/*
 *  Copyright 2015 Adobe Systems Incorporated. All rights reserved.
 *  This file is licensed to you 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 REPRESENTATIONS
 *  OF ANY KIND, either express or implied. See the License for the specific language
 *  governing permissions and limitations under the License.
 */

'use strict';

var put = require('put');
var binary = require('binary');
var logger = require('winston').loggers.get('smb');
var _ = require('lodash');

var ntstatus = require('../../ntstatus');
var SMB = require('../constants');
var utils = require('../../utils');

/**
 * SMB_COM_LOCKING_ANDX (0x24): This command is used to explicitly lock and/or
 * unlock a contiguous range of bytes in a regular file.
 *
 * @param {Object} msg - an SMB message object
 * @param {Number} commandId - the command id
 * @param {Buffer} commandParams - the command parameters
 * @param {Buffer} commandData - the command data
 * @param {Number} commandParamsOffset - the command parameters offset within the SMB
 * @param {Number} commandDataOffset - the command data offset within the SMB
 * @param {Object} connection - an SMBConnection instance
 * @param {Object} server - an SMBServer instance
 * @param {Function} cb callback called with the command's result
 * @param {Object} cb.result - an object with the command's result params and data
 *                             or null if the handler already sent the response and
 *                             no further processing is required by the caller
 * @param {Number} cb.result.status
 * @param {Buffer} cb.result.params
 * @param {Buffer} cb.result.data
 */
function handle(msg, commandId, commandParams, commandData, commandParamsOffset, commandDataOffset, connection, server, cb) {
  // decode params
  var parser = binary.parse(commandParams);
  var paramsObj = parser.skip(4) // skip andX header
    .word16le('fid')
    .word8('typeOfLock')
    .word8('newOpLockLevel')
    .word32le('timeout')
    .word16le('numberOfRequestedUnlocks')
    .word16le('numberOfRequestedLocks')
    .vars;
  _.assign(msg, paramsObj);

  // decode data
  parser = binary.parse(commandData);
  msg.unlocks = parseRanges(parser, msg.numberOfRequestedUnlocks, msg.typeOfLock & SMB.LARGE_FILES);
  msg.locks = parseRanges(parser, msg.numberOfRequestedLocks, msg.typeOfLock & SMB.LARGE_FILES);

  var tree = server.getTree(msg.header.tid);
  var fileName = tree && tree.getFile(msg.fid) && tree.getFile(msg.fid).getName() || null;

  logger.debug('[%s] fid: %d [fileName: %s], typeOfLock: %s, newOpLockLevel: %d, timeout: 0x%s, numberOfRequestedUnlocks: %d, numberOfRequestedLocks: %d', SMB.COMMAND_TO_STRING[commandId].toUpperCase(), msg.fid, fileName, msg.typeOfLock.toString(2), msg.newOpLockLevel, msg.timeout.toString(16), msg.numberOfRequestedUnlocks, msg.numberOfRequestedLocks);

  var result;

  if (!tree) {
    result = {
      status: ntstatus.STATUS_SMB_BAD_TID,
      params: utils.EMPTY_BUFFER,
      data: utils.EMPTY_BUFFER
    };
    process.nextTick(function () { cb(result); });
    return;
  }
  var file = tree.getFile(msg.fid);
  if (!file) {
    result = {
      status: ntstatus.STATUS_SMB_BAD_FID,
      params: utils.EMPTY_BUFFER,
      data: utils.EMPTY_BUFFER
    };
    process.nextTick(function () { cb(result); });
    return;
  }

  // todo implement locking

  // build result

  // params
  var out = put();
  out.word8(commandParams.readUInt8(0)) // andX next cmd id
    .word8(0) // andX reserved
    .word16le(commandParams.readUInt16LE(2));  // andX offset (needs to be recalculated by caller!)
  var params = out.buffer();

  // return result
  result = {
    status: ntstatus.STATUS_SUCCESS,
    params: params,
    data: utils.EMPTY_BUFFER
  };
  process.nextTick(function () { cb(result); });
}

function parseRanges(parser, count, largeFiles) {
  var result = [];
  while (count-- > 0) {
    if (largeFiles) {
      // 64bit offset & length
      result.push(parser.word16le('pid')
        .skip(2)
        .word32le('byteOffsetHigh')
        .word32le('byteOffsetLow')
        .word32le('lengthInBytesHigh')
        .word32le('lengthInBytesLow')
        .vars);
    } else {
      // 32bit offset & length
      result.push(parser.word16le('pid')
        .word32le('byteOffset')
        .word32le('lengthInBytes')
        .vars);
    }
  }
  return result;
}

module.exports = handle;