clanker-agent/packages/web-ui/src/components/sandbox/FileDownloadRuntimeProvider.ts

import type { SandboxRuntimeProvider } from "./SandboxRuntimeProvider.js";

export interface DownloadableFile {
  fileName: string;
  content: string | Uint8Array;
  mimeType: string;
}

/**
 * File Download Runtime Provider
 *
 * Provides returnDownloadableFile() for creating user downloads.
 * Files returned this way are NOT accessible to the LLM later (one-time download).
 * Works both online (sends to extension) and offline (triggers browser download directly).
 * Collects files for retrieval by caller.
 */
export class FileDownloadRuntimeProvider implements SandboxRuntimeProvider {
  private files: DownloadableFile[] = [];

  getData(): Record<string, any> {
    // No data needed
    return {};
  }

  getRuntime(): (sandboxId: string) => void {
    return (_sandboxId: string) => {
      (window as any).returnDownloadableFile = async (
        fileName: string,
        content: any,
        mimeType?: string,
      ) => {
        let finalContent: any, finalMimeType: string;

        if (content instanceof Blob) {
          const arrayBuffer = await content.arrayBuffer();
          finalContent = new Uint8Array(arrayBuffer);
          finalMimeType =
            mimeType || content.type || "application/octet-stream";
          if (!mimeType && !content.type) {
            throw new Error(
              "returnDownloadableFile: MIME type is required for Blob content. Please provide a mimeType parameter (e.g., 'image/png').",
            );
          }
        } else if (content instanceof Uint8Array) {
          finalContent = content;
          if (!mimeType) {
            throw new Error(
              "returnDownloadableFile: MIME type is required for Uint8Array content. Please provide a mimeType parameter (e.g., 'image/png').",
            );
          }
          finalMimeType = mimeType;
        } else if (typeof content === "string") {
          finalContent = content;
          finalMimeType = mimeType || "text/plain";
        } else {
          finalContent = JSON.stringify(content, null, 2);
          finalMimeType = mimeType || "application/json";
        }

        // Send to extension if in extension context (online mode)
        if ((window as any).sendRuntimeMessage) {
          const response = await (window as any).sendRuntimeMessage({
            type: "file-returned",
            fileName,
            content: finalContent,
            mimeType: finalMimeType,
          });
          if (response.error) throw new Error(response.error);
        } else {
          // Offline mode: trigger browser download directly
          const blob = new Blob(
            [finalContent instanceof Uint8Array ? finalContent : finalContent],
            {
              type: finalMimeType,
            },
          );
          const url = URL.createObjectURL(blob);
          const a = document.createElement("a");
          a.href = url;
          a.download = fileName;
          a.click();
          URL.revokeObjectURL(url);
        }
      };
    };
  }

  async handleMessage(
    message: any,
    respond: (response: any) => void,
  ): Promise<void> {
    if (message.type === "file-returned") {
      // Collect file for caller
      this.files.push({
        fileName: message.fileName,
        content: message.content,
        mimeType: message.mimeType,
      });

      respond({ success: true });
    }
  }

  /**
   * Get collected files
   */
  getFiles(): DownloadableFile[] {
    return this.files;
  }

  /**
   * Reset state for reuse
   */
  reset(): void {
    this.files = [];
  }

  getDescription(): string {
    return "returnDownloadableFile(filename, content, mimeType?) - Create downloadable file for user (one-time download, not accessible later)";
  }
}