/**
 * Copyright (c) 2017-2018 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * @author David Sehnal <david.sehnal@gmail.com>
 * @author Alexander Rose <alexander.rose@weirdbyte.de>
 */

/*
 * This code has been modified from https://github.com/toji/gl-matrix/,
 * copyright (c) 2015, Brandon Jones, Colin MacKenzie IV.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 */

/*
 * Quat.fromUnitVec3 has been modified from https://github.com/Jam3/quat-from-unit-vec3,
 * copyright (c) 2015 Jam3. MIT License
 */

import Mat3 from './mat3';
import Vec3 from './vec3';
import { EPSILON } from './common';

interface Quat extends Array<number> { [d: number]: number, '@type': 'quat', length: 4 }

function Quat() {
    return Quat.zero();
}

namespace Quat {
    export function zero(): Quat {
        // force double backing array by 0.1.
        const ret = [0.1, 0, 0, 0];
        ret[0] = 0.0;
        return ret as any;
    }

    export function identity(): Quat {
        const out = zero();
        out[3] = 1;
        return out;
    }

    export function create(x: number, y: number, z: number, w: number) {
        const out = identity();
        out[0] = x;
        out[1] = y;
        out[2] = z;
        out[3] = w;
        return out;
    }

    export function setAxisAngle(out: Quat, axis: Vec3, rad: number) {
        rad = rad * 0.5;
        let s = Math.sin(rad);
        out[0] = s * axis[0];
        out[1] = s * axis[1];
        out[2] = s * axis[2];
        out[3] = Math.cos(rad);
        return out;
    }

    /**
     * Gets the rotation axis and angle for a given
     *  quaternion. If a quaternion is created with
     *  setAxisAngle, this method will return the same
     *  values as providied in the original parameter list
     *  OR functionally equivalent values.
     * Example: The quaternion formed by axis [0, 0, 1] and
     *  angle -90 is the same as the quaternion formed by
     *  [0, 0, 1] and 270. This method favors the latter.
     */
    export function getAxisAngle(out_axis: Vec3, q: Quat) {
        let rad = Math.acos(q[3]) * 2.0;
        let s = Math.sin(rad / 2.0);
        if (s !== 0.0) {
            out_axis[0] = q[0] / s;
            out_axis[1] = q[1] / s;
            out_axis[2] = q[2] / s;
        } else {
            // If s is zero, return any axis (no rotation - axis does not matter)
            out_axis[0] = 1;
            out_axis[1] = 0;
            out_axis[2] = 0;
        }
        return rad;
    }

    export function multiply(out: Quat, a: Quat, b: Quat) {
        let ax = a[0], ay = a[1], az = a[2], aw = a[3];
        let bx = b[0], by = b[1], bz = b[2], bw = b[3];

        out[0] = ax * bw + aw * bx + ay * bz - az * by;
        out[1] = ay * bw + aw * by + az * bx - ax * bz;
        out[2] = az * bw + aw * bz + ax * by - ay * bx;
        out[3] = aw * bw - ax * bx - ay * by - az * bz;
        return out;
    }

    export function rotateX(out: Quat, a: Quat, rad: number) {
        rad *= 0.5;

        let ax = a[0], ay = a[1], az = a[2], aw = a[3];
        let bx = Math.sin(rad), bw = Math.cos(rad);

        out[0] = ax * bw + aw * bx;
        out[1] = ay * bw + az * bx;
        out[2] = az * bw - ay * bx;
        out[3] = aw * bw - ax * bx;
        return out;
    }

    export function rotateY(out: Quat, a: Quat, rad: number) {
        rad *= 0.5;

        let ax = a[0], ay = a[1], az = a[2], aw = a[3];
        let by = Math.sin(rad), bw = Math.cos(rad);

        out[0] = ax * bw - az * by;
        out[1] = ay * bw + aw * by;
        out[2] = az * bw + ax * by;
        out[3] = aw * bw - ay * by;
        return out;
    }

    export function rotateZ(out: Quat, a: Quat, rad: number) {
        rad *= 0.5;

        let ax = a[0], ay = a[1], az = a[2], aw = a[3];
        let bz = Math.sin(rad), bw = Math.cos(rad);

        out[0] = ax * bw + ay * bz;
        out[1] = ay * bw - ax * bz;
        out[2] = az * bw + aw * bz;
        out[3] = aw * bw - az * bz;
        return out;
    }

    /**
     * Calculates the W component of a quat from the X, Y, and Z components.
     * Assumes that quaternion is 1 unit in length.
     * Any existing W component will be ignored.
     */
    export function calculateW(out: Quat, a: Quat) {
        let x = a[0], y = a[1], z = a[2];

        out[0] = x;
        out[1] = y;
        out[2] = z;
        out[3] = Math.sqrt(Math.abs(1.0 - x * x - y * y - z * z));
        return out;
    }

