// @flow
// A database adapter that works with data exported from the hosted
// Parse database.

// @flow-disable-next
import { Parse }              from 'parse/node';
// @flow-disable-next
import _                      from 'lodash';
// @flow-disable-next
import intersect              from 'intersect';
// @flow-disable-next
import deepcopy               from 'deepcopy';
import logger                 from '../logger';
import * as SchemaController       from './SchemaController';
import { StorageAdapter }     from '../Adapters/Storage/StorageAdapter';
import type { QueryOptions,
  FullQueryOptions }          from '../Adapters/Storage/StorageAdapter';

function addWriteACL(query, acl) {
  const newQuery = _.cloneDeep(query);
  //Can't be any existing '_wperm' query, we don't allow client queries on that, no need to $and
  newQuery._wperm = { "$in" : [null, ...acl]};
  return newQuery;
}

function addReadACL(query, acl) {
  const newQuery = _.cloneDeep(query);
  //Can't be any existing '_rperm' query, we don't allow client queries on that, no need to $and
  newQuery._rperm = {"$in": [null, "*", ...acl]};
  return newQuery;
}

// Transforms a REST API formatted ACL object to our two-field mongo format.
const transformObjectACL = ({ ACL, ...result }) => {
  if (!ACL) {
    return result;
  }

  result._wperm = [];
  result._rperm = [];

  for (const entry in ACL) {
    if (ACL[entry].read) {
      result._rperm.push(entry);
    }
    if (ACL[entry].write) {
      result._wperm.push(entry);
    }
  }
  return result;
}

const specialQuerykeys = ['$and', '$or', '$nor', '_rperm', '_wperm', '_perishable_token', '_email_verify_token', '_email_verify_token_expires_at', '_account_lockout_expires_at', '_failed_login_count'];

const isSpecialQueryKey = key => {
  return specialQuerykeys.indexOf(key) >= 0;
}

const validateQuery = (query: any): void => {
  if (query.ACL) {
    throw new Parse.Error(Parse.Error.INVALID_QUERY, 'Cannot query on ACL.');
  }

  if (query.$or) {
    if (query.$or instanceof Array) {
      query.$or.forEach(validateQuery);

      /* In MongoDB, $or queries which are not alone at the top level of the
       * query can not make efficient use of indexes due to a long standing
       * bug known as SERVER-13732.
       *
       * This block restructures queries in which $or is not the sole top
       * level element by moving all other top-level predicates inside every
       * subdocument of the $or predicate, allowing MongoDB's query planner
       * to make full use of the most relevant indexes.
       *
       * EG:      {$or: [{a: 1}, {a: 2}], b: 2}
       * Becomes: {$or: [{a: 1, b: 2}, {a: 2, b: 2}]}
       *
       * The only exceptions are $near and $nearSphere operators, which are
       * constrained to only 1 operator per query. As a result, these ops
       * remain at the top level
       *
       * https://jira.mongodb.org/browse/SERVER-13732
       * https://github.com/parse-community/parse-server/issues/3767
       */
      Object.keys(query).forEach(key => {
        const noCollisions = !query.$or.some(subq => subq.hasOwnProperty(key))
        let hasNears = false
        if (query[key] != null && typeof query[key] == 'object') {
          hasNears = ('$near' in query[key] || '$nearSphere' in query[key])
        }
        if (key != '$or' && noCollisions && !hasNears) {
          query.$or.forEach(subquery => {
            subquery[key] = query[key];
          });
          delete query[key];
        }
      });
      query.$or.forEach(validateQuery);
    } else {
      throw new Parse.Error(Parse.Error.INVALID_QUERY, 'Bad $or format - use an array value.');
    }
  }

  if (query.$and) {
    if (query.$and instanceof Array) {
      query.$and.forEach(validateQuery);
    } else {
      throw new Parse.Error(Parse.Error.INVALID_QUERY, 'Bad $and format - use an array value.');
    }
  }

  if (query.$nor) {
    if (query.$nor instanceof Array && query.$nor.length > 0) {
      query.$nor.forEach(validateQuery);
    } else {
      throw new Parse.Error(Parse.Error.INVALID_QUERY, 'Bad $nor format - use an array of at least 1 value.');
    }
  }

  Object.keys(query).forEach(key => {
    if (query && query[key] && query[key].$regex) {
      if (typeof query[key].$options === 'string') {
        if (!query[key].$options.match(/^[imxs]+$/)) {
          throw new Parse.Error(Parse.Error.INVALID_QUERY, `Bad $options value for query: ${query[key].$options}`);
        }
      }
    }
    if (!isSpecialQueryKey(key) && !key.match(/^[a-zA-Z][a-zA-Z0-9_\.]*$/)) {
      throw new Parse.Error(Parse.Error.INVALID_KEY_NAME, `Invalid key name: ${key}`);
    }
  });
}

