import { type BSONSerializeOptions, type Document, resolveBSONOptions } from './bson';
import type { AnyBulkWriteOperation, BulkWriteOptions, BulkWriteResult } from './bulk/common';
import { OrderedBulkOperation } from './bulk/ordered';
import { UnorderedBulkOperation } from './bulk/unordered';
import { ChangeStream, type ChangeStreamDocument, type ChangeStreamOptions } from './change_stream';
import { AggregationCursor } from './cursor/aggregation_cursor';
import { FindCursor } from './cursor/find_cursor';
import { ListIndexesCursor } from './cursor/list_indexes_cursor';
import {
  ListSearchIndexesCursor,
  type ListSearchIndexesOptions
} from './cursor/list_search_indexes_cursor';
import type { Db } from './db';
import { MongoInvalidArgumentError, MongoOperationTimeoutError } from './error';
import type { MongoClient, PkFactory } from './mongo_client';
import type {
  Filter,
  Flatten,
  OptionalUnlessRequiredId,
  TODO_NODE_3286,
  UpdateFilter,
  WithId,
  WithoutId
} from './mongo_types';
import type { AggregateOptions } from './operations/aggregate';
import { BulkWriteOperation } from './operations/bulk_write';
import { CountOperation, type CountOptions } from './operations/count';
import {
  DeleteManyOperation,
  DeleteOneOperation,
  type DeleteOptions,
  type DeleteResult
} from './operations/delete';
import { DistinctOperation, type DistinctOptions } from './operations/distinct';
import { DropCollectionOperation, type DropCollectionOptions } from './operations/drop';
import {
  EstimatedDocumentCountOperation,
  type EstimatedDocumentCountOptions
} from './operations/estimated_document_count';
import { executeOperation } from './operations/execute_operation';
import type { FindOptions } from './operations/find';
import {
  FindOneAndDeleteOperation,
  type FindOneAndDeleteOptions,
  FindOneAndReplaceOperation,
  type FindOneAndReplaceOptions,
  FindOneAndUpdateOperation,
  type FindOneAndUpdateOptions
} from './operations/find_and_modify';
import {
  CreateIndexesOperation,
  type CreateIndexesOptions,
  type DropIndexesOptions,
  DropIndexOperation,
  type IndexDescription,
  type IndexDescriptionCompact,
  type IndexDescriptionInfo,
  type IndexInformationOptions,
  type IndexSpecification,
  type ListIndexesOptions
} from './operations/indexes';
import {
  InsertManyOperation,
  type InsertManyResult,
  InsertOneOperation,
  type InsertOneOptions,
  type InsertOneResult
} from './operations/insert';
import { IsCappedOperation } from './operations/is_capped';
import type { Hint, OperationOptions } from './operations/operation';
import { OptionsOperation } from './operations/options_operation';
import { RenameOperation, type RenameOptions } from './operations/rename';
import {
  CreateSearchIndexesOperation,
  type SearchIndexDescription
} from './operations/search_indexes/create';
import { DropSearchIndexOperation } from './operations/search_indexes/drop';
import { UpdateSearchIndexOperation } from './operations/search_indexes/update';
import {
  ReplaceOneOperation,
  type ReplaceOptions,
  UpdateManyOperation,
  UpdateOneOperation,
  type UpdateOptions,
  type UpdateResult
} from './operations/update';
import { ReadConcern, type ReadConcernLike } from './read_concern';
import { ReadPreference, type ReadPreferenceLike } from './read_preference';
import {
  DEFAULT_PK_FACTORY,
  MongoDBCollectionNamespace,
  normalizeHintField,
  resolveOptions
} from './utils';
import { WriteConcern, type WriteConcernOptions } from './write_concern';

/** @public */
export interface ModifyResult<TSchema = Document> {
  value: WithId<TSchema> | null;
  lastErrorObject?: Document;
  ok: 0 | 1;
}

/** @public */
export interface CountDocumentsOptions extends AggregateOptions {
  /** The number of documents to skip. */
  skip?: number;
  /** The maximum amount of documents to consider. */
  limit?: number;
}

/** @public */
export interface CollectionOptions extends BSONSerializeOptions, WriteConcernOptions {
  /** Specify a read concern for the collection. (only MongoDB 3.2 or higher supported) */
  readConcern?: ReadConcernLike;
  /** The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST). */
  readPreference?: ReadPreferenceLike;
  /**
   * @experimental
   * Specifies the time an operation will run until it throws a timeout error
   */
  timeoutMS?: number;
}

/** @internal */
export interface CollectionPrivate {
  pkFactory: PkFactory;
  db: Db;
  options: any;
  namespace: MongoDBCollectionNamespace;
  readPreference?: ReadPreference;
  bsonOptions: BSONSerializeOptions;
  collectionHint?: Hint;
  readConcern?: ReadConcern;
  writeConcern?: WriteConcern;
}

/**
 * The **Collection** class is an internal class that embodies a MongoDB collection
 * allowing for insert/find/update/delete and other command operation on that MongoDB collection.
 *
 * **COLLECTION Cannot directly be instantiated**
 * @public
 *
 * @example
 * ```ts
 * import { MongoClient } from 'mongodb';
 *
 * interface Pet {
 *   name: string;
 *   kind: 'dog' | 'cat' | 'fish';
 * }
 *
 * const client = new MongoClient('mongodb://localhost:27017');
 * const pets = client.db().collection<Pet>('pets');
 *
 * const petCursor = pets.find();
 *
 * for await (const pet of petCursor) {
 *   console.log(`${pet.name} is a ${pet.kind}!`);
 * }
 * ```
 */
export class Collection<TSchema extends Document = Document> {
  /** @internal */
  s: CollectionPrivate;

