/*!
 * Tmp
 *
 * Copyright (c) 2011-2015 KARASZI Istvan <github@spam.raszi.hu>
 *
 * MIT Licensed
 */

/**
 * Module dependencies.
 */
var
  fs     = require('fs'),
  path   = require('path'),
  os     = require('os'),
  crypto = require('crypto'),
  exists = fs.exists || path.exists,
  existsSync = fs.existsSync || path.existsSync,
  tmpDir = require('os-tmpdir'),
  _c     = require('constants');


/**
 * The working inner variables.
 */
var
  // store the actual TMP directory
  _TMP = tmpDir(),

  // the random characters to choose from
  RANDOM_CHARS = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz',

  TEMPLATE_PATTERN = /XXXXXX/,

  DEFAULT_TRIES = 3,

  CREATE_FLAGS = _c.O_CREAT | _c.O_EXCL | _c.O_RDWR,

  DIR_MODE = 448 /* 0700 */,
  FILE_MODE = 384 /* 0600 */,

  // this will hold the objects need to be removed on exit
  _removeObjects = [],

  _gracefulCleanup = false,
  _uncaughtException = false;

/**
 * Random name generator based on crypto.
 * Adapted from http://blog.tompawlak.org/how-to-generate-random-values-nodejs-javascript
 *
 * @param {Number} howMany
 * @return {String}
 * @api private
 */
function _randomChars(howMany) {
  var
    value = [],
    rnd = null;

  // make sure that we do not fail because we ran out of entropy
  try {
    rnd = crypto.randomBytes(howMany);
  } catch (e) {
    rnd = crypto.pseudoRandomBytes(howMany);
  }

  for (var i = 0; i < howMany; i++) {
    value.push(RANDOM_CHARS[rnd[i] % RANDOM_CHARS.length]);
  }

  return value.join('');
}

/**
 * Checks whether the `obj` parameter is defined or not.
 *
 * @param {Object} obj
 * @return {Boolean}
 * @api private
 */
function _isUndefined(obj) {
  return typeof obj === 'undefined';
}

/**
 * Parses the function arguments.
 *
 * This function helps to have optional arguments.
 *
 * @param {Object} options
 * @param {Function} callback
 * @api private
 */
function _parseArguments(options, callback) {
  if (typeof options == 'function') {
    var
      tmp = options;
      options = callback || {};
      callback = tmp;
  } else if (typeof options == 'undefined') {
    options = {};
  }

  return [options, callback];
}

/**
 * Generates a new temporary name.
 *
 * @param {Object} opts
 * @returns {String}
 * @api private
 */
function _generateTmpName(opts) {
  if (opts.name) {
    return path.join(opts.dir || _TMP, opts.name);
  }

  // mkstemps like template
  if (opts.template) {
    return opts.template.replace(TEMPLATE_PATTERN, _randomChars(6));
  }

  // prefix and postfix
  var name = [
    opts.prefix || 'tmp-',
    process.pid,
    _randomChars(12),
    opts.postfix || ''
  ].join('');

  return path.join(opts.dir || _TMP, name);
}

/**
 * Gets a temporary file name.
 *
 * @param {Object} options
 * @param {Function} callback
 * @api private
 */
function _getTmpName(options, callback) {
  var
    args = _parseArguments(options, callback),
    opts = args[0],
    cb = args[1],
    tries = opts.tries || DEFAULT_TRIES;

  if (isNaN(tries) || tries < 0)
    return cb(new Error('Invalid tries'));

  if (opts.template && !opts.template.match(TEMPLATE_PATTERN))
    return cb(new Error('Invalid template provided'));

  (function _getUniqueName() {
    var name = _generateTmpName(opts);

    // check whether the path exists then retry if needed
    exists(name, function _pathExists(pathExists) {
      if (pathExists) {
        if (tries-- > 0) return _getUniqueName();

        return cb(new Error('Could not get a unique tmp filename, max tries reached ' + name));
      }

      cb(null, name);
    });
  }());
}

/**
 * Synchronous version of _getTmpName.
 *
 * @param {Object} options
 * @returns {String}
 * @api private
 */
function _getTmpNameSync(options) {
  var
    args = _parseArguments(options),
    opts = args[0],
    tries = opts.tries || DEFAULT_TRIES;

  if (isNaN(tries) || tries < 0)
    throw new Error('Invalid tries');

  if (opts.template && !opts.template.match(TEMPLATE_PATTERN))
    throw new Error('Invalid template provided');

  do {
    var name = _generateTmpName(opts);
    if (!existsSync(name)) {
      return name;
    }
  } while (tries-- > 0);

  throw new Error('Could not get a unique tmp filename, max tries reached');
}

/**
 * Creates and opens a temporary file.
 *
 * @param {Object} options
 * @param {Function} callback
 * @api public
 */
function _createTmpFile(options, callback) {
  var
    args = _parseArguments(options, callback),
    opts = args[0],
    cb = args[1];

    opts.postfix = (_isUndefined(opts.postfix)) ? '.tmp' : opts.postfix;

  // gets a temporary filename
  _getTmpName(opts, function _tmpNameCreated(err, name) {
    if (err) return cb(err);

    // create and open the file
    fs.open(name, CREATE_FLAGS, opts.mode || FILE_MODE, function _fileCreated(err, fd) {
      if (err) return cb(err);

      cb(null, name, fd, _prepareTmpFileRemoveCallback(name, fd, opts));
    });
  });
}

