// Copyright 2011 Mark Cavage, Inc.  All rights reserved.

var assert = require('assert');
var EventEmitter = require('events').EventEmitter;
var net = require('net');
var tls = require('tls');
var util = require('util');

var asn1 = require('asn1');
var sprintf = require('sprintf').sprintf;

var dn = require('./dn');
var errors = require('./errors');
var Protocol = require('./protocol');
var logStub = require('./log_stub');

var Parser = require('./messages').Parser;
var AddResponse = require('./messages/add_response');
var BindResponse = require('./messages/bind_response');
var CompareResponse = require('./messages/compare_response');
var DeleteResponse = require('./messages/del_response');
var ExtendedResponse = require('./messages/ext_response');
var ModifyResponse = require('./messages/modify_response');
var ModifyDNResponse = require('./messages/moddn_response');
var SearchResponse = require('./messages/search_response');
var UnbindResponse = require('./messages/unbind_response');



///--- Globals

var Ber = asn1.Ber;
var BerReader = asn1.BerReader;



///--- Helpers

function mergeFunctionArgs(argv, start, end) {
  assert.ok(argv);

  if (!start)
    start = 0;
  if (!end)
    end = argv.length;

  var handlers = [];

  for (var i = start; i < end; i++) {
    if (argv[i] instanceof Array) {
      var arr = argv[i];
      for (var j = 0; j < arr.length; j++) {
        if (!(arr[j] instanceof Function)) {
          throw new TypeError('Invalid argument type: ' + typeof(arr[j]));
        }
        handlers.push(arr[j]);
      }
    } else if (argv[i] instanceof Function) {
      handlers.push(argv[i]);
    } else {
      throw new TypeError('Invalid argument type: ' + typeof(argv[i]));
    }
  }

  return handlers;
}


function getResponse(req) {
  assert.ok(req);

  var Response;

  switch (req.protocolOp) {
  case Protocol.LDAP_REQ_BIND:
    Response = BindResponse;
    break;
  case Protocol.LDAP_REQ_ABANDON:
    return; // Noop
  case Protocol.LDAP_REQ_ADD:
    Response = AddResponse;
    break;
  case Protocol.LDAP_REQ_COMPARE:
    Response = CompareResponse;
    break;
  case Protocol.LDAP_REQ_DELETE:
    Response = DeleteResponse;
    break;
  case Protocol.LDAP_REQ_EXTENSION:
    Response = ExtendedResponse;
    break;
  case Protocol.LDAP_REQ_MODIFY:
    Response = ModifyResponse;
    break;
  case Protocol.LDAP_REQ_MODRDN:
    Response = ModifyDNResponse;
    break;
  case Protocol.LDAP_REQ_SEARCH:
    Response = SearchResponse;
    break;
  case Protocol.LDAP_REQ_UNBIND:
    Response = UnbindResponse;
    break;
  default:
    return null;
  }
  assert.ok(Response);

  var res = new Response({
    messageID: req.messageID,
    log4js: req.log4js
  });
  res.connection = req.connection;
  res.logId = req.logId;

  return res;
}


function defaultHandler(req, res, next) {
  assert.ok(req);
  assert.ok(res);
  assert.ok(next);

  res.matchedDN = req.dn.toString();
  res.errorMessage = 'Server method not implemented';
  res.end(errors.LDAP_OTHER);
  return next();
}


function defaultUnbindHandler(req, res, next) {
  assert.ok(req);
  assert.ok(res);
  assert.ok(next);

  res.end();
  return next();
}


function noSuffixHandler(req, res, next) {
  assert.ok(req);
  assert.ok(res);
  assert.ok(next);

  res.errorMessage = 'No tree found for: ' + req.dn.toString();
  res.end(errors.LDAP_NO_SUCH_OBJECT);
  return next();
}


function noExOpHandler(req, res, next) {
  assert.ok(req);
  assert.ok(res);
  assert.ok(next);

  res.errorMessage = req.requestName + ' not supported';
  res.end(errors.LDAP_PROTOCOL_ERROR);
  return next();
}



///--- API

/**
 * Constructs a new server that you can call .listen() on, in the various
 * forms node supports.  You need to first assign some handlers to the various
 * LDAP operations however.
 *
 * The options object currently only takes a certificate/private key, and a
 * log4js handle.
 *
 * This object exposes the following events:
 *  - 'error'
 *  - 'close'
 *
 * @param {Object} options (optional) parameterization object.
 * @throws {TypeError} on bad input.
 */
function Server(options) {
  if (options) {
    if (typeof(options) !== 'object')
      throw new TypeError('options (object) required');
    if (options.log4js && typeof(options.log4js) !== 'object')
      throw new TypeError('options.log4s must be an object');

    if (options.certificate || options.key) {
      if (!(options.certificate && options.key) ||
          typeof(options.certificate) !== 'string' ||
          typeof(options.key) !== 'string') {
        throw new TypeError('options.certificate and options.key (string) ' +
                            'are both required for TLS');
      }
    }
  } else {
    options = {};
  }
  var self = this;
  if (!options.log4js)
    options.log4js = logStub;