// Filters out any data that shouldn't be on this REST-formatted object.
const filterSensitiveData = (isMaster, aclGroup, className, object) => {
  if (className !== '_User') {
    return object;
  }

  object.password = object._hashed_password;
  delete object._hashed_password;

  delete object.sessionToken;

  if (isMaster) {
    return object;
  }
  delete object._email_verify_token;
  delete object._perishable_token;
  delete object._perishable_token_expires_at;
  delete object._tombstone;
  delete object._email_verify_token_expires_at;
  delete object._failed_login_count;
  delete object._account_lockout_expires_at;
  delete object._password_changed_at;
  delete object._password_history;

  if ((aclGroup.indexOf(object.objectId) > -1)) {
    return object;
  }
  delete object.authData;
  return object;
};

import type { LoadSchemaOptions } from './types';

// Runs an update on the database.
// Returns a promise for an object with the new values for field
// modifications that don't know their results ahead of time, like
// 'increment'.
// Options:
//   acl:  a list of strings. If the object to be updated has an ACL,
//         one of the provided strings must provide the caller with
//         write permissions.
const specialKeysForUpdate = ['_hashed_password', '_perishable_token', '_email_verify_token', '_email_verify_token_expires_at', '_account_lockout_expires_at', '_failed_login_count', '_perishable_token_expires_at', '_password_changed_at', '_password_history'];

const isSpecialUpdateKey = key => {
  return specialKeysForUpdate.indexOf(key) >= 0;
}

function expandResultOnKeyPath(object, key, value) {
  if (key.indexOf('.') < 0) {
    object[key] = value[key];
    return object;
  }
  const path = key.split('.');
  const firstKey = path[0];
  const nextPath = path.slice(1).join('.');
  object[firstKey] = expandResultOnKeyPath(object[firstKey] || {}, nextPath, value[firstKey]);
  delete object[key];
  return object;
}

function sanitizeDatabaseResult(originalObject, result): Promise<any> {
  const response = {};
  if (!result) {
    return Promise.resolve(response);
  }
  Object.keys(originalObject).forEach(key => {
    const keyUpdate = originalObject[key];
    // determine if that was an op
    if (keyUpdate && typeof keyUpdate === 'object' && keyUpdate.__op
      && ['Add', 'AddUnique', 'Remove', 'Increment'].indexOf(keyUpdate.__op) > -1) {
      // only valid ops that produce an actionable result
      // the op may have happend on a keypath
      expandResultOnKeyPath(response, key, result);
    }
  });
  return Promise.resolve(response);
}

function joinTableName(className, key) {
  return `_Join:${key}:${className}`;
}

const flattenUpdateOperatorsForCreate = object => {
  for (const key in object) {
    if (object[key] && object[key].__op) {
      switch (object[key].__op) {
      case 'Increment':
        if (typeof object[key].amount !== 'number') {
          throw new Parse.Error(Parse.Error.INVALID_JSON, 'objects to add must be an array');
        }
        object[key] = object[key].amount;
        break;
      case 'Add':
        if (!(object[key].objects instanceof Array)) {
          throw new Parse.Error(Parse.Error.INVALID_JSON, 'objects to add must be an array');
        }
        object[key] = object[key].objects;
        break;
      case 'AddUnique':
        if (!(object[key].objects instanceof Array)) {
          throw new Parse.Error(Parse.Error.INVALID_JSON, 'objects to add must be an array');
        }
        object[key] = object[key].objects;
        break;
      case 'Remove':
        if (!(object[key].objects instanceof Array)) {
          throw new Parse.Error(Parse.Error.INVALID_JSON, 'objects to add must be an array');
        }
        object[key] = []
        break;
      case 'Delete':
        delete object[key];
        break;
      default:
        throw new Parse.Error(Parse.Error.COMMAND_UNAVAILABLE, `The ${object[key].__op} operator is not supported yet.`);
      }
    }
  }
}

const transformAuthData = (className, object, schema) => {
  if (object.authData && className === '_User') {
    Object.keys(object.authData).forEach(provider => {
      const providerData = object.authData[provider];
      const fieldName = `_auth_data_${provider}`;
      if (providerData == null) {
        object[fieldName] = {
          __op: 'Delete'
        }
      } else {
        object[fieldName] = providerData;
        schema.fields[fieldName] = { type: 'Object' }
      }
    });
    delete object.authData;
  }
}
// Transforms a Database format ACL to a REST API format ACL
const untransformObjectACL = ({_rperm, _wperm, ...output}) => {
  if (_rperm || _wperm) {
    output.ACL = {};