  /** @internal */
  client: MongoClient;

  /**
   * Create a new Collection instance
   * @internal
   */
  constructor(db: Db, name: string, options?: CollectionOptions) {
    // Internal state
    this.s = {
      db,
      options,
      namespace: new MongoDBCollectionNamespace(db.databaseName, name),
      pkFactory: db.options?.pkFactory ?? DEFAULT_PK_FACTORY,
      readPreference: ReadPreference.fromOptions(options),
      bsonOptions: resolveBSONOptions(options, db),
      readConcern: ReadConcern.fromOptions(options),
      writeConcern: WriteConcern.fromOptions(options)
    };

    this.client = db.client;
  }

  /**
   * The name of the database this collection belongs to
   */
  get dbName(): string {
    return this.s.namespace.db;
  }

  /**
   * The name of this collection
   */
  get collectionName(): string {
    return this.s.namespace.collection;
  }

  /**
   * The namespace of this collection, in the format `${this.dbName}.${this.collectionName}`
   */
  get namespace(): string {
    return this.fullNamespace.toString();
  }

  /**
   *  @internal
   *
   * The `MongoDBNamespace` for the collection.
   */
  get fullNamespace(): MongoDBCollectionNamespace {
    return this.s.namespace;
  }

  /**
   * The current readConcern of the collection. If not explicitly defined for
   * this collection, will be inherited from the parent DB
   */
  get readConcern(): ReadConcern | undefined {
    if (this.s.readConcern == null) {
      return this.s.db.readConcern;
    }
    return this.s.readConcern;
  }

  /**
   * The current readPreference of the collection. If not explicitly defined for
   * this collection, will be inherited from the parent DB
   */
  get readPreference(): ReadPreference | undefined {
    if (this.s.readPreference == null) {
      return this.s.db.readPreference;
    }

    return this.s.readPreference;
  }

  get bsonOptions(): BSONSerializeOptions {
    return this.s.bsonOptions;
  }

  /**
   * The current writeConcern of the collection. If not explicitly defined for
   * this collection, will be inherited from the parent DB
   */
  get writeConcern(): WriteConcern | undefined {
    if (this.s.writeConcern == null) {
      return this.s.db.writeConcern;
    }
    return this.s.writeConcern;
  }

  /** The current index hint for the collection */
  get hint(): Hint | undefined {
    return this.s.collectionHint;
  }

  set hint(v: Hint | undefined) {
    this.s.collectionHint = normalizeHintField(v);
  }

  public get timeoutMS(): number | undefined {
    return this.s.options.timeoutMS;
  }

  /**
   * Inserts a single document into MongoDB. If documents passed in do not contain the **_id** field,
   * one will be added to each of the documents missing it by the driver, mutating the document. This behavior
   * can be overridden by setting the **forceServerObjectId** flag.
   *
   * @param doc - The document to insert
   * @param options - Optional settings for the command
   */
  async insertOne(
    doc: OptionalUnlessRequiredId<TSchema>,
    options?: InsertOneOptions
  ): Promise<InsertOneResult<TSchema>> {
    return await executeOperation(
      this.client,
      new InsertOneOperation(
        this as TODO_NODE_3286,
        doc,
        resolveOptions(this, options)
      ) as TODO_NODE_3286
    );
  }

  /**
   * Inserts an array of documents into MongoDB. If documents passed in do not contain the **_id** field,
   * one will be added to each of the documents missing it by the driver, mutating the document. This behavior
   * can be overridden by setting the **forceServerObjectId** flag.
   *
   * @param docs - The documents to insert
   * @param options - Optional settings for the command
   */
  async insertMany(
    docs: ReadonlyArray<OptionalUnlessRequiredId<TSchema>>,
    options?: BulkWriteOptions
  ): Promise<InsertManyResult<TSchema>> {
    return await executeOperation(
      this.client,
      new InsertManyOperation(
        this as TODO_NODE_3286,
        docs,
        resolveOptions(this, options ?? { ordered: true })
      ) as TODO_NODE_3286
    );
  }

  /**
   * Perform a bulkWrite operation without a fluent API
   *
   * Legal operation types are
   * - `insertOne`
   * - `replaceOne`
   * - `updateOne`
   * - `updateMany`
   * - `deleteOne`
   * - `deleteMany`
   *
   * If documents passed in do not contain the **_id** field,
   * one will be added to each of the documents missing it by the driver, mutating the document. This behavior
   * can be overridden by setting the **forceServerObjectId** flag.
   *
   * @param operations - Bulk operations to perform
   * @param options - Optional settings for the command
   * @throws MongoDriverError if operations is not an array
   */
  async bulkWrite(
    operations: ReadonlyArray<AnyBulkWriteOperation<TSchema>>,
    options?: BulkWriteOptions
  ): Promise<BulkWriteResult> {
    if (!Array.isArray(operations)) {
      throw new MongoInvalidArgumentError('Argument "operations" must be an array of documents');
    }

    return await executeOperation(
      this.client,
      new BulkWriteOperation(
        this as TODO_NODE_3286,
        operations,
        resolveOptions(this, options ?? { ordered: true })
      )
    );
  }

