// Copyright 2017-2021 @polkadot/react-components authors & contributors
// SPDX-License-Identifier: Apache-2.0

import type BN from 'bn.js';
import type { LineProps } from './types';

import ChartJs from 'chart.js';
import React, { useMemo } from 'react';
import * as Chart from 'react-chartjs-2';

import { isBn } from '@polkadot/util';

interface State {
  chartData: ChartJs.ChartData;
  chartOptions: ChartJs.ChartOptions;
}

interface Dataset {
  data: number[];
  fill: boolean;
  label: string;
  backgroundColor: string;
  borderColor: string;
  hoverBackgroundColor: string;
}

interface Config {
  labels: string[];
  datasets: Dataset[];
}

const COLORS = ['#ff8c00', '#008c8c', '#8c008c'];

const alphaColor = (hexColor: string): string =>
  // eslint-disable-next-line @typescript-eslint/no-unsafe-return,@typescript-eslint/no-unsafe-call,@typescript-eslint/no-unsafe-member-access
  ChartJs.helpers.color(hexColor).alpha(0.65).rgbString();

const chartOptions = {
  // no need for the legend, expect the labels contain everything
  legend: {
    display: false
  },
  scales: {
    xAxes: [{
      ticks: {
        beginAtZero: true
      }
    }]
  }
};

function calculateOptions (colors: (string | undefined)[] = [], legends: string[], labels: string[], values: (number | BN)[][]): State {
  const chartData = values.reduce((chartData, values, index): Config => {
    const color = colors[index] || alphaColor(COLORS[index]);
    const data = values.map((value): number => isBn(value) ? value.toNumber() : value);

    chartData.datasets.push({
      backgroundColor: color,
      borderColor: color,
      data,
      fill: false,
      hoverBackgroundColor: color,
      label: legends[index]
    });

    return chartData;
  }, { datasets: [] as Dataset[], labels });

  return {
    chartData,
    chartOptions
  };
}

function LineChart ({ className, colors, labels, legends, values }: LineProps): React.ReactElement<LineProps> | null {
  const { chartData, chartOptions } = useMemo(
    () => calculateOptions(colors, legends, labels, values),
    [colors, labels, legends, values]
  );

  return (
    <div className={className}>
      <Chart.Line
        data={chartData}
        options={chartOptions}
      />
    </div>
  );
}

export default React.memo(LineChart);