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

var assert = require('assert');

var Attribute = require('./attribute');
var Protocol = require('./protocol');



///--- API

function Change(options) {
  if (options) {
    if (typeof (options) !== 'object')
      throw new TypeError('options must be an object');
    if (options.operation && typeof (options.operation) !== 'string')
      throw new TypeError('options.operation must be a string');
  } else {
    options = {};
  }

  var self = this;
  this._modification = false;

  this.__defineGetter__('operation', function () {
    switch (self._operation) {
    case 0x00: return 'add';
    case 0x01: return 'delete';
    case 0x02: return 'replace';
    default:
      throw new Error('0x' + self._operation.toString(16) + ' is invalid');
    }
  });
  this.__defineSetter__('operation', function (val) {
    if (typeof (val) !== 'string')
      throw new TypeError('operation must be a string');

    switch (val.toLowerCase()) {
    case 'add':
      self._operation = 0x00;
      break;
    case 'delete':
      self._operation = 0x01;
      break;
    case 'replace':
      self._operation = 0x02;
      break;
    default:
      throw new Error('Invalid operation type: 0x' + val.toString(16));
    }
  });
  this.__defineGetter__('modification', function () {
    return self._modification;
  });

  this.__defineSetter__('modification', function (attr) {
    if (Attribute.isAttribute(attr)) {
      self._modification = attr;
      return;
    }
    var keys = Object.keys(attr);
    if (keys.length > 1)
      throw new Error('Only one attribute per Change allowed');

    keys.forEach(function (k) {
      var _attr = new Attribute({type: k});
      if (Array.isArray(attr[k])) {
        attr[k].forEach(function (v) {
          _attr.addValue(v.toString());
        });
      } else {
        _attr.addValue(attr[k].toString());
      }
      self._modification = _attr;
    });
  });
  this.__defineGetter__('json', function () {
    return {
      operation: self.operation,
      modification: self._modification ? self._modification.json : {}
    };
  });

  this.operation = options.operation || options.type || 'add';
  this.modification = options.modification || {};
}
module.exports = Change;

Change.isChange = function isChange(change) {
  if (!change || typeof (change) !== 'object') {
    return false;
  }
  if ((change instanceof Change) ||
      ((typeof (change.toBer) === 'function') &&
      (change.modification !== undefined) &&
      (change.operation !== undefined))) {
    return true;
  }
  return false;
};

Change.compare = function (a, b) {
  if (!Change.isChange(a) || !Change.isChange(b))
    throw new TypeError('can only compare Changes');

  if (a.operation < b.operation)
    return -1;
  if (a.operation > b.operation)
    return 1;

  return Attribute.compare(a.modification, b.modification);
};


Change.prototype.parse = function (ber) {
  assert.ok(ber);

  ber.readSequence();
  this._operation = ber.readEnumeration();
  this._modification = new Attribute();
  this._modification.parse(ber);

  return true;
};


Change.prototype.toBer = function (ber) {
  assert.ok(ber);

  ber.startSequence();
  ber.writeEnumeration(this._operation);
  ber = this._modification.toBer(ber);
  ber.endSequence();

  return ber;
};