  /**
   * Update a single document in a collection
   *
   * The value of `update` can be either:
   * - UpdateFilter<TSchema> - A document that contains update operator expressions,
   * - Document[] - an aggregation pipeline.
   *
   * @param filter - The filter used to select the document to update
   * @param update - The modifications to apply
   * @param options - Optional settings for the command
   */
  async updateOne(
    filter: Filter<TSchema>,
    update: UpdateFilter<TSchema> | Document[],
    options?: UpdateOptions
  ): Promise<UpdateResult<TSchema>> {
    return await executeOperation(
      this.client,
      new UpdateOneOperation(
        this as TODO_NODE_3286,
        filter,
        update,
        resolveOptions(this, options)
      ) as TODO_NODE_3286
    );
  }

  /**
   * Replace a document in a collection with another document
   *
   * @param filter - The filter used to select the document to replace
   * @param replacement - The Document that replaces the matching document
   * @param options - Optional settings for the command
   */
  async replaceOne(
    filter: Filter<TSchema>,
    replacement: WithoutId<TSchema>,
    options?: ReplaceOptions
  ): Promise<UpdateResult<TSchema> | Document> {
    return await executeOperation(
      this.client,
      new ReplaceOneOperation(
        this as TODO_NODE_3286,
        filter,
        replacement,
        resolveOptions(this, options)
      )
    );
  }

  /**
   * Update multiple documents in a collection
   *
   * The value of `update` can be either:
   * - UpdateFilter<TSchema> - A document that contains update operator expressions,
   * - Document[] - an aggregation pipeline.
   *
   * @param filter - The filter used to select the document to update
   * @param update - The modifications to apply
   * @param options - Optional settings for the command
   */
  async updateMany(
    filter: Filter<TSchema>,
    update: UpdateFilter<TSchema> | Document[],
    options?: UpdateOptions
  ): Promise<UpdateResult<TSchema>> {
    return await executeOperation(
      this.client,
      new UpdateManyOperation(
        this as TODO_NODE_3286,
        filter,
        update,
        resolveOptions(this, options)
      ) as TODO_NODE_3286
    );
  }

  /**
   * Delete a document from a collection
   *
   * @param filter - The filter used to select the document to remove
   * @param options - Optional settings for the command
   */
  async deleteOne(
    filter: Filter<TSchema> = {},
    options: DeleteOptions = {}
  ): Promise<DeleteResult> {
    return await executeOperation(
      this.client,
      new DeleteOneOperation(this as TODO_NODE_3286, filter, resolveOptions(this, options))
    );
  }

  /**
   * Delete multiple documents from a collection
   *
   * @param filter - The filter used to select the documents to remove
   * @param options - Optional settings for the command
   */
  async deleteMany(
    filter: Filter<TSchema> = {},
    options: DeleteOptions = {}
  ): Promise<DeleteResult> {
    return await executeOperation(
      this.client,
      new DeleteManyOperation(this as TODO_NODE_3286, filter, resolveOptions(this, options))
    );
  }

  /**
   * Rename the collection.
   *
   * @remarks
   * This operation does not inherit options from the Db or MongoClient.
   *
   * @param newName - New name of of the collection.
   * @param options - Optional settings for the command
   */
  async rename(newName: string, options?: RenameOptions): Promise<Collection> {
    // Intentionally, we do not inherit options from parent for this operation.
    return await executeOperation(
      this.client,
      new RenameOperation(
        this as TODO_NODE_3286,
        newName,
        resolveOptions(undefined, {
          ...options,
          readPreference: ReadPreference.PRIMARY
        })
      ) as TODO_NODE_3286
    );
  }

  /**
   * Drop the collection from the database, removing it permanently. New accesses will create a new collection.
   *
   * @param options - Optional settings for the command
   */
  async drop(options?: DropCollectionOptions): Promise<boolean> {
    return await executeOperation(
      this.client,
      new DropCollectionOperation(this.s.db, this.collectionName, options)
    );
  }

  /**
   * Fetches the first document that matches the filter
   *
   * @param filter - Query for find Operation
   * @param options - Optional settings for the command
   */
  async findOne(): Promise<WithId<TSchema> | null>;
  async findOne(filter: Filter<TSchema>): Promise<WithId<TSchema> | null>;
  async findOne(
    filter: Filter<TSchema>,
    options: Omit<FindOptions, 'timeoutMode'>
  ): Promise<WithId<TSchema> | null>;

  // allow an override of the schema.
  async findOne<T = TSchema>(): Promise<T | null>;
  async findOne<T = TSchema>(filter: Filter<TSchema>): Promise<T | null>;
  async findOne<T = TSchema>(
    filter: Filter<TSchema>,
    options?: Omit<FindOptions, 'timeoutMode'>
  ): Promise<T | null>;

  async findOne(
    filter: Filter<TSchema> = {},
    options: FindOptions = {}
  ): Promise<WithId<TSchema> | null> {
    const cursor = this.find(filter, options).limit(-1).batchSize(1);
    const res = await cursor.next();
    await cursor.close();
    return res;
  }