  EventEmitter.call(this, options);

  var log = this.log = options.log4js.getLogger('LDAPServer');

  function setupConnection(c) {
    assert.ok(c);

    c.ldap = {
      id: c.remoteAddress + ':' + c.remotePort,
      config: options
    };
    c.addListener('timeout', function() {
      log.trace('%s timed out', c.ldap.id);
      c.destroy();
    });
    c.addListener('end', function() {
      log.trace('%s shutdown', c.ldap.id);
    });
    c.addListener('error', function(err) {
      log.warn('%s unexpected connection error', c.ldap.id, err);
      c.destroy();
    });
    c.addListener('close', function(had_err) {
      log.trace('%s close; had_err=%j', c.ldap.id, had_err);
      c.end();
    });
    return c;
  }

  function newConnection(c) {
    if (c.type === 'unix') {
      c.remoteAddress = self.server.path;
      c.remotePort = c.fd;
    }

    setupConnection(c);
    if (log.isTraceEnabled())
      log.trace('new connection from %s', c.ldap.id);

    c.parser = new Parser({
      log4js: options.log4js
    });
    c.parser.on('message', function(req) {
      req.connection = c;
      req.logId = c.remoteAddress + '::' + req.messageID;

      if (log.isDebugEnabled())
        log.debug('%s: message received: req=%j', c.ldap.id, req.json);

      var res = getResponse(req);
      if (!res) {
        log.warn('Unimplemented server method: %s', req.type);
        c.destroy();
        return;
      }

      var chain = self._getHandlerChain(req);

      var i = 0;
      return function(err) {
        if (err) {
          res.status = err.code || errors.LDAP_OPERATIONS_ERROR;
          res.matchedDN = err.dn ? err.dn.toString() : req.dn.toString();
          res.errorMessage = err.message || '';
          return res.end();
        }

        var next = arguments.callee;
        if (chain.handlers[i])
          return chain.handlers[i++].call(chain.backend, req, res, next);
      }();
    });

    c.parser.on('protocolError', function(err, messageID) {
      log.warn('%s sent invalid protocol message', c.ldap.id, err);
      c.destroy();
    });
    c.parser.on('error', function(err) {
      log.error('Exception happened parsing for %s: %s',
                c.ldap.id, err.stack);
      c.destroy();
    });
    c.on('data', function(data) {
      if (log.isTraceEnabled())
        log.trace('data on %s: %s', c.ldap.id, util.inspect(data));
      c.parser.write(data);
    });

  }; // end newConnection

  this.routes = {};
  if (options.certificate && options.key) {
    this.server = tls.createServer(options, newConnection);
  } else {
    this.server = net.createServer(newConnection);
  }
  this.server.log4js = options.log4js;
  this.server.ldap = {
    config: options
  };
  this.server.on('close', function() {
    self.emit('close');
  });
  this.server.on('error', function(err) {
    self.emit('error', err);
  });

  this.__defineGetter__('maxConnections', function() {
    return self.server.maxConnections;
  });
  this.__defineSetter__('maxConnections', function(val) {
    self.server.maxConnections = val;
  });
  this.__defineGetter__('connections', function() {
    return self.server.connections;
  });
}
util.inherits(Server, EventEmitter);
module.exports = Server;


/**
 * Adds a handler (chain) for the LDAP add method.
 *
 * Note that this is of the form f(name, [function]) where the second...N
 * arguments can all either be functions or arrays of functions.
 *
 * @param {String} name the DN to mount this handler chain at.
 * @return {Server} this so you can chain calls.
 * @throws {TypeError} on bad input
 */
Server.prototype.add = function(name) {
  if (!name || typeof(name) !== 'string')
    throw new TypeError('name (string) required');
  if (arguments.length < 2)
    throw new TypeError('name and at least one handler required');

  var route = this._getRoute(dn.parse(name));
  route['0x' + Protocol.LDAP_REQ_ADD.toString(16)] =
    mergeFunctionArgs(Array.prototype.slice.call(arguments, 1));

  return this;
};