    (_rperm || []).forEach(entry => {
      if (!output.ACL[entry]) {
        output.ACL[entry] = { read: true };
      } else {
        output.ACL[entry]['read'] = true;
      }
    });

    (_wperm || []).forEach(entry => {
      if (!output.ACL[entry]) {
        output.ACL[entry] = { write: true };
      } else {
        output.ACL[entry]['write'] = true;
      }
    });
  }
  return output;
}

/**
 * When querying, the fieldName may be compound, extract the root fieldName
 *     `temperature.celsius` becomes `temperature`
 * @param {string} fieldName that may be a compound field name
 * @returns {string} the root name of the field
 */
const getRootFieldName = (fieldName: string): string => {
  return fieldName.split('.')[0]
}

const relationSchema = { fields: { relatedId: { type: 'String' }, owningId: { type: 'String' } } };

class DatabaseController {
  adapter: StorageAdapter;
  schemaCache: any;
  schemaPromise: ?Promise<SchemaController.SchemaController>;

  constructor(adapter: StorageAdapter, schemaCache: any) {
    this.adapter = adapter;
    this.schemaCache = schemaCache;
    // We don't want a mutable this.schema, because then you could have
    // one request that uses different schemas for different parts of
    // it. Instead, use loadSchema to get a schema.
    this.schemaPromise = null;
  }

  collectionExists(className: string): Promise<boolean> {
    return this.adapter.classExists(className);
  }

  purgeCollection(className: string): Promise<void> {
    return this.loadSchema()
      .then(schemaController => schemaController.getOneSchema(className))
      .then(schema => this.adapter.deleteObjectsByQuery(className, schema, {}));
  }

  validateClassName(className: string): Promise<void> {
    if (!SchemaController.classNameIsValid(className)) {
      return Promise.reject(new Parse.Error(Parse.Error.INVALID_CLASS_NAME, 'invalid className: ' + className));
    }
    return Promise.resolve();
  }

  // Returns a promise for a schemaController.
  loadSchema(options: LoadSchemaOptions = {clearCache: false}): Promise<SchemaController.SchemaController> {
    if (this.schemaPromise != null) {
      return this.schemaPromise;
    }
    this.schemaPromise = SchemaController.load(this.adapter, this.schemaCache, options);
    this.schemaPromise.then(() => delete this.schemaPromise,
      () => delete this.schemaPromise);
    return this.loadSchema(options);
  }

  // Returns a promise for the classname that is related to the given
  // classname through the key.
  // TODO: make this not in the DatabaseController interface
  redirectClassNameForKey(className: string, key: string): Promise<?string> {
    return this.loadSchema().then((schema) => {
      var t  = schema.getExpectedType(className, key);
      if (t != null && typeof t !== 'string' && t.type === 'Relation') {
        return t.targetClass;
      }
      return className;
    });
  }

  // Uses the schema to validate the object (REST API format).
  // Returns a promise that resolves to the new schema.
  // This does not update this.schema, because in a situation like a
  // batch request, that could confuse other users of the schema.
  validateObject(className: string, object: any, query: any, { acl }: QueryOptions): Promise<boolean> {
    let schema;
    const isMaster = acl === undefined;
    var aclGroup: string[]  = acl || [];
    return this.loadSchema().then(s => {
      schema = s;
      if (isMaster) {
        return Promise.resolve();
      }
      return this.canAddField(schema, className, object, aclGroup);
    }).then(() => {
      return schema.validateObject(className, object, query);
    });
  }