  /**
   * Creates a cursor for a filter that can be used to iterate over results from MongoDB
   *
   * @param filter - The filter predicate. If unspecified, then all documents in the collection will match the predicate
   */
  find(): FindCursor<WithId<TSchema>>;
  find(filter: Filter<TSchema>, options?: FindOptions): FindCursor<WithId<TSchema>>;
  find<T extends Document>(filter: Filter<TSchema>, options?: FindOptions): FindCursor<T>;
  find(filter: Filter<TSchema> = {}, options: FindOptions = {}): FindCursor<WithId<TSchema>> {
    return new FindCursor<WithId<TSchema>>(
      this.client,
      this.s.namespace,
      filter,
      resolveOptions(this as TODO_NODE_3286, options)
    );
  }

  /**
   * Returns the options of the collection.
   *
   * @param options - Optional settings for the command
   */
  async options(options?: OperationOptions): Promise<Document> {
    return await executeOperation(
      this.client,
      new OptionsOperation(this as TODO_NODE_3286, resolveOptions(this, options))
    );
  }

  /**
   * Returns if the collection is a capped collection
   *
   * @param options - Optional settings for the command
   */
  async isCapped(options?: OperationOptions): Promise<boolean> {
    return await executeOperation(
      this.client,
      new IsCappedOperation(this as TODO_NODE_3286, resolveOptions(this, options))
    );
  }

  /**
   * Creates an index on the db and collection collection.
   *
   * @param indexSpec - The field name or index specification to create an index for
   * @param options - Optional settings for the command
   *
   * @example
   * ```ts
   * const collection = client.db('foo').collection('bar');
   *
   * await collection.createIndex({ a: 1, b: -1 });
   *
   * // Alternate syntax for { c: 1, d: -1 } that ensures order of indexes
   * await collection.createIndex([ [c, 1], [d, -1] ]);
   *
   * // Equivalent to { e: 1 }
   * await collection.createIndex('e');
   *
   * // Equivalent to { f: 1, g: 1 }
   * await collection.createIndex(['f', 'g'])
   *
   * // Equivalent to { h: 1, i: -1 }
   * await collection.createIndex([ { h: 1 }, { i: -1 } ]);
   *
   * // Equivalent to { j: 1, k: -1, l: 2d }
   * await collection.createIndex(['j', ['k', -1], { l: '2d' }])
   * ```
   */
  async createIndex(
    indexSpec: IndexSpecification,
    options?: CreateIndexesOptions
  ): Promise<string> {
    const indexes = await executeOperation(
      this.client,
      CreateIndexesOperation.fromIndexSpecification(
        this,
        this.collectionName,
        indexSpec,
        resolveOptions(this, options)
      )
    );

    return indexes[0];
  }

  /**
   * Creates multiple indexes in the collection, this method is only supported for
   * MongoDB 2.6 or higher. Earlier version of MongoDB will throw a command not supported
   * error.
   *
   * **Note**: Unlike {@link Collection#createIndex| createIndex}, this function takes in raw index specifications.
   * Index specifications are defined {@link https://www.mongodb.com/docs/manual/reference/command/createIndexes/| here}.
   *
   * @param indexSpecs - An array of index specifications to be created
   * @param options - Optional settings for the command
   *
   * @example
   * ```ts
   * const collection = client.db('foo').collection('bar');
   * await collection.createIndexes([
   *   // Simple index on field fizz
   *   {
   *     key: { fizz: 1 },
   *   }
   *   // wildcard index
   *   {
   *     key: { '$**': 1 }
   *   },
   *   // named index on darmok and jalad
   *   {
   *     key: { darmok: 1, jalad: -1 }
   *     name: 'tanagra'
   *   }
   * ]);
   * ```
   */
  async createIndexes(
    indexSpecs: IndexDescription[],
    options?: CreateIndexesOptions
  ): Promise<string[]> {
    return await executeOperation(
      this.client,
      CreateIndexesOperation.fromIndexDescriptionArray(
        this,
        this.collectionName,
        indexSpecs,
        resolveOptions(this, { ...options, maxTimeMS: undefined })
      )
    );
  }

  /**
   * Drops an index from this collection.
   *
   * @param indexName - Name of the index to drop.
   * @param options - Optional settings for the command
   */
  async dropIndex(indexName: string, options?: DropIndexesOptions): Promise<Document> {
    return await executeOperation(
      this.client,
      new DropIndexOperation(this as TODO_NODE_3286, indexName, {
        ...resolveOptions(this, options),
        readPreference: ReadPreference.primary
      })
    );
  }

  /**
   * Drops all indexes from this collection.
   *
   * @param options - Optional settings for the command
   */
  async dropIndexes(options?: DropIndexesOptions): Promise<boolean> {
    try {
      await executeOperation(
        this.client,
        new DropIndexOperation(this as TODO_NODE_3286, '*', resolveOptions(this, options))
      );
      return true;
    } catch (error) {
      // TODO(NODE-6517): Driver should only filter for namespace not found error. Other errors should be thrown.
      if (error instanceof MongoOperationTimeoutError) throw error;
      return false;
    }
  }

  /**
   * Get the list of all indexes information for the collection.
   *
   * @param options - Optional settings for the command
   */
  listIndexes(options?: ListIndexesOptions): ListIndexesCursor {
    return new ListIndexesCursor(this as TODO_NODE_3286, resolveOptions(this, options));
  }

