import jQuery from 'jquery';

export function getCookie(name) {
  let cookieValue = null;
  if (document.cookie && document.cookie !== '') {
    const cookies = document.cookie.split(';');
    for (let i = 0; i < cookies.length; ++i) { /* eslint-disable-line no-plusplus */
      const cookie = jQuery.trim(cookies[i]);
      // Does this cookie string begin with the name we want?
      if (cookie.substring(0, name.length + 1) === (name + '=')) { /* eslint-disable-line prefer-template */
        cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
        break;
      }
    }
  }
  return cookieValue;
}

// {{{ file upload support

function embedUploadedFileViewer(mimeType, dataUrl) {
  jQuery('#file_upload_viewer_div').html(
    `<object id="file_upload_viewer" data='${dataUrl}' type='${mimeType}' style='width:100%; height: 80vh;'>
    <p>(
    Your browser reported itself unable to render <tt>${mimeType}</tt> inline.
    )</p>
    </object>`,
  );
}

function matchUploadDataURL(dataUrl) {
  // take apart data URL
  const parts = dataUrl.match(/data:([^;]*)(;base64)?,([0-9A-Za-z+/]+)/);
  return {
    mimeType: parts[1],
    encoding: parts[2],
    base64Data: parts[3],
  };
}

function convertUploadDataUrlToObjectUrl(dataUrlParts) {
  // https://code.google.com/p/chromium/issues/detail?id=69227#37
  const isWebKit = /WebKit/.test(navigator.userAgent);

  if (isWebKit) {
    // assume base64 encoding
    const binStr = atob(dataUrlParts.base64Data);

    // convert to binary in ArrayBuffer
    const buf = new ArrayBuffer(binStr.length);
    const view = new Uint8Array(buf);
    for (let i = 0; i < view.length; i += 1) {
      view[i] = binStr.charCodeAt(i);
    }

    const blob = new Blob([view], { type: dataUrlParts.mimeType });
    return webkitURL.createObjectURL(blob); // eslint-disable-line no-undef
  }
  return null;
}

export function enablePreviewForFileUpload() {
  let dataUrl = document.getElementById('file_upload_download_link').href;
  const dataUrlParts = matchUploadDataURL(dataUrl);

  const objUrl = convertUploadDataUrlToObjectUrl(dataUrlParts);
  if (objUrl) {
    dataUrl = objUrl;
  }

  jQuery('#file_upload_download_link').attr('href', dataUrl);

  if (dataUrlParts.mimeType === 'application/pdf') {
    embedUploadedFileViewer(dataUrlParts.mimeType, dataUrl);
  }
}

// }}}

// {{{ grading ui: next/previous points field

// based on https://codemirror.net/addon/search/searchcursor.js (MIT)

const pointsRegexp = /\[pts:/g;

export function goToNextPointsField(view) {
  pointsRegexp.lastIndex = view.state.selection.main.head;
  const match = pointsRegexp.exec(view.state.doc.toString());
  if (match) {
    view.dispatch({ selection: { anchor: match.index + match[0].length } });
    return true;
  }
  return false;
}

// based on https://stackoverflow.com/a/274094
function regexLastMatch(string, regex, startpos) {
  if (!regex.global) {
    throw new Error('Passed regex not global');
  }

  let start;
  if (typeof (startpos) === 'undefined') {
    start = string.length;
  } else if (startpos < 0) {
    start = 0;
  } else {
    start = startpos;
  }

  const stringToWorkWith = string.substring(0, start);
  let match;
  let lastMatch = null;
  // eslint-disable-next-line no-param-reassign
  regex.lastIndex = 0;

  // eslint-disable-next-line no-cond-assign
  while ((match = regex.exec(stringToWorkWith)) != null) {
    lastMatch = match;
    // eslint-disable-next-line no-param-reassign
    regex.lastIndex = match.index + 1;
  }
  return lastMatch;
}

export function goToPreviousPointsField(view) {
  const match = regexLastMatch(
    view.state.doc.toString(),
    pointsRegexp,
    // "[pts:" is five characters
    view.state.selection.main.head - 5,
  );

  if (match) {
    view.dispatch({ selection: { anchor: match.index + match[0].length } });
    return true;
  }
  return false;
}

// }}}

// {{{ grading UI: points spec processing

function parseFloatRobust(s) {
  const result = Number.parseFloat(s);
  if (Number.isNaN(result)) {
    throw new Error(`Numeral not understood: ${s}`);
  }
  return result;
}

export function parsePointsSpecs(feedbackText) {
  const result = [];
  const pointsRegex = /\[pts:\s*([^\]]*)\]/g;
  const pointsBodyRegex = /^([-0-9.]*)\s*((?:\/\s*[-0-9.]*)?)\s*((?:#[a-zA-Z_]\w*)?)\s*$/;

  // eslint-disable-next-line no-constant-condition
  while (true) {
    const bodyMatch = pointsRegex.exec(feedbackText);
    if (bodyMatch === null) {
      break;
    }

    const pointsBody = bodyMatch[1];
    const match = pointsBody.match(pointsBodyRegex);
    if (match === null) {
      throw new Error(`Points spec not understood: '${pointsBody}'`);
    }

    const [_fullMatch, pointsStr, maxPointsStr, identifierStr] = match;
    let points = null;
    if (pointsStr.length) {
      points = parseFloatRobust(pointsStr);
    }

    let maxPoints = null;
    if (maxPointsStr.length) {
      maxPoints = parseFloatRobust(maxPointsStr.substring(1));
      if (maxPoints <= 0) {
        throw new Error(`Point denominator must be positive: '${pointsBody}'`);
      }
    }

    let identifier = null;
    if (identifierStr.length) {
      identifier = identifierStr;
    }

    result.push({
      points,
      maxPoints,
      identifier,
      matchStart: bodyMatch.index,
      matchLength: bodyMatch[0].length,
    });
  }

  return result;
}

// }}}

// http://stackoverflow.com/a/30558011
const SURROGATE_PAIR_REGEXP = /[\uD800-\uDBFF][\uDC00-\uDFFF]/g;
// Match everything outside of normal chars and " (quote character)
const NON_ALPHANUMERIC_REGEXP = /([^#-~| |!])/g;

export function encodeEntities(value) {
  return value
    .replace(/&/g, '&amp;')
    .replace(SURROGATE_PAIR_REGEXP, (val) => {
      const hi = val.charCodeAt(0);
      const low = val.charCodeAt(1);
      return `&#${((hi - 0xD800) * 0x400) + (low - 0xDC00) + 0x10000};`;
    })
    .replace(NON_ALPHANUMERIC_REGEXP, (val) => `&#${val.charCodeAt(0)};`)
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;');
}

export function truncateText(s, length) {
  if (s.length > length) {
    return `${s.slice(0, length)}...`;
  }
  return s;
}

// vim: foldmethod=marker