/**
 * Synchronous version of _createTmpFile.
 *
 * @param {Object} options
 * @returns {Object} object consists of name, fd and removeCallback
 * @api private
 */
function _createTmpFileSync(options) {
  var
    args = _parseArguments(options),
    opts = args[0];

    opts.postfix = opts.postfix || '.tmp';

  var name = _getTmpNameSync(opts);
  var fd = fs.openSync(name, CREATE_FLAGS, opts.mode || FILE_MODE);

  return {
    name : name,
    fd : fd,
    removeCallback : _prepareTmpFileRemoveCallback(name, fd, opts)
  };
}

/**
 * Removes files and folders in a directory recursively.
 *
 * @param {String} root
 * @api private
 */
function _rmdirRecursiveSync(root) {
  var dirs = [root];

  do {
    var
      dir = dirs.pop(),
      deferred = false,
      files = fs.readdirSync(dir);

    for (var i = 0, length = files.length; i < length; i++) {
      var
        file = path.join(dir, files[i]),
        stat = fs.lstatSync(file); // lstat so we don't recurse into symlinked directories

      if (stat.isDirectory()) {
        if (!deferred) {
          deferred = true;
          dirs.push(dir);
        }  
        dirs.push(file);
      } else {
        fs.unlinkSync(file);
      }
    }

    if (!deferred) {
      fs.rmdirSync(dir);
    }
  } while (dirs.length !== 0);
}

/**
 * Creates a temporary directory.
 *
 * @param {Object} options
 * @param {Function} callback
 * @api public
 */
function _createTmpDir(options, callback) {
  var
    args = _parseArguments(options, callback),
    opts = args[0],
    cb = args[1];

  // gets a temporary filename
  _getTmpName(opts, function _tmpNameCreated(err, name) {
    if (err) return cb(err);

    // create the directory
    fs.mkdir(name, opts.mode || DIR_MODE, function _dirCreated(err) {
      if (err) return cb(err);

      cb(null, name, _prepareTmpDirRemoveCallback(name, opts));
    });
  });
}

/**
 * Synchronous version of _createTmpDir.
 *
 * @param {Object} options
 * @returns {Object} object consists of name and removeCallback
 * @api private
 */
function _createTmpDirSync(options) {
  var
    args = _parseArguments(options),
    opts = args[0];

  var name = _getTmpNameSync(opts);
  fs.mkdirSync(name, opts.mode || DIR_MODE);

  return {
    name : name,
    removeCallback : _prepareTmpDirRemoveCallback(name, opts)
  };
}

/**
 * Prepares the callback for removal of the temporary file.
 *
 * @param {String} name
 * @param {int} fd
 * @param {Object} opts
 * @api private
 * @returns {Function} the callback
 */
function _prepareTmpFileRemoveCallback(name, fd, opts) {
  var removeCallback = _prepareRemoveCallback(function _removeCallback(fdPath) {
    try {
      fs.closeSync(fdPath[0]);
    }
    catch (e) {
      // under some node/windows related circumstances, a temporary file 
      // may have not be created as expected or the file was already closed
      // by the user, in which case we will simply ignore the error
      if (e.errno != -_c.EBADF && e.errno != -c.ENOENT) {
        // reraise any unanticipated error
        throw e;
      }
    }
    fs.unlinkSync(fdPath[1]);
  }, [fd, name]);

  if (!opts.keep) {
    _removeObjects.unshift(removeCallback);
  }

  return removeCallback;
}

/**
 * Prepares the callback for removal of the temporary directory.
 *
 * @param {String} name
 * @param {Object} opts
 * @returns {Function} the callback
 * @api private
 */
function _prepareTmpDirRemoveCallback(name, opts) {
  var removeFunction = opts.unsafeCleanup ? _rmdirRecursiveSync : fs.rmdirSync.bind(fs);
  var removeCallback = _prepareRemoveCallback(removeFunction, name);

  if (!opts.keep) {
    _removeObjects.unshift(removeCallback);
  }

  return removeCallback;
}

/**
 * Creates a guarded function wrapping the removeFunction call.
 *
 * @param {Function} removeFunction
 * @param {Object} arg
 * @returns {Function}
 * @api private
 */
function _prepareRemoveCallback(removeFunction, arg) {
  var called = false;

  return function _cleanupCallback() {
    if (called) return;

    var index = _removeObjects.indexOf(removeFunction);
    if (index >= 0) {
      _removeObjects.splice(index, 1);
    }

    called = true;
    removeFunction(arg);
  };
}

/**
 * The garbage collector.
 *
 * @api private
 */
function _garbageCollector() {
  if (_uncaughtException && !_gracefulCleanup) {
    return;
  }

  for (var i = 0, length = _removeObjects.length; i < length; i++) {
    try {
      _removeObjects[i].call(null);
    } catch (e) {
      // already removed?
    }
  }
}

function _setGracefulCleanup() {
  _gracefulCleanup = true;
}

var version = process.versions.node.split('.').map(function (value) {
  return parseInt(value, 10);
});

if (version[0] === 0 && (version[1] < 9 || version[1] === 9 && version[2] < 5)) {
  process.addListener('uncaughtException', function _uncaughtExceptionThrown(err) {
    _uncaughtException = true;
    _garbageCollector();

    throw err;
  });
}

process.addListener('exit', function _exit(code) {
  if (code) _uncaughtException = true;
  _garbageCollector();
});

// exporting all the needed methods
module.exports.tmpdir = _TMP;
module.exports.dir = _createTmpDir;
module.exports.dirSync = _createTmpDirSync;
module.exports.file = _createTmpFile;
module.exports.fileSync = _createTmpFileSync;
module.exports.tmpName = _getTmpName;
module.exports.tmpNameSync = _getTmpNameSync;
module.exports.setGracefulCleanup = _setGracefulCleanup;