  /**
   * Checks if one or more indexes exist on the collection, fails on first non-existing index
   *
   * @param indexes - One or more index names to check.
   * @param options - Optional settings for the command
   */
  async indexExists(indexes: string | string[], options?: ListIndexesOptions): Promise<boolean> {
    const indexNames: string[] = Array.isArray(indexes) ? indexes : [indexes];
    const allIndexes: Set<string> = new Set(
      await this.listIndexes(options)
        .map(({ name }) => name)
        .toArray()
    );
    return indexNames.every(name => allIndexes.has(name));
  }

  /**
   * Retrieves this collections index info.
   *
   * @param options - Optional settings for the command
   */
  indexInformation(
    options: IndexInformationOptions & { full: true }
  ): Promise<IndexDescriptionInfo[]>;
  indexInformation(
    options: IndexInformationOptions & { full?: false }
  ): Promise<IndexDescriptionCompact>;
  indexInformation(
    options: IndexInformationOptions
  ): Promise<IndexDescriptionCompact | IndexDescriptionInfo[]>;
  indexInformation(): Promise<IndexDescriptionCompact>;
  async indexInformation(
    options?: IndexInformationOptions
  ): Promise<IndexDescriptionCompact | IndexDescriptionInfo[]> {
    return await this.indexes({
      ...options,
      full: options?.full ?? false
    });
  }

  /**
   * Gets an estimate of the count of documents in a collection using collection metadata.
   * This will always run a count command on all server versions.
   *
   * due to an oversight in versions 5.0.0-5.0.8 of MongoDB, the count command,
   * which estimatedDocumentCount uses in its implementation, was not included in v1 of
   * the Stable API, and so users of the Stable API with estimatedDocumentCount are
   * recommended to upgrade their server version to 5.0.9+ or set apiStrict: false to avoid
   * encountering errors.
   *
   * @see {@link https://www.mongodb.com/docs/manual/reference/command/count/#behavior|Count: Behavior}
   * @param options - Optional settings for the command
   */
  async estimatedDocumentCount(options?: EstimatedDocumentCountOptions): Promise<number> {
    return await executeOperation(
      this.client,
      new EstimatedDocumentCountOperation(this as TODO_NODE_3286, resolveOptions(this, options))
    );
  }

  /**
   * Gets the number of documents matching the filter.
   * For a fast count of the total documents in a collection see {@link Collection#estimatedDocumentCount| estimatedDocumentCount}.
   *
   * Due to countDocuments using the $match aggregation pipeline stage, certain query operators cannot be used in countDocuments. This includes the $where and $near query operators, among others. Details can be found in the documentation for the $match aggregation pipeline stage.
   *
   * **Note**: When migrating from {@link Collection#count| count} to {@link Collection#countDocuments| countDocuments}
   * the following query operators must be replaced:
   *
   * | Operator | Replacement |
   * | -------- | ----------- |
   * | `$where`   | [`$expr`][1] |
   * | `$near`    | [`$geoWithin`][2] with [`$center`][3] |
   * | `$nearSphere` | [`$geoWithin`][2] with [`$centerSphere`][4] |
   *
   * [1]: https://www.mongodb.com/docs/manual/reference/operator/query/expr/
   * [2]: https://www.mongodb.com/docs/manual/reference/operator/query/geoWithin/
   * [3]: https://www.mongodb.com/docs/manual/reference/operator/query/center/#op._S_center
   * [4]: https://www.mongodb.com/docs/manual/reference/operator/query/centerSphere/#op._S_centerSphere
   *
   * @param filter - The filter for the count
   * @param options - Optional settings for the command
   *
   * @see https://www.mongodb.com/docs/manual/reference/operator/query/expr/
   * @see https://www.mongodb.com/docs/manual/reference/operator/query/geoWithin/
   * @see https://www.mongodb.com/docs/manual/reference/operator/query/center/#op._S_center
   * @see https://www.mongodb.com/docs/manual/reference/operator/query/centerSphere/#op._S_centerSphere
   */
  async countDocuments(
    filter: Filter<TSchema> = {},
    options: CountDocumentsOptions = {}
  ): Promise<number> {
    const pipeline = [];
    pipeline.push({ $match: filter });

    if (typeof options.skip === 'number') {
      pipeline.push({ $skip: options.skip });
    }

    if (typeof options.limit === 'number') {
      pipeline.push({ $limit: options.limit });
    }

    pipeline.push({ $group: { _id: 1, n: { $sum: 1 } } });

    const cursor = this.aggregate<{ n: number }>(pipeline, options);
    const doc = await cursor.next();
    await cursor.close();
    return doc?.n ?? 0;
  }

  /**
   * The distinct command returns a list of distinct values for the given key across a collection.
   *
   * @param key - Field of the document to find distinct values for
   * @param filter - The filter for filtering the set of documents to which we apply the distinct filter.
   * @param options - Optional settings for the command
   */
  distinct<Key extends keyof WithId<TSchema>>(
    key: Key
  ): Promise<Array<Flatten<WithId<TSchema>[Key]>>>;
  distinct<Key extends keyof WithId<TSchema>>(
    key: Key,
    filter: Filter<TSchema>
  ): Promise<Array<Flatten<WithId<TSchema>[Key]>>>;
  distinct<Key extends keyof WithId<TSchema>>(
    key: Key,
    filter: Filter<TSchema>,
    options: DistinctOptions
  ): Promise<Array<Flatten<WithId<TSchema>[Key]>>>;

