import { BufferAttribute, BufferGeometry, FileLoader, Float32BufferAttribute, Loader, LoaderUtils, Vector3 } from '../lib/three.module.js'

/**
 * 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);
 */

class STLLoader extends Loader {
    constructor(manager) {
        super(manager)
    }

    load(url, onLoad, onProgress, onError) {
        const scope = this

        const loader = new 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 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 BufferAttribute(vertices, 3))
            geometry.setAttribute('normal', new BufferAttribute(normals, 3))

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

            return geometry
        }

        function parseASCII(data) {
            const geometry = new 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 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 Float32BufferAttribute(vertices, 3))
            geometry.setAttribute('normal', new Float32BufferAttribute(normals, 3))

            return geometry
        }

        function ensureString(buffer) {
            if (typeof buffer !== 'string') {
                return 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))
    }
}

export { STLLoader }