/**
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at

 * http://www.apache.org/licenses/LICENSE-2.0

 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import type TViewData from '../../common/TViewData';
import {
  type Indicator,
  type IndicatorTemplate,
  IndicatorSeries,
} from '../../component/Indicator';

interface Boll {
  up?: number;
  mid?: number;
  dn?: number;
}

/**
 * 计算布林指标中的标准差
 * @param dataList
 * @param ma
 * @return {number}
 */
function getBollMd(dataList: TViewData[], ma: number): number {
  const dataSize = dataList.length;
  let sum = 0;
  dataList.forEach((data) => {
    const closeMa = data.close - ma;
    sum += closeMa * closeMa;
  });
  sum = Math.abs(sum);
  return Math.sqrt(sum / dataSize);
}

/**
 * BOLL
 */
const bollingerBands: IndicatorTemplate<Boll> = {
  name: 'BOLL',
  shortName: 'BOLL',
  series: IndicatorSeries.Price,
  calcParams: [20, 2],
  precision: 2,
  shouldOhlc: true,
  figures: [
    { key: 'up', title: 'UP: ', type: 'line' },
    { key: 'mid', title: 'MID: ', type: 'line' },
    { key: 'dn', title: 'DN: ', type: 'line' },
  ],
  calc: (dataList: TViewData[], indicator: Indicator<Boll>) => {
    const params = indicator.calcParams;
    const p = params[0] - 1;
    let closeSum = 0;
    return dataList.map((TViewData: TViewData, i: number) => {
      const close = TViewData.close;
      const boll: Boll = {};
      closeSum += close;
      if (i >= p) {
        boll.mid = closeSum / params[0];
        const md = getBollMd(dataList.slice(i - p, i + 1), boll.mid);
        boll.up = boll.mid + params[1] * md;
        boll.dn = boll.mid - params[1] * md;
        closeSum -= dataList[i - p].close;
      }
      return boll;
    });
  },
};

export default bollingerBands;