  // Embedded documents overload
  distinct(key: string): Promise<any[]>;
  distinct(key: string, filter: Filter<TSchema>): Promise<any[]>;
  distinct(key: string, filter: Filter<TSchema>, options: DistinctOptions): Promise<any[]>;

  async distinct<Key extends keyof WithId<TSchema>>(
    key: Key,
    filter: Filter<TSchema> = {},
    options: DistinctOptions = {}
  ): Promise<any[]> {
    return await executeOperation(
      this.client,
      new DistinctOperation(
        this as TODO_NODE_3286,
        key as TODO_NODE_3286,
        filter,
        resolveOptions(this, options)
      )
    );
  }

  /**
   * Retrieve all the indexes on the collection.
   *
   * @param options - Optional settings for the command
   */
  indexes(options: IndexInformationOptions & { full?: true }): Promise<IndexDescriptionInfo[]>;
  indexes(options: IndexInformationOptions & { full: false }): Promise<IndexDescriptionCompact>;
  indexes(
    options: IndexInformationOptions
  ): Promise<IndexDescriptionCompact | IndexDescriptionInfo[]>;
  indexes(options?: ListIndexesOptions): Promise<IndexDescriptionInfo[]>;
  async indexes(
    options?: IndexInformationOptions
  ): Promise<IndexDescriptionCompact | IndexDescriptionInfo[]> {
    const indexes: IndexDescriptionInfo[] = await this.listIndexes(options).toArray();
    const full = options?.full ?? true;
    if (full) {
      return indexes;
    }

    const object: IndexDescriptionCompact = Object.fromEntries(
      indexes.map(({ name, key }) => [name, Object.entries(key)])
    );

    return object;
  }

  /**
   * Find a document and delete it in one atomic operation. Requires a write lock for the duration of the operation.
   *
   * @param filter - The filter used to select the document to remove
   * @param options - Optional settings for the command
   */
  async findOneAndDelete(
    filter: Filter<TSchema>,
    options: FindOneAndDeleteOptions & { includeResultMetadata: true }
  ): Promise<ModifyResult<TSchema>>;
  async findOneAndDelete(
    filter: Filter<TSchema>,
    options: FindOneAndDeleteOptions & { includeResultMetadata: false }
  ): Promise<WithId<TSchema> | null>;
  async findOneAndDelete(
    filter: Filter<TSchema>,
    options: FindOneAndDeleteOptions
  ): Promise<WithId<TSchema> | null>;
  async findOneAndDelete(filter: Filter<TSchema>): Promise<WithId<TSchema> | null>;
  async findOneAndDelete(
    filter: Filter<TSchema>,
    options?: FindOneAndDeleteOptions
  ): Promise<WithId<TSchema> | ModifyResult<TSchema> | null> {
    return await executeOperation(
      this.client,
      new FindOneAndDeleteOperation(
        this as TODO_NODE_3286,
        filter,
        resolveOptions(this, options)
      ) as TODO_NODE_3286
    );
  }

  /**
   * Find a document and replace it in one atomic operation. Requires a write lock for the duration of the operation.
   *
   * @param filter - The filter used to select the document to replace
   * @param replacement - The Document that replaces the matching document
   * @param options - Optional settings for the command
   */
  async findOneAndReplace(
    filter: Filter<TSchema>,
    replacement: WithoutId<TSchema>,
    options: FindOneAndReplaceOptions & { includeResultMetadata: true }
  ): Promise<ModifyResult<TSchema>>;
  async findOneAndReplace(
    filter: Filter<TSchema>,
    replacement: WithoutId<TSchema>,
    options: FindOneAndReplaceOptions & { includeResultMetadata: false }
  ): Promise<WithId<TSchema> | null>;
  async findOneAndReplace(
    filter: Filter<TSchema>,
    replacement: WithoutId<TSchema>,
    options: FindOneAndReplaceOptions
  ): Promise<WithId<TSchema> | null>;
  async findOneAndReplace(
    filter: Filter<TSchema>,
    replacement: WithoutId<TSchema>
  ): Promise<WithId<TSchema> | null>;
  async findOneAndReplace(
    filter: Filter<TSchema>,
    replacement: WithoutId<TSchema>,
    options?: FindOneAndReplaceOptions
  ): Promise<WithId<TSchema> | ModifyResult<TSchema> | null> {
    return await executeOperation(
      this.client,
      new FindOneAndReplaceOperation(
        this as TODO_NODE_3286,
        filter,
        replacement,
        resolveOptions(this, options)
      ) as TODO_NODE_3286
    );
  }

  /**
   * Find a document and update it in one atomic operation. Requires a write lock for the duration of the operation.
   *
   * @param filter - The filter used to select the document to update
   * @param update - Update operations to be performed on the document
   * @param options - Optional settings for the command
   */
  async findOneAndUpdate(
    filter: Filter<TSchema>,
    update: UpdateFilter<TSchema>,
    options: FindOneAndUpdateOptions & { includeResultMetadata: true }
  ): Promise<ModifyResult<TSchema>>;
  async findOneAndUpdate(
    filter: Filter<TSchema>,
    update: UpdateFilter<TSchema>,
    options: FindOneAndUpdateOptions & { includeResultMetadata: false }
  ): Promise<WithId<TSchema> | null>;
  async findOneAndUpdate(
    filter: Filter<TSchema>,
    update: UpdateFilter<TSchema>,
    options: FindOneAndUpdateOptions
  ): Promise<WithId<TSchema> | null>;
  async findOneAndUpdate(
    filter: Filter<TSchema>,
    update: UpdateFilter<TSchema>
  ): Promise<WithId<TSchema> | null>;
  async findOneAndUpdate(
    filter: Filter<TSchema>,
    update: UpdateFilter<TSchema>,
    options?: FindOneAndUpdateOptions
  ): Promise<WithId<TSchema> | ModifyResult<TSchema> | null> {
    return await executeOperation(
      this.client,
      new FindOneAndUpdateOperation(
        this as TODO_NODE_3286,
        filter,
        update,
        resolveOptions(this, options)
      ) as TODO_NODE_3286
    );
  }

