import express             from 'express';
import BodyParser          from 'body-parser';
import * as Middlewares    from '../middlewares';
import { randomHexString } from '../cryptoUtils';
import Config              from '../Config';
import mime                from 'mime';

export class FilesRouter {

  expressRouter(options = {}) {
    var router = express.Router();
    router.get('/files/:appId/:filename', this.getHandler);

    router.post('/files', function(req, res, next) {
      next(new Parse.Error(Parse.Error.INVALID_FILE_NAME,
        'Filename not provided.'));
    });

    router.post('/files/:filename',
      Middlewares.allowCrossDomain,
      BodyParser.raw({type: () => { return true; }, limit: options.maxUploadSize || '20mb'}), // Allow uploads without Content-Type, or with any Content-Type.
      Middlewares.handleParseHeaders,
      this.createHandler
    );

    router.delete('/files/:filename',
      Middlewares.allowCrossDomain,
      Middlewares.handleParseHeaders,
      Middlewares.enforceMasterKeyAccess,
      this.deleteHandler
    );
    return router;
  }

  getHandler(req, res) {
    const config = new Config(req.params.appId);
    const filesController = config.filesController;
    const filename = req.params.filename;
    const contentType = mime.lookup(filename);
    if (isFileStreamable(req, filesController)) {
      filesController.getFileStream(config, filename).then((stream) => {
        handleFileStream(stream, req, res, contentType);
      }).catch((err) => {
        res.status(404);
        res.set('Content-Type', 'text/plain');
        res.end('File not found.');
      });
    } else {
      filesController.getFileData(config, filename).then((data) => {
        res.status(200);
        res.set('Content-Type', contentType);
        res.set('Content-Length', data.length);
        res.end(data);
      }).catch((err) => {
        res.status(404);
        res.set('Content-Type', 'text/plain');
        res.end('File not found.');
      });
    }
  }

  createHandler(req, res, next) {
    if (!req.body || !req.body.length) {
      next(new Parse.Error(Parse.Error.FILE_SAVE_ERROR,
        'Invalid file upload.'));
      return;
    }

    if (req.params.filename.length > 128) {
      next(new Parse.Error(Parse.Error.INVALID_FILE_NAME,
        'Filename too long.'));
      return;
    }

    if (!req.params.filename.match(/^[_a-zA-Z0-9][a-zA-Z0-9@\.\ ~_-]*$/)) {
      next(new Parse.Error(Parse.Error.INVALID_FILE_NAME,
        'Filename contains invalid characters.'));
      return;
    }

    const filename = req.params.filename;
    const contentType = req.get('Content-type');
    const config = req.config;
    const filesController = config.filesController;

    filesController.createFile(config, filename, req.body, contentType).then((result) => {
      res.status(201);
      res.set('Location', result.url);
      res.json(result);
    }).catch((err) => {
      next(new Parse.Error(Parse.Error.FILE_SAVE_ERROR, 'Could not store file.'));
    });
  }

  deleteHandler(req, res, next) {
    const filesController = req.config.filesController;
    filesController.deleteFile(req.config, req.params.filename).then(() => {
      res.status(200);
      // TODO: return useful JSON here?
      res.end();
    }).catch((error) => {
      next(new Parse.Error(Parse.Error.FILE_DELETE_ERROR,
        'Could not delete file.'));
    });
  }
}

function isFileStreamable(req, filesController){
  if (req.get('Range')) {
    if (!(typeof filesController.adapter.getFileStream === 'function')) {
      return false;
    }
    if (typeof filesController.adapter.constructor.name !== 'undefined') {
      if (filesController.adapter.constructor.name == 'GridStoreAdapter') {
        return true;
      }
    }
  }
  return false;
}

// handleFileStream is licenced under Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
// Author: LEROIB at weightingformypizza (https://weightingformypizza.wordpress.com/2015/06/24/stream-html5-media-content-like-video-audio-from-mongodb-using-express-and-gridstore/).
function handleFileStream(stream, req, res, contentType) {
  var buffer_size = 1024 * 1024;//1024Kb
  // Range request, partiall stream the file
  var parts = req.get('Range').replace(/bytes=/, "").split("-");
  var partialstart = parts[0];
  var partialend = parts[1];
  var start = partialstart ? parseInt(partialstart, 10) : 0;
  var end = partialend ? parseInt(partialend, 10) : stream.length - 1;
  var chunksize = (end - start) + 1;

  if (chunksize == 1) {
    start = 0;
    partialend = false;
  }

  if (!partialend) {
    if (((stream.length-1) - start) < (buffer_size)) {
        end = stream.length - 1;
    }else{
      end = start + (buffer_size);
    }
    chunksize = (end - start) + 1;
  }

  if (start == 0 && end == 2) {
    chunksize = 1;
  }

  res.writeHead(206, {
    'Content-Range': 'bytes ' + start + '-' + end + '/' + stream.length,
    'Accept-Ranges': 'bytes',
    'Content-Length': chunksize,
    'Content-Type': contentType,
  });

  stream.seek(start, function () {
    // get gridFile stream
    var gridFileStream = stream.stream(true);
    var ended = false;
    var bufferIdx = 0;
    var bufferAvail = 0;
    var range = (end - start) + 1;
    var totalbyteswanted = (end - start) + 1;
    var totalbyteswritten = 0;
    // write to response
    gridFileStream.on('data', function (buff) {
      bufferAvail += buff.length;
      //Ok check if we have enough to cover our range
      if (bufferAvail < range) {
        //Not enough bytes to satisfy our full range
        if (bufferAvail > 0) {
          //Write full buffer
          res.write(buff);
          totalbyteswritten += buff.length;
          range -= buff.length;
          bufferIdx += buff.length;
          bufferAvail -= buff.length;
        }
      } else {
        //Enough bytes to satisfy our full range!
        if (bufferAvail > 0) {
          const buffer = buff.slice(0,range);
          res.write(buffer);
          totalbyteswritten += buffer.length;
          bufferIdx += range;
          bufferAvail -= range;
        }
      }
      if (totalbyteswritten >= totalbyteswanted) {
        //totalbytes = 0;
        stream.close();
        res.end();
        this.destroy();
      }
    });
  });
}