const DOCUMENT_TEMPLATE_IDS = {
  Certification: '1V0uMuM80BGpjpdt1AmuzlU97tDI_u-y2rOfdl4tkqmc',
};

const OUTPUT_FOLDER_ID = '1ROyJXk-QANTHM6Jiw0ne3EQiR1f2UsLr';

declare namespace GoogleAppsScript {
  namespace Spreadsheet {
    interface RichTextValue {
      getLinkUrl(): string | null;
      getLinkUrl(startOffset: number, endOffset: number): string | null;
    }
  }
}

type DocSection =
  | GoogleAppsScript.Document.Body
  | GoogleAppsScript.Document.HeaderSection
  | GoogleAppsScript.Document.FooterSection;

function onOpen() {
  const ui = SpreadsheetApp.getUi();
  ui.createMenu('CMS Document Generation')
    .addItem('Generate document for current row', 'generateForCurrentRow')
    .addItem('Generate document for all rows', 'generateForAllRows')
    // .addItem('CAUTION! Write list of all files to current sheet', 'dumpFiles')
    .addToUi();
}

function findAllFiles(path: string, folder: GoogleAppsScript.Drive.Folder) {
  const out: string[][] = [];

  const files = folder.getFiles();
  while (files.hasNext()) {
    const file = files.next();
    if (!file.isTrashed()) {
      out.push([
        path,
        file.getId(),
        file.getName(),
        `=HYPERLINK("${file.getUrl()}", "${file.getName()}")`,
      ]);
    }
  }

  const subfolders = folder.getFolders();
  while (subfolders.hasNext()) {
    const subfolder = subfolders.next();
    out.push(...findAllFiles(path + '/' + subfolder.getName(), subfolder));
  }

  return out;
}

function dumpFiles() {
  const root = DriveApp.getFolderById('1mWOQDmQjQsi8the09VXpnKnvFUzj4wiv');

  const out = findAllFiles('', root);

  const active_sheet = SpreadsheetApp.getActive();
  const range = active_sheet.getRange(`R1C1:R${out.length}C${out[0].length}`);
  range.setValues(out);
}

function copyElement(
  source_element: GoogleAppsScript.Document.Element,
  dest: DocSection,
  index?: number
) {
  const element = source_element.copy();
  switch (element.getType()) {
    case DocumentApp.ElementType.PARAGRAPH:
      if (index !== undefined)
        dest.insertParagraph(index, element.asParagraph());
      else dest.appendParagraph(element.asParagraph());
      break;
    case DocumentApp.ElementType.TABLE:
      if (index !== undefined) dest.insertTable(index, element.asTable());
      else dest.appendTable(element.asTable());
      break;
    case DocumentApp.ElementType.LIST_ITEM:
      if (index !== undefined) dest.insertListItem(index, element.asListItem());
      else dest.appendListItem(element.asListItem());
      break;
    case DocumentApp.ElementType.INLINE_IMAGE:
      if (index !== undefined) dest.insertImage(index, element.asInlineImage());
      else dest.appendImage(element.asInlineImage());
      break;
    default:
      throw new Error(
        "According to the doc this type couldn't appear in the body: " +
          element.getType()
      );
  }
}

function copySection(source: DocSection, dest: DocSection, index?: number) {
  const totalElements = source.getNumChildren();
  for (let j = 0; j < totalElements; ++j) {
    if (index) copyElement(source.getChild(j), dest, index + j);
    else copyElement(source.getChild(j), dest);
  }
}

function spreadsheetRowToObject(
  sheet: GoogleAppsScript.Spreadsheet.Sheet,
  rownum: number
): { [key: string]: GoogleAppsScript.Spreadsheet.RichTextValue } {
  // TODO: could be more efficient
  const range = sheet.getDataRange();
  const headers = range.getValues()[0];
  const row_data = range.getRichTextValues()[rownum - 1];

