minimax.ts

import { getEnvironmentVariable } from "@langchain/core/utils/env";
import { Embeddings, EmbeddingsParams } from "@langchain/core/embeddings";
import { chunkArray } from "@langchain/core/utils/chunk_array";
import { ConfigurationParameters } from "../chat_models/minimax.js";

/**
 * Interface for MinimaxEmbeddings parameters. Extends EmbeddingsParams and
 * defines additional parameters specific to the MinimaxEmbeddings class.
 */
export interface MinimaxEmbeddingsParams extends EmbeddingsParams {
  /** Model name to use */
  modelName: string;

  /**
   * API key to use when making requests. Defaults to the value of
   * `MINIMAX_GROUP_ID` environment variable.
   */
  minimaxGroupId?: string;

  /**
   * Secret key to use when making requests. Defaults to the value of
   * `MINIMAX_API_KEY` environment variable.
   */
  minimaxApiKey?: string;

  /**
   * The maximum number of documents to embed in a single request. This is
   * limited by the Minimax API to a maximum of 4096.
   */
  batchSize?: number;

  /**
   * Whether to strip new lines from the input text. This is recommended by
   * Minimax, but may not be suitable for all use cases.
   */
  stripNewLines?: boolean;

  /**
   *  The target use-case after generating the vector.
   *  When using embeddings, the vector of the target content is first generated through the db and stored in the vector database,
   *  and then the vector of the retrieval text is generated through the query.
   *  Note: For the parameters of the partial algorithm, we adopted a separate algorithm plan for query and db.
   *  Therefore, for a paragraph of text, if it is to be used as a retrieval text, it should use the db,
   *  and if it is used as a retrieval text, it should use the query.
   */
  type?: "db" | "query";
}

export interface CreateMinimaxEmbeddingRequest {
  /**
   * @type {string}
   * @memberof CreateMinimaxEmbeddingRequest
   */
  model: string;

  /**
   *  Text to generate vector expectation
   * @type {CreateEmbeddingRequestInput}
   * @memberof CreateMinimaxEmbeddingRequest
   */
  texts: string[];

  /**
   *  The target use-case after generating the vector. When using embeddings,
   *  first generate the vector of the target content through the db and store it in the vector database,
   *  and then generate the vector of the retrieval text through the query.
   *  Note: For the parameter of the algorithm, we use the algorithm scheme of query and db separation,
   *  so a text, if it is to be retrieved as a text, should use the db,
   *  if it is used as a retrieval text, should use the query.
   * @type {string}
   * @memberof CreateMinimaxEmbeddingRequest
   */
  type: "db" | "query";
}

/**
 * Class for generating embeddings using the Minimax API. Extends the
 * Embeddings class and implements MinimaxEmbeddingsParams
 * @example
 * ```typescript
 * const embeddings = new MinimaxEmbeddings();
 *
 * // Embed a single query
 * const queryEmbedding = await embeddings.embedQuery("Hello world");
 * console.log(queryEmbedding);
 *
 * // Embed multiple documents
 * const documentsEmbedding = await embeddings.embedDocuments([
 *   "Hello world",
 *   "Bye bye",
 * ]);
 * console.log(documentsEmbedding);
 * ```
 */
export class MinimaxEmbeddings
  extends Embeddings
  implements MinimaxEmbeddingsParams
{
  modelName = "embo-01";

  batchSize = 512;

  stripNewLines = true;

  minimaxGroupId?: string;

  minimaxApiKey?: string;

  type: "db" | "query" = "db";

  apiUrl: string;

  basePath?: string = "https://api.minimax.chat/v1";

  headers?: Record<string, string>;

  constructor(
    fields?: Partial<MinimaxEmbeddingsParams> & {
      configuration?: ConfigurationParameters;
    }
  ) {
    const fieldsWithDefaults = { maxConcurrency: 2, ...fields };
    super(fieldsWithDefaults);

    this.minimaxGroupId =
      fields?.minimaxGroupId ?? getEnvironmentVariable("MINIMAX_GROUP_ID");
    if (!this.minimaxGroupId) {
      throw new Error("Minimax GroupID  not found");
    }

    this.minimaxApiKey =
      fields?.minimaxApiKey ?? getEnvironmentVariable("MINIMAX_API_KEY");

    if (!this.minimaxApiKey) {
      throw new Error("Minimax ApiKey not found");
    }

    this.modelName = fieldsWithDefaults?.modelName ?? this.modelName;
    this.batchSize = fieldsWithDefaults?.batchSize ?? this.batchSize;
    this.type = fieldsWithDefaults?.type ?? this.type;
    this.stripNewLines =
      fieldsWithDefaults?.stripNewLines ?? this.stripNewLines;
    this.basePath = fields?.configuration?.basePath ?? this.basePath;
    this.apiUrl = `${this.basePath}/embeddings`;
    this.headers = fields?.configuration?.headers ?? this.headers;
  }

  /**
   * Method to generate embeddings for an array of documents. Splits the
   * documents into batches and makes requests to the Minimax API to generate
   * embeddings.
   * @param texts Array of documents to generate embeddings for.
   * @returns Promise that resolves to a 2D array of embeddings for each document.
   */
  async embedDocuments(texts: string[]): Promise<number[][]> {
    const batches = chunkArray(
      this.stripNewLines ? texts.map((t) => t.replace(/\n/g, " ")) : texts,
      this.batchSize
    );

    const batchRequests = batches.map((batch) =>
      this.embeddingWithRetry({
        model: this.modelName,
        texts: batch,
        type: this.type,
      })
    );
    const batchResponses = await Promise.all(batchRequests);

    const embeddings: number[][] = [];
    for (let i = 0; i < batchResponses.length; i += 1) {
      const batch = batches[i];
      const { vectors: batchResponse } = batchResponses[i];
      for (let j = 0; j < batch.length; j += 1) {
        embeddings.push(batchResponse[j]);
      }
    }
    return embeddings;
  }

  /**
   * Method to generate an embedding for a single document. Calls the
   * embeddingWithRetry method with the document as the input.
   * @param text Document to generate an embedding for.
   * @returns Promise that resolves to an embedding for the document.
   */
  async embedQuery(text: string): Promise<number[]> {
    const { vectors } = await this.embeddingWithRetry({
      model: this.modelName,
      texts: [this.stripNewLines ? text.replace(/\n/g, " ") : text],
      type: this.type,
    });
    return vectors[0];
  }

  /**
   * Private method to make a request to the Minimax API to generate
   * embeddings. Handles the retry logic and returns the response from the
   * API.
   * @param request Request to send to the Minimax API.
   * @returns Promise that resolves to the response from the API.
   */
  private async embeddingWithRetry(request: CreateMinimaxEmbeddingRequest) {
    const makeCompletionRequest = async () => {
      const url = `${this.apiUrl}?GroupId=${this.minimaxGroupId}`;
      const response = await fetch(url, {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
          Authorization: `Bearer ${this.minimaxApiKey}`,
          ...this.headers,
        },
        body: JSON.stringify(request),
      });

      const json = await response.json();
      return json;
    };

    return this.caller.call(makeCompletionRequest);
  }
}