module.exports = function () {
  var ArrayCtor = typeof Float32Array === 'undefined' ? Array : Float32Array;
  /**
   * @typedef {Float32Array|Array.<number>} Vector2
   */

  /**
   * 二维向量类
   * @exports zrender/tool/vector
   */

  var vector = {
    /**
     * 创建一个向量
     * @param {number} [x=0]
     * @param {number} [y=0]
     * @return {Vector2}
     */
    create: function (x, y) {
      var out = new ArrayCtor(2);
      out[0] = x || 0;
      out[1] = y || 0;
      return out;
    },

    /**
     * 复制向量数据
     * @param {Vector2} out
     * @param {Vector2} v
     * @return {Vector2}
     */
    copy: function (out, v) {
      out[0] = v[0];
      out[1] = v[1];
      return out;
    },

    /**
     * 克隆一个向量
     * @param {Vector2} v
     * @return {Vector2}
     */
    clone: function (v) {
      var out = new ArrayCtor(2);
      out[0] = v[0];
      out[1] = v[1];
      return out;
    },

    /**
     * 设置向量的两个项
     * @param {Vector2} out
     * @param {number} a
     * @param {number} b
     * @return {Vector2} 结果
     */
    set: function (out, a, b) {
      out[0] = a;
      out[1] = b;
      return out;
    },

    /**
     * 向量相加
     * @param {Vector2} out
     * @param {Vector2} v1
     * @param {Vector2} v2
     */
    add: function (out, v1, v2) {
      out[0] = v1[0] + v2[0];
      out[1] = v1[1] + v2[1];
      return out;
    },

    /**
     * 向量缩放后相加
     * @param {Vector2} out
     * @param {Vector2} v1
     * @param {Vector2} v2
     * @param {number} a
     */
    scaleAndAdd: function (out, v1, v2, a) {
      out[0] = v1[0] + v2[0] * a;
      out[1] = v1[1] + v2[1] * a;
      return out;
    },

    /**
     * 向量相减
     * @param {Vector2} out
     * @param {Vector2} v1
     * @param {Vector2} v2
     */
    sub: function (out, v1, v2) {
      out[0] = v1[0] - v2[0];
      out[1] = v1[1] - v2[1];
      return out;
    },

    /**
     * 向量长度
     * @param {Vector2} v
     * @return {number}
     */
    len: function (v) {
      return Math.sqrt(this.lenSquare(v));
    },

    /**
     * 向量长度平方
     * @param {Vector2} v
     * @return {number}
     */
    lenSquare: function (v) {
      return v[0] * v[0] + v[1] * v[1];
    },

    /**
     * 向量乘法
     * @param {Vector2} out
     * @param {Vector2} v1
     * @param {Vector2} v2
     */
    mul: function (out, v1, v2) {
      out[0] = v1[0] * v2[0];
      out[1] = v1[1] * v2[1];
      return out;
    },

    /**
     * 向量除法
     * @param {Vector2} out
     * @param {Vector2} v1
     * @param {Vector2} v2
     */
    div: function (out, v1, v2) {
      out[0] = v1[0] / v2[0];
      out[1] = v1[1] / v2[1];
      return out;
    },

    /**
     * 向量点乘
     * @param {Vector2} v1
     * @param {Vector2} v2
     * @return {number}
     */
    dot: function (v1, v2) {
      return v1[0] * v2[0] + v1[1] * v2[1];
    },

    /**
     * 向量缩放
     * @param {Vector2} out
     * @param {Vector2} v
     * @param {number} s
     */
    scale: function (out, v, s) {
      out[0] = v[0] * s;
      out[1] = v[1] * s;
      return out;
    },

    /**
     * 向量归一化
     * @param {Vector2} out
     * @param {Vector2} v
     */
    normalize: function (out, v) {
      var d = vector.len(v);

      if (d === 0) {
        out[0] = 0;
        out[1] = 0;
      } else {
        out[0] = v[0] / d;
        out[1] = v[1] / d;
      }

      return out;
    },

    /**
     * 计算向量间距离
     * @param {Vector2} v1
     * @param {Vector2} v2
     * @return {number}
     */
    distance: function (v1, v2) {
      return Math.sqrt((v1[0] - v2[0]) * (v1[0] - v2[0]) + (v1[1] - v2[1]) * (v1[1] - v2[1]));
    },

    /**
     * 向量距离平方
     * @param {Vector2} v1
     * @param {Vector2} v2
     * @return {number}
     */
    distanceSquare: function (v1, v2) {
      return (v1[0] - v2[0]) * (v1[0] - v2[0]) + (v1[1] - v2[1]) * (v1[1] - v2[1]);
    },

    /**
     * 求负向量
     * @param {Vector2} out
     * @param {Vector2} v
     */
    negate: function (out, v) {
      out[0] = -v[0];
      out[1] = -v[1];
      return out;
    },

    /**
     * 插值两个点
     * @param {Vector2} out
     * @param {Vector2} v1
     * @param {Vector2} v2
     * @param {number} t
     */
    lerp: function (out, v1, v2, t) {
      // var ax = v1[0];
      // var ay = v1[1];
      out[0] = v1[0] + t * (v2[0] - v1[0]);
      out[1] = v1[1] + t * (v2[1] - v1[1]);
      return out;
    },

    /**
     * 矩阵左乘向量
     * @param {Vector2} out
     * @param {Vector2} v
     * @param {Vector2} m
     */
    applyTransform: function (out, v, m) {
      var x = v[0];
      var y = v[1];
      out[0] = m[0] * x + m[2] * y + m[4];
      out[1] = m[1] * x + m[3] * y + m[5];
      return out;
    },

    /**
     * 求两个向量最小值
     * @param  {Vector2} out
     * @param  {Vector2} v1
     * @param  {Vector2} v2
     */
    min: function (out, v1, v2) {
      out[0] = Math.min(v1[0], v2[0]);
      out[1] = Math.min(v1[1], v2[1]);
      return out;
    },

    /**
     * 求两个向量最大值
     * @param  {Vector2} out
     * @param  {Vector2} v1
     * @param  {Vector2} v2
     */
    max: function (out, v1, v2) {
      out[0] = Math.max(v1[0], v2[0]);
      out[1] = Math.max(v1[1], v2[1]);
      return out;
    }
  };
  vector.length = vector.len;
  vector.lengthSquare = vector.lenSquare;
  vector.dist = vector.distance;
  vector.distSquare = vector.distanceSquare;
  return vector;
}();