/**
 * Handles the import requests
 */

/*
 * 2011 Peter 'Pita' Martischka (Primary Technology Ltd)
 * 2012 Iván Eixarch
 * 2014 John McLear (Etherpad Foundation / McLear Ltd)
 *
 * 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
 *
 *      http://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.
 */

const padManager = require('../db/PadManager');
const padMessageHandler = require('./PadMessageHandler');
const fs = require('fs');
const path = require('path');
const settings = require('../utils/Settings');
const formidable = require('formidable');
const os = require('os');
const importHtml = require('../utils/ImportHtml');
const importEtherpad = require('../utils/ImportEtherpad');
const log4js = require('log4js');
const hooks = require('ep_etherpad-lite/static/js/pluginfw/hooks.js');
const util = require('util');

const fsp_exists = util.promisify(fs.exists);
const fsp_rename = util.promisify(fs.rename);
const fsp_readFile = util.promisify(fs.readFile);
const fsp_unlink = util.promisify(fs.unlink);

let convertor = null;
let exportExtension = 'htm';

// load abiword only if it is enabled and if soffice is disabled
if (settings.abiword != null && settings.soffice === null) {
  convertor = require('../utils/Abiword');
}

// load soffice only if it is enabled
if (settings.soffice != null) {
  convertor = require('../utils/LibreOffice');
  exportExtension = 'html';
}

const tmpDirectory = os.tmpdir();

/**
 * do a requested import
 */
async function doImport(req, res, padId) {
  const apiLogger = log4js.getLogger('ImportHandler');

  // pipe to a file
  // convert file to html via abiword or soffice
  // set html in the pad
  const randNum = Math.floor(Math.random() * 0xFFFFFFFF);

  // setting flag for whether to use convertor or not
  let useConvertor = (convertor != null);

  const form = new formidable.IncomingForm();
  form.keepExtensions = true;
  form.uploadDir = tmpDirectory;
  form.maxFileSize = settings.importMaxFileSize;

  // Ref: https://github.com/node-formidable/formidable/issues/469
  // Crash in Etherpad was Uploading Error: Error: Request aborted
  // [ERR_STREAM_DESTROYED]: Cannot call write after a stream was destroyed
  form.onPart = (part) => {
    form.handlePart(part);
    if (part.filename !== undefined) {
      form.openedFiles[form.openedFiles.length - 1]._writeStream.on('error', (err) => {
        form.emit('error', err);
      });
    }
  };

  // locally wrapped Promise, since form.parse requires a callback
  let srcFile = await new Promise((resolve, reject) => {
    form.parse(req, (err, fields, files) => {
      if (err || files.file === undefined) {
        // the upload failed, stop at this point
        if (err) {
          console.warn(`Uploading Error: ${err.stack}`);
        }

        // I hate doing indexOf here but I can't see anything to use...
        if (err && err.stack && err.stack.indexOf('maxFileSize') !== -1) {
          reject('maxFileSize');
        }

        reject('uploadFailed');
      }
      if (!files.file) { // might not be a graceful fix but it works
        reject('uploadFailed');
      } else {
        resolve(files.file.path);
      }
    });
  });

  // ensure this is a file ending we know, else we change the file ending to .txt
  // this allows us to accept source code files like .c or .java
  const fileEnding = path.extname(srcFile).toLowerCase();
  const knownFileEndings = ['.txt', '.doc', '.docx', '.pdf', '.odt', '.html', '.htm', '.etherpad', '.rtf'];
  const fileEndingUnknown = (knownFileEndings.indexOf(fileEnding) < 0);

  if (fileEndingUnknown) {
    // the file ending is not known

    if (settings.allowUnknownFileEnds === true) {
      // we need to rename this file with a .txt ending
      const oldSrcFile = srcFile;

      srcFile = path.join(path.dirname(srcFile), `${path.basename(srcFile, fileEnding)}.txt`);
      await fsp_rename(oldSrcFile, srcFile);
    } else {
      console.warn('Not allowing unknown file type to be imported', fileEnding);
      throw 'uploadFailed';
    }
  }

  const destFile = path.join(tmpDirectory, `etherpad_import_${randNum}.${exportExtension}`);

  // Logic for allowing external Import Plugins
  const result = await hooks.aCallAll('import', {srcFile, destFile, fileEnding});
  const importHandledByPlugin = (result.length > 0); // This feels hacky and wrong..