    /**
     * Performs a spherical linear interpolation between two quat
     */
    export function slerp(out: Quat, a: Quat, b: Quat, t: number) {
        // benchmarks:
        //    http://jsperf.com/quaternion-slerp-implementations
        let ax = a[0], ay = a[1], az = a[2], aw = a[3];
        let bx = b[0], by = b[1], bz = b[2], bw = b[3];

        let omega, cosom, sinom, scale0, scale1;

        // calc cosine
        cosom = ax * bx + ay * by + az * bz + aw * bw;
        // adjust signs (if necessary)
        if ( cosom < 0.0 ) {
        cosom = -cosom;
        bx = - bx;
        by = - by;
        bz = - bz;
        bw = - bw;
        }
        // calculate coefficients
        if ( (1.0 - cosom) > 0.000001 ) {
            // standard case (slerp)
            omega  = Math.acos(cosom);
            sinom  = Math.sin(omega);
            scale0 = Math.sin((1.0 - t) * omega) / sinom;
            scale1 = Math.sin(t * omega) / sinom;
        } else {
            // "from" and "to" quaternions are very close
            //  ... so we can do a linear interpolation
            scale0 = 1.0 - t;
            scale1 = t;
        }
        // calculate final values
        out[0] = scale0 * ax + scale1 * bx;
        out[1] = scale0 * ay + scale1 * by;
        out[2] = scale0 * az + scale1 * bz;
        out[3] = scale0 * aw + scale1 * bw;

        return out;
    }

    export function invert(out: Quat, a: Quat) {
        let a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3];
        let dot = a0 * a0 + a1 * a1 + a2 * a2 + a3 * a3;
        let invDot = dot ? 1.0/dot : 0;

        // TODO: Would be faster to return [0,0,0,0] immediately if dot == 0

        out[0] = -a0 * invDot;
        out[1] = -a1 * invDot;
        out[2] = -a2 * invDot;
        out[3] = a3 * invDot;
        return out;
    }

    /**
     * Calculates the conjugate of a quat
     * If the quaternion is normalized, this function is faster than quat.inverse and produces the same result.
     */
    export function conjugate(out: Quat, a: Quat) {
        out[0] = -a[0];
        out[1] = -a[1];
        out[2] = -a[2];
        out[3] = a[3];
        return out;
    }

    /**
     * Creates a quaternion from the given 3x3 rotation matrix.
     *
     * NOTE: The resultant quaternion is not normalized, so you should be sure
     * to renormalize the quaternion yourself where necessary.
     */
    export function fromMat3(out: Quat, m: Mat3) {
        // Algorithm in Ken Shoemake's article in 1987 SIGGRAPH course notes
        // article "Quaternion Calculus and Fast Animation".
        const fTrace = m[0] + m[4] + m[8];
        let fRoot;

        if ( fTrace > 0.0 ) {
            // |w| > 1/2, may as well choose w > 1/2
            fRoot = Math.sqrt(fTrace + 1.0);  // 2w
            out[3] = 0.5 * fRoot;
            fRoot = 0.5/fRoot;  // 1/(4w)
            out[0] = (m[5]-m[7])*fRoot;
            out[1] = (m[6]-m[2])*fRoot;
            out[2] = (m[1]-m[3])*fRoot;
            } else {
            // |w| <= 1/2
            let i = 0;
            if ( m[4] > m[0] ) i = 1;
            if ( m[8] > m[i*3+i] ) i = 2;
            let j = (i+1)%3;
            let k = (i+2)%3;

            fRoot = Math.sqrt(m[i*3+i]-m[j*3+j]-m[k*3+k] + 1.0);
            out[i] = 0.5 * fRoot;
            fRoot = 0.5 / fRoot;
            out[3] = (m[j*3+k] - m[k*3+j]) * fRoot;
            out[j] = (m[j*3+i] + m[i*3+j]) * fRoot;
            out[k] = (m[k*3+i] + m[i*3+k]) * fRoot;
        }

        return out;
    }

    const fromUnitVec3Temp = Vec3.zero()
    /** Quaternion from two normalized unit vectors. */
    export function fromUnitVec3 (out: Quat, a: Vec3, b: Vec3) {
        // assumes a and b are normalized
        let r = Vec3.dot(a, b) + 1
        if (r < EPSILON.Value) {
            // If u and v are exactly opposite, rotate 180 degrees
            // around an arbitrary orthogonal axis. Axis normalisation
            // can happen later, when we normalise the quaternion.
            r = 0
            if (Math.abs(a[0]) > Math.abs(a[2])) {
                Vec3.set(fromUnitVec3Temp, -a[1], a[0], 0)
            } else {
                Vec3.set(fromUnitVec3Temp, 0, -a[2], a[1])
            }
        } else {
            // Otherwise, build quaternion the standard way.
            Vec3.cross(fromUnitVec3Temp, a, b)
        }

