function doSplitUserInput()

in website/src/components/explorer/index.tsx [132:211]
60 lines of code
13 McCabe index (conditional complexity)

function doSplitUserInput(userInput: string, userResolution: number) {
  if (userInput) {
    // Acceptable inputs, in order of test preference:
    // GeoJSON
    // WKT
    // Valid hexadecimal cell ID
    // Valid hexadecimal cell ID, prefixed by 0x
    // Valid decimal cell ID
    // lat,lng coordinate pairs

    const resultPolygon = tryParsePolygonInput(userInput, userResolution);
    if (resultPolygon) {
      return resultPolygon;
    }

    let showCellId = false;
    let showResolutionInput = null;
    const unwrapAnyArray = fullyUnwrap(userInput);
    const split = unwrapAnyArray.split(/\s/).filter((str) => str !== "");
    const result = [];

    for (let i = 0; i < split.length; i++) {
      const currentInput = fullyTrim(split[i]);
      const nextInput = fullyTrim(split[i + 1]);
      const cellIdFromDecimal = maybeDecimalCell(currentInput);
      const cellIdFromPrefixedHex = maybePrefixedHexCell(currentInput);

      if (isValidCell(currentInput)) {
        result.push(currentInput);
      } else if (
        cellIdFromPrefixedHex !== null &&
        isValidCell(cellIdFromPrefixedHex)
      ) {
        result.push(cellIdFromPrefixedHex);
        showCellId = true;
      } else if (cellIdFromDecimal) {
        result.push(cellIdFromDecimal);
        // Show what the cell ID would look like normally
        showCellId = true;
      } else if (
        i < split.length - 1 &&
        Number.isFinite(Number.parseFloat(currentInput)) &&
        Number.isFinite(Number.parseFloat(nextInput))
      ) {
        const lat = Number.parseFloat(currentInput);
        const lng = Number.parseFloat(nextInput);

        if (userResolution === -1) {
          // Note this order is important for picking to work correctly
          for (let res = 0; res < 16; res++) {
            result.push(latLngToCell(lat, lng, res));
          }

          // We don't need to set showCellId, because we are showing multiple cell IDs
          // anyways, so they will be clickable.
        } else {
          result.push(latLngToCell(lat, lng, userResolution));
          showCellId = true;
        }
        showResolutionInput = -1;
        // consumed, skip next coordinate
        i++;
      }
    }

    return {
      splitUserInput: result,
      showResolutionInput,
      showCellId,
      inputGeoJson: null,
    };
  }

  return {
    splitUserInput: [],
    showCellId: false,
    showResolutionInput: null,
    inputGeoJson: null,
  };
}