/**
 * Adds a handler (chain) for the LDAP bind method.
 *
 * Note that this is of the form f(name, [function]) where the second...N
 * arguments can all either be functions or arrays of functions.
 *
 * @param {String} name the DN to mount this handler chain at.
 * @return {Server} this so you can chain calls.
 * @throws {TypeError} on bad input
 */
Server.prototype.bind = function(name) {
  if (!name || typeof(name) !== 'string')
    throw new TypeError('name (string) required');
  if (arguments.length < 2)
    throw new TypeError('name and at least one handler required');

  var route = this._getRoute(dn.parse(name));
  route['0x' + Protocol.LDAP_REQ_BIND.toString(16)] =
    mergeFunctionArgs(Array.prototype.slice.call(arguments, 1));

  return this;
};


/**
 * Adds a handler (chain) for the LDAP compare method.
 *
 * Note that this is of the form f(name, [function]) where the second...N
 * arguments can all either be functions or arrays of functions.
 *
 * @param {String} name the DN to mount this handler chain at.
 * @return {Server} this so you can chain calls.
 * @throws {TypeError} on bad input
 */
Server.prototype.compare = function(name) {
  if (!name || typeof(name) !== 'string')
    throw new TypeError('name (string) required');
  if (arguments.length < 2)
    throw new TypeError('name and at least one handler required');

  var route = this._getRoute(dn.parse(name));
  route['0x' + Protocol.LDAP_REQ_COMPARE.toString(16)] =
    mergeFunctionArgs(Array.prototype.slice.call(arguments, 1));

  return this;
};


/**
 * Adds a handler (chain) for the LDAP delete method.
 *
 * Note that this is of the form f(name, [function]) where the second...N
 * arguments can all either be functions or arrays of functions.
 *
 * @param {String} name the DN to mount this handler chain at.
 * @return {Server} this so you can chain calls.
 * @throws {TypeError} on bad input
 */
Server.prototype.del = function(name) {
  if (!name || typeof(name) !== 'string')
    throw new TypeError('name (string) required');
  if (arguments.length < 2)
    throw new TypeError('name and at least one handler required');

  var route = this._getRoute(dn.parse(name));
  route['0x' + Protocol.LDAP_REQ_DELETE.toString(16)] =
    mergeFunctionArgs(Array.prototype.slice.call(arguments, 1));

  return this;
};


/**
 * Adds a handler (chain) for the LDAP exop method.
 *
 * Note that this is of the form f(name, [function]) where the second...N
 * arguments can all either be functions or arrays of functions.
 *
 * @param {String} name OID to assign this handler chain to.
 * @return {Server} this so you can chain calls.
 * @throws {TypeError} on bad input.
 */
Server.prototype.exop = function(name) {
  if (!name || typeof(name) !== 'string')
    throw new TypeError('name (string) required');
  if (arguments.length < 2)
    throw new TypeError('name and at least one handler required');

  var route = this._getRoute(name, this.server);
  route['0x' + Protocol.LDAP_REQ_EXTENSION.toString(16)] =
    mergeFunctionArgs(Array.prototype.slice.call(arguments, 1));

  return this;
};


/**
 * Adds a handler (chain) for the LDAP modify method.
 *
 * Note that this is of the form f(name, [function]) where the second...N
 * arguments can all either be functions or arrays of functions.
 *
 * @param {String} name the DN to mount this handler chain at.
 * @return {Server} this so you can chain calls.
 * @throws {TypeError} on bad input
 */
Server.prototype.modify = function(name) {
  if (!name || typeof(name) !== 'string')
    throw new TypeError('name (string) required');
  if (arguments.length < 2)
    throw new TypeError('name and at least one handler required');

  var route = this._getRoute(dn.parse(name));
  route['0x' + Protocol.LDAP_REQ_MODIFY.toString(16)] =
    mergeFunctionArgs(Array.prototype.slice.call(arguments, 1));

  return this;
};


/**
 * Adds a handler (chain) for the LDAP modifyDN method.
 *
 * Note that this is of the form f(name, [function]) where the second...N
 * arguments can all either be functions or arrays of functions.
 *
 * @param {String} name the DN to mount this handler chain at.
 * @return {Server} this so you can chain calls.
 * @throws {TypeError} on bad input
 */
Server.prototype.modifyDN = function(name) {
  if (!name || typeof(name) !== 'string')
    throw new TypeError('name (string) required');
  if (arguments.length < 2)
    throw new TypeError('name and at least one handler required');

  var route = this._getRoute(dn.parse(name));
  route['0x' + Protocol.LDAP_REQ_MODRDN.toString(16)] =
    mergeFunctionArgs(Array.prototype.slice.call(arguments, 1));

  return this;
};


/**
 * Adds a handler (chain) for the LDAP search method.
 *
 * Note that this is of the form f(name, [function]) where the second...N
 * arguments can all either be functions or arrays of functions.
 *
 * @param {String} name the DN to mount this handler chain at.
 * @return {Server} this so you can chain calls.
 * @throws {TypeError} on bad input
 */
Server.prototype.search = function(name) {
  if (!name || typeof(name) !== 'string')
    throw new TypeError('name (string) required');
  if (arguments.length < 2)
    throw new TypeError('name and at least one handler required');

  var route = this._getRoute(dn.parse(name));
  route['0x' + Protocol.LDAP_REQ_SEARCH.toString(16)] =
    mergeFunctionArgs(Array.prototype.slice.call(arguments, 1));

  return this;
};


