var Backbone = require('backbone');
var _ = require('underscore');
var Utils = require('builder/helpers/utils');
var UserModel = require('./user-model');
var OrganizationModel = require('./organization-model');
var GroupModel = require('./group-model');
var ACLItemModel = require('./acl-item-model');
var READ_ONLY = 'r';
var READ_WRITE = 'rw';

/**
 * manages a cartodb permission object, it contains:
 * - owner: an UserModel instance
 * - acl: a collection which includes the user and their permission.
 *
 *   see https://github.com/Vizzuality/cartodb-management/wiki/multiuser-REST-API#permissions-object
 *
 *   this object is not created to work alone, it should be a member of
 *   an object like visualization table
 *
 */
var PermissionModel = module.exports = Backbone.Model.extend({
  urlRoot: function () {
    var baseUrl = this._configModel.get('base_url');
    var version = this._configModel.urlVersion('perm');
    return baseUrl + '/api/' + version + '/perm';
  },

  initialize: function (attrs, opts) {
    if (!opts.configModel) throw new Error('configModel is required');

    this._configModel = opts.configModel;
    this.acl = new Backbone.Collection();
    this.owner = opts._userModel;
    this._generateOwner();
    this._generateAcl();
    this._initBinds();
  },

  _initBinds: function () {
    this.bind('change:owner', this._generateOwner, this);
    this.bind('change:acl', this._generateAcl, this);
  },

  _generateOwner: function () {
    if (!this.owner) {
      this.owner = new UserModel(null, {
        configModel: this._configModel
      });
    }
    this.owner.set(this.get('owner'));
  },

  getOwner: function () {
    return this.owner;
  },

  _generateAcl: function () {
    var self = this;
    this.acl.reset([], { silent: true });
    _.each(this.get('acl'), function (aclItem) {
      var model;
      switch (aclItem.type) {
        case 'user':
          model = new UserModel(aclItem.entity, {
            configModel: self._configModel
          });
          break;
        case 'org':
          model = new OrganizationModel(aclItem.entity, {
            configModel: self._configModel
          });
          break;
        case 'group':
          model = new GroupModel(aclItem.entity, {
            configModel: self._configModel
          });
          break;
        default:
          throw new Error('Unknown ACL item type: ' + aclItem.type);
      }
      this._grantAccess(model, aclItem.access);
    }, this);
  },

  cleanPermissions: function () {
    this.acl.reset();
  },

  hasAccess: function (model) {
    // Having at least read access is the same as having any access
    return this.hasReadAccess(model);
  },

  hasReadAccess: function (model) {
    // If there is a representable ACL item it must be one of at least READ_ONLY access
    return !!this.findRepresentableAclItem(model);
  },

  hasWriteAccess: function (model) {
    var access = Utils.result(this.findRepresentableAclItem(model), 'get', 'access');
    return access === READ_WRITE;
  },

  canChangeReadAccess: function (model) {
    return this._canChangeAccess(model);
  },

  canChangeWriteAccess: function (model) {
    return (!model.isBuilder || model.isBuilder()) && this._canChangeAccess(model, function (representableAclItem) {
      return Utils.result(representableAclItem, 'get', 'access') !== READ_WRITE;
    });
  },

  _canChangeAccess: function (model) {
    var representableAclItem = this.findRepresentableAclItem(model);
    return this.isOwner(model) || !representableAclItem ||
    representableAclItem === this._ownAclItem(model) || Utils.result(arguments, 1, representableAclItem) || false;
  },

  grantWriteAccess: function (model) {
    this._grantAccess(model, READ_WRITE);
  },

  grantReadAccess: function (model) {
    this._grantAccess(model, READ_ONLY);
  },

  revokeWriteAccess: function (model) {
    // Effectively "downgrades" to READ_ONLY
    this.grantReadAccess(model);
  },

