/**
 *
 * Google Drive を対象にドキュメントインデックスを生成する Google Apps Script.
 *
 * Google Spreadsheet にバンドルして使用する.
 *
 */

var MAX_DEPTH = 3

var PATH_DELIMITER = " > "

function onOpen() {
  setupMenu()
}

function setupMenu() {
  var ui = SpreadsheetApp.getUi()
  var menu = ui.createMenu("Document Index")
  menu.addItem("Generate Document Index (starting on root folder)",
               "onGenerateDocumentIndexStartingOnRootFolder")
  menu.addItem("Generate Document Index (starting on current folder)",
               "onGenerateDocumentIndexStartingOnCurrentFolder")
  menu.addToUi()
}

function onGenerateDocumentIndexStartingOnRootFolder() {
  var sheet = SpreadsheetApp.getActiveSheet()
  var rootFolder = DriveApp.getRootFolder()
  generateDocumentIndex(sheet, rootFolder, MAX_DEPTH)
}

function onGenerateDocumentIndexStartingOnCurrentFolder() {
  var sheet = SpreadsheetApp.getActiveSheet()
  var spreadsheetId = sheet.getParent().getId()
  var spreadsheetFile = DriveApp.getFileById(spreadsheetId)
  var rootFolder = spreadsheetFile.getParents().next()
  generateDocumentIndex(sheet, rootFolder, MAX_DEPTH)
}

function generateDocumentIndex(sheet, rootFolder, maxDepth) {
  var filePaths = getFilePaths(rootFolder, maxDepth)
  updateSheet(sheet, filePaths)
}

function getFilePaths(rootFolder, maxDepth) {
  var filePaths = []
  traverseDrive(rootFolder, maxDepth, function(parents, file) {
    filePaths.push({parents: parents, paths: parents.concat(file), file: file})
  })
  return filePaths
}

function traverseDrive(rootFolder, maxDepth, callback) {
  function traverse(parents, folder, depth) {
    if (depth > maxDepth) {
      return
    }
    var query = "'" + folder.getId() + "' in parents"
    var files = DriveApp.searchFiles(query)
    while (files.hasNext()) {
      var file = files.next()
      callback(parents.concat(folder), file)
    }
    var folders = DriveApp.searchFolders(query)
    while (folders.hasNext()) {
      var subFolder = folders.next()
      callback(parents.concat(folder), subFolder)
      traverse(parents.concat(folder), subFolder, depth + 1)
    }
  }
  traverse([], rootFolder, 1)
}

function updateSheet(sheet, filePaths) {
  initializeSheet(sheet)
  generateHeaderRow(sheet, filePaths)
  generateValueRows(sheet, filePaths)
}

function initializeSheet(sheet) {
  sheet.clear()
}

function generateHeaderRow(sheet, filePaths) {
  var headers = ["No.", "Type", "MIME Type", "Full Path"]

  var maxDepth = 0
  for (var i = 0; i < filePaths.length; i++) {
    maxDepth = Math.max(maxDepth, filePaths[i].parents.length + 1)
  }
  for (var i = 0; i < maxDepth; i++) {
    headers.push("Path (Level " + i + ")")
  }

  var row = 1
  var range = sheet.getRange(row, 1, 1, headers.length)
  range.setValues([headers])
  range.setBackground("orange")
  range.setHorizontalAlignment("center")
}

function generateValueRows(sheet, filePaths) {
  var row = 2
  for (var i = 0; i < filePaths.length; i++) {
    generateValueRow(sheet, filePaths[i], i, row++)
  }
}

function generateValueRow(sheet, filePath, index, row) {
  function setNoCell(column) {
    var range = sheet.getRange(row, column)
    CellUtils.setNumber(range, index + 1)
  }
  function setTypeCell(column) {
    var range = sheet.getRange(row, column)
    var value = FileUtils.isFile(filePath.file) ? "File" : "Directory"
    CellUtils.setText(range, value)
  }
  function setMimeTypeCell(column) {
    var range = sheet.getRange(row, column)
    if (FileUtils.isFile(filePath.file)) {
      CellUtils.setText(range, filePath.file.getMimeType())
    }
  }
  function setFullPathCell(column) {
    var value = ""
    var delimiter = ""
    for (var i = 0; i < filePath.paths.length; i++) {
      value += delimiter + filePath.paths[i].getName()
      delimiter = PATH_DELIMITER
    }
    var range = sheet.getRange(row, column)
    CellUtils.setTextLink(range, filePath.file.getUrl(), value)
  }
  function setPathCells(column) {
    for (var i = 0; i < filePath.paths.length; i++) {
      var range = sheet.getRange(row, column++)
      var path = filePath.paths[i]
      CellUtils.setTextLink(range, path.getUrl(), path.getName())
    }
  }

  var column = 1
  setNoCell(column++)
  setTypeCell(column++)
  setMimeTypeCell(column++)
  setFullPathCell(column++)
  setPathCells(column++)
}

var FileUtils = {
  isFile: function(file) {
    return !file.addFile
  },
  isFolder: function(file) {
    return !!file.addFile
  },
}

var CellUtils = {
  setNumber: function(range, value) {
    range.setValue(value)
    range.setNumberFormat("0")
  },
  setText: function(range, value) {
    range.setValue(value)
    range.setNumberFormat("@")
  },
  setTextLink: function(range, url, value) {
    value = value.replace(/"/g, '""')
    range.setValue('=HYPERLINK("' + url + '", "' + value + '")')
    range.setNumberFormat("@")
    range.setShowHyperlink(true)
  },
}