@assistant-ui/react/src/runtimes/adapters/attachment/CompositeAttachmentAdapter.ts

Typescript/React library for AI Chat

import { Attachment, PendingAttachment } from "../../../types/AttachmentTypes";
import { AttachmentAdapter } from "./AttachmentAdapter";

function fileMatchesAccept(
  file: { name: string; type: string },
  acceptString: string,
) {
  // Check if the accept string is "*", which allows any file
  if (acceptString === "*") {
    return true;
  }

  // Split the accept string into an array of allowed types
  const allowedTypes = acceptString
    .split(",")
    .map((type) => type.trim().toLowerCase());

  // Get the file's extension and MIME type
  const fileExtension = "." + file.name.split(".").pop()!.toLowerCase();
  const fileMimeType = file.type.toLowerCase();

  for (const type of allowedTypes) {
    // Check for file extension match
    if (type.startsWith(".") && type === fileExtension) {
      return true;
    }

    // Check for exact MIME type match
    if (type.includes("/") && type === fileMimeType) {
      return true;
    }

    if (type === "image/*" || type === "video/*" || type === "audio/*") {
      // Check for wildcard MIME type match
      if (type.endsWith("/*")) {
        const generalType = type.split("/")[0]!;
        if (fileMimeType.startsWith(generalType + "/")) {
          return true;
        }
      }
    }
  }

  return false;
}

export class CompositeAttachmentAdapter implements AttachmentAdapter {
  private _adapters: AttachmentAdapter[];

  public accept: string;

  constructor(adapters: AttachmentAdapter[]) {
    this._adapters = adapters;

    const wildcardIdx = adapters.findIndex((a) => a.accept === "*");
    if (wildcardIdx !== -1) {
      if (wildcardIdx !== adapters.length - 1)
        throw new Error(
          "A wildcard adapter (handling all files) can only be specified as the last adapter.",
        );

      this.accept = "*";
    } else {
      this.accept = adapters.map((a) => a.accept).join(",");
    }
  }

  public add(state: { file: File }) {
    for (const adapter of this._adapters) {
      if (fileMatchesAccept(state.file, adapter.accept)) {
        return adapter.add(state);
      }
    }
    throw new Error("No matching adapter found for file");
  }

  public async send(attachment: PendingAttachment) {
    const adapters = this._adapters.slice();
    for (const adapter of adapters) {
      if (fileMatchesAccept(attachment.file, adapter.accept)) {
        return adapter.send(attachment);
      }
    }
    throw new Error("No matching adapter found for attachment");
  }

  public async remove(attachment: Attachment) {
    const adapters = this._adapters.slice();
    for (const adapter of adapters) {
      if (
        fileMatchesAccept(
          {
            name: attachment.name,
            type: attachment.contentType,
          },
          adapter.accept,
        )
      ) {
        return adapter.remove(attachment);
      }
    }
    throw new Error("No matching adapter found for attachment");
  }
}