        out[0] = fromUnitVec3Temp[0]
        out[1] = fromUnitVec3Temp[1]
        out[2] = fromUnitVec3Temp[2]
        out[3] = r
        normalize(out, out)
        return out
    }

    export function clone(a: Quat) {
        const out = zero();
        out[0] = a[0];
        out[1] = a[1];
        out[2] = a[2];
        out[3] = a[3];
        return out;
    }

    export function toArray(a: Quat, out: Helpers.NumberArray, offset: number) {
        out[offset + 0] = a[0];
        out[offset + 1] = a[1];
        out[offset + 2] = a[2];
        out[offset + 3] = a[3];
    }

    export function fromArray(a: Quat, array: Helpers.NumberArray, offset: number) {
        a[0] = array[offset + 0]
        a[1] = array[offset + 1]
        a[2] = array[offset + 2]
        a[3] = array[offset + 3]
        return a
    }

    export function copy(out: Quat, a: Quat) {
        out[0] = a[0];
        out[1] = a[1];
        out[2] = a[2];
        out[3] = a[3];
        return out;
    }

    export function set(out: Quat, x: number, y: number, z: number, w: number) {
        out[0] = x;
        out[1] = y;
        out[2] = z;
        out[3] = w;
        return out;
    }

    export function add(out: Quat, a: Quat, b: Quat) {
        out[0] = a[0] + b[0];
        out[1] = a[1] + b[1];
        out[2] = a[2] + b[2];
        out[3] = a[3] + b[3];
        return out;
    }

    export function normalize(out: Quat, a: Quat) {
        let x = a[0];
        let y = a[1];
        let z = a[2];
        let w = a[3];
        let len = x*x + y*y + z*z + w*w;
        if (len > 0) {
            len = 1 / Math.sqrt(len);
            out[0] = x * len;
            out[1] = y * len;
            out[2] = z * len;
            out[3] = w * len;
        }
        return out;
    }

    /**
     * Sets a quaternion to represent the shortest rotation from one
     * vector to another.
     *
     * Both vectors are assumed to be unit length.
     */
    const rotTmpVec3 = Vec3.zero();
    const rotTmpVec3UnitX = Vec3.create(1, 0, 0);
    const rotTmpVec3UnitY = Vec3.create(0, 1, 0);
    export function rotationTo(out: Quat, a: Vec3, b: Vec3) {
        let dot = Vec3.dot(a, b);
        if (dot < -0.999999) {
            Vec3.cross(rotTmpVec3, rotTmpVec3UnitX, a);
            if (Vec3.magnitude(rotTmpVec3) < 0.000001)
            Vec3.cross(rotTmpVec3, rotTmpVec3UnitY, a);
            Vec3.normalize(rotTmpVec3, rotTmpVec3);
            setAxisAngle(out, rotTmpVec3, Math.PI);
            return out;
        } else if (dot > 0.999999) {
            out[0] = 0;
            out[1] = 0;
            out[2] = 0;
            out[3] = 1;
            return out;
        } else {
            Vec3.cross(rotTmpVec3, a, b);
            out[0] = rotTmpVec3[0];
            out[1] = rotTmpVec3[1];
            out[2] = rotTmpVec3[2];
            out[3] = 1 + dot;
            return normalize(out, out);
        }
    }

    /**
     * Performs a spherical linear interpolation with two control points
     */
    let sqlerpTemp1 = Quat.zero();
    let sqlerpTemp2 = Quat.zero();
    export function sqlerp(out: Quat, a: Quat, b: Quat, c: Quat, d: Quat, t: number) {
        slerp(sqlerpTemp1, a, d, t);
        slerp(sqlerpTemp2, b, c, t);
        slerp(out, sqlerpTemp1, sqlerpTemp2, 2 * t * (1 - t));
        return out;
    }

    /**
     * Sets the specified quaternion with values corresponding to the given
     * axes. Each axis is a vec3 and is expected to be unit length and
     * perpendicular to all other specified axes.
     */
    const axesTmpMat = Mat3.zero();
    export function setAxes(out: Quat, view: Vec3, right: Vec3, up: Vec3) {
        axesTmpMat[0] = right[0];
        axesTmpMat[3] = right[1];
        axesTmpMat[6] = right[2];

        axesTmpMat[1] = up[0];
        axesTmpMat[4] = up[1];
        axesTmpMat[7] = up[2];

        axesTmpMat[2] = -view[0];
        axesTmpMat[5] = -view[1];
        axesTmpMat[8] = -view[2];

        return normalize(out, Quat.fromMat3(out, axesTmpMat));
    }
}

export default Quat