  update(className: string, query: any, update: any, {
    acl,
    many,
    upsert,
  }: FullQueryOptions = {}, skipSanitization: boolean = false): Promise<any> {
    const originalQuery = query;
    const originalUpdate = update;
    // Make a copy of the object, so we don't mutate the incoming data.
    update = deepcopy(update);
    var relationUpdates = [];
    var isMaster = acl === undefined;
    var aclGroup = acl || [];
    return this.loadSchema()
      .then(schemaController => {
        return (isMaster ? Promise.resolve() : schemaController.validatePermission(className, aclGroup, 'update'))
          .then(() => {
            relationUpdates = this.collectRelationUpdates(className, originalQuery.objectId, update);
            if (!isMaster) {
              query = this.addPointerPermissions(schemaController, className, 'update', query, aclGroup);
            }
            if (!query) {
              return Promise.resolve();
            }
            if (acl) {
              query = addWriteACL(query, acl);
            }
            validateQuery(query);
            return schemaController.getOneSchema(className, true)
              .catch(error => {
                // If the schema doesn't exist, pretend it exists with no fields. This behavior
                // will likely need revisiting.
                if (error === undefined) {
                  return { fields: {} };
                }
                throw error;
              })
              .then(schema => {
                Object.keys(update).forEach(fieldName => {
                  if (fieldName.match(/^authData\.([a-zA-Z0-9_]+)\.id$/)) {
                    throw new Parse.Error(Parse.Error.INVALID_KEY_NAME, `Invalid field name for update: ${fieldName}`);
                  }
                  const rootFieldName = getRootFieldName(fieldName);
                  if (!SchemaController.fieldNameIsValid(rootFieldName) && !isSpecialUpdateKey(rootFieldName)) {
                    throw new Parse.Error(Parse.Error.INVALID_KEY_NAME, `Invalid field name for update: ${fieldName}`);
                  }
                });
                for (const updateOperation: any in update) {
                  if (Object.keys(updateOperation).some(innerKey => innerKey.includes('$') || innerKey.includes('.'))) {
                    throw new Parse.Error(Parse.Error.INVALID_NESTED_KEY, "Nested keys should not contain the '$' or '.' characters");
                  }
                }
                update = transformObjectACL(update);
                transformAuthData(className, update, schema);
                if (many) {
                  return this.adapter.updateObjectsByQuery(className, schema, query, update);
                } else if (upsert) {
                  return this.adapter.upsertOneObject(className, schema, query, update);
                } else {
                  return this.adapter.findOneAndUpdate(className, schema, query, update)
                }
              });
          })
          .then((result: any) => {
            if (!result) {
              throw new Parse.Error(Parse.Error.OBJECT_NOT_FOUND, 'Object not found.');
            }
            return this.handleRelationUpdates(className, originalQuery.objectId, update, relationUpdates).then(() => {
              return result;
            });
          }).then((result) => {
            if (skipSanitization) {
              return Promise.resolve(result);
            }
            return sanitizeDatabaseResult(originalUpdate, result);
          });
      });
  }

  // Collect all relation-updating operations from a REST-format update.
  // Returns a list of all relation updates to perform
  // This mutates update.
  collectRelationUpdates(className: string, objectId: ?string, update: any) {
    var ops = [];
    var deleteMe = [];
    objectId = update.objectId || objectId;

    var process = (op, key) => {
      if (!op) {
        return;
      }
      if (op.__op == 'AddRelation') {
        ops.push({key, op});
        deleteMe.push(key);
      }

      if (op.__op == 'RemoveRelation') {
        ops.push({key, op});
        deleteMe.push(key);
      }

      if (op.__op == 'Batch') {
        for (var x of op.ops) {
          process(x, key);
        }
      }
    };

    for (const key in update) {
      process(update[key], key);
    }
    for (const key of deleteMe) {
      delete update[key];
    }
    return ops;
  }

  // Processes relation-updating operations from a REST-format update.
  // Returns a promise that resolves when all updates have been performed
  handleRelationUpdates(className: string, objectId: string, update: any, ops: any) {
    var pending = [];
    objectId = update.objectId || objectId;
    ops.forEach(({key, op}) => {
      if (!op) {
        return;
      }
      if (op.__op == 'AddRelation') {
        for (const object of op.objects) {
          pending.push(this.addRelation(key, className,
            objectId,
            object.objectId));
        }
      }

      if (op.__op == 'RemoveRelation') {
        for (const object of op.objects) {
          pending.push(this.removeRelation(key, className,
            objectId,
            object.objectId));
        }
      }
    });

    return Promise.all(pending);
  }

  // Adds a relation.
  // Returns a promise that resolves successfully iff the add was successful.
  addRelation(key: string, fromClassName: string, fromId: string, toId: string) {
    const doc = {
      relatedId: toId,
      owningId: fromId
    };
    return this.adapter.upsertOneObject(`_Join:${key}:${fromClassName}`, relationSchema, doc, doc);
  }

  // Removes a relation.
  // Returns a promise that resolves successfully iff the remove was
  // successful.
  removeRelation(key: string, fromClassName: string, fromId: string, toId: string) {
    var doc = {
      relatedId: toId,
      owningId: fromId
    };
    return this.adapter.deleteObjectsByQuery(`_Join:${key}:${fromClassName}`, relationSchema, doc)
      .catch(error => {
        // We don't care if they try to delete a non-existent relation.
        if (error.code == Parse.Error.OBJECT_NOT_FOUND) {
          return;
        }
        throw error;
      });
  }

