// To learn how to use this script, refer to the documentation:
// https://developers.google.com/apps-script/samples/custom-functions/calculate-driving-distance

/*
Copyright 2022 Google LLC

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

/**
 * @OnlyCurrentDoc Limits the script to only accessing the current sheet.
 */

/**
 * A special function that runs when the spreadsheet is open, used to add a
 * custom menu to the spreadsheet.
 */
function onOpen() {
  try {
    const spreadsheet = SpreadsheetApp.getActive();
    const menuItems = [
      {name: 'Prepare sheet...', functionName: 'prepareSheet_'},
      {name: 'Generate step-by-step...', functionName: 'generateStepByStep_'}
    ];
    spreadsheet.addMenu('Directions', menuItems);
  } catch (e) {
    // TODO (Developer) - Handle Exception
    console.log('Failed with error: %s' + e.error);
  }
}

/**
 * A custom function that converts meters to miles.
 *
 * @param {Number} meters The distance in meters.
 * @return {Number} The distance in miles.
 */
function metersToMiles(meters) {
  if (typeof meters !== 'number') {
    return null;
  }
  return meters / 1000 * 0.621371;
}

/**
 * A custom function that gets the driving distance between two addresses.
 *
 * @param {String} origin The starting address.
 * @param {String} destination The ending address.
 * @return {Number} The distance in meters.
 */
function drivingDistance(origin, destination) {
  const directions = getDirections_(origin, destination);
  return directions.routes[0].legs[0].distance.value;
}

/**
 * A function that adds headers and some initial data to the spreadsheet.
 */
function prepareSheet_() {
  try {
    const sheet = SpreadsheetApp.getActiveSheet().setName('Settings');
    const headers = [
      'Start Address',
      'End Address',
      'Driving Distance (meters)',
      'Driving Distance (miles)'];
    const initialData = [
      '350 5th Ave, New York, NY 10118',
      '405 Lexington Ave, New York, NY 10174'];
    sheet.getRange('A1:D1').setValues([headers]).setFontWeight('bold');
    sheet.getRange('A2:B2').setValues([initialData]);
    sheet.setFrozenRows(1);
    sheet.autoResizeColumns(1, 4);
  } catch (e) {
    // TODO (Developer) - Handle Exception
    console.log('Failed with error: %s' + e.error);
  }
}

/**
 * Creates a new sheet containing step-by-step directions between the two
 * addresses on the "Settings" sheet that the user selected.
 */
function generateStepByStep_() {
  try {
    const spreadsheet = SpreadsheetApp.getActive();
    const settingsSheet = spreadsheet.getSheetByName('Settings');
    settingsSheet.activate();

    // Prompt the user for a row number.
    const selectedRow = Browser
        .inputBox('Generate step-by-step', 'Please enter the row number of' +
        ' the' + ' addresses to use' + ' (for example, "2"):',
        Browser.Buttons.OK_CANCEL);
    if (selectedRow === 'cancel') {
      return;
    }
    const rowNumber = Number(selectedRow);
    if (isNaN(rowNumber) || rowNumber < 2 ||
      rowNumber > settingsSheet.getLastRow()) {
      Browser.msgBox('Error',
          Utilities.formatString('Row "%s" is not valid.', selectedRow),
          Browser.Buttons.OK);
      return;
    }


    // Retrieve the addresses in that row.
    const row = settingsSheet.getRange(rowNumber, 1, 1, 2);
    const rowValues = row.getValues();
    const origin = rowValues[0][0];
    const destination = rowValues[0][1];
    if (!origin || !destination) {
      Browser.msgBox('Error', 'Row does not contain two addresses.',
          Browser.Buttons.OK);
      return;
    }

    // Get the raw directions information.
    const directions = getDirections_(origin, destination);

    // Create a new sheet and append the steps in the directions.
    const sheetName = 'Driving Directions for Row ' + rowNumber;
    let directionsSheet = spreadsheet.getSheetByName(sheetName);
    if (directionsSheet) {
      directionsSheet.clear();
      directionsSheet.activate();
    } else {
      directionsSheet =
        spreadsheet.insertSheet(sheetName, spreadsheet.getNumSheets());
    }
    const sheetTitle = Utilities
        .formatString('Driving Directions from %s to %s', origin, destination);
    const headers = [
      [sheetTitle, '', ''],
      ['Step', 'Distance (Meters)', 'Distance (Miles)']
    ];
    const newRows = [];
    for (const step of directions.routes[0].legs[0].steps) {
      // Remove HTML tags from the instructions.
      const instructions = step.html_instructions
          .replace(/<br>|<div.*?>/g, '\n').replace(/<.*?>/g, '');
      newRows.push([
        instructions,
        step.distance.value
      ]);
    }
    directionsSheet.getRange(1, 1, headers.length, 3).setValues(headers);
    directionsSheet.getRange(headers.length + 1, 1, newRows.length, 2)
        .setValues(newRows);
    directionsSheet.getRange(headers.length + 1, 3, newRows.length, 1)
        .setFormulaR1C1('=METERSTOMILES(R[0]C[-1])');

    // Format the new sheet.
    directionsSheet.getRange('A1:C1').merge().setBackground('#ddddee');
    directionsSheet.getRange('A1:2').setFontWeight('bold');
    directionsSheet.setColumnWidth(1, 500);
    directionsSheet.getRange('B2:C').setVerticalAlignment('top');
    directionsSheet.getRange('C2:C').setNumberFormat('0.00');
    const stepsRange = directionsSheet.getDataRange()
        .offset(2, 0, directionsSheet.getLastRow() - 2);
    setAlternatingRowBackgroundColors_(stepsRange, '#ffffff', '#eeeeee');
    directionsSheet.setFrozenRows(2);
    SpreadsheetApp.flush();
  } catch (e) {
    // TODO (Developer) - Handle Exception
    console.log('Failed with error: %s' + e.error);
  }
}

/**
 * Sets the background colors for alternating rows within the range.
 * @param {Range} range The range to change the background colors of.
 * @param {string} oddColor The color to apply to odd rows (relative to the
 *     start of the range).
 * @param {string} evenColor The color to apply to even rows (relative to the
 *     start of the range).
 */
function setAlternatingRowBackgroundColors_(range, oddColor, evenColor) {
  const backgrounds = [];
  for (let row = 1; row <= range.getNumRows(); row++) {
    const rowBackgrounds = [];
    for (let column = 1; column <= range.getNumColumns(); column++) {
      if (row % 2 === 0) {
        rowBackgrounds.push(evenColor);
      } else {
        rowBackgrounds.push(oddColor);
      }
    }
    backgrounds.push(rowBackgrounds);
  }
  range.setBackgrounds(backgrounds);
}

/**
 * A shared helper function used to obtain the full set of directions
 * information between two addresses. Uses the Apps Script Maps Service.
 *
 * @param {String} origin The starting address.
 * @param {String} destination The ending address.
 * @return {Object} The directions response object.
 */
function getDirections_(origin, destination) {
  const directionFinder = Maps.newDirectionFinder();
  directionFinder.setOrigin(origin);
  directionFinder.setDestination(destination);
  const directions = directionFinder.getDirections();
  if (directions.status !== 'OK') {
    throw directions.error_message;
  }
  return directions;
}
