import {
    BufferGeometry,
    FileLoader,
    Float32BufferAttribute,
    Group,
    LineBasicMaterial,
    LineSegments,
    Loader,
    Material,
    Mesh,
    MeshPhongMaterial,
    Points,
    PointsMaterial,
    Vector3
} from '../lib/three.module.js'

// o object_name | g group_name
const _object_pattern = /^[og]\s*(.+)?/
// mtllib file_reference
const _material_library_pattern = /^mtllib /
// usemtl material_name
const _material_use_pattern = /^usemtl /
// usemap map_name
const _map_use_pattern = /^usemap /

const _vA = new Vector3()
const _vB = new Vector3()
const _vC = new Vector3()

const _ab = new Vector3()
const _cb = new Vector3()

function ParserState() {
    const state = {
        objects: [],
        object: {},

        vertices: [],
        normals: [],
        colors: [],
        uvs: [],

        materials: {},
        materialLibraries: [],

        startObject: function(name, fromDeclaration) {
            // If the current object (initial from reset) is not from a g/o declaration in the parsed
            // file. We need to use it for the first parsed g/o to keep things in sync.
            if (this.object && this.object.fromDeclaration === false) {
                this.object.name = name
                this.object.fromDeclaration = fromDeclaration !== false
                return
            }

            const previousMaterial = this.object && typeof this.object.currentMaterial === 'function' ? this.object.currentMaterial() : undefined

            if (this.object && typeof this.object._finalize === 'function') {
                this.object._finalize(true)
            }

            this.object = {
                name: name || '',
                fromDeclaration: fromDeclaration !== false,

                geometry: {
                    vertices: [],
                    normals: [],
                    colors: [],
                    uvs: [],
                    hasUVIndices: false
                },
                materials: [],
                smooth: true,

                startMaterial: function(name, libraries) {
                    const previous = this._finalize(false)

                    // New usemtl declaration overwrites an inherited material, except if faces were declared
                    // after the material, then it must be preserved for proper MultiMaterial continuation.
                    if (previous && (previous.inherited || previous.groupCount <= 0)) {
                        this.materials.splice(previous.index, 1)
                    }

                    const material = {
                        index: this.materials.length,
                        name: name || '',
                        mtllib: Array.isArray(libraries) && libraries.length > 0 ? libraries[libraries.length - 1] : '',
                        smooth: previous !== undefined ? previous.smooth : this.smooth,
                        groupStart: previous !== undefined ? previous.groupEnd : 0,
                        groupEnd: -1,
                        groupCount: -1,
                        inherited: false,

                        clone: function(index) {
                            const cloned = {
                                index: typeof index === 'number' ? index : this.index,
                                name: this.name,
                                mtllib: this.mtllib,
                                smooth: this.smooth,
                                groupStart: 0,
                                groupEnd: -1,
                                groupCount: -1,
                                inherited: false
                            }
                            cloned.clone = this.clone.bind(cloned)
                            return cloned
                        }
                    }

                    this.materials.push(material)

                    return material
                },

                currentMaterial: function() {
                    if (this.materials.length > 0) {
                        return this.materials[this.materials.length - 1]
                    }

                    return undefined
                },

                _finalize: function(end) {
                    const lastMultiMaterial = this.currentMaterial()
                    if (lastMultiMaterial && lastMultiMaterial.groupEnd === -1) {
                        lastMultiMaterial.groupEnd = this.geometry.vertices.length / 3
                        lastMultiMaterial.groupCount = lastMultiMaterial.groupEnd - lastMultiMaterial.groupStart
                        lastMultiMaterial.inherited = false
                    }

                    // Ignore objects tail materials if no face declarations followed them before a new o/g started.
                    if (end && this.materials.length > 1) {
                        for (let mi = this.materials.length - 1; mi >= 0; mi--) {
                            if (this.materials[mi].groupCount <= 0) {
                                this.materials.splice(mi, 1)
                            }
                        }
                    }