  /**
   * Execute an aggregation framework pipeline against the collection, needs MongoDB \>= 2.2
   *
   * @param pipeline - An array of aggregation pipelines to execute
   * @param options - Optional settings for the command
   */
  aggregate<T extends Document = Document>(
    pipeline: Document[] = [],
    options?: AggregateOptions
  ): AggregationCursor<T> {
    if (!Array.isArray(pipeline)) {
      throw new MongoInvalidArgumentError(
        'Argument "pipeline" must be an array of aggregation stages'
      );
    }

    return new AggregationCursor(
      this.client,
      this.s.namespace,
      pipeline,
      resolveOptions(this, options)
    );
  }

  /**
   * Create a new Change Stream, watching for new changes (insertions, updates, replacements, deletions, and invalidations) in this collection.
   *
   * @remarks
   * watch() accepts two generic arguments for distinct use cases:
   * - The first is to override the schema that may be defined for this specific collection
   * - The second is to override the shape of the change stream document entirely, if it is not provided the type will default to ChangeStreamDocument of the first argument
   * @example
   * By just providing the first argument I can type the change to be `ChangeStreamDocument<{ _id: number }>`
   * ```ts
   * collection.watch<{ _id: number }>()
   *   .on('change', change => console.log(change._id.toFixed(4)));
   * ```
   *
   * @example
   * Passing a second argument provides a way to reflect the type changes caused by an advanced pipeline.
   * Here, we are using a pipeline to have MongoDB filter for insert changes only and add a comment.
   * No need start from scratch on the ChangeStreamInsertDocument type!
   * By using an intersection we can save time and ensure defaults remain the same type!
   * ```ts
   * collection
   *   .watch<Schema, ChangeStreamInsertDocument<Schema> & { comment: string }>([
   *     { $addFields: { comment: 'big changes' } },
   *     { $match: { operationType: 'insert' } }
   *   ])
   *   .on('change', change => {
   *     change.comment.startsWith('big');
   *     change.operationType === 'insert';
   *     // No need to narrow in code because the generics did that for us!
   *     expectType<Schema>(change.fullDocument);
   *   });
   * ```
   *
   * @remarks
   * When `timeoutMS` is configured for a change stream, it will have different behaviour depending
   * on whether the change stream is in iterator mode or emitter mode. In both cases, a change
   * stream will time out if it does not receive a change event within `timeoutMS` of the last change
   * event.
   *
   * Note that if a change stream is consistently timing out when watching a collection, database or
   * client that is being changed, then this may be due to the server timing out before it can finish
   * processing the existing oplog. To address this, restart the change stream with a higher
   * `timeoutMS`.
   *
   * If the change stream times out the initial aggregate operation to establish the change stream on
   * the server, then the client will close the change stream. If the getMore calls to the server
   * time out, then the change stream will be left open, but will throw a MongoOperationTimeoutError
   * when in iterator mode and emit an error event that returns a MongoOperationTimeoutError in
   * emitter mode.
   *
   * To determine whether or not the change stream is still open following a timeout, check the
   * {@link ChangeStream.closed} getter.
   *
   * @example
   * In iterator mode, if a next() call throws a timeout error, it will attempt to resume the change stream.
   * The next call can just be retried after this succeeds.
   * ```ts
   * const changeStream = collection.watch([], { timeoutMS: 100 });
   * try {
   *     await changeStream.next();
   * } catch (e) {
   *     if (e instanceof MongoOperationTimeoutError && !changeStream.closed) {
   *       await changeStream.next();
   *     }
   *     throw e;
   * }
   * ```
   *
   * @example
   * In emitter mode, if the change stream goes `timeoutMS` without emitting a change event, it will
   * emit an error event that returns a MongoOperationTimeoutError, but will not close the change
   * stream unless the resume attempt fails. There is no need to re-establish change listeners as
   * this will automatically continue emitting change events once the resume attempt completes.
   *
   * ```ts
   * const changeStream = collection.watch([], { timeoutMS: 100 });
   * changeStream.on('change', console.log);
   * changeStream.on('error', e => {
   *     if (e instanceof MongoOperationTimeoutError && !changeStream.closed) {
   *         // do nothing
   *     } else {
   *         changeStream.close();
   *     }
   * });
   * ```
   *
   * @param pipeline - An array of {@link https://www.mongodb.com/docs/manual/reference/operator/aggregation-pipeline/|aggregation pipeline stages} through which to pass change stream documents. This allows for filtering (using $match) and manipulating the change stream documents.
   * @param options - Optional settings for the command
   * @typeParam TLocal - Type of the data being detected by the change stream
   * @typeParam TChange - Type of the whole change stream document emitted
   */
  watch<TLocal extends Document = TSchema, TChange extends Document = ChangeStreamDocument<TLocal>>(
    pipeline: Document[] = [],
    options: ChangeStreamOptions = {}
  ): ChangeStream<TLocal, TChange> {
    // Allow optionally not specifying a pipeline
    if (!Array.isArray(pipeline)) {
      options = pipeline;
      pipeline = [];
    }

    return new ChangeStream<TLocal, TChange>(this, pipeline, resolveOptions(this, options));
  }