  /**
   * Revokes access to a set of items
   * @param {Object} model A single model or an array of models
   */
  revokeAccess: function (model) {
    var aclItem = this._ownAclItem(model);
    if (aclItem) {
      this.acl.remove(aclItem);
    }
  },

  isOwner: function (model) {
    return _.result(this.owner, 'id') === _.result(model, 'id');
  },

  toJSON: function () {
    return {
      entity: this.get('entity'),
      acl: this.acl.toJSON()
    };
  },

  getUsersWithAnyPermission: function () {
    return this.acl.chain()
      .filter(this._hasTypeUser)
      .map(this._getEntity)
      .value();
  },

  isSharedWithOrganization: function () {
    return this.acl.any(this._hasTypeOrg);
  },

  clone: function () {
    var attrs = _.clone(this.attributes);
    delete attrs.id;
    return new PermissionModel(attrs, {
      configModel: this._configModel
    });
  },

  /**
   * Overwrite this ACL list from other permission object
   * @param otherPermission {Object} instance of PermissionModel
   */
  overwriteAcl: function (otherPermission) {
    this.acl.reset(otherPermission.acl.models);
  },

  // Note that this may return an inherited ACL item
  // use ._ownAclItem instead if only model's own is wanted (if there is any)
  findRepresentableAclItem: function (model) {
    if (this.isOwner(model)) {
      return this._newAclItem(model, READ_WRITE);
    } else {
      var checkList = ['_ownAclItem', '_organizationAclItem', '_mostPrivilegedGroupAclItem'];

      return this._findMostPrivilegedAclItem(checkList, function (fnName) {
        return this[fnName](model);
      });
    }
  },

  _hasTypeUser: function (m) {
    return m.get('type') === 'user';
  },

  _getEntity: function (m) {
    return m.get('entity');
  },

  _hasTypeOrg: function (m) {
    return m.get('type') === 'org';
  },

  _isOrganization: function (object) {
    return object instanceof OrganizationModel;
  },

  _ownAclItem: function (model) {
    if (!model || !_.isFunction(model.isNew)) {
      console.log('model is required to find an ACL item');
    }

    if (!model.isNew()) {
      return this.acl.find(function (aclItem) {
        return aclItem.get('entity').id === model.id;
      });
    }
  },

  _organizationAclItem: function (m) {
    // try to get the organization from the user groups collection,
    // then from the user model (Editor),
    // and finally from the user model (Builder)
    var org = _.result(m.collection, 'organization') || m.organization || m._organizationModel;

    if (org) {
      return this._ownAclItem(org);
    }
  },

  _mostPrivilegedGroupAclItem: function (m) {
    var groups = _.result(m.groups, 'models');

    if (groups) {
      return this._findMostPrivilegedAclItem(groups, this._ownAclItem);
    }
  },

  /**
   * Iterates over a items in given list using the iteratee, stops and returns when found the ACL item with best access (i.e. READ_WRITE), or the
   * list is completed.
   * @param {Array} list
   * @param {Function} iteratee that takes an item from list and returns an access
   *   iteratee is called in context of this model.
   * @Return {String} 'r', 'rw', or undefined if there were no access for given item
   */
  _findMostPrivilegedAclItem: function (list, iteratee) {
    var aclItem;
    for (var i = 0, x = list[i]; x && Utils.result(aclItem, 'get', 'access') !== READ_WRITE; x = list[++i]) {
      // Keep last ACL item if iteratee returns nothing
      aclItem = iteratee.call(this, x) || aclItem;
    }
    return aclItem;
  },

  /**
   * Grants access to a set of items
   * @param {Object} model
   * @param {String} access can take the following values:
   * - 'r': read only
   * - 'rw': read and write permission
   */
  _grantAccess: function (model, access) {
    var aclItem = this._ownAclItem(model);
    if (aclItem) {
      aclItem.set('access', access);
    } else {
      aclItem = this._newAclItem(model, access);
      if (aclItem.isValid()) {
        this.acl.add(aclItem);
      } else {
        throw new Error(access + ' is not a valid ACL access');
      }
    }
  },

  _newAclItem: function (model, access) {
    var type;
    if (model instanceof UserModel) {
      type = 'user';
    } else if (model instanceof GroupModel) {
      type = 'group';
    } else if (this._isOrganization(model)) {
      type = 'org';
    } else {
      throw new Error('model not recognized as a valid ACL entity ' + model);
    }

    return new ACLItemModel({
      type: type,
      entity: model,
      access: access
    });
  }
});

exports.READ_ONLY = READ_ONLY;
exports.READ_WRITE = READ_WRITE;