  const fileIsEtherpad = (fileEnding === '.etherpad');
  const fileIsHTML = (fileEnding === '.html' || fileEnding === '.htm');
  const fileIsTXT = (fileEnding === '.txt');

  if (fileIsEtherpad) {
    // we do this here so we can see if the pad has quite a few edits
    const _pad = await padManager.getPad(padId);
    const headCount = _pad.head;

    if (headCount >= 10) {
      apiLogger.warn("Direct database Import attempt of a pad that already has content, we won't be doing this");
      throw 'padHasData';
    }

    const fsp_readFile = util.promisify(fs.readFile);
    const _text = await fsp_readFile(srcFile, 'utf8');
    req.directDatabaseAccess = true;
    await importEtherpad.setPadRaw(padId, _text);
  }

  // convert file to html if necessary
  if (!importHandledByPlugin && !req.directDatabaseAccess) {
    if (fileIsTXT) {
      // Don't use convertor for text files
      useConvertor = false;
    }

    // See https://github.com/ether/etherpad-lite/issues/2572
    if (fileIsHTML || !useConvertor) {
      // if no convertor only rename
      fs.renameSync(srcFile, destFile);
    } else {
      // @TODO - no Promise interface for convertors (yet)
      await new Promise((resolve, reject) => {
        convertor.convertFile(srcFile, destFile, exportExtension, (err) => {
          // catch convert errors
          if (err) {
            console.warn('Converting Error:', err);
            reject('convertFailed');
          }
          resolve();
        });
      });
    }
  }

  if (!useConvertor && !req.directDatabaseAccess) {
    // Read the file with no encoding for raw buffer access.
    const buf = await fsp_readFile(destFile);

    // Check if there are only ascii chars in the uploaded file
    const isAscii = !Array.prototype.some.call(buf, (c) => (c > 240));

    if (!isAscii) {
      throw 'uploadFailed';
    }
  }

  // get the pad object
  let pad = await padManager.getPad(padId);

  // read the text
  let text;

  if (!req.directDatabaseAccess) {
    text = await fsp_readFile(destFile, 'utf8');

    // node on windows has a delay on releasing of the file lock.
    // We add a 100ms delay to work around this
    if (os.type().indexOf('Windows') > -1) {
      await new Promise((resolve) => setTimeout(resolve, 100));
    }
  }

  // change text of the pad and broadcast the changeset
  if (!req.directDatabaseAccess) {
    if (importHandledByPlugin || useConvertor || fileIsHTML) {
      try {
        await importHtml.setPadHTML(pad, text);
      } catch (e) {
        apiLogger.warn('Error importing, possibly caused by malformed HTML');
      }
    } else {
      await pad.setText(text);
    }
  }

  // Load the Pad into memory then broadcast updates to all clients
  padManager.unloadPad(padId);
  pad = await padManager.getPad(padId);
  padManager.unloadPad(padId);

  // direct Database Access means a pad user should perform a switchToPad
  // and not attempt to receive updated pad data
  if (req.directDatabaseAccess) {
    return;
  }

  // tell clients to update
  await padMessageHandler.updatePadClients(pad);

  // clean up temporary files

  /*
   * TODO: directly delete the file and handle the eventual error. Checking
   * before for existence is prone to race conditions, and does not handle any
   * errors anyway.
   */
  if (await fsp_exists(srcFile)) {
    fsp_unlink(srcFile);
  }

  if (await fsp_exists(destFile)) {
    fsp_unlink(destFile);
  }
}

exports.doImport = function (req, res, padId) {
  /**
   * NB: abuse the 'req' object by storing an additional
   * 'directDatabaseAccess' property on it so that it can
   * be passed back in the HTML below.
   *
   * this is necessary because in the 'throw' paths of
   * the function above there's no other way to return
   * a value to the caller.
   */
  let status = 'ok';
  doImport(req, res, padId).catch((err) => {
    // check for known errors and replace the status
    if (err == 'uploadFailed' || err == 'convertFailed' || err == 'padHasData' || err == 'maxFileSize') {
      status = err;
    } else {
      throw err;
    }
  }).then(() => {
    // close the connection
    res.send(`<script>document.addEventListener('DOMContentLoaded', function(){ var impexp = window.parent.padimpexp.handleFrameCall('${req.directDatabaseAccess}', '${status}'); })</script>`);
  });
};