// Copyright 2017-2020 @polkadot/app-staking authors & contributors
// This software may be modified and distributed under the terms
// of the Apache-2.0 license. See the LICENSE file for details.

import React from 'react';
import styled from 'styled-components';

import { useTranslation } from './translate';

interface Props {
  className?: string;
  variant?: 'app' | 'push' | 'mini';
}

function Spinner ({ className, variant = 'app' }: Props): React.ReactElement<Props> | null {
  const { t } = useTranslation();
  const strokeWidth = variant === 'app' ? 2 : 4;

  return (
    <div className={`${className} ui--Spinner ${variant}`}>
      <div className='loader'>
        <svg className='circular ui--highlight--stroke' viewBox='25 25 50 50'>
          <circle className='path' cx='50' cy='50' r='20' fill='none' strokeWidth={strokeWidth} strokeMiterlimit='10' />
        </svg>
      </div>
      {variant === 'app' && (
        <div className='text'>{t('Retrieving data')}</div>
      )}
    </div>
  );
}

export default React.memo(styled(Spinner)`
  .loader {
    position: relative;
    margin: 0 auto;
    width: 64px;

    &:before {
      content: '';
      display: block;
      padding-top: 100%;
    }
  }

  .text {
    margin: 0.25rem auto 1.5rem auto;
    opacity: 0.6;
    text-align: center;
  }

  .circular {
    animation: rotate 2s linear infinite;
    height: 100%;
    transform-origin: center center;
    width: 100%;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
  }

  .path {
    stroke-dasharray: 1, 200;
    stroke-dashoffset: 0;
    animation: dash 1.5s ease-in-out infinite;
    stroke-linecap: round;
  }

  @keyframes rotate {
    100% {
      transform: rotate(360deg);
    }
  }

  @keyframes dash {
    0% {
      stroke-dasharray: 1, 200;
      stroke-dashoffset: 0;
    }
    50% {
      stroke-dasharray: 89, 200;
      stroke-dashoffset: -35px;
    }
    100% {
      stroke-dasharray: 89, 200;
      stroke-dashoffset: -124px;
    }
  }

  &.mini {
    .loader {
      width: 22px;
    }
  }

  &.push {
    .loader {
      width: 40px;
    }

    .circular {
      stroke: #eee !important;
    }
  }
`);