                    // Guarantee at least one empty material, this makes the creation later more straight forward.
                    if (end && this.materials.length === 0) {
                        this.materials.push({
                            name: '',
                            smooth: this.smooth
                        })
                    }

                    return lastMultiMaterial
                }
            }

            // Inherit previous objects material.
            // Spec tells us that a declared material must be set to all objects until a new material is declared.
            // If a usemtl declaration is encountered while this new object is being parsed, it will
            // overwrite the inherited material. Exception being that there was already face declarations
            // to the inherited material, then it will be preserved for proper MultiMaterial continuation.

            if (previousMaterial && previousMaterial.name && typeof previousMaterial.clone === 'function') {
                const declared = previousMaterial.clone(0)
                declared.inherited = true
                this.object.materials.push(declared)
            }

            this.objects.push(this.object)
        },

        finalize: function() {
            if (this.object && typeof this.object._finalize === 'function') {
                this.object._finalize(true)
            }
        },

        parseVertexIndex: function(value, len) {
            const index = parseInt(value, 10)
            return (index >= 0 ? index - 1 : index + len / 3) * 3
        },

        parseNormalIndex: function(value, len) {
            const index = parseInt(value, 10)
            return (index >= 0 ? index - 1 : index + len / 3) * 3
        },

        parseUVIndex: function(value, len) {
            const index = parseInt(value, 10)
            return (index >= 0 ? index - 1 : index + len / 2) * 2
        },

        addVertex: function(a, b, c) {
            const src = this.vertices
            const dst = this.object.geometry.vertices

            dst.push(src[a + 0], src[a + 1], src[a + 2])
            dst.push(src[b + 0], src[b + 1], src[b + 2])
            dst.push(src[c + 0], src[c + 1], src[c + 2])
        },

        addVertexPoint: function(a) {
            const src = this.vertices
            const dst = this.object.geometry.vertices

            dst.push(src[a + 0], src[a + 1], src[a + 2])
        },

        addVertexLine: function(a) {
            const src = this.vertices
            const dst = this.object.geometry.vertices

            dst.push(src[a + 0], src[a + 1], src[a + 2])
        },

        addNormal: function(a, b, c) {
            const src = this.normals
            const dst = this.object.geometry.normals

            dst.push(src[a + 0], src[a + 1], src[a + 2])
            dst.push(src[b + 0], src[b + 1], src[b + 2])
            dst.push(src[c + 0], src[c + 1], src[c + 2])
        },

        addFaceNormal: function(a, b, c) {
            const src = this.vertices
            const dst = this.object.geometry.normals

            _vA.fromArray(src, a)
            _vB.fromArray(src, b)
            _vC.fromArray(src, c)

            _cb.subVectors(_vC, _vB)
            _ab.subVectors(_vA, _vB)
            _cb.cross(_ab)

            _cb.normalize()

            dst.push(_cb.x, _cb.y, _cb.z)
            dst.push(_cb.x, _cb.y, _cb.z)
            dst.push(_cb.x, _cb.y, _cb.z)
        },

        addColor: function(a, b, c) {
            const src = this.colors
            const dst = this.object.geometry.colors

            if (src[a] !== undefined) dst.push(src[a + 0], src[a + 1], src[a + 2])
            if (src[b] !== undefined) dst.push(src[b + 0], src[b + 1], src[b + 2])
            if (src[c] !== undefined) dst.push(src[c + 0], src[c + 1], src[c + 2])
        },

        addUV: function(a, b, c) {
            const src = this.uvs
            const dst = this.object.geometry.uvs

            dst.push(src[a + 0], src[a + 1])
            dst.push(src[b + 0], src[b + 1])
            dst.push(src[c + 0], src[c + 1])
        },

        addDefaultUV: function() {
            const dst = this.object.geometry.uvs

            dst.push(0, 0)
            dst.push(0, 0)
            dst.push(0, 0)
        },

        addUVLine: function(a) {
            const src = this.uvs
            const dst = this.object.geometry.uvs

            dst.push(src[a + 0], src[a + 1])
        },

        addFace: function(a, b, c, ua, ub, uc, na, nb, nc) {
            const vLen = this.vertices.length

            let ia = this.parseVertexIndex(a, vLen)
            let ib = this.parseVertexIndex(b, vLen)
            let ic = this.parseVertexIndex(c, vLen)

            this.addVertex(ia, ib, ic)
            this.addColor(ia, ib, ic)