  // Removes objects matches this query from the database.
  // Returns a promise that resolves successfully iff the object was
  // deleted.
  // Options:
  //   acl:  a list of strings. If the object to be updated has an ACL,
  //         one of the provided strings must provide the caller with
  //         write permissions.
  destroy(className: string, query: any, { acl }: QueryOptions = {}): Promise<any> {
    const isMaster = acl === undefined;
    const aclGroup = acl || [];

    return this.loadSchema()
      .then(schemaController => {
        return (isMaster ? Promise.resolve() : schemaController.validatePermission(className, aclGroup, 'delete'))
          .then(() => {
            if (!isMaster) {
              query = this.addPointerPermissions(schemaController, className, 'delete', query, aclGroup);
              if (!query) {
                throw new Parse.Error(Parse.Error.OBJECT_NOT_FOUND, 'Object not found.');
              }
            }
            // delete by query
            if (acl) {
              query = addWriteACL(query, acl);
            }
            validateQuery(query);
            return schemaController.getOneSchema(className)
              .catch(error => {
              // If the schema doesn't exist, pretend it exists with no fields. This behavior
              // will likely need revisiting.
                if (error === undefined) {
                  return { fields: {} };
                }
                throw error;
              })
              .then(parseFormatSchema => this.adapter.deleteObjectsByQuery(className, parseFormatSchema, query))
              .catch(error => {
              // When deleting sessions while changing passwords, don't throw an error if they don't have any sessions.
                if (className === "_Session" && error.code === Parse.Error.OBJECT_NOT_FOUND) {
                  return Promise.resolve({});
                }
                throw error;
              });
          });
      });
  }

  // Inserts an object into the database.
  // Returns a promise that resolves successfully iff the object saved.
  create(className: string, object: any, { acl }: QueryOptions = {}): Promise<any> {
  // Make a copy of the object, so we don't mutate the incoming data.
    const originalObject = object;
    object = transformObjectACL(object);

    object.createdAt = { iso: object.createdAt, __type: 'Date' };
    object.updatedAt = { iso: object.updatedAt, __type: 'Date' };

    var isMaster = acl === undefined;
    var aclGroup = acl || [];
    const relationUpdates = this.collectRelationUpdates(className, null, object);
    return this.validateClassName(className)
      .then(() => this.loadSchema())
      .then(schemaController => {
        return (isMaster ? Promise.resolve() : schemaController.validatePermission(className, aclGroup, 'create'))
          .then(() => schemaController.enforceClassExists(className))
          .then(() => schemaController.reloadData())
          .then(() => schemaController.getOneSchema(className, true))
          .then(schema => {
            transformAuthData(className, object, schema);
            flattenUpdateOperatorsForCreate(object);
            return this.adapter.createObject(className, SchemaController.convertSchemaToAdapterSchema(schema), object);
          })
          .then(result => {
            return this.handleRelationUpdates(className, object.objectId, object, relationUpdates).then(() => {
              return sanitizeDatabaseResult(originalObject, result.ops[0])
            });
          });
      })
  }

  canAddField(schema: SchemaController.SchemaController, className: string, object: any, aclGroup: string[]): Promise<void> {
    const classSchema = schema.data[className];
    if (!classSchema) {
      return Promise.resolve();
    }
    const fields = Object.keys(object);
    const schemaFields = Object.keys(classSchema);
    const newKeys = fields.filter((field) => {
      // Skip fields that are unset
      if (object[field] && object[field].__op && object[field].__op === 'Delete') {
        return false;
      }
      return schemaFields.indexOf(field) < 0;
    });
    if (newKeys.length > 0) {
      return schema.validatePermission(className, aclGroup, 'addField');
    }
    return Promise.resolve();
  }

  // Won't delete collections in the system namespace
  // Returns a promise.
  deleteEverything() {
    this.schemaPromise = null;
    return Promise.all([
      this.adapter.deleteAllClasses(),
      this.schemaCache.clear()
    ]);
  }


  // Returns a promise for a list of related ids given an owning id.
  // className here is the owning className.
  relatedIds(className: string, key: string, owningId: string, queryOptions: QueryOptions): Promise<Array<string>> {
    const { skip, limit, sort } = queryOptions;
    const findOptions = {};
    if (sort && sort.createdAt && this.adapter.canSortOnJoinTables) {
      findOptions.sort = { '_id' : sort.createdAt };
      findOptions.limit = limit;
      findOptions.skip = skip;
      queryOptions.skip = 0;
    }
    return this.adapter.find(joinTableName(className, key), relationSchema, { owningId }, findOptions)
      .then(results => results.map(result => result.relatedId));
  }

  // Returns a promise for a list of owning ids given some related ids.
  // className here is the owning className.
  owningIds(className: string, key: string, relatedIds: string[]): Promise<string[]> {
    return this.adapter.find(joinTableName(className, key), relationSchema, { relatedId: { '$in': relatedIds } }, {})
      .then(results => results.map(result => result.owningId));
  }

