import React from 'react';
// import dynamic from 'next/dynamic'
// import {buildURI} from 'react-csv';
// /**
//  * See https://github.com/react-csv/react-csv/issues/87
//  */
export const isSafari = () => /^((?!chrome|android).)*safari/i.test(navigator.userAgent);

export const isJsons = ((array) => Array.isArray(array) && array.every(
  row => (typeof row === 'object' && !(row instanceof Array))
));

export const isArrays = ((array) => Array.isArray(array) && array.every(
  row => Array.isArray(row)
));

export const jsonsHeaders = ((array) => Array.from(
  array.map(json => Object.keys(json))
    .reduce((a, b) => new Set([...a, ...b]), [])
));

export const jsons2arrays = (jsons, headers) => {
  headers = headers || jsonsHeaders(jsons);

  // allow headers to have custom labels, defaulting to having the header data key be the label
  let headerLabels = headers;
  let headerKeys = headers;
  if (isJsons(headers)) {
    headerLabels = headers.map((header) => header.label);
    headerKeys = headers.map((header) => header.key);
  }

  const data = jsons.map((object) => headerKeys.map((header) => getHeaderValue(header, object)));
  return [headerLabels, ...data];
};

export const getHeaderValue = (property, obj) => {
  const foundValue = property
    .replace(/\[([^\]]+)]/g, ".$1")
    .split(".")
    .reduce(function (o, p, i, arr) {
      // if at any point the nested keys passed do not exist, splice the array so it doesnt keep reducing
      const value = o[p];
      if (value === undefined || value === null) {
        arr.splice(1);
      } else {
        return value;
      }
    }, obj);
  // if at any point the nested keys passed do not exist then looks for key `property` in object obj
  return (foundValue === undefined) ? ((property in obj) ? obj[property] : '') : foundValue;
}

export const elementOrEmpty = (element) =>
  (typeof element === 'undefined' || element === null) ? '' : element;

export const joiner = ((data, separator = ',', enclosingCharacter = '"') => {
  return data
    .filter(e => e)
    .map(
      row => row
        .map((element) => elementOrEmpty(element))
        .map(column => `${enclosingCharacter}${column}${enclosingCharacter}`)
        .join(separator)
    )
    .join(`\n`);
});

export const arrays2csv = ((data, headers, separator, enclosingCharacter) =>
  joiner(headers ? [headers, ...data] : data, separator, enclosingCharacter)
);

export const jsons2csv = ((data, headers, separator, enclosingCharacter) =>
  joiner(jsons2arrays(data, headers), separator, enclosingCharacter)
);

export const string2csv = ((data, headers, separator) =>
  (headers) ? `${headers.join(separator)}\n${data}` : data.replace(/"/g, '""')
);

export const toCSV = (data, headers, separator, enclosingCharacter) => {
  if (isJsons(data)) return jsons2csv(data, headers, separator, enclosingCharacter);
  if (isArrays(data)) return arrays2csv(data, headers, separator, enclosingCharacter);
  if (typeof data === 'string') return string2csv(data, headers, separator);
  throw new TypeError(`Data should be a "String", "Array of arrays" OR "Array of objects" `);
};


const CSVLink = ({filename, data, children, ...rest}) => {

  const buildURI = ((data, uFEFF, headers, separator, enclosingCharacter) => {
    const csv = toCSV(data, headers, separator, enclosingCharacter);
    const type = isSafari() ? 'application/csv' : 'text/csv';
    const blob = new Blob([uFEFF ? '\uFEFF' : '', csv], {type});
    const dataURI = `data:${type};charset=utf-8,${uFEFF ? '\uFEFF' : ''}${csv}`;

    const URL = window.URL || window.webkitURL;

    return (typeof URL.createObjectURL === 'undefined')
      ? dataURI
      : URL.createObjectURL(blob);
  });

  const isNodeEnvironment = typeof window === 'undefined';
  const uFEFF = true;
  const headers = undefined;
  const separator = ",";
  const enclosingCharacter = '"';
  const href = isNodeEnvironment ? '' : buildURI(data, uFEFF, headers, separator, enclosingCharacter)

  return (
    <a
      download={filename}
      target="_blank"
      {...rest}
      href={href}
    >
      {children}
    </a>
  );
}

export default CSVLink;