&
          /*COLO*/
          reader.getUint8(index + 4) == 0x52 &&
          /*'R'*/
          reader.getUint8(index + 5) == 0x3d
          /*'='*/
        ) {
          hasColors = true;
          colors = new Float32Array(faces * 3 * 3);
          defaultR = reader.getUint8(index + 6) / 255;
          defaultG = reader.getUint8(index + 7) / 255;
          defaultB = reader.getUint8(index + 8) / 255;
          alpha = reader.getUint8(index + 9) / 255;
        }
      }

      const dataOffset = 84;
      const faceLength = 12 * 4 + 2;
      const geometry = new THREE.BufferGeometry();
      const vertices = new Float32Array(faces * 3 * 3);
      const normals = new Float32Array(faces * 3 * 3);

      for (let face = 0; face < faces; face++) {
        const start = dataOffset + face * faceLength;
        const normalX = reader.getFloat32(start, true);
        const normalY = reader.getFloat32(start + 4, true);
        const normalZ = reader.getFloat32(start + 8, true);

        if (hasColors) {
          const packedColor = reader.getUint16(start + 48, true);

          if ((packedColor & 0x8000) === 0) {
            // facet has its own unique color
            r = (packedColor & 0x1f) / 31;
            g = ((packedColor >> 5) & 0x1f) / 31;
            b = ((packedColor >> 10) & 0x1f) / 31;
          } else {
            r = defaultR;
            g = defaultG;
            b = defaultB;
          }
        }

        for (let i = 1; i <= 3; i++) {
          const vertexstart = start + i * 12;
          const componentIdx = face * 3 * 3 + (i - 1) * 3;
          vertices[componentIdx] = reader.getFloat32(vertexstart, true);
          vertices[componentIdx + 1] = reader.getFloat32(vertexstart + 4, true);
          vertices[componentIdx + 2] = reader.getFloat32(vertexstart + 8, true);
          normals[componentIdx] = normalX;
          normals[componentIdx + 1] = normalY;
          normals[componentIdx + 2] = normalZ;

          if (hasColors) {
            colors[componentIdx] = r;
            colors[componentIdx + 1] = g;
            colors[componentIdx + 2] = b;
          }
        }
      }

      geometry.setAttribute('position', new THREE.BufferAttribute(vertices, 3));
      geometry.setAttribute('normal', new THREE.BufferAttribute(normals, 3));

      if (hasColors) {
        geometry.setAttribute('color', new THREE.BufferAttribute(colors, 3));
        geometry.hasColors = true;
        geometry.alpha = alpha;
      }

      return geometry;
    }

    function parseASCII(data) {
      const geometry = new THREE.BufferGeometry();
      const patternSolid = /solid([\s\S]*?)endsolid/g;
      const patternFace = /facet([\s\S]*?)endfacet/g;
      let faceCounter = 0;
      const patternFloat = /[\s]+([+-]?(?:\d*)(?:\.\d*)?(?:[eE][+-]?\d+)?)/.source;
      const patternVertex = new RegExp('vertex' + patternFloat + patternFloat + patternFloat, 'g');
      const patternNormal = new RegExp('normal' + patternFloat + patternFloat + patternFloat, 'g');
      const vertices = [];
      const normals = [];
      const normal = new THREE.Vector3();
      let result;
      let groupCount = 0;
      let startVertex = 0;
      let endVertex = 0;

      while ((result = patternSolid.exec(data)) !== null) {
        startVertex = endVertex;
        const solid = result[0];

        while ((result = patternFace.exec(solid)) !== null) {
          let vertexCountPerFace = 0;
          let normalCountPerFace = 0;
          const text = result[0];

          while ((result = patternNormal.exec(text)) !== null) {
            normal.x = parseFloat(result[1]);
            normal.y = parseFloat(result[2]);
            normal.z = parseFloat(result[3]);
            normalCountPerFace++;
          }

          while ((result = patternVertex.exec(text)) !== null) {
            vertices.push(parseFloat(result[1]), parseFloat(result[2]), parseFloat(result[3]));
            normals.push(normal.x, normal.y, normal.z);
            vertexCountPerFace++;
            endVertex++;
          } // every face have to own ONE valid normal

          if (normalCountPerFace !== 1) {
            console.error(
              "THREE.STLLoader: Something isn't right with the normal of face number " + faceCounter
            );
          } // each face have to own THREE valid vertices

          if (vertexCountPerFace !== 3) {
            console.error(
              "THREE.STLLoader: Something isn't right with the vertices of face number " +
                faceCounter
            );
          }

          faceCounter++;
        }

        const start = startVertex;
        const count = endVertex - startVertex;
        geometry.addGroup(start, count, groupCount);
        groupCount++;
      }

      geometry.setAttribute('position', new THREE.Float32BufferAttribute(vertices, 3));
      geometry.setAttribute('normal', new THREE.Float32BufferAttribute(normals, 3));
      return geometry;
    }

    function ensureString(buffer) {
      if (typeof buffer !== 'string') {
        return THREE.LoaderUtils.decodeText(new Uint8Array(buffer));
      }

      return buffer;
    }

    function ensureBinary(buffer) {
      if (typeof buffer === 'string') {
        const array_buffer = new Uint8Array(buffer.length);

        for (let i = 0; i < buffer.length; i++) {
          array_buffer[i] = buffer.charCodeAt(i) & 0xff; // implicitly assumes little-endian
        }

        return array_buffer.buffer || array_buffer;
      } else {
        return buffer;
      }
    } // start

    const binData = ensureBinary(data);
    return isBinary(binData) ? parseBinary(binData) : parseASCII(ensureString(data));
  }
}