  // Modifies query so that it no longer has $in on relation fields, or
  // equal-to-pointer constraints on relation fields.
  // Returns a promise that resolves when query is mutated
  reduceInRelation(className: string, query: any, schema: any): Promise<any> {
  // Search for an in-relation or equal-to-relation
  // Make it sequential for now, not sure of paralleization side effects
    if (query['$or']) {
      const ors = query['$or'];
      return Promise.all(ors.map((aQuery, index) => {
        return this.reduceInRelation(className, aQuery, schema).then((aQuery) => {
          query['$or'][index] = aQuery;
        });
      })).then(() => {
        return Promise.resolve(query);
      });
    }

    const promises = Object.keys(query).map((key) => {
      const t = schema.getExpectedType(className, key);
      if (!t || t.type !== 'Relation') {
        return Promise.resolve(query);
      }
      let queries: ?any[] = null;
      if (query[key] && (query[key]['$in'] || query[key]['$ne'] || query[key]['$nin'] || query[key].__type == 'Pointer')) {
      // Build the list of queries
        queries = Object.keys(query[key]).map((constraintKey) => {
          let relatedIds;
          let isNegation = false;
          if (constraintKey === 'objectId') {
            relatedIds = [query[key].objectId];
          } else if (constraintKey == '$in') {
            relatedIds = query[key]['$in'].map(r => r.objectId);
          } else if (constraintKey == '$nin') {
            isNegation = true;
            relatedIds = query[key]['$nin'].map(r => r.objectId);
          } else if (constraintKey == '$ne') {
            isNegation = true;
            relatedIds = [query[key]['$ne'].objectId];
          } else {
            return;
          }
          return {
            isNegation,
            relatedIds
          }
        });
      } else {
        queries = [{isNegation: false, relatedIds: []}];
      }

      // remove the current queryKey as we don,t need it anymore
      delete query[key];
      // execute each query independently to build the list of
      // $in / $nin
      const promises = queries.map((q) => {
        if (!q) {
          return Promise.resolve();
        }
        return this.owningIds(className, key, q.relatedIds).then((ids) => {
          if (q.isNegation) {
            this.addNotInObjectIdsIds(ids, query);
          } else {
            this.addInObjectIdsIds(ids, query);
          }
          return Promise.resolve();
        });
      });

      return Promise.all(promises).then(() => {
        return Promise.resolve();
      })

    })

    return Promise.all(promises).then(() => {
      return Promise.resolve(query);
    })
  }

  // Modifies query so that it no longer has $relatedTo
  // Returns a promise that resolves when query is mutated
  reduceRelationKeys(className: string, query: any, queryOptions: any): ?Promise<void> {

    if (query['$or']) {
      return Promise.all(query['$or'].map((aQuery) => {
        return this.reduceRelationKeys(className, aQuery, queryOptions);
      }));
    }

    var relatedTo = query['$relatedTo'];
    if (relatedTo) {
      return this.relatedIds(
        relatedTo.object.className,
        relatedTo.key,
        relatedTo.object.objectId,
        queryOptions)
        .then((ids) => {
          delete query['$relatedTo'];
          this.addInObjectIdsIds(ids, query);
          return this.reduceRelationKeys(className, query, queryOptions);
        }).then(() => {});
    }
  }

  addInObjectIdsIds(ids: ?Array<string> = null, query: any) {
    const idsFromString: ?Array<string> = typeof query.objectId === 'string' ? [query.objectId] : null;
    const idsFromEq: ?Array<string> = query.objectId && query.objectId['$eq'] ? [query.objectId['$eq']] : null;
    const idsFromIn: ?Array<string> = query.objectId && query.objectId['$in'] ? query.objectId['$in'] : null;

    // @flow-disable-next
    const allIds: Array<Array<string>> = [idsFromString, idsFromEq, idsFromIn, ids].filter(list => list !== null);
    const totalLength = allIds.reduce((memo, list) => memo + list.length, 0);

    let idsIntersection = [];
    if (totalLength > 125) {
      idsIntersection = intersect.big(allIds);
    } else {
      idsIntersection = intersect(allIds);
    }

    // Need to make sure we don't clobber existing shorthand $eq constraints on objectId.
    if (!('objectId' in query)) {
      query.objectId = {
        $in: undefined,
      };
    } else if (typeof query.objectId === 'string') {
      query.objectId = {
        $in: undefined,
        $eq: query.objectId
      };
    }
    query.objectId['$in'] = idsIntersection;

    return query;
  }

  addNotInObjectIdsIds(ids: string[] = [], query: any) {
    const idsFromNin = query.objectId && query.objectId['$nin'] ? query.objectId['$nin'] : [];
    let allIds = [...idsFromNin,...ids].filter(list => list !== null);