/**
 * Adds a handler (chain) for the LDAP unbind method.
 *
 * This method is different than the others and takes no mount point, as unbind
 * is a connection-wide operation, not constrianed to part of the DIT.
 *
 * @return {Server} this so you can chain calls.
 * @throws {TypeError} on bad input
 */
Server.prototype.unbind = function() {
  if (arguments.length < 1)
    throw new TypeError('at least one handler required');

  var route = this._getRoute('unbind');
  route['0x' + Protocol.LDAP_REQ_UNBIND.toString(16)] =
    mergeFunctionArgs(Array.prototype.slice.call(arguments, 0));

  return this;
};


/**
 * It's likely you'll write an entire backend for LDAP that does a series
 * of things, like check schema, support entries, write an audit trail, etc.
 * If such a plugin is "bundled", you can simply call `mount` with that plugin
 * and assign it a point in the DIT, to save you manually building up the
 * handler chains for all the ops.
 *
 * @param {String} name the point in the tree to mount at.
 * @param {Object} backend an LDAP Backend (See the docs).
 * @return {Server} this so you can chain.
 * @throws {TypeError} on bad input.
 */
Server.prototype.mount = function(name, backend) {
  if (!name || typeof(name) !== 'string')
    throw new TypeError('name (string) required');
  if (!backend || typeof(backend) !== 'object')
    throw new TypeError('backend (object) required');
  if (!backend.name || typeof(backend.name) !== 'string')
    throw new TypeError('backend is not a valid LDAP Backend');
  if (!backend.register || typeof(backend.register) !== 'function')
    throw new TypeError('backend is not a valid LDAP Backend');

  var _dn = dn.parse(name).toString();
  name = _dn.toString();

  var self = this;

  // This is slightly ghetto, but easier than repeating all the code here.
  var ops = ['add', 'bind', 'compare', 'del', 'modify', 'modifyDN', 'search'];
  ops.forEach(function(o) {
    self[o](name, backend.register(o));
  });

  // Overwrite the route table's backend with backend
  var route = this._getRoute(_dn);
  route.backend = backend;

  return this;
};


// All these just reexpose the requisite net.Server APIs
Server.prototype.listen = function(port, host, callback) {
  if (typeof(host) === 'function')
    callback = host;

  return this.server.listen(port, function() {
    if (typeof(callback) === 'function')
      return callback();
  });
};
Server.prototype.listenFD = function(fd) {
  return this.server.listenFD(fd);
};
Server.prototype.close = function() {
  return this.server.close();
};
Server.prototype.address = function() {
  return this.server.address();
};


Server.prototype._getRoute = function(_dn, backend) {
  assert.ok(dn);

  if (!backend)
    backend = this;

  var name;
  if (_dn instanceof dn.DN) {
    name = _dn.toString();
  } else {
    name = _dn;
  }

  if (!this.routes[name]) {
    this.routes[name] = {};
    this.routes[name].backend = backend;
    this.routes[name].dn = _dn;
  }

  return this.routes[name];
};


Server.prototype._getHandlerChain = function(req) {
  assert.ok(req);

  var op = '0x' + req.protocolOp.toString(16);

  var self = this;
  var routes = this.routes;
  for (var r in routes) {
    if (routes.hasOwnProperty(r)) {
      var route = routes[r];
      // Special cases are exops and unbinds, handle those first.
      if (req.protocolOp === Protocol.LDAP_REQ_EXTENSION) {
        if (r !== req.requestName)
          continue;

        return {
          backend: routes.backend,
          handlers: route[op] || [defaultExopHandler]
        };
      } else if (req.protocolOp === Protocol.LDAP_REQ_UNBIND) {
        return {
          backend: routes['unbind'].backend,
          handlers: routes['unbind'][op] || [defaultUnbindHandler]
        };
      }

      if (!route[op])
        continue;

      // Otherwise, match via DN rules
      assert.ok(req.dn);
      assert.ok(route.dn);
      if (r !== req.dn.toString() && (!route.dn.parentOf(req.dn)))
        continue;

      // We should be good to go.
      return {
        backend: route.backend,
        handlers: route[op] || [defaultHandler]
      };
    }
  }

  // We're here, so nothing matched.
  return {
    backend: self,
    handlers: [(req.protocolOp !== Protocol.LDAP_REQ_EXTENSION ?
                noSuffixHandler : noExOpHandler)]
  };
};