            // normals

            if (na !== undefined && na !== '') {
                const nLen = this.normals.length

                ia = this.parseNormalIndex(na, nLen)
                ib = this.parseNormalIndex(nb, nLen)
                ic = this.parseNormalIndex(nc, nLen)

                this.addNormal(ia, ib, ic)
            } else {
                this.addFaceNormal(ia, ib, ic)
            }

            // uvs

            if (ua !== undefined && ua !== '') {
                const uvLen = this.uvs.length

                ia = this.parseUVIndex(ua, uvLen)
                ib = this.parseUVIndex(ub, uvLen)
                ic = this.parseUVIndex(uc, uvLen)

                this.addUV(ia, ib, ic)

                this.object.geometry.hasUVIndices = true
            } else {
                // add placeholder values (for inconsistent face definitions)

                this.addDefaultUV()
            }
        },

        addPointGeometry: function(vertices) {
            this.object.geometry.type = 'Points'

            const vLen = this.vertices.length

            for (let vi = 0, l = vertices.length; vi < l; vi++) {
                const index = this.parseVertexIndex(vertices[vi], vLen)

                this.addVertexPoint(index)
                this.addColor(index)
            }
        },

        addLineGeometry: function(vertices, uvs) {
            this.object.geometry.type = 'Line'

            const vLen = this.vertices.length
            const uvLen = this.uvs.length

            for (let vi = 0, l = vertices.length; vi < l; vi++) {
                this.addVertexLine(this.parseVertexIndex(vertices[vi], vLen))
            }

            for (let uvi = 0, l = uvs.length; uvi < l; uvi++) {
                this.addUVLine(this.parseUVIndex(uvs[uvi], uvLen))
            }
        }
    }

    state.startObject('', false)

    return state
}

//

class OBJLoader extends Loader {
    constructor(manager) {
        super(manager)

        this.materials = null
    }

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

        const loader = new FileLoader(this.manager)
        loader.setPath(this.path)
        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
        )
    }

    setMaterials(materials) {
        this.materials = materials

        return this
    }

    parse(text) {
        const state = new ParserState()

        if (text.indexOf('\r\n') !== -1) {
            // This is faster than String.split with regex that splits on both
            text = text.replace(/\r\n/g, '\n')
        }

        if (text.indexOf('\\\n') !== -1) {
            // join lines separated by a line continuation character (\)
            text = text.replace(/\\\n/g, '')
        }

        const lines = text.split('\n')
        let line = '',
            lineFirstChar = ''
        let lineLength = 0
        let result = []

        // Faster to just trim left side of the line. Use if available.
        const trimLeft = typeof ''.trimLeft === 'function'

        for (let i = 0, l = lines.length; i < l; i++) {
            line = lines[i]

            line = trimLeft ? line.trimLeft() : line.trim()

            lineLength = line.length

            if (lineLength === 0) continue

            lineFirstChar = line.charAt(0)

            // @todo invoke passed in handler if any
            if (lineFirstChar === '#') continue

            if (lineFirstChar === 'v') {
                const data = line.split(/\s+/)

                switch (data[0]) {
                    case 'v':
                        state.vertices.push(parseFloat(data[1]), parseFloat(data[2]), parseFloat(data[3]))
                        if (data.length >= 7) {
                            state.colors.push(parseFloat(data[4]), parseFloat(data[5]), parseFloat(data[6]))
                        } else {
                            // if no colors are defined, add placeholders so color and vertex indices match

                            state.colors.push(undefined, undefined, undefined)
                        }

                        break
                    case 'vn':
                        state.normals.push(parseFloat(data[1]), parseFloat(data[2]), parseFloat(data[3]))
                        break
                    case 'vt':
                        state.uvs.push(parseFloat(data[1]), parseFloat(data[2]))
                        break
                }
            } else if (lineFirstChar === 'f') {
                const lineData = line.substr(1).trim()
                const vertexData = lineData.split(/\s+/)
                const faceVertices = []

                // Parse the face vertex data into an easy to work with format

                for (let j = 0, jl = vertexData.length; j < jl; j++) {
                    const vertex = vertexData[j]

                    if (vertex.length > 0) {
                        const vertexParts = vertex.split('/')
                        faceVertices.push(vertexParts)
                    }
                }