  /**
   * Initiate an Out of order batch write operation. All operations will be buffered into insert/update/remove commands executed out of order.
   *
   * @throws MongoNotConnectedError
   * @remarks
   * **NOTE:** MongoClient must be connected prior to calling this method due to a known limitation in this legacy implementation.
   * However, `collection.bulkWrite()` provides an equivalent API that does not require prior connecting.
   */
  initializeUnorderedBulkOp(options?: BulkWriteOptions): UnorderedBulkOperation {
    return new UnorderedBulkOperation(this as TODO_NODE_3286, resolveOptions(this, options));
  }

  /**
   * Initiate an In order bulk write operation. Operations will be serially executed in the order they are added, creating a new operation for each switch in types.
   *
   * @throws MongoNotConnectedError
   * @remarks
   * **NOTE:** MongoClient must be connected prior to calling this method due to a known limitation in this legacy implementation.
   * However, `collection.bulkWrite()` provides an equivalent API that does not require prior connecting.
   */
  initializeOrderedBulkOp(options?: BulkWriteOptions): OrderedBulkOperation {
    return new OrderedBulkOperation(this as TODO_NODE_3286, resolveOptions(this, options));
  }

  /**
   * An estimated count of matching documents in the db to a filter.
   *
   * **NOTE:** This method has been deprecated, since it does not provide an accurate count of the documents
   * in a collection. To obtain an accurate count of documents in the collection, use {@link Collection#countDocuments| countDocuments}.
   * To obtain an estimated count of all documents in the collection, use {@link Collection#estimatedDocumentCount| estimatedDocumentCount}.
   *
   * @deprecated use {@link Collection#countDocuments| countDocuments} or {@link Collection#estimatedDocumentCount| estimatedDocumentCount} instead
   *
   * @param filter - The filter for the count.
   * @param options - Optional settings for the command
   */
  async count(filter: Filter<TSchema> = {}, options: CountOptions = {}): Promise<number> {
    return await executeOperation(
      this.client,
      new CountOperation(this.fullNamespace, filter, resolveOptions(this, options))
    );
  }

  /**
   * Returns all search indexes for the current collection.
   *
   * @param options - The options for the list indexes operation.
   *
   * @remarks Only available when used against a 7.0+ Atlas cluster.
   */
  listSearchIndexes(options?: ListSearchIndexesOptions): ListSearchIndexesCursor;
  /**
   * Returns all search indexes for the current collection.
   *
   * @param name - The name of the index to search for.  Only indexes with matching index names will be returned.
   * @param options - The options for the list indexes operation.
   *
   * @remarks Only available when used against a 7.0+ Atlas cluster.
   */
  listSearchIndexes(name: string, options?: ListSearchIndexesOptions): ListSearchIndexesCursor;
  listSearchIndexes(
    indexNameOrOptions?: string | ListSearchIndexesOptions,
    options?: ListSearchIndexesOptions
  ): ListSearchIndexesCursor {
    options =
      typeof indexNameOrOptions === 'object' ? indexNameOrOptions : options == null ? {} : options;

    const indexName =
      indexNameOrOptions == null
        ? null
        : typeof indexNameOrOptions === 'object'
          ? null
          : indexNameOrOptions;

    return new ListSearchIndexesCursor(this as TODO_NODE_3286, indexName, options);
  }

  /**
   * Creates a single search index for the collection.
   *
   * @param description - The index description for the new search index.
   * @returns A promise that resolves to the name of the new search index.
   *
   * @remarks Only available when used against a 7.0+ Atlas cluster.
   */
  async createSearchIndex(description: SearchIndexDescription): Promise<string> {
    const [index] = await this.createSearchIndexes([description]);
    return index;
  }

  /**
   * Creates multiple search indexes for the current collection.
   *
   * @param descriptions - An array of `SearchIndexDescription`s for the new search indexes.
   * @returns A promise that resolves to an array of the newly created search index names.
   *
   * @remarks Only available when used against a 7.0+ Atlas cluster.
   * @returns
   */
  async createSearchIndexes(descriptions: SearchIndexDescription[]): Promise<string[]> {
    return await executeOperation(
      this.client,
      new CreateSearchIndexesOperation(this as TODO_NODE_3286, descriptions)
    );
  }

  /**
   * Deletes a search index by index name.
   *
   * @param name - The name of the search index to be deleted.
   *
   * @remarks Only available when used against a 7.0+ Atlas cluster.
   */
  async dropSearchIndex(name: string): Promise<void> {
    return await executeOperation(
      this.client,
      new DropSearchIndexOperation(this as TODO_NODE_3286, name)
    );
  }

  /**
   * Updates a search index by replacing the existing index definition with the provided definition.
   *
   * @param name - The name of the search index to update.
   * @param definition - The new search index definition.
   *
   * @remarks Only available when used against a 7.0+ Atlas cluster.
   */
  async updateSearchIndex(name: string, definition: Document): Promise<void> {
    return await executeOperation(
      this.client,
      new UpdateSearchIndexOperation(this as TODO_NODE_3286, name, definition)
    );
  }
}