  return headers.reduce((acc, header, index) => {
    acc[String(header)] = row_data[index];
    return acc;
  }, {});
}

function trashFiles(files: GoogleAppsScript.Drive.FileIterator) {
  while (files.hasNext()) {
    files.next().setTrashed(true);
  }
}

function generateForRow(
  spreadsheet: GoogleAppsScript.Spreadsheet.Spreadsheet,
  row_num: number
) {
  const row = spreadsheetRowToObject(spreadsheet.getActiveSheet(), row_num);

  if (!(row['Type'].getText() in DOCUMENT_TEMPLATE_IDS))
    throw new Error(`${row['Type']} is not a valid type of document!`);

  const template_doc = DocumentApp.openById(
    DOCUMENT_TEMPLATE_IDS[
      row['Type'].getText() as keyof typeof DOCUMENT_TEMPLATE_IDS
    ]
  );

  const link = row['Document'].getLinkUrl();
  if (link === null) {
    throw new Error(`Link missing for ${row['Document'].getText()}`);
  }
  // TODO: should probably handle this better
  if (!link.includes('document')) return;

  const source_file = DriveApp.getFileById(DocumentApp.openByUrl(link).getId());
  const out_folder = DriveApp.getFolderById(OUTPUT_FOLDER_ID);

  const out_name = row['Document'] + '_' + row['Version'];

  // Delete old files with the same name
  trashFiles(out_folder.getFilesByName(out_name));
  trashFiles(out_folder.getFilesByName(out_name + '.pdf'));

  // Duplicate source document and open
  const out_file = source_file.makeCopy(out_name, out_folder);
  const out_doc = DocumentApp.openById(out_file.getId());

  // Copy header
  if (!out_doc.getHeader()) out_doc.addHeader();
  copySection(template_doc.getHeader(), out_doc.getHeader().clear());

  // Copy footer
  if (!out_doc.getFooter()) out_doc.addFooter();
  copySection(template_doc.getFooter(), out_doc.getFooter().clear());

  const insert_point = template_doc
    .getBody()
    .findText('{{body}}')
    ?.getElement();

  if (!insert_point) {
    throw new Error("Could not find insert point '{{body}}'");
  }

  // find the parent element that is a direct descendant of the body
  let parent = insert_point;
  while (parent.getParent().getType() != DocumentApp.ElementType.BODY_SECTION) {
    parent = parent.getParent();
  }
  const index = template_doc.getBody().getChildIndex(parent);

  // Copy body contents above and below {{body}} tag
  for (let j = 0; j < template_doc.getBody().getNumChildren(); j++) {
    if (j < index)
      copyElement(template_doc.getBody().getChild(j), out_doc.getBody(), j);
    // don't copy {{body}} tag
    else if (j == index) continue;
    else copyElement(template_doc.getBody().getChild(j), out_doc.getBody());
  }

  // do text replacement
  Object.entries(row).forEach(([header, data]) => {
    let replacement = data.getText();
    out_doc.getBody().replaceText(`{{${header}}}`, replacement);
    out_doc.getHeader().replaceText(`{{${header}}}`, replacement);
    out_doc.getFooter().replaceText(`{{${header}}}`, replacement);
  });

  out_doc.saveAndClose();

  // create PDF file
  out_folder.createFile(out_file.getAs('application/pdf'));
}

function generateForCurrentRow() {
  const spreadsheet = SpreadsheetApp.getActive();

  const cell = spreadsheet.getCurrentCell();
  if (!cell) throw new Error('No Cell selected for operation on row');

  generateForRow(spreadsheet, cell.getRow());
}

function generateForAllRows() {
  const spreadsheet = SpreadsheetApp.getActive();

  const row_count = spreadsheet.getActiveSheet().getDataRange().getNumRows();

  for (let row_num = 2; row_num < row_count; row_num++) {
    generateForRow(spreadsheet, row_num);
  }
}