                // Draw an edge between the first vertex and all subsequent vertices to form an n-gon

                const v1 = faceVertices[0]

                for (let j = 1, jl = faceVertices.length - 1; j < jl; j++) {
                    const v2 = faceVertices[j]
                    const v3 = faceVertices[j + 1]

                    state.addFace(v1[0], v2[0], v3[0], v1[1], v2[1], v3[1], v1[2], v2[2], v3[2])
                }
            } else if (lineFirstChar === 'l') {
                const lineParts = line
                    .substring(1)
                    .trim()
                    .split(' ')
                let lineVertices = []
                const lineUVs = []

                if (line.indexOf('/') === -1) {
                    lineVertices = lineParts
                } else {
                    for (let li = 0, llen = lineParts.length; li < llen; li++) {
                        const parts = lineParts[li].split('/')

                        if (parts[0] !== '') lineVertices.push(parts[0])
                        if (parts[1] !== '') lineUVs.push(parts[1])
                    }
                }

                state.addLineGeometry(lineVertices, lineUVs)
            } else if (lineFirstChar === 'p') {
                const lineData = line.substr(1).trim()
                const pointData = lineData.split(' ')

                state.addPointGeometry(pointData)
            } else if ((result = _object_pattern.exec(line)) !== null) {
                // o object_name
                // or
                // g group_name

                // WORKAROUND: https://bugs.chromium.org/p/v8/issues/detail?id=2869
                // let name = result[ 0 ].substr( 1 ).trim();
                const name = (' ' + result[0].substr(1).trim()).substr(1)

                state.startObject(name)
            } else if (_material_use_pattern.test(line)) {
                // material

                state.object.startMaterial(line.substring(7).trim(), state.materialLibraries)
            } else if (_material_library_pattern.test(line)) {
                // mtl file

                state.materialLibraries.push(line.substring(7).trim())
            } else if (_map_use_pattern.test(line)) {
                // the line is parsed but ignored since the loader assumes textures are defined MTL files
                // (according to https://www.okino.com/conv/imp_wave.htm, 'usemap' is the old-style Wavefront texture reference method)

                console.warn('THREE.OBJLoader: Rendering identifier "usemap" not supported. Textures must be defined in MTL files.')
            } else if (lineFirstChar === 's') {
                result = line.split(' ')

                // smooth shading

                // @todo Handle files that have varying smooth values for a set of faces inside one geometry,
                // but does not define a usemtl for each face set.
                // This should be detected and a dummy material created (later MultiMaterial and geometry groups).
                // This requires some care to not create extra material on each smooth value for "normal" obj files.
                // where explicit usemtl defines geometry groups.
                // Example asset: examples/models/obj/cerberus/Cerberus.obj

                /*
                 * http://paulbourke.net/dataformats/obj/
                 * or
                 * http://www.cs.utah.edu/~boulos/cs3505/obj_spec.pdf
                 *
                 * From chapter "Grouping" Syntax explanation "s group_number":
                 * "group_number is the smoothing group number. To turn off smoothing groups, use a value of 0 or off.
                 * Polygonal elements use group numbers to put elements in different smoothing groups. For free-form
                 * surfaces, smoothing groups are either turned on or off; there is no difference between values greater
                 * than 0."
                 */
                if (result.length > 1) {
                    const value = result[1].trim().toLowerCase()
                    state.object.smooth = value !== '0' && value !== 'off'
                } else {
                    // ZBrush can produce "s" lines #11707
                    state.object.smooth = true
                }

                const material = state.object.currentMaterial()
                if (material) material.smooth = state.object.smooth
            } else {
                // Handle null terminated files without exception
                if (line === '\0') continue

                console.warn('THREE.OBJLoader: Unexpected line: "' + line + '"')
            }
        }

        state.finalize()

        const container = new Group()
        container.materialLibraries = [].concat(state.materialLibraries)

        const hasPrimitives = !(state.objects.length === 1 && state.objects[0].geometry.vertices.length === 0)

        if (hasPrimitives === true) {
            for (let i = 0, l = state.objects.length; i < l; i++) {
                const object = state.objects[i]
                const geometry = object.geometry
                const materials = object.materials
                const isLine = geometry.type === 'Line'
                const isPoints = geometry.type === 'Points'
                let hasVertexColors = false