    // make a set and spread to remove duplicates
    allIds = [...new Set(allIds)];

    // Need to make sure we don't clobber existing shorthand $eq constraints on objectId.
    if (!('objectId' in query)) {
      query.objectId = {
        $nin: undefined,
      };
    } else if (typeof query.objectId === 'string') {
      query.objectId = {
        $nin: undefined,
        $eq: query.objectId
      };
    }

    query.objectId['$nin'] = allIds;
    return query;
  }

  // Runs a query on the database.
  // Returns a promise that resolves to a list of items.
  // Options:
  //   skip    number of results to skip.
  //   limit   limit to this number of results.
  //   sort    an object where keys are the fields to sort by.
  //           the value is +1 for ascending, -1 for descending.
  //   count   run a count instead of returning results.
  //   acl     restrict this operation with an ACL for the provided array
  //           of user objectIds and roles. acl: null means no user.
  //           when this field is not present, don't do anything regarding ACLs.
  // TODO: make userIds not needed here. The db adapter shouldn't know
  // anything about users, ideally. Then, improve the format of the ACL
  // arg to work like the others.
  find(className: string, query: any, {
    skip,
    limit,
    acl,
    sort = {},
    count,
    keys,
    op,
    distinct,
    pipeline,
    readPreference,
    isWrite,
  }: any = {}): Promise<any> {
    const isMaster = acl === undefined;
    const aclGroup = acl || [];
    op = op || (typeof query.objectId == 'string' && Object.keys(query).length === 1 ? 'get' : 'find');
    // Count operation if counting
    op = (count === true ? 'count' : op);

    let classExists = true;
    return this.loadSchema()
      .then(schemaController => {
        //Allow volatile classes if querying with Master (for _PushStatus)
        //TODO: Move volatile classes concept into mongo adapter, postgres adapter shouldn't care
        //that api.parse.com breaks when _PushStatus exists in mongo.
        return schemaController.getOneSchema(className, isMaster)
          .catch(error => {
          // Behavior for non-existent classes is kinda weird on Parse.com. Probably doesn't matter too much.
          // For now, pretend the class exists but has no objects,
            if (error === undefined) {
              classExists = false;
              return { fields: {} };
            }
            throw error;
          })
          .then(schema => {
          // Parse.com treats queries on _created_at and _updated_at as if they were queries on createdAt and updatedAt,
          // so duplicate that behavior here. If both are specified, the correct behavior to match Parse.com is to
          // use the one that appears first in the sort list.
            if (sort._created_at) {
              sort.createdAt = sort._created_at;
              delete sort._created_at;
            }
            if (sort._updated_at) {
              sort.updatedAt = sort._updated_at;
              delete sort._updated_at;
            }
            const queryOptions = { skip, limit, sort, keys, readPreference };
            Object.keys(sort).forEach(fieldName => {
              if (fieldName.match(/^authData\.([a-zA-Z0-9_]+)\.id$/)) {
                throw new Parse.Error(Parse.Error.INVALID_KEY_NAME, `Cannot sort by ${fieldName}`);
              }
              const rootFieldName = getRootFieldName(fieldName);
              if (!SchemaController.fieldNameIsValid(rootFieldName)) {
                throw new Parse.Error(Parse.Error.INVALID_KEY_NAME, `Invalid field name: ${fieldName}.`);
              }
            });
            return (isMaster ? Promise.resolve() : schemaController.validatePermission(className, aclGroup, op))
              .then(() => this.reduceRelationKeys(className, query, queryOptions))
              .then(() => this.reduceInRelation(className, query, schemaController))
              .then(() => {
                if (!isMaster) {
                  query = this.addPointerPermissions(schemaController, className, op, query, aclGroup);
                }
                if (!query) {
                  if (op == 'get') {
                    throw new Parse.Error(Parse.Error.OBJECT_NOT_FOUND, 'Object not found.');
                  } else {
                    return [];
                  }
                }
                if (!isMaster) {
                  if (isWrite) {
                    query = addWriteACL(query, aclGroup);
                  } else {
                    query = addReadACL(query, aclGroup);
                  }
                }
                validateQuery(query);
                if (count) {
                  if (!classExists) {
                    return 0;
                  } else {
                    return this.adapter.count(className, schema, query, readPreference);
                  }
                }  else if (distinct) {
                  if (!classExists) {
                    return [];
                  } else {
                    return this.adapter.distinct(className, schema, query, distinct);
                  }
                }  else if (pipeline) {
                  if (!classExists) {
                    return [];
                  } else {
                    return this.adapter.aggregate(className, schema, pipeline, readPreference);
                  }
                } else {
                  return this.adapter.find(className, schema, query, queryOptions)
                    .then(objects => objects.map(object => {
                      object = untransformObjectACL(object);
                      return filterSensitiveData(isMaster, aclGroup, className, object)
                    })).catch((error) => {
                      throw new Parse.Error(Parse.Error.INTERNAL_SERVER_ERROR, error);
                    });
                }
              });
          });
      });
  }

  deleteSchema(className: string): Promise<void> {
    return this.loadSchema({ clearCache: true })
      .then(schemaController => schemaController.getOneSchema(className, true))
      .catch(error => {
        if (error === undefined) {
          return { fields: {} };
        } else {
          throw error;
        }
      })
      .then((schema: any) => {
        return this.collectionExists(className)
          .then(() => this.adapter.count(className, { fields: {} }))
          .then(count => {
            if (count > 0) {
              throw new Parse.Error(255, `Class ${className} is not empty, contains ${count} objects, cannot drop schema.`);
            }
            return this.adapter.deleteClass(className);
          })
          .then(wasParseCollection => {
            if (wasParseCollection) {
              const relationFieldNames = Object.keys(schema.fields).filter(fieldName => schema.fields[fieldName].type === 'Relation');
              return Promise.all(relationFieldNames.map(name => this.adapter.deleteClass(joinTableName(className, name)))).then(() => {
                return;
              });
            } else {
              return Promise.resolve();
            }
          });
      })
  }

  addPointerPermissions(schema: any, className: string, operation: string, query: any, aclGroup: any[] = []) {
  // Check if class has public permission for operation
  // If the BaseCLP pass, let go through
    if (schema.testBaseCLP(className, aclGroup, operation)) {
      return query;
    }
    const perms = schema.perms[className];
    const field = ['get', 'find'].indexOf(operation) > -1 ? 'readUserFields' : 'writeUserFields';
    const userACL = aclGroup.filter((acl) => {
      return acl.indexOf('role:') != 0 && acl != '*';
    });
    // the ACL should have exactly 1 user
    if (perms && perms[field] && perms[field].length > 0) {
    // No user set return undefined
    // If the length is > 1, that means we didn't de-dupe users correctly
      if (userACL.length != 1) {
        return;
      }
      const userId = userACL[0];
      const userPointer =  {
        "__type": "Pointer",
        "className": "_User",
        "objectId": userId
      };

      const permFields = perms[field];
      const ors = permFields.map((key) => {
        const q = {
          [key]: userPointer
        };
        // if we already have a constraint on the key, use the $and
        if (query.hasOwnProperty(key)) {
          return {'$and': [q, query]};
        }
        // otherwise just add the constaint
        return Object.assign({}, query, {
          [`${key}`]: userPointer,
        })
      });
      if (ors.length > 1) {
        return {'$or': ors};
      }
      return ors[0];
    } else {
      return query;
    }
  }

  // TODO: create indexes on first creation of a _User object. Otherwise it's impossible to
  // have a Parse app without it having a _User collection.
  performInitialization() {
    const requiredUserFields = { fields: { ...SchemaController.defaultColumns._Default, ...SchemaController.defaultColumns._User } };
    const requiredRoleFields = { fields: { ...SchemaController.defaultColumns._Default, ...SchemaController.defaultColumns._Role } };

    const userClassPromise = this.loadSchema()
      .then(schema => schema.enforceClassExists('_User'))
    const roleClassPromise = this.loadSchema()
      .then(schema => schema.enforceClassExists('_Role'))

    const usernameUniqueness = userClassPromise
      .then(() => this.adapter.ensureUniqueness('_User', requiredUserFields, ['username']))
      .catch(error => {
        logger.warn('Unable to ensure uniqueness for usernames: ', error);
        throw error;
      });

    const emailUniqueness = userClassPromise
      .then(() => this.adapter.ensureUniqueness('_User', requiredUserFields, ['email']))
      .catch(error => {
        logger.warn('Unable to ensure uniqueness for user email addresses: ', error);
        throw error;
      });

    const roleUniqueness = roleClassPromise
      .then(() => this.adapter.ensureUniqueness('_Role', requiredRoleFields, ['name']))
      .catch(error => {
        logger.warn('Unable to ensure uniqueness for role name: ', error);
        throw error;
      });

    const indexPromise = this.adapter.updateSchemaWithIndexes();

    // Create tables for volatile classes
    const adapterInit = this.adapter.performInitialization({ VolatileClassesSchemas: SchemaController.VolatileClassesSchemas });
    return Promise.all([usernameUniqueness, emailUniqueness, roleUniqueness, adapterInit, indexPromise]);
  }

  static _validateQuery: ((any) => void)
}

module.exports = DatabaseController;
// Expose validateQuery for tests
module.exports._validateQuery = validateQuery;