/*
 * Copyright (C) 2019 StApps
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation, version 3.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <https://www.gnu.org/licenses/>.
 */
import {asyncPool} from '@krlwlfrt/async-pool/lib/async-pool';
import {
  isThing,
  SCAssociatedThingWithoutReferences,
  SCBulkResponse,
  SCBulkRoute,
  SCLicensePlate,
  SCNamespaces,
  SCThings,
  SCThingType,
  SCThingUpdateResponse,
  SCThingUpdateRoute,
} from '@openstapps/core';
import clone = require('fast-clone');
import moment from 'moment';
import {v5} from 'uuid';
import {Bulk} from './bulk';
import {Client} from './client';
import {EmptyBulkError, NamespaceNotDefinedError} from './errors';

/**
 * StApps-API client
 */
export class ConnectorClient extends Client {
  /**
   * The default timeout for the bulk to expire
   */
  static readonly BULK_TIMEOUT = 3600;
  /**
   * The limit of how many items should be indexed concurrently
   */
  static readonly ITEM_CONCURRENT_LIMIT = 5;

  /**
   * Instance of multi search request route
   */
  private readonly bulkRoute = new SCBulkRoute();

  /**
   * Instance of multi search request route
   */
  private readonly thingUpdateRoute = new SCThingUpdateRoute();

  /**
   * Make a UUID from a UID and a namespace ID
   *
   * *Note: valid namespace IDs are license plates of StApps universities.
   * See documentation of `NAMESPACES` for valid namespace IDs.*
   *
   * @param uid UID to make UUID from
   * @param namespaceId Namespace ID to use to make UUID
   */
  static makeUUID(uid: string, namespaceId: SCLicensePlate): string {
    if (typeof SCNamespaces[namespaceId] === 'undefined') {
      throw new NamespaceNotDefinedError(namespaceId);
    }

    return v5(uid.toString(), SCNamespaces[namespaceId]!);
  }

  /**
   * Remove fields from a thing that are references
   *
   * This effectively turns a thing into a thing without references, e.g. SCDish into SCDishWithoutReferences.
   *
   * @param thing Thing to remove references from
   */
  static removeReferences<THING extends SCThings>(thing: THING): SCAssociatedThingWithoutReferences<THING> {

    // tslint:disable-next-line:no-any
    const thingWithoutReferences = clone<any>(thing);

    delete thingWithoutReferences.origin;

    // iterate over all properties
    for (const key in thingWithoutReferences) {

      /* istanbul ignore if  */
      if (!thingWithoutReferences.hasOwnProperty(key)) {
        continue;
      }

      const property = thingWithoutReferences[key];

      // check if property itself is a thing
      if (isThing(property)) {
        // delete said property
        delete thingWithoutReferences[key];
        continue;
      }

      // check if property is an array
      if (Array.isArray(property)) {
        if (property.every(isThing)) {
          // delete property if every item in it is a thing
          delete thingWithoutReferences[key];
        } else {
          // check every item in array
          for (const item of property) {
            if (['boolean', 'number', 'string'].indexOf(typeof item) >= 0) {
              // skip primitives
              continue;
            }

            // check every property
            for (const itemKey in item) {
              /* istanbul ignore if  */
              if (!item.hasOwnProperty(itemKey)) {
                continue;
              }

              if (isThing(item[itemKey])) {
                // delete properties that are things
                delete item[itemKey];
              }
            }
          }
        }
      } else if (typeof property === 'object') {
        // iterate over all properties in nested objects
        for (const nestedKey in property) {
          if (isThing(property[nestedKey])) {
            // delete properties that are things
            delete property[nestedKey];
          }
        }
      }
    }

    return thingWithoutReferences as SCAssociatedThingWithoutReferences<THING>;
  }

  /**
   * Recursively deletes all undefined properties from an object instance
   *
   * @param obj Object to delete undefined properties from
   */
  static removeUndefinedProperties(obj: object): void {
    // return atomic data types and arrays (recursion anchor)
    if (typeof obj !== 'object' || Array.isArray(obj)) {
      return;
    }

    // check each key
    for (const key in obj) {
      /* istanbul ignore if */
      if (!obj.hasOwnProperty(key)) {
        continue;
      }

      const indexedObj = obj as { [k: string]: unknown; };

      if (typeof indexedObj[key] === 'undefined') {
        // delete undefined keyss
        delete indexedObj[key];
      } else {
        // check recursive
        ConnectorClient.removeUndefinedProperties(indexedObj[key] as object);
      }
    }

    return;
  }

  /**
   * Request a bulk transfer to the backend
   *
   * This uses the Bulk API supplied by the backend and returns an object that can be used
   * just like the client itself, while handling the information necessary in bulk transfers.
   *
   * @param type StAppsCore thing type
   * @param source Source identifier (should be unique per actual data source)
   * @param timeout Timeout in seconds when the bulk should expire
   */
  async bulk<T extends SCThings>(type: SCThingType, source: string, timeout?: number): Promise<Bulk<T>> {
    let bulkTimeout: number;
    // set default value for timeout to one hour
    if (typeof timeout !== 'number') {
      bulkTimeout = ConnectorClient.BULK_TIMEOUT;
    } else {
      bulkTimeout = timeout;
    }

    const bulkData = await this.invokeRoute<SCBulkResponse>(this.bulkRoute, undefined, {
      expiration: moment()
        .add(bulkTimeout, 'seconds')
        .format(),
      source: source,
      type: type,
    });

    return new Bulk(type, this, bulkData);
  }

  /**
   * Index a list of things
   *
   * Note that source is optional but is set to `'stapps-api'` in that case.
   * This will override any previous bulk that you indexed with that source.
   *
   * @param things List of things to index
   * @param source Source of the things
   * @param timeout Timeout of the bulk in seconds
   * @see ConnectorClient.bulk
   */
  async index<T extends SCThings>(things: T[], source?: string, timeout?: number): Promise<void> {
    // check that number of things is not zero
    if (things.length === 0) {
      throw new EmptyBulkError();
    }

    let thingSource: string;
    // set default source if none is given
    if (typeof source === 'undefined') {
      thingSource = 'stapps-api';
    } else {
      thingSource = source;
    }

    // request a new bulk
    const bulk = await this.bulk(things[0].type, thingSource, timeout);

    // add items to the bulk - 5 concurrently
    await asyncPool(ConnectorClient.ITEM_CONCURRENT_LIMIT, things, (thing) => bulk.add(thing));

    // close bulk
    await bulk.done();
  }

  /**
   * Update an existing StAppsCore thing
   *
   * @param thing StAppsCore thing to update
   */
  async update(thing: SCThings): Promise<SCThingUpdateResponse> {
    return this.invokeRoute<SCThingUpdateResponse>(this.thingUpdateRoute, {
      TYPE: encodeURIComponent(thing.type),
      UID: encodeURIComponent(thing.uid),
    }, thing);
  }
}