                // Skip o/g line declarations that did not follow with any faces
                if (geometry.vertices.length === 0) continue

                const buffergeometry = new BufferGeometry()

                buffergeometry.setAttribute('position', new Float32BufferAttribute(geometry.vertices, 3))

                if (geometry.normals.length > 0) {
                    buffergeometry.setAttribute('normal', new Float32BufferAttribute(geometry.normals, 3))
                }

                if (geometry.colors.length > 0) {
                    hasVertexColors = true
                    buffergeometry.setAttribute('color', new Float32BufferAttribute(geometry.colors, 3))
                }

                if (geometry.hasUVIndices === true) {
                    buffergeometry.setAttribute('uv', new Float32BufferAttribute(geometry.uvs, 2))
                }

                // Create materials

                const createdMaterials = []

                for (let mi = 0, miLen = materials.length; mi < miLen; mi++) {
                    const sourceMaterial = materials[mi]
                    const materialHash = sourceMaterial.name + '_' + sourceMaterial.smooth + '_' + hasVertexColors
                    let material = state.materials[materialHash]

                    if (this.materials !== null) {
                        material = this.materials.create(sourceMaterial.name)

                        // mtl etc. loaders probably can't create line materials correctly, copy properties to a line material.
                        if (isLine && material && !(material instanceof LineBasicMaterial)) {
                            const materialLine = new LineBasicMaterial()
                            Material.prototype.copy.call(materialLine, material)
                            materialLine.color.copy(material.color)
                            material = materialLine
                        } else if (isPoints && material && !(material instanceof PointsMaterial)) {
                            const materialPoints = new PointsMaterial({ size: 10, sizeAttenuation: false })
                            Material.prototype.copy.call(materialPoints, material)
                            materialPoints.color.copy(material.color)
                            materialPoints.map = material.map
                            material = materialPoints
                        }
                    }

                    if (material === undefined) {
                        if (isLine) {
                            material = new LineBasicMaterial()
                        } else if (isPoints) {
                            material = new PointsMaterial({ size: 1, sizeAttenuation: false })
                        } else {
                            material = new MeshPhongMaterial()
                        }

                        material.name = sourceMaterial.name
                        material.flatShading = sourceMaterial.smooth ? false : true
                        material.vertexColors = hasVertexColors

                        state.materials[materialHash] = material
                    }

                    createdMaterials.push(material)
                }

                // Create mesh

                let mesh

                if (createdMaterials.length > 1) {
                    for (let mi = 0, miLen = materials.length; mi < miLen; mi++) {
                        const sourceMaterial = materials[mi]
                        buffergeometry.addGroup(sourceMaterial.groupStart, sourceMaterial.groupCount, mi)
                    }

                    if (isLine) {
                        mesh = new LineSegments(buffergeometry, createdMaterials)
                    } else if (isPoints) {
                        mesh = new Points(buffergeometry, createdMaterials)
                    } else {
                        mesh = new Mesh(buffergeometry, createdMaterials)
                    }
                } else {
                    if (isLine) {
                        mesh = new LineSegments(buffergeometry, createdMaterials[0])
                    } else if (isPoints) {
                        mesh = new Points(buffergeometry, createdMaterials[0])
                    } else {
                        mesh = new Mesh(buffergeometry, createdMaterials[0])
                    }
                }

                mesh.name = object.name

                container.add(mesh)
            }
        } else {
            // if there is only the default parser state object with no geometry data, interpret data as point cloud

            if (state.vertices.length > 0) {
                const material = new PointsMaterial({ size: 1, sizeAttenuation: false })

                const buffergeometry = new BufferGeometry()

                buffergeometry.setAttribute('position', new Float32BufferAttribute(state.vertices, 3))

                if (state.colors.length > 0 && state.colors[0] !== undefined) {
                    buffergeometry.setAttribute('color', new Float32BufferAttribute(state.colors, 3))
                    material.vertexColors = true
                }

                const points = new Points(buffergeometry, material)
                container.add(points)
            }
        }

        return container
    }
}

export { OBJLoader }