interface CoverArgs {
  customer: string;
  number: string;
  numberPrefix?: string;
  hlColor?: string;
}

interface CoverError {
  error: string;
}

declare global {
  interface Window {
    generateCover(args: CoverArgs): Uint8Array | CoverError;

    generateSplitCover(
      args: CoverArgs
    ): { front: Uint8Array; back: Uint8Array } | CoverError;
  }
}

const go = new Go();
WebAssembly.instantiateStreaming(fetch('covergen.wasm'), go.importObject).then(
  (result) => {
    go.run(result.instance);
  }
);

export function generateCover(args: CoverArgs): File {
  const result = window.generateCover(args);
  if ('error' in result) {
    throw result.error;
  }

  return new File([result], 'cover.pdf', { type: 'application/pdf' });
}

export function generateSplitCover(args: CoverArgs): {
  front: File;
  back: File;
} {
  const result = window.generateSplitCover(args);
  if ('error' in result) {
    throw result.error;
  }

  return {
    front: new File([result.front], 'front.pdf', { type: 'application/pdf' }),
    back: new File([result.back], 'back.pdf', { type: 'application/